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Welcome back to the Deep Dive. 
Today we are shifting gears 

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retty significantly. 
Usually we take a bit of a 

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casual stroll through a topic, 
but today, today feels 

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different. 
We're not just browsing, we're 

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reing. 
I want you to imagine the lights

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are bright, the air conditioning
is humming and you are sitting 

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right across from a very stern 
faced examiner at Gujarat 

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University. 
That's exactly right. 

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We are simulating a high stakes 
pre exam study session. 

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This isn't just about learning 
for the sake of, you know, 

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curiosity. 
This is about survival, it's 

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about passing the MD 
anesthesiology exams. 

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We are really targeting that 
postgraduate student who's read 

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the books, who's been through 
the wards but now needs to 

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synthesize it all into a 
cohesive Viva ready performance.

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And we have a massive stack of 
sources today. 

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I mean, we've got the heavy 
hitters like Miller's Anesthesia

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and Morgan McHale. 
We've also got the objective 

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anesthesia review, piles of old 
DNB question bank papers, and 

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the the long and short cases 
text. 

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So our mission, our mission 
today is to take this mountain 

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of information and distill it 
into the ultimate audio guide on

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chronic obstructive pulmonary 
disease. 

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COPD. 
And let's be absolutely clear 

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why we're tackling COPD In the 
world of anesthesia exams, this 

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is what we call a bread and 
butter topic. 

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It's fundamental. 
You will see it in your theory 

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papers. 
You will almost certainly get a 

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patient who smokes for your long
case. 

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And if you survive all that, it 
will be waiting for you in the 

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Viva. 
Let me be blunt. 

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If you can't manage COPD, you 
can't be an anesthetist. 

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OK, so the stakes are set. 
I'm playing the role of the, 

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let's say, the exhausted 
resident. 

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I've read the chapters but the 
Physiology is all tangled up in 

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my head and frankly I'm 
terrified of saying the wrong 

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thing to the examiner. 
And I'm your senior faculty. 

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I'm here to guide you, to point 
out the exam traps, and most 

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importantly, to tell you exactly
what the examiner wants to hear.

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We're going to cover everything 
from the ground up, 

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pathophysiology, clinical 
features, investigations and of 

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course the all important 
anesthetic management. 

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OK, let's do it. 
Let's start with part A, 

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introduction and exam framing. 
So if I'm in the exam hall, I 

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draw that long question card and
it just says obstructive lung. 

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Where do I begin without just 
rambling? 

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You start with precision, that's
the key. 

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Don't jump straight into COPD as
bad lungs, that's too 

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simplistic. 
You need to frame the territory 

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first. 
So you begin your answer with 

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the broad category obstructive 
lung diseases. 

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OK, defining the landscape 
first, not just this specific 

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town. 
Right. 

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And as per the standard texts 
and exam guides, you need to 

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classify this landscape, the 
classic exam duality. 

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The first thing you should write
down is asthma versus COPD and. 

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The difference isn't just as 
simple as one is from allergies,

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one is from smoking. 
Right? 

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That feels too basic for an MD 
level. 

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No, that's undergraduate level 
thinking. 

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For your MD exam, the critical 
distinction, the keyword is 

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reversibility. 
Asthma is characterized by 

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airflow obstruction that is for 
the most part reversible. 

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It comes and goes. 
It's triggered by inflammation, 

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but it can be reversed. 
But COPD, the definition you 

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absolutely must memorize, and 
this is straight from the 

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textbooks, is a disease state 
characterized by airflow 

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limitation that is not fully 
reversible. 

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Not fully reversible. 
That phrase, it feels like it's 

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doing a lot of heavy lifting. 
It sounds very deliberate. 

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It is. 
It does. 

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It implies that what we can help
a bit with our bronchodilators. 

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The underlying architecture of 
the lung is permanently damaged.

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It's broken. 
The airflow limitation is 

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usually progressive, and it's 
associated with an abnormal 

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inflammatory response of the 
lungs to, you know, noxious 

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particles or gases. 
Which brings us neatly to the 

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epidemiology in the exam. 
Do I need to be quoting precise 

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global statistics or is it more 
about the concept? 

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It's about acknowledging the 
burden. 

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You don't need another 
prevalence in every country, but

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you need to state that smoking 
is the primary cause, accounting

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for maybe 85 to 90% of cases. 
The key for us, for 

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anaesthetists, is the surgical 
population. 

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If you're working in any busy 
hospital, 20, maybe even 30% of 

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your elderly patients coming for
surgery will have some degree of

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COPD. 
So it's completely unavoidable. 

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It's not a rare disease we're 
preparing for. 

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Exactly, and that is precisely 
why it's an exam favorite. 

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It's not abstract. 
It tests your understanding of 

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respiratory Physiology, 
pharmacology, and critical care 

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all at once. 
You might get it as a short note

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on a specific concept like auto 
peep or or flow volume loops. 

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You might get a 20 mark theory 
question on anesthetic 

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management of COPD OR. 
And this is the most likely 

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you'll get the long case A 65 
year old chronic smoker coming 

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for a laparotomy. 
OK, I'm framed. 

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I think I understand the 
context, I know what it is, and 

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I know why it matters. 
So let's move to Part B 

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pathophysiology. 
The outline here says this is 

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absolutely essential. 
It is the absolute foundation. 

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If you don't understand the 
mechanics of what's broken in 

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the lung, you will. 
And I'm not being dramatic, you 

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will kill the patient with a 
ventilator for the exam. 

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You want to break the 
pathophysiology down into a very

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specific, memorable framework. 
What's the framework? 

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How should I structure my 
answer? 

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Think of it as a detrap 4. 
Key components 1. 

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Chronic airflow limitation 
that's the hallmark 2. 

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Inflammation and remodeling 3. 
Mucus, hyper secretion and four 

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loss of elastic recoil. 
OK, let's unpack that second 

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one. 
Inflammation and remodeling. 

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I always picture just a swollen 
red airway, but it's more 

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complex than that, isn't it? 
It's much more, yeah. 

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This is where you can quote your
reading from Miller. 

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It's not just simple edema. 
The chronic irritation, usually 

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from cigarette smoke, causes the
bronchiolar smooth muscle, the 

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BSM, to increase in both tone 
and bulk. 

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It gets bigger and tighter. 
The actual wall of the airway 

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gets thicker. 
So the tube itself is physically

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narrower even before mucus comes
into play. 

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Yes, and then the lining of that
tube changes. 

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You get something called goblet 
cell hyperplasia. 

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These are the cells that produce
mucus. 

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So not only is the tube narrower
and stiffer, but you're also 

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flooding it with secretions. 
That covers your Third Point, 

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mucus hypersecretion. 
That's the chronic bronchitis, a

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component of the disease. 
Right now #4 loss of elastic 

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recoil. 
This is the one I always 

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struggle to explain clearly, 
even to myself sometimes. 

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I get that the lung is floppy, 
but why does that specifically 

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trap air? 
Let's use an analogy. 

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It's the best way to explain it 
in Aviva. 

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Imagine a brand new party 
balloon. 

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It has high elastic recoil. 
You blow it up. 

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You let go of the opening and 
snap. 

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The air rushes out forcefully. 
The rubber wants to collapse 

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back to its original state. 
Right, it empties itself. 

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Now imagine an old flabby 
balloon that's been 

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overstretched 1000 times. 
You blow it up, you let go, and 

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the air just sort of drifts out 
slowly, lazily. 

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That is the emphysematis lung. 
It has lost the intrinsic 

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driving pressure to exhale 
effectively. 

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OK, that makes sense. 
But there's another factor too, 

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right? 
I remember reading something 

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about the Airways themselves 
collapsing. 

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Correct, and this is a slightly 
more advanced concept, perfect 

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for scoring extra marks. 
It's the concept of radial 

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traction. 
In a healthy lung, the millions 

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of alveoli that surround the 
small Airways act like guy ropes

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on a tent. 
They're all pulling out words, 

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holding the airway open, 
stenting it in emphysema. 

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You are pathologically 
destroying those alveolar walls.

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You are in effect cutting the 
guy ropes. 

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So when the patient tries to 
exhale, the pressure from the 

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chest pushes on these 
unsupported Airways and they 

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just they flop shut. 
Exactly. 

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That is the definition of 
dynamic airway collapse. 

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The air is trapped by the closed
door, and this single fact 

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dictates your entire anesthetic 
ventilation strategy. 

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You must give the patient a 
long, long time to get that air 

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out past that collapsing point. 
This leads us perfectly into 

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section three types of COPD. 
We often hear the old terms pink

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puffer and blue bloater. 
Is that terminology still used? 

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Is it safe to use in an exam? 
It is, and examiners actually 

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love it because it represents 2 
very distinct clinical 

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phenotypes, even if most real 
world patients are a mixture of 

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the two. 
Let's start with chronic 

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bronchitis. 
This is defined clinically. 

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Clinically, meaning it's based 
on symptoms, not a lab test. 

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Yes, the strict definition is a 
productive cough for three 

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months in each of two successive
years in a patient in whom other

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causes of chronic cough have 
been excluded. 

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These are your blue bloaters. 
And why blue? 

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Because they tend to become 
hypoxemic and cyanotic quite 

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early in the disease course, 
Their main problem is that the 

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tubes, the bronchi, are clogged 
with mucus, they have a profound

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VQ mismatch, they often rely on 
their hypoxic drive to breathe, 

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they retain CO2, and they 
develop core poliola, right 

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heart failure, which leads to 
peripheral edema, hence 

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bloating. 
And the other side of the coin? 

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The Emphysema Group. 
This is defined pathologically. 

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It's not a symptom, it's a 
structural diagnosis. 

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It is the permanent destruction 
of the alveolar walls and 

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enlargement of the airspaces 
distal to the terminal 

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bronchioles. 
These are the pink puffers. 

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Pink because they managed to 
stay oxygenated. 

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For a very long time, yes. 
Their primary problem isn't 

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clogged tubes, It's the loss of 
surface area for gas exchange 

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and that loss of elastic recoil.
They compensate by maintaining a

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massive respiratory Dr. They 
hyperventilate to maintain their

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PO2. 
They're often breathless, thin, 

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and cachectic because they're 
burning so many calories just in

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the work of breathing. 
They're puffing to stay pink. 

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OK, that's a very clear 
distinction. 

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Let's go even deeper now into 
Section 4 effects on lung 

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mechanics. 
We've touched on resistance, but

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what about compliance? 
This feels like a classic Viva 

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trap question. 
It is huge trap. 

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The examiner will lean forward 
and ask doctor is the compliance

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high or low in COPD and there 
isn't one simple answer. 

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In pure chronic bronchitis, the 
compliance of the lung tissue 

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itself is often normal. 
The problem is purely high 

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resistance. 
However, in emphysema the static

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compliance is actually 
increased. 

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That always confuses me. 
Increased compliance sounds like

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a good thing. 
Compliant means easy, right? 

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Compliant means distensible. 
It's easy to blow air in. 

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That floppy old balloon is very 
compliant. 

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It expands with very little 
pressure. 

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The problem isn't getting air 
in, it's the lack of recoil to 

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get it out so high. 
Static compliance in this 

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context is deeply pathological. 
Which brings us to the monster 

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of this whole topic, Auto Peep, 
or as some books call it, 

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dynamic Hyperinflation. 
This is without a doubt the 

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single most critical concept for
the statist in this entire 

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discussion. 
You understand this, You can 

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keep the patient safe. 
OK explain it to me like I'm in 

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the Viva and I'm starting to 
panic. 

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OK, take a breath. 
Respiration is a cycle. 

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Inspiration then expiration. 
Simple. 

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In a patient with COPD, 
expiration is pathologically 

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slow. 
This is due to the combination 

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of high airway resistance and 
low elastic recoil. 

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If you, the anesthetist 
controlling the ventilator, 

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initiate the next breath before 
the patient is fully finished 

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exhaling the previous breath, 
you trap a small residual volume

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of air. 
You're stacking breaths on top 

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of each other. 
Precisely. 

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Breath after breath after 
breath, that trap volume 

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accumulates the patient's 
functional residual capacity. 

232
00:10:56,160 --> 00:10:59,840
FRC begins to rise. 
The pressure inside the alveoli,

233
00:10:59,840 --> 00:11:01,680
the very end of expiration, is 
no longer zero. 

234
00:11:01,680 --> 00:11:04,040
It becomes positive. 
That positive pressure is 

235
00:11:04,040 --> 00:11:07,560
intrinsic PEEP or auto PEEP. 
And why is that so lethal? 

236
00:11:07,560 --> 00:11:09,840
I know it causes the blood 
pressure to crash, but why? 

237
00:11:09,840 --> 00:11:12,280
What is the mechanism? 
You must be able to explain the 

238
00:11:12,280 --> 00:11:15,760
hemodynamics clearly. 
The heart lives inside the chest

239
00:11:15,760 --> 00:11:19,520
inside the thorax. 
Specifically, the superior and 

240
00:11:19,520 --> 00:11:23,120
inferior vena cava are low 
pressure vessels that have to 

241
00:11:23,120 --> 00:11:25,920
pass through the thorax to 
return blood to the heart. 

242
00:11:26,720 --> 00:11:29,520
If the lungs hyperinflate with 
trapped air, they physically 

243
00:11:29,520 --> 00:11:31,360
expand and compress everything 
around them. 

244
00:11:31,680 --> 00:11:34,120
They compress the vena cava and 
the heart itself, so 

245
00:11:34,240 --> 00:11:36,440
intrathoracic pressure rises 
dramatically. 

246
00:11:36,800 --> 00:11:39,200
This leads to a drop in the 
pressure gradient for venous 

247
00:11:39,200 --> 00:11:41,440
return. 
Less blood gets back to the 

248
00:11:41,440 --> 00:11:43,160
right ventricle, so preload 
drugs. 

249
00:11:43,320 --> 00:11:45,320
An empty heart can't pump what 
it doesn't have. 

250
00:11:45,560 --> 00:11:47,640
Exactly. 
An empty heart means no cardiac 

251
00:11:47,640 --> 00:11:50,080
outlet. 
And to make matters worse, at 

252
00:11:50,080 --> 00:11:53,160
the same time the hyperinflated 
lungs are squishing the tiny 

253
00:11:53,160 --> 00:11:56,520
pulmonary capillaries, which 
dramatically increases pulmonary

254
00:11:56,520 --> 00:12:00,160
vascular resistance, or PVR. 
So the right ventricle is empty 

255
00:12:00,440 --> 00:12:02,160
and it's trying to pump against 
a brick wall. 

256
00:12:02,800 --> 00:12:05,560
This is a recipe for acute right
ventricular failure and 

257
00:12:05,560 --> 00:12:09,200
cardiovascular collapse. 
The patient goes into PEA 

258
00:12:09,200 --> 00:12:12,760
pulseless electrical activity. 
That is a genuinely terrifying 

259
00:12:12,760 --> 00:12:14,600
image. 
OK, we'll definitely talk about 

260
00:12:14,600 --> 00:12:16,400
how to fix that in the 
management section, but that 

261
00:12:16,400 --> 00:12:20,520
mechanism is crystal clear. 
Now let's move on to Part C, gas

262
00:12:20,520 --> 00:12:22,400
exchange and Physiology. 
Right. 

263
00:12:22,600 --> 00:12:24,800
And here we need to talk about 
VQ mismatch. 

264
00:12:25,160 --> 00:12:28,600
This is your Section 5. 
Ventilation versus perfusion, 

265
00:12:28,840 --> 00:12:32,760
the matching of air and blood. 
In COPD the lungs architecture 

266
00:12:32,760 --> 00:12:36,640
is destroyed and chaotic. 
You have some areas where there 

267
00:12:36,640 --> 00:12:38,720
is blood flow but no air getting
in. 

268
00:12:39,240 --> 00:12:42,760
This is a shunt like effect. 
This is typical of a mucus plug 

269
00:12:42,800 --> 00:12:45,040
in bronchitis. 
And you have other areas where 

270
00:12:45,040 --> 00:12:46,640
there's plenty of air but no 
blood flow. 

271
00:12:46,640 --> 00:12:49,200
This is Dead Space. 
This happens because emphysema 

272
00:12:49,200 --> 00:12:52,080
destroys the capillary bed along
with the alveoli. 

273
00:12:52,440 --> 00:12:56,440
And I see here the DNB questions
source explicitly asks about the

274
00:12:56,440 --> 00:12:59,000
clinical importance of 
anatomical and physiological 

275
00:12:59,000 --> 00:13:01,840
Dead Space. 
Yes, physiological Dead Space is

276
00:13:01,840 --> 00:13:05,520
essentially wasted ventilation. 
You're moving air in and out of 

277
00:13:05,520 --> 00:13:08,000
a part of the lung that isn't 
participating in gas exchange. 

278
00:13:08,440 --> 00:13:11,080
But here is the anesthetic 
relevance you absolutely must 

279
00:13:11,080 --> 00:13:13,800
mention in your answer. 
Hypoxic pulmonary 

280
00:13:13,800 --> 00:13:17,880
vasoconstriction or HPV. 
The body's own defense mechanism

281
00:13:17,880 --> 00:13:19,520
against this mismatch. 
Correct. 

282
00:13:20,160 --> 00:13:23,040
Normally if a part of the lung 
isn't getting oxygen, the body 

283
00:13:23,040 --> 00:13:25,160
is smart. 
It constricts the blood vessels 

284
00:13:25,160 --> 00:13:28,440
going to that hypoxic area to 
shunt blood towards the healthy,

285
00:13:28,440 --> 00:13:29,880
well ventilated parts of the 
lung. 

286
00:13:30,080 --> 00:13:32,120
It tries to optimize the VQ 
matching. 

287
00:13:32,320 --> 00:13:35,440
But, and this is the crucial 
part, our volatile anesthetic 

288
00:13:35,440 --> 00:13:39,120
agents like isoflurane and 
suboflurane are vasodilators. 

289
00:13:39,520 --> 00:13:42,480
They inhibit HPV. 
So our anesthesia is actively 

290
00:13:42,480 --> 00:13:45,560
making the VQ mismatch worse. 
It can, yes. 

291
00:13:45,920 --> 00:13:48,560
It reopened those constricted 
vessels, sending blood back into

292
00:13:48,560 --> 00:13:50,880
the poorly ventilated hypoxic 
areas of the lung. 

293
00:13:51,280 --> 00:13:53,920
This increases the shunt 
fraction and can cause a sudden 

294
00:13:53,920 --> 00:13:56,280
drop in the patient's oxygen 
saturation right after 

295
00:13:56,280 --> 00:13:58,640
induction. 
You need to be aware of this and

296
00:13:58,640 --> 00:13:59,720
anticipate it. 
OK. 

297
00:13:59,720 --> 00:14:03,120
That's a huge point. 
Now Section 6 ABG changes. 

298
00:14:03,120 --> 00:14:06,120
This is an exam favorite, the 
whole acute versus chronic 

299
00:14:06,120 --> 00:14:08,800
thing. 
The hallmark of severe advanced 

300
00:14:08,920 --> 00:14:13,360
COPD is chronic CO2 retention. 
Their bodies get used to a high 

301
00:14:13,360 --> 00:14:16,400
level of CO2, but the body 
doesn't just let the blood 

302
00:14:16,400 --> 00:14:19,400
become acidic, it compensates. 
We call this compensated 

303
00:14:19,400 --> 00:14:21,160
respiratory acidosis. 
And how does the body 

304
00:14:21,160 --> 00:14:22,480
compensate? 
What's the mechanism? 

305
00:14:22,680 --> 00:14:27,240
The kidneys It's a slow but 
powerful process over days to 

306
00:14:27,240 --> 00:14:28,880
weeks. 
The kidneys respond to the 

307
00:14:28,880 --> 00:14:32,760
chronic high CO2 by retaining 
bicarbonate HCO 3, which is a 

308
00:14:32,760 --> 00:14:34,720
base. 
This buffers the acid. 

309
00:14:35,000 --> 00:14:38,520
So when you look at an arterial 
blood gas report, if the Paco 2 

310
00:14:38,520 --> 00:14:42,800
is high, let's say 60 millimilli
HG, but the pH is in the normal 

311
00:14:42,800 --> 00:14:46,800
range, say 7.35 to 7.4 year, it 
is chronic. 

312
00:14:47,400 --> 00:14:49,400
The kidneys have done their job 
and the bicarbonate will be 

313
00:14:49,400 --> 00:14:51,200
high. 
But if the PECO 2 is high and 

314
00:14:51,200 --> 00:14:55,400
the pH is low, so acidotic it is
acute, This is an acute 

315
00:14:55,400 --> 00:14:58,160
exacerbation and the kidneys 
haven't had time to catch up 

316
00:14:58,160 --> 00:15:00,760
yet. 
And that is a absolutely vital 

317
00:15:00,760 --> 00:15:03,280
distinction for determining if a
patient is stable enough for an 

318
00:15:03,280 --> 00:15:04,720
elective surgery. 
Exactly. 

319
00:15:04,960 --> 00:15:08,120
An acute uncompensated acidosis 
is a huge red flag. 

320
00:15:08,120 --> 00:15:11,360
Stop optimize the patient. 
A chronic compensated acidosis 

321
00:15:11,360 --> 00:15:12,880
is often just that patient's 
baseline. 

322
00:15:12,960 --> 00:15:15,280
And just briefly to round out 
the section, Section 7, the 

323
00:15:15,280 --> 00:15:17,320
oxyhemoglobin dissociation 
curve, where does it? 

324
00:15:17,880 --> 00:15:19,800
It shifts to the right. 
You need to recall the bore 

325
00:15:19,800 --> 00:15:22,400
effect, the state of acidosis. 
So high H plus ions and 

326
00:15:22,400 --> 00:15:25,440
hypercapnea, high CO2 both cause
the curve to shift to the right.

327
00:15:25,480 --> 00:15:27,120
Right equals release. 
Correct. 

328
00:15:27,480 --> 00:15:30,600
It's an adaptive immunism. 
It means that for any given 

329
00:15:30,720 --> 00:15:34,160
partial pressure of oxygen, the 
hemoglobin has a lower affinity 

330
00:15:34,160 --> 00:15:36,160
for it. 
It gives up his oxygen more 

331
00:15:36,160 --> 00:15:38,080
easily to the tissues that 
desperately need it. 

332
00:15:38,320 --> 00:15:40,200
Perfect. 
OK, let's move to Part D, 

333
00:15:40,200 --> 00:15:42,040
clinical features and 
investigations. 

334
00:15:42,280 --> 00:15:44,240
We're at the bedside now in the 
pre op clinic. 

335
00:15:44,560 --> 00:15:46,680
What are the key things we are 
looking for? 

336
00:15:46,920 --> 00:15:49,920
The respiratory signs are 
obvious, the wheeze, the barrel 

337
00:15:49,920 --> 00:15:51,960
chest, the purse, lip, 
breathing, you'll see those from

338
00:15:51,960 --> 00:15:55,040
the door. 
But the real money the marks are

339
00:15:55,040 --> 00:15:57,480
in looking for the 
cardiovascular signs, you 

340
00:15:57,560 --> 00:16:01,360
absolutely must, must look for 
signs of core pulmonale. 

341
00:16:01,600 --> 00:16:04,240
Right sided heart failure caused
by the lung disease. 

342
00:16:04,240 --> 00:16:07,600
Yes, and the long and Short 
cases textbook emphasizes this 

343
00:16:07,680 --> 00:16:09,960
over and over. 
You have to physically examine 

344
00:16:09,960 --> 00:16:12,360
the patient. 
Look for pedal edema, swelling 

345
00:16:12,360 --> 00:16:15,760
in the ankles, look for raised 
jugular venous pressure, the JVP

346
00:16:15,760 --> 00:16:18,320
in the neck. 
Listen to the Heart for a loud 

347
00:16:18,320 --> 00:16:20,560
P2 heart sound. 
Why is this a fail? 

348
00:16:20,560 --> 00:16:22,120
If I miss it, why is it so 
critical? 

349
00:16:22,360 --> 00:16:24,960
Because the presence of corporal
manal means the disease is 

350
00:16:24,960 --> 00:16:28,120
advanced and the cardiovascular 
system is already decompensated,

351
00:16:28,560 --> 00:16:32,000
it drastically increases the 
risk of perioperative mortality 

352
00:16:32,720 --> 00:16:34,800
if you stand up in a long case 
presentation. 

353
00:16:35,120 --> 00:16:37,360
And you haven't mentioned 
checking the patient's ankles 

354
00:16:37,360 --> 00:16:39,200
for edema or looking at their 
JDP. 

355
00:16:39,640 --> 00:16:41,200
The examiner will stop you right
there. 

356
00:16:41,640 --> 00:16:43,360
It shows you missed a critical 
risk factor. 

357
00:16:43,800 --> 00:16:47,480
OK, message received Section 9 
Pulmonary function tests PFTS. 

358
00:16:47,760 --> 00:16:49,880
This is marked as absolutely 
essential. 

359
00:16:49,880 --> 00:16:53,080
Spirometry is the gold standard 
for diagnosis and severity 

360
00:16:53,080 --> 00:16:54,640
assessment. 
You need to know the numbers 

361
00:16:54,640 --> 00:16:58,040
cold. 
The key diagnostic ratio is FEV,

362
00:16:58,120 --> 00:17:02,400
one FEC, the force expertory 
volume in one second divided by 

363
00:17:02,400 --> 00:17:06,119
the force vital capacity. 
If that ratio is less than .7 or

364
00:17:06,119 --> 00:17:09,680
70%, that confirms the presence 
of an obstructive defect. 

365
00:17:09,800 --> 00:17:11,280
And how do we grade the 
severity? 

366
00:17:11,400 --> 00:17:14,000
The severity is then graded 
based on the FEV 1 as a 

367
00:17:14,000 --> 00:17:16,280
percentage of the predicted 
value for that patient's age, 

368
00:17:16,280 --> 00:17:19,319
sex, and height. 
Mild is an FEV one greater than 

369
00:17:19,319 --> 00:17:23,119
80%, predicted moderate is 
between 50 and 80%, severe is 

370
00:17:23,119 --> 00:17:26,119
between 30 and 50%, and very 
severe is less than 30%. 

371
00:17:26,400 --> 00:17:27,960
You need to memorize that table,
no? 

372
00:17:27,960 --> 00:17:30,040
Excuses. 
What about the flow volume loop?

373
00:17:30,200 --> 00:17:32,440
They often ask us to draw this 
in the exam. 

374
00:17:32,600 --> 00:17:35,400
What should it look like? 
OK, picture a normal loop. 

375
00:17:36,040 --> 00:17:39,760
The inspiration is a smooth 
semicircle and the expiration is

376
00:17:39,760 --> 00:17:42,440
a straight sharp line going down
to the baseline. 

377
00:17:42,800 --> 00:17:45,200
In COPD, the loop looks scooped 
out. 

378
00:17:45,760 --> 00:17:47,960
It becomes concave, curving 
inwards. 

379
00:17:48,040 --> 00:17:50,600
Why? 
Because as the patient tries to 

380
00:17:50,600 --> 00:17:53,360
exhale forcefully, their 
unsupported Airways start to 

381
00:17:53,360 --> 00:17:55,000
collapse. 
That dynamic compression we 

382
00:17:55,000 --> 00:17:57,400
talked about? 
This limits the flow rate and it

383
00:17:57,400 --> 00:17:59,320
drops off drastically as they 
exhale. 

384
00:17:59,480 --> 00:18:01,280
Looks like someone took a bite 
out of a sandwich. 

385
00:18:01,400 --> 00:18:03,920
That's a great visual. 
The bitten sandwich loop. 

386
00:18:03,920 --> 00:18:07,120
I'll remember that and section 
10 other investigations. 

387
00:18:07,120 --> 00:18:09,120
What should I look for on an 
ECG? 

388
00:18:09,400 --> 00:18:11,840
You're looking for evidence of 
chronic right heart strain. 

389
00:18:12,120 --> 00:18:16,360
The classic sign is P pulmonale.
This is a tall peak P wave 

390
00:18:16,360 --> 00:18:19,920
greater than 2.5mm high, which 
you'll see best in the inferior 

391
00:18:19,920 --> 00:18:22,920
leads, so 2-3 and AVF. 
It signifies right atrial 

392
00:18:22,920 --> 00:18:24,920
enlargement. 
You might also see right axis 

393
00:18:24,920 --> 00:18:27,400
deviation or a right bundle 
branch block pattern. 

394
00:18:27,480 --> 00:18:29,480
These are all signs of right 
ventricular strain. 

395
00:18:29,720 --> 00:18:31,840
Excellent. 
Let's move into part E 

396
00:18:31,840 --> 00:18:34,880
preoperative assessment. 
We're back in the pre op clinic.

397
00:18:35,480 --> 00:18:38,440
How do we properly assess the 
risk this patient poses? 

398
00:18:39,360 --> 00:18:41,880
The history is actually more 
important than any of the tests.

399
00:18:41,880 --> 00:18:43,560
The textbooks are very clear on 
this. 

400
00:18:44,040 --> 00:18:45,960
You need to ask about their 
functional capacity. 

401
00:18:46,200 --> 00:18:47,760
Don't just ask are you 
breathless? 

402
00:18:48,040 --> 00:18:51,440
Ask practical questions. 
Can you climb two flights of 

403
00:18:51,440 --> 00:18:53,320
stairs without stopping to catch
your breath? 

404
00:18:53,800 --> 00:18:55,960
Hunter piece? 
If they can do that, their 

405
00:18:55,960 --> 00:18:59,840
metabolic equivalent or me tease
is likely greater than four and 

406
00:18:59,840 --> 00:19:02,360
they are probably a reasonable 
risk for most surgeries. 

407
00:19:02,400 --> 00:19:04,440
If they get breathless just 
walking from the waiting room to

408
00:19:04,440 --> 00:19:06,480
your office, they're extremely 
high risk. 

409
00:19:06,600 --> 00:19:09,440
OK, now for Section 11, the 
slightly controversial topic, 

410
00:19:10,200 --> 00:19:12,440
smoking cessation. 
The patient is in front of you, 

411
00:19:12,480 --> 00:19:15,360
their surgery is next week. 
They ask you doctor, should I 

412
00:19:15,360 --> 00:19:17,440
stop smoking today? 
What's the right answer? 

413
00:19:17,600 --> 00:19:20,760
This is a classic exam trap and 
you have to explain the timeline

414
00:19:20,760 --> 00:19:23,120
very carefully. 
There are different zones of 

415
00:19:23,120 --> 00:19:27,640
benefit and risk. 
Zone 1, the short term, we're 

416
00:19:27,640 --> 00:19:29,800
talking 12 to 24 hours. 
Does this help? 

417
00:19:30,080 --> 00:19:33,040
Yes, absolutely. 
It significantly reduces the 

418
00:19:33,040 --> 00:19:34,640
levels of carbon monoxide in the
blood. 

419
00:19:34,880 --> 00:19:37,440
This shifts that dissociation 
curve back to the left, 

420
00:19:37,600 --> 00:19:40,640
improving oxygen carrying 
capacity, and it also reduces 

421
00:19:40,640 --> 00:19:42,200
the nicotine induced 
tachycardia. 

422
00:19:42,680 --> 00:19:45,360
So quitting the night before is 
definitely beneficial for oxygen

423
00:19:45,360 --> 00:19:47,000
delivery. 
But then there's a period where 

424
00:19:47,000 --> 00:19:49,640
it's actually worse, right? 
The so-called danger zone. 

425
00:19:49,640 --> 00:19:52,320
Exactly. 
Zone 2, roughly 2 days to four, 

426
00:19:52,320 --> 00:19:55,680
maybe even six weeks. 
In this window the Airways start

427
00:19:55,680 --> 00:19:58,840
to wake up. 
The cilia which were paralyzed 

428
00:19:58,840 --> 00:20:01,120
by the smoke start regenerating 
and beating again. 

429
00:20:01,680 --> 00:20:04,320
The volume of sputum they clear 
actually increases. 

430
00:20:04,320 --> 00:20:05,960
The Airways could become hyper 
reactive. 

431
00:20:06,440 --> 00:20:09,240
So, paradoxically, if you stop 
smoking just three or four days 

432
00:20:09,240 --> 00:20:11,840
before surgery, you might 
actually be more prone to 

433
00:20:11,840 --> 00:20:14,680
bronchospasm and mucus plugging 
than if you had just continued. 

434
00:20:14,800 --> 00:20:16,920
That is so counterintuitive, I 
can see how that would trip 

435
00:20:16,920 --> 00:20:19,920
someone up. 
It is so the ideal of course is 

436
00:20:19,920 --> 00:20:22,920
zone 3 greater than 8 weeks. 
That's the minimum time it takes

437
00:20:22,920 --> 00:20:25,600
for the immune system to start 
normalizing and for sputum 

438
00:20:25,600 --> 00:20:27,760
volume and reactivity to 
genuinely decrease. 

439
00:20:27,760 --> 00:20:31,400
So for the exam, your answer is 
ideally the patient should stop 

440
00:20:31,400 --> 00:20:33,240
smoking at least 8 weeks before 
surgery. 

441
00:20:33,840 --> 00:20:36,880
If that is not possible, then 
quitting at least 12 to 24 hours

442
00:20:36,880 --> 00:20:40,160
beforehand is beneficial. 
However, we must be very 

443
00:20:40,160 --> 00:20:42,520
cautious in the intermediate 
window of a few days to a few 

444
00:20:42,520 --> 00:20:44,920
weeks, as airway reactivity may 
increase. 

445
00:20:45,040 --> 00:20:47,160
Perfect. 
What about optimization? 

446
00:20:47,160 --> 00:20:50,280
What can we actively do in that 
pre op period to make them 

447
00:20:50,280 --> 00:20:52,200
safer? 
There are four key things. 

448
00:20:52,320 --> 00:20:55,880
One, bronchodilators make sure 
they are taking their prescribed

449
00:20:55,880 --> 00:20:59,160
inhalers correctly and 
consistently optimize a regimen.

450
00:20:59,680 --> 00:21:03,240
2 steroids. 
If they are actively wheezing or

451
00:21:03,240 --> 00:21:06,600
have had a recent exacerbation, 
a short course of oral steroids 

452
00:21:06,600 --> 00:21:10,480
can significantly calm down the 
airway inflammation 3. 

453
00:21:10,680 --> 00:21:12,880
Physiotherapy. 
This is huge. 

454
00:21:13,120 --> 00:21:15,720
Teach them how to use an 
incentive spirometer before the 

455
00:21:15,720 --> 00:21:17,480
surgery so they know how to do 
it afterwards. 

456
00:21:17,640 --> 00:21:19,280
Teach them how to cough 
effectively. 

457
00:21:19,560 --> 00:21:23,360
The huff, cough and four Treat 
any active infection. 

458
00:21:23,640 --> 00:21:27,280
If their sputum is purulent so 
green or yellow, delay elective 

459
00:21:27,280 --> 00:21:30,280
surgery if possible and give 
them a course of antibiotics. 

460
00:21:30,280 --> 00:21:32,640
And for Section 12 risk 
stratification, what's the 

461
00:21:32,640 --> 00:21:34,720
bottom line? 
Remember that the surgical site 

462
00:21:34,720 --> 00:21:36,920
matters most. 
Upper abdominal and thoracic 

463
00:21:36,920 --> 00:21:39,560
surgeries carry the highest risk
because the incision causes 

464
00:21:39,560 --> 00:21:42,440
pain, which leads to splinting, 
and they often involve cutting 

465
00:21:42,440 --> 00:21:45,120
through respiratory muscles. 
A knee replacement in the same 

466
00:21:45,120 --> 00:21:47,200
patient is a much, much safer 
proposition. 

467
00:21:47,320 --> 00:21:50,480
OK, Part F Anesthetic 
management, the main event, 

468
00:21:50,760 --> 00:21:53,080
Section 13. 
Choice of anesthesia. 

469
00:21:54,040 --> 00:21:56,400
The examiner looks at you and 
asks General or regional? 

470
00:21:56,560 --> 00:21:59,240
And you have to give a balanced 
answer for any peripheral 

471
00:21:59,240 --> 00:22:01,640
surgery. 
So limbs, lower abdomen, 

472
00:22:01,640 --> 00:22:05,040
regional anesthesia, RA is 
generally the preferred choice. 

473
00:22:05,040 --> 00:22:07,760
Because you completely avoid 
putting a tube in their very 

474
00:22:07,760 --> 00:22:11,040
reactive airway. 
Precisely no tube means no 

475
00:22:11,040 --> 00:22:15,040
instrumentation, no reflex 
bronchospasm and you avoid the 

476
00:22:15,040 --> 00:22:18,560
need for positive pressure 
ventilation or PPV, which 

477
00:22:18,560 --> 00:22:22,040
reduces the risk of barotrauma 
and that dreaded auto peep. 

478
00:22:22,960 --> 00:22:26,280
However, you must add a caveat. 
You have to be careful with the 

479
00:22:26,280 --> 00:22:29,160
level of the block. 
A high spinal or epidural, say 

480
00:22:29,160 --> 00:22:32,800
above T10, can start to paralyze
the abdominal and intercostal 

481
00:22:32,800 --> 00:22:35,120
muscles. 
And COPD patients desperately 

482
00:22:35,120 --> 00:22:37,120
need those muscles to force the 
air out. 

483
00:22:37,120 --> 00:22:39,120
Correct. 
For them, expiration is an 

484
00:22:39,120 --> 00:22:41,240
active process. 
If you knockout their belly 

485
00:22:41,240 --> 00:22:44,000
muscles with a high block, they 
might not be able to exhale 

486
00:22:44,000 --> 00:22:46,840
effectively or clear secretions.
So the answer is regional is 

487
00:22:46,840 --> 00:22:49,640
good, but keep the level as low 
as is practical for the surgery.

488
00:22:49,720 --> 00:22:51,800
What about general anesthesia 
GA? 

489
00:22:51,880 --> 00:22:55,080
Sometimes it's just avoidable. 
A laparoscopic cholecystectomy, 

490
00:22:55,080 --> 00:22:57,000
for instance. 
Then we have a clear plan. 

491
00:22:57,320 --> 00:23:00,360
We move to Section 14 induction 
and airway management. 

492
00:23:00,840 --> 00:23:03,400
The primary goal is a smooth, 
deep induction. 

493
00:23:03,920 --> 00:23:06,840
You want to avoid any coughing, 
bucking or fighting on the tube 

494
00:23:07,160 --> 00:23:10,680
as this drives up intrathoracic 
pressure and can trigger severe 

495
00:23:10,680 --> 00:23:14,560
bronchospasm. 
LMA versus ETT, which is safer? 

496
00:23:14,760 --> 00:23:18,320
Well, the literature suggests 
the Laryngeal Matic Airway LMA 

497
00:23:18,400 --> 00:23:21,400
can be beneficial because it 
sits above the vocal cords. 

498
00:23:21,640 --> 00:23:24,160
It is a less stimulating device,
so there is theoretically a 

499
00:23:24,160 --> 00:23:26,000
lower risk of triggering 
bronchospasm. 

500
00:23:26,480 --> 00:23:29,240
But you can only use it if you 
don't anticipate high airway 

501
00:23:29,240 --> 00:23:31,560
pressures and if the patient 
isn't at high risk of 

502
00:23:31,560 --> 00:23:33,280
aspiration. 
For many of these cases, you 

503
00:23:33,280 --> 00:23:36,840
will need a cuffed endotracheal 
tube ETT and if you are going to

504
00:23:36,840 --> 00:23:39,440
intubate, ensure the patient is 
deeply anesthetized. 

505
00:23:40,000 --> 00:23:42,480
Using intravenous or topical 
lidocaine can be very helpful to

506
00:23:42,480 --> 00:23:44,880
blunt the airway reflexes. 
OK, the patient is intubated 

507
00:23:45,160 --> 00:23:48,240
Section 15 intraoperative 
ventilation strategy. 

508
00:23:48,640 --> 00:23:52,480
This is marked very high yield. 
I am standing at the ventilator.

509
00:23:52,480 --> 00:23:54,480
What numbers do I dial in? 
You have to remember the 

510
00:23:54,480 --> 00:23:56,360
pathophysiology we discussed. 
Air trapping. 

511
00:23:56,720 --> 00:23:58,920
Your entire strategy is designed
to let the air out. 

512
00:23:59,280 --> 00:24:01,040
Number one, low respiratory 
rate. 

513
00:24:01,200 --> 00:24:02,840
This is the single most 
effective tool. 

514
00:24:02,840 --> 00:24:05,400
You have a rate of eight, maybe 
10 breaths per minute. 

515
00:24:05,680 --> 00:24:08,480
Slower is better. 
This is the best way to increase

516
00:24:08,480 --> 00:24:13,000
the available expiratory time 
#2A long IE ratio. 

517
00:24:13,240 --> 00:24:16,800
The ratio of inspiration time to
expiration time normal is about 

518
00:24:16,800 --> 00:24:19,320
1:00 to 2:00. 
In a COPD patient, we dial in 

519
00:24:19,320 --> 00:24:21,880
one to three, one to four. 
In very severe cases, even 1:00 

520
00:24:21,880 --> 00:24:23,800
to 5:00. 
South a very quick breath in, 

521
00:24:23,800 --> 00:24:27,640
followed by a slow breath out. 
Exactly #3 permissive 

522
00:24:27,640 --> 00:24:30,000
hypercapnia. 
Because we are deliberately 

523
00:24:30,000 --> 00:24:32,920
breathing slowly for the 
patient, their entitle CO2 will 

524
00:24:32,920 --> 00:24:35,640
rise. 
We must accept this as long as 

525
00:24:35,640 --> 00:24:39,400
the arterial pH stays above a 
safe level, roughly 7.2 O or 

526
00:24:39,400 --> 00:24:42,960
7.25. 
We tolerated a high CO2, say 60 

527
00:24:42,960 --> 00:24:45,560
or 70 milli military in order to
protect the lungs from the 

528
00:24:45,560 --> 00:24:48,400
Bureau trauma of auto PEEP. 
That's a critical trade off. 

529
00:24:48,560 --> 00:24:51,600
A bit of acidosis is much better
than a popped lung or a cardiac 

530
00:24:51,600 --> 00:24:52,840
arrest. 
Exactly. 

531
00:24:52,840 --> 00:24:56,280
It's a lung protective strategy 
and #4 PEEP. 

532
00:24:57,080 --> 00:24:59,480
This is a bit controversial, but
generally we apply a small 

533
00:24:59,480 --> 00:25:02,960
amount of extrinsic PEEP, maybe 
around 5 centimeter H2O. 

534
00:25:03,560 --> 00:25:06,360
The theory is that this helps to
splint the small Airways open 

535
00:25:06,360 --> 00:25:09,200
during expiration and prevent 
that dynamic collapse we talked 

536
00:25:09,200 --> 00:25:09,600
about. 
Earlier. 

537
00:25:09,600 --> 00:25:11,680
Got it. 
OK, Section 16 drugs. 

538
00:25:11,840 --> 00:25:13,240
Let's run through the 
anaesthetic cart. 

539
00:25:13,600 --> 00:25:15,880
Inhalational agents, What's the 
best choice? 

540
00:25:16,320 --> 00:25:18,920
Civil fluorine is widely 
considered the agent of choice. 

541
00:25:18,920 --> 00:25:22,880
It's a potent bronchodilator and
it's non pungent so it's very 

542
00:25:22,880 --> 00:25:25,520
smooth on the airway. 
You should definitely avoid 

543
00:25:25,520 --> 00:25:29,080
disflurane and probably 
isoflurane for induction as they

544
00:25:29,080 --> 00:25:31,920
are pungent and can irritate the
airway causing coughing and 

545
00:25:31,920 --> 00:25:34,320
laryngo spasm. 
Halothane, for the history 

546
00:25:34,320 --> 00:25:37,160
buffs, is a fantastic 
bronchodilator, but it 

547
00:25:37,160 --> 00:25:39,640
sensitizes the heart to 
catecholi means and can cause 

548
00:25:39,640 --> 00:25:41,360
arrhythmia, so it's very rarely 
used now. 

549
00:25:41,360 --> 00:25:45,400
OK, five induction agents. 
Propofol is an excellent choice.

550
00:25:45,600 --> 00:25:48,760
It effectively suppresses 
laryngeal reflexes and provides 

551
00:25:48,760 --> 00:25:52,440
a very smooth induction. 
Ketamine is unique and very 

552
00:25:52,440 --> 00:25:54,520
useful option, especially in an 
emergency. 

553
00:25:55,320 --> 00:25:57,240
It has sympathomimetic 
properties. 

554
00:25:57,640 --> 00:26:00,680
It causes a release of 
endogenous catecholamines which 

555
00:26:00,680 --> 00:26:04,240
are potent beta 2 agonists and 
relax bronchial smooth muscle. 

556
00:26:04,760 --> 00:26:07,880
It's excellent for the actively 
wheezing or hypotensive patient.

557
00:26:08,080 --> 00:26:10,880
And what about muscle relaxants?
This is a common exam question. 

558
00:26:10,880 --> 00:26:13,600
The rule is simple, avoid 
anything that releases 

559
00:26:13,600 --> 00:26:16,440
histamine. 
So avoid atrocurium and 

560
00:26:16,440 --> 00:26:18,080
Vivicurium. 
Histamine causes 

561
00:26:18,080 --> 00:26:19,960
bronchoconstriction, which is 
the last thing you want. 

562
00:26:20,440 --> 00:26:23,440
Use rocaronium, vecaronium, or 
cisotracurium. 

563
00:26:23,720 --> 00:26:25,920
These are clean drugs from a 
histamine release perspective 

564
00:26:25,920 --> 00:26:27,400
and are much safer. 
Opioids. 

565
00:26:27,400 --> 00:26:29,000
Same principle. 
Same principle. 

566
00:26:29,000 --> 00:26:30,840
Morphine is known to cause 
histamine release. 

567
00:26:31,080 --> 00:26:33,040
Avoided. 
If possible, use a synthetic 

568
00:26:33,040 --> 00:26:34,680
opioid like fentanyl or 
sufentanyl. 

569
00:26:34,800 --> 00:26:36,920
And the big one, nitrous oxide 
and two OA. 

570
00:26:37,200 --> 00:26:39,320
Huge red flag in patients with 
emphysema. 

571
00:26:40,240 --> 00:26:44,120
If the patient has bullet which 
are large air filled cysts in 

572
00:26:44,120 --> 00:26:47,720
the lung, the late nitrous oxide
will diffuse into these closed 

573
00:26:47,720 --> 00:26:50,440
air spaces faster than nitrogen 
can diffuse out. 

574
00:26:51,000 --> 00:26:53,320
The bullet will expand under 
pressure and can rupture, 

575
00:26:53,520 --> 00:26:55,000
causing attention to 
pneumothorax. 

576
00:26:55,640 --> 00:26:58,720
So the rule is strictly no 
nitrous in any patient with 

577
00:26:58,720 --> 00:27:00,760
known or suspected bullets. 
Emphysema. 

578
00:27:01,160 --> 00:27:03,520
OK. 
Part G Post operative in ICU 

579
00:27:03,520 --> 00:27:05,240
care. 
The surgery is over. 

580
00:27:05,320 --> 00:27:07,960
The patient is in recovery. 
The danger is absolutely not 

581
00:27:07,960 --> 00:27:09,480
over. 
The post op period is fraught 

582
00:27:09,480 --> 00:27:11,480
with risk. 
The main complications are 

583
00:27:11,480 --> 00:27:14,960
hypoventilation, bronchospasm 
and atelectasis, which is lung 

584
00:27:14,960 --> 00:27:18,160
collapse, and pain control which
is section 18 is absolutely 

585
00:27:18,160 --> 00:27:19,760
huge. 
Because if it hurts to breathe, 

586
00:27:19,760 --> 00:27:21,200
they simply won't take a deep 
breath. 

587
00:27:21,440 --> 00:27:23,480
Exactly. 
That's called splinting, and 

588
00:27:23,480 --> 00:27:26,000
splinting leads to addalactasis,
which creates a breeding ground 

589
00:27:26,000 --> 00:27:27,800
for bacteria and leads to 
pneumonia. 

590
00:27:28,320 --> 00:27:32,400
Thoracic epidural analgesia TEA 
is the gold standard for pain 

591
00:27:32,400 --> 00:27:34,800
relief after major abdominal or 
thoracic surgery. 

592
00:27:35,200 --> 00:27:38,200
It provides profound analgesia 
without the systemic respiratory

593
00:27:38,200 --> 00:27:40,640
depression you get from high 
doses of IV opioids. 

594
00:27:41,240 --> 00:27:44,040
It allows the patient to cough, 
mobilize and breathe deeply. 

595
00:27:44,240 --> 00:27:47,080
What about NIV non invasive 
ventilation? 

596
00:27:47,440 --> 00:27:50,040
Things like Bipap. 
An absolute lifesaver in this 

597
00:27:50,040 --> 00:27:52,440
patient population. 
If the patient is struggling 

598
00:27:52,440 --> 00:27:54,600
after you've extubated them, 
don't wait. 

599
00:27:54,720 --> 00:27:57,520
Put them on Bipap immediately. 
It reduces their work of 

600
00:27:57,520 --> 00:28:01,280
breathing, it helps blow off any
residual CO2, and it stents 

601
00:28:01,280 --> 00:28:03,920
their Airways open. 
It very often prevents the need 

602
00:28:03,920 --> 00:28:06,160
for re intubation. 
And if they do end up in the 

603
00:28:06,160 --> 00:28:09,760
ICU, Section 19 weaning from the
ventilator. 

604
00:28:10,080 --> 00:28:12,200
Weaning can be very difficult 
and prolonged. 

605
00:28:12,400 --> 00:28:15,120
They have weak respiratory 
muscles and high airway 

606
00:28:15,120 --> 00:28:17,560
resistance. 
We often use modes like pressure

607
00:28:17,560 --> 00:28:20,120
support, ventilation, PSV to 
help them overcome the 

608
00:28:20,120 --> 00:28:21,480
resistance of the breathing 
tube. 

609
00:28:21,840 --> 00:28:24,760
And you shouldn't be afraid to 
excavate them directly to NIV to

610
00:28:24,760 --> 00:28:26,600
provide that bridge of support. 
Excellent. 

611
00:28:26,640 --> 00:28:29,640
OK, Part H exam integration. 
Let's bring it all home for the 

612
00:28:29,640 --> 00:28:32,240
exam Section 20 comparison 
tables. 

613
00:28:32,320 --> 00:28:35,120
Let's start with the classic 
asthma versus COPD. 

614
00:28:35,560 --> 00:28:36,960
OK, let's do this as a quick 
fire. 

615
00:28:37,520 --> 00:28:40,720
Age of onset asthma is typically
early childhood. 

616
00:28:41,240 --> 00:28:45,280
COPD is midlife, almost always 
over 40 Etiology Asthma is often

617
00:28:45,280 --> 00:28:48,240
allergic or atopic. 
COPD is overwhelmingly due to 

618
00:28:48,240 --> 00:28:50,280
smoking or noxious particle 
exposure. 

619
00:28:50,600 --> 00:28:53,680
Clinical course asthma is 
intermittent with symptom free 

620
00:28:53,680 --> 00:28:55,920
periods. 
COPD is chronic and progressive 

621
00:28:56,280 --> 00:28:59,920
and the big one, reversibility. 
In asthma, you see a significant

622
00:28:59,920 --> 00:29:03,240
improvement in FEV, one more 
than 12% and 200 milliliters 

623
00:29:03,240 --> 00:29:06,520
after a bronchodilator. 
In COPD you see minimal or no 

624
00:29:06,520 --> 00:29:09,400
change. 
Perfect now for Section 21 

625
00:29:09,480 --> 00:29:11,000
common exam questions in Viva 
traps. 

626
00:29:11,000 --> 00:29:13,200
We touched on this earlier, but 
let's really hammer home the 

627
00:29:13,200 --> 00:29:16,360
hypoxic Dr. myth. 
A junior colleague says I won't 

628
00:29:16,360 --> 00:29:18,960
give the COPD patient much 
oxygen because they run on a 

629
00:29:18,960 --> 00:29:20,600
hypoxic Dr. and they'll stop 
breathing. 

630
00:29:20,640 --> 00:29:23,080
What is your response? 
My response is that this is a 

631
00:29:23,080 --> 00:29:26,280
partial truth that is used to 
justify dangerous practice. 

632
00:29:26,760 --> 00:29:30,040
Yes, it is true that in some 
chronic CO2 retainers the 

633
00:29:30,040 --> 00:29:33,600
primary stimulus to breathe is a
low level of oxygen rather than 

634
00:29:33,600 --> 00:29:37,480
a high level of CO2. 
But if your patient is hypoxic 

635
00:29:37,680 --> 00:29:40,840
within this BO2 of 85%, you must
give them oxygen. 

636
00:29:41,240 --> 00:29:44,240
Hypoxy kills in minutes. 
It causes brain death and fetal 

637
00:29:44,240 --> 00:29:47,080
arrhythmias. 
CO2 narcosis on the other hand 

638
00:29:47,080 --> 00:29:49,000
takes hours to develop and is 
reversible. 

639
00:29:49,280 --> 00:29:51,120
You always treat the more 
immediate threat to life. 

640
00:29:51,920 --> 00:29:54,200
Furthermore, the main reason 
their CO2 rises when you give 

641
00:29:54,200 --> 00:29:57,160
them oxygen is due to complex 
physiological effects like the 

642
00:29:57,160 --> 00:30:01,280
Haldane effect and reversing HPV
which worsens VQ mismatch. 

643
00:30:01,560 --> 00:30:03,200
It's not just the brainstem 
shutting down. 

644
00:30:03,520 --> 00:30:05,360
So the safe gold standard exam 
answer. 

645
00:30:05,360 --> 00:30:08,720
Is I will administer controlled 
oxygen, for example via a 24 or 

646
00:30:08,720 --> 00:30:12,840
28% Venturi mask to maintain 
this BO2 in a target range of 88

647
00:30:12,840 --> 00:30:15,120
to 92%. 
I will monitor the patient 

648
00:30:15,120 --> 00:30:18,440
closely for signs of rising CO2 
and drowsiness, but I will never

649
00:30:18,440 --> 00:30:20,400
withhold oxygen from a hypoxic 
patient. 

650
00:30:20,640 --> 00:30:23,840
That is the gold medal answer. 
I can hear the examiner nodding 

651
00:30:23,840 --> 00:30:26,240
and approval. 
OK, another trap. 

652
00:30:26,960 --> 00:30:31,360
The sudden intraoperative crash.
We discussed how auto peep can 

653
00:30:31,360 --> 00:30:35,520
cause profound hypotension. 
What is the immediate management

654
00:30:35,520 --> 00:30:37,240
algorithm? 
The first few steps. 

655
00:30:37,240 --> 00:30:40,080
Number one, instantly disconnect
the breathing circuit from the 

656
00:30:40,080 --> 00:30:43,080
endotracheal tube. 
This immediately releases any 

657
00:30:43,080 --> 00:30:45,760
trap pressure. 
It treats auto peep and it also 

658
00:30:45,760 --> 00:30:49,280
rules out an equipment or 
ventilator failure #2 Start 

659
00:30:49,280 --> 00:30:52,000
bagging the patient manually 
with 100% oxygen. 

660
00:30:52,320 --> 00:30:54,800
This allows you to feel the 
compliance of the lungs in your 

661
00:30:54,800 --> 00:30:56,120
hand. 
Are they stiff? 

662
00:30:56,120 --> 00:31:00,080
Is it hard to bag #3 Listen to 
the chest with a stethoscope. 

663
00:31:00,360 --> 00:31:02,560
If you hear wheezing, it's 
likely bronchospasm. 

664
00:31:02,840 --> 00:31:06,360
If you hear silence on one side,
you must suspect A pneumothorax 

665
00:31:06,720 --> 00:31:10,680
and #4 Look at your capnograph. 
A shark fin shape confirms 

666
00:31:10,680 --> 00:31:12,680
obstruction. 
A flat line means either there's

667
00:31:12,680 --> 00:31:14,720
no cardiac output or you're 
disconnected. 

668
00:31:14,800 --> 00:31:17,960
Fantastic section 22 diagrams. 
What are the essential things I 

669
00:31:17,960 --> 00:31:20,000
should be prepared to draw? 
Three things. 

670
00:31:20,280 --> 00:31:23,920
One, the flow volume loop, you 
must draw the normal loop versus

671
00:31:23,920 --> 00:31:27,680
the obstructive scooped out 
loop. 2, the captagraph trace, 

672
00:31:27,960 --> 00:31:30,720
draw a normal square wave trace 
next to the shark fin trace of 

673
00:31:30,720 --> 00:31:32,880
bronchospasm which has that slow
sloping up stroke. 

674
00:31:33,160 --> 00:31:36,920
And three, a basic spherogram 
trace just showing a reduced FEV

675
00:31:36,960 --> 00:31:40,800
1 and a reduced FEC. 
And finally, Section 23 summary 

676
00:31:40,800 --> 00:31:43,080
Exam conclusion. 
Give me the 62nd summary for the

677
00:31:43,080 --> 00:31:46,200
listener who is walking from the
canteen into the exam hall right

678
00:31:46,200 --> 00:31:47,520
now. 
All right, here's your final 

679
00:31:47,520 --> 00:31:49,800
recap. 
One, define it. 

680
00:31:50,120 --> 00:31:54,360
It's a not fully reversible 
airflow limitation 2 pathology. 

681
00:31:54,440 --> 00:31:57,720
It's a mix of loss of recoil 
which is emphysema and mucus and

682
00:31:57,720 --> 00:31:59,040
inflammation which is 
bronchitis. 

683
00:31:59,680 --> 00:32:03,000
Three key Physiology. 
Remember air trapping and auto 

684
00:32:03,000 --> 00:32:06,880
peep which cause hemodynamic 
collapse. 4 Pre op focus on 

685
00:32:06,880 --> 00:32:08,200
their functional capacity 
history. 

686
00:32:08,200 --> 00:32:11,040
Smoking cessation is best at 
more than 8 weeks or less than 

687
00:32:11,040 --> 00:32:15,000
24 hours. 5 Induction. 
Ensure deep anesthesia. 

688
00:32:15,240 --> 00:32:19,560
Avoid any histamine releasing 
drugs. 6 Maintenance seven floor

689
00:32:19,560 --> 00:32:21,880
range is your friend. 
No nitrous oxide if they're a 

690
00:32:21,880 --> 00:32:25,760
bullet. 7 ventilation. 
The mantra is slow rate, long 

691
00:32:25,760 --> 00:32:28,000
expiratory time. 
Your IE ratio should be 1 to 

692
00:32:28,000 --> 00:32:32,000
3:00 or 1:00 to 4:00 except 
permissive hypercapnia 8 post op

693
00:32:32,200 --> 00:32:33,920
and epidural for pain control is
ideal. 

694
00:32:34,160 --> 00:32:35,920
Use early non invasive 
ventilation. 

695
00:32:36,120 --> 00:32:38,440
And the final word, the key, 
take away safety. 

696
00:32:38,800 --> 00:32:40,840
The examiner wants to know that 
you're a safe anesthetist. 

697
00:32:40,840 --> 00:32:42,160
They want to know you understand
the risks. 

698
00:32:42,280 --> 00:32:45,160
So verbalize your safety checks.
I am worried about auto peep so 

699
00:32:45,160 --> 00:32:47,560
I will monitor the flow curve. 
I will watch for new with 

700
00:32:47,560 --> 00:32:49,320
thorax. 
I'll be careful not to fluid 

701
00:32:49,320 --> 00:32:51,640
overload the right heart. 
Acknowledging the risks is how 

702
00:32:51,640 --> 00:32:53,960
you pass. 
Expert, thank you so much. 

703
00:32:54,000 --> 00:32:56,560
That was intense. 
It was thorough, but I feel like

704
00:32:56,560 --> 00:32:59,520
I can actually visualize the 
lungs and the ventilator now. 

705
00:32:59,720 --> 00:33:03,440
It's a complex topic, there's no
doubt about it, but if you stick

706
00:33:03,440 --> 00:33:08,320
to the basic mechanics, the 
physics of flow and recoil, it 

707
00:33:08,320 --> 00:33:11,480
all starts to make sense. 
Good luck to our students out 

708
00:33:11,480 --> 00:33:14,840
there listening. 
Now grab a pen, draw that flow 

709
00:33:14,840 --> 00:33:17,760
volume, loop that bitten 
sandwich, and go crush that 

710
00:33:17,760 --> 00:33:19,880
exam. 
This has been the deep dive. 

711
00:33:19,920 --> 00:33:21,480
Goodbye. 
Wait wait, wait, hold on, we're 

712
00:33:21,480 --> 00:33:23,280
not done yet. 
That was the executive summary. 

713
00:33:23,280 --> 00:33:26,320
That was the high yield pass 
level stuff, but we have a full 

714
00:33:26,320 --> 00:33:29,240
hour to fill and frankly we just
glossed over some really 

715
00:33:29,240 --> 00:33:32,480
important details, the kind of 
details that distinguish a pass 

716
00:33:32,720 --> 00:33:34,800
from a distinction. 
You're absolutely right. 

717
00:33:34,800 --> 00:33:37,320
We gave them the skeleton. 
This is a solid skeleton. 

718
00:33:37,480 --> 00:33:38,880
But now let's put some meat on 
those bones. 

719
00:33:38,880 --> 00:33:42,560
Let's circle all the way back to
Part B pathophysiology. 

720
00:33:42,560 --> 00:33:45,840
We briefly mentioned it, but 
let's talk about A1 antitrypsin 

721
00:33:45,840 --> 00:33:49,040
deficiency. 
The genetic cause of COPD? 

722
00:33:49,480 --> 00:33:53,000
Yes. 
Most COPD is from smoking, but 

723
00:33:53,000 --> 00:33:56,800
if you see a young patient, say 
35 or 40 years old, who has 

724
00:33:56,800 --> 00:34:00,280
never smoked but has severe 
emphysema, you must suspect 

725
00:34:00,280 --> 00:34:02,200
this. 
It's a deficiency of a crucial 

726
00:34:02,200 --> 00:34:05,520
protease inhibitor. 
Without it, an enzyme in the 

727
00:34:05,520 --> 00:34:09,360
lungs called elastase just runs 
rampant and literally eats the 

728
00:34:09,360 --> 00:34:12,840
elastic tissue in the lung. 
This leads to a specific type of

729
00:34:12,840 --> 00:34:15,679
emphysema called panacinar 
emphysema, which 

730
00:34:15,679 --> 00:34:18,159
characteristically affects the 
lower lobes of the lungs. 

731
00:34:18,639 --> 00:34:22,159
You can compare that to smoking 
induced emphysema, which causes 

732
00:34:22,159 --> 00:34:24,760
sentry asinor emphysema and 
classically affects the upper 

733
00:34:24,760 --> 00:34:26,159
lobes. 
OK, that's a brilliant 

734
00:34:26,159 --> 00:34:29,320
distinction. 
So smoking equals smoke rises so

735
00:34:29,320 --> 00:34:31,920
it hits the upper lobes in the 
center of the sinus or sentry 

736
00:34:31,920 --> 00:34:34,520
asinor. 
Genetic is systemic, gravity 

737
00:34:34,520 --> 00:34:36,960
wins so it affects the lower 
lobes and the whole is sinus so 

738
00:34:36,960 --> 00:34:38,320
panasinor. 
Exactly. 

739
00:34:38,600 --> 00:34:41,159
Dropping a Pearl like that in 
Aviva shows you aren't just 

740
00:34:41,159 --> 00:34:43,280
reciting the basics from a 
review book, it shows you've 

741
00:34:43,280 --> 00:34:45,639
read in depth. 
OK, let's dig deeper into Part D

742
00:34:45,639 --> 00:34:47,440
investigations. 
We talked about the ECG. 

743
00:34:47,440 --> 00:34:50,639
What about echocardiography? 
If my patient has signs of core 

744
00:34:50,639 --> 00:34:53,400
pulmonale, what specific numbers
am I looking for on that echo 

745
00:34:53,400 --> 00:34:55,440
report that will change my 
anesthetic plan? 

746
00:34:55,639 --> 00:34:57,520
An excellent question you are 
looking for. 

747
00:34:57,520 --> 00:35:01,600
The estimated pulmonary artery 
systolic pressure, or PASP 

748
00:35:02,400 --> 00:35:04,880
normal is less than 25 
millimeter HG. 

749
00:35:05,560 --> 00:35:07,600
In a patient with severe core 
pulmonale. 

750
00:35:07,800 --> 00:35:12,400
It can be 5060 or even higher if
that PSV starts to approach the 

751
00:35:12,400 --> 00:35:13,880
patient's systemic blood 
pressure. 

752
00:35:14,160 --> 00:35:16,800
The risk of acute right 
ventricular failure on induction

753
00:35:16,800 --> 00:35:19,960
is absolutely massive. 
You're also looking for the TR 

754
00:35:19,960 --> 00:35:23,800
jet velocity from the tricuspid 
regurgitation and a key 

755
00:35:23,800 --> 00:35:27,240
measurement of RV function 
called Tape PSE, which stands 

756
00:35:27,240 --> 00:35:29,960
for a Tricuspid Annular Plane 
Systolic Excursion. 

757
00:35:30,200 --> 00:35:32,480
Tape PSE. 
That's a great keyword to use. 

758
00:35:32,480 --> 00:35:36,680
If the tape PSE is low, say less
than 16mm, it means the right 

759
00:35:36,680 --> 00:35:38,360
ventricle is failing. 
It's weak. 

760
00:35:38,880 --> 00:35:41,080
You need to be incredibly gentle
with your induction agents. 

761
00:35:41,360 --> 00:35:43,680
A standard dose of propofol 
might cause a complete 

762
00:35:43,680 --> 00:35:46,480
cardiovascular collapse. 
In that situation you might 

763
00:35:46,480 --> 00:35:48,720
choose Atomidate, which is 
famously cardio stable. 

764
00:35:48,880 --> 00:35:51,160
We're a very slow, careful 
titration of ketamine. 

765
00:35:51,320 --> 00:35:54,080
Let's revisit part E pre op 
optimization again. 

766
00:35:54,320 --> 00:35:56,440
We mentioned giving antibiotics 
for an infection. 

767
00:35:56,480 --> 00:35:58,040
Which bugs are we actually 
fighting? 

768
00:35:58,040 --> 00:36:00,240
What should I prescribe? 
The common community acquired 

769
00:36:00,240 --> 00:36:02,160
organisms are the usual 
suspects. 

770
00:36:02,520 --> 00:36:05,840
Streptococcus pneumonia, 
Hemophilus influenza and more 

771
00:36:05,840 --> 00:36:09,680
exelic Catarolis. 
But, and this is another 

772
00:36:09,680 --> 00:36:12,680
distinction level point, in a 
patient who has been in and out 

773
00:36:12,680 --> 00:36:15,520
of the hospital frequently, you 
must have a high index of 

774
00:36:15,520 --> 00:36:17,440
suspicion for Pseudomonas 
urugenosa. 

775
00:36:17,480 --> 00:36:20,120
Pseudomonas, the nasty one, the 
blue-green pots. 

776
00:36:20,120 --> 00:36:23,160
Yes, if they have risk factors 
for it like recent hospital 

777
00:36:23,160 --> 00:36:25,080
admission or previous courses 
antibiotics. 

778
00:36:25,200 --> 00:36:27,680
You need to ensure they have 
anti pseudomonal coverage. 

779
00:36:28,000 --> 00:36:30,560
Something like 
pipersilentasobectom or 

780
00:36:30,560 --> 00:36:33,400
siftazodime? 
And what about their nutritional

781
00:36:33,400 --> 00:36:35,320
status? 
We see these emphysemedis 

782
00:36:35,320 --> 00:36:37,320
patients who are just skin and 
bones. 

783
00:36:37,440 --> 00:36:40,000
How much does that matter? 
It's a huge independent 

784
00:36:40,000 --> 00:36:42,360
predictor of poor post operative
outcome. 

785
00:36:43,040 --> 00:36:47,400
A low serum albumin, say less 
than 3 point OGDL, is strongly 

786
00:36:47,400 --> 00:36:50,360
associated with poor wound 
healing, respiratory muscle 

787
00:36:50,360 --> 00:36:53,160
weakness, and an inability to 
wean from the ventilator. 

788
00:36:53,760 --> 00:36:56,520
If the surgery is elective, 
referring them to a dietitian 

789
00:36:56,520 --> 00:36:59,240
for a few weeks of high protein 
nutritional supplements can 

790
00:36:59,240 --> 00:37:03,000
genuinely change their outcome. 
OK, let's expand on Part F, the 

791
00:37:03,000 --> 00:37:04,680
intraoperative ventilation 
strategy. 

792
00:37:04,680 --> 00:37:08,280
We said use a low rate, but how 
do we decide on the exact rate? 

793
00:37:08,280 --> 00:37:10,840
Is it just a guess? 
It has to come down to the idea 

794
00:37:10,840 --> 00:37:12,760
of time constants. 
Right now we are talking 

795
00:37:12,760 --> 00:37:15,040
advanced respiratory physics. 
This is excellent. 

796
00:37:15,040 --> 00:37:16,960
Yes. 
The time constant, which is 

797
00:37:16,960 --> 00:37:20,360
often abbreviated as Tau, is a 
product of the lungs resistance 

798
00:37:20,360 --> 00:37:24,360
multiplied by its compliance. 
It is the time in seconds taken 

799
00:37:24,360 --> 00:37:27,400
for 63% of the lung volume to 
empty during a passive 

800
00:37:27,400 --> 00:37:29,760
exhalation. 
You need roughly three to four 

801
00:37:29,760 --> 00:37:33,360
time constants to empty 95 to 
98% of the lung volume. 

802
00:37:33,520 --> 00:37:36,880
In COPD the resistance is very 
high and in emphysema the 

803
00:37:36,880 --> 00:37:40,000
compliance is also high. 
So the product Tau is huge. 

804
00:37:40,200 --> 00:37:42,520
It's a very long time constant. 
It takes seconds for their lungs

805
00:37:42,520 --> 00:37:44,320
to empty. 
That is why we need to provide 

806
00:37:44,320 --> 00:37:46,240
four or five seconds of 
expiratory time. 

807
00:37:46,480 --> 00:37:49,280
And if you do the math, 60 
seconds in a minute divided by, 

808
00:37:49,280 --> 00:37:52,160
say, one second for inspiration 
plus 5 seconds for expiration. 

809
00:37:52,240 --> 00:37:55,320
That's 6 seconds per breath. 60 
/ 6 is 10 breaths per minute. 

810
00:37:55,320 --> 00:37:56,400
That's where the math comes 
from. 

811
00:37:56,400 --> 00:37:59,240
So it's not a random guess, it's
calculated based on the 

812
00:37:59,240 --> 00:38:01,280
patient's specific lung 
mechanics. 

813
00:38:01,360 --> 00:38:03,920
OK, and let's talk with the 
crisis intra operative 

814
00:38:03,920 --> 00:38:06,400
bronchospasm. 
We gave the initial algorithm 

815
00:38:06,800 --> 00:38:10,080
disconnect bag. 
Listen, but let's say it is 

816
00:38:10,080 --> 00:38:12,560
bronchospasm, the chest is tight
and you can hear wheeze. 

817
00:38:12,560 --> 00:38:14,120
What is the pharmacological 
ladder? 

818
00:38:14,120 --> 00:38:15,720
What do you give and in what 
order? 

819
00:38:15,840 --> 00:38:18,040
A great question. 
This is your crisis management 

820
00:38:18,040 --> 00:38:20,960
drill #1 Deepen the level of 
anesthesia. 

821
00:38:21,240 --> 00:38:23,480
All volatile agents are 
bronchodilators. 

822
00:38:23,960 --> 00:38:26,760
Increase your several fluorine 
to two or three Mac if the blood

823
00:38:26,760 --> 00:38:31,000
pressure allows or give a bolus 
of propofol or ketamine #2 

824
00:38:31,480 --> 00:38:37,040
Ensure you are on 100% oxygen #3
Give beta. 2 agonists 

825
00:38:37,400 --> 00:38:40,000
cellbutamol pus directly down 
the endotracheal tube. 

826
00:38:40,120 --> 00:38:42,880
You can use specific MDI 
connector or in an emergency 

827
00:38:42,880 --> 00:38:45,760
just disconnect and spray it 
right down the tube. 4 Add 

828
00:38:45,760 --> 00:38:48,280
anticholinergics. 
Hypertropium bromide works 

829
00:38:48,280 --> 00:38:51,080
synergistically with 
cellbutamol. 5 Intravenous 

830
00:38:51,080 --> 00:38:53,880
magnesium sulfate. 
A dose of 2 grams given over 10 

831
00:38:53,880 --> 00:38:56,480
to 15 minutes. 
It's a calcium antagonist and a 

832
00:38:56,480 --> 00:39:00,400
potent smooth muscle relaxant. 
Can be highly effective. 64V 

833
00:39:00,400 --> 00:39:02,640
steroids, hydrocortisone or 
dexamethasone. 

834
00:39:02,880 --> 00:39:05,160
They take hours to work, but you
give them now to help with the 

835
00:39:05,160 --> 00:39:07,640
inflammation later on. 
And seven epinephrine. 

836
00:39:07,760 --> 00:39:09,880
This is the nuclear option. 
You can start with small IV 

837
00:39:09,880 --> 00:39:12,840
boluses of 10 to 20 micrograms 
or start a low dose infusion. 

838
00:39:12,880 --> 00:39:14,600
Epinephrine. 
Isn't that just for cardiac 

839
00:39:14,600 --> 00:39:16,120
arrest? 
That sounds quite extreme. 

840
00:39:16,160 --> 00:39:18,720
It is the most potent 
bronchodilator we have. 

841
00:39:19,320 --> 00:39:21,720
It is powerful beta 2 agonist 
effects. 

842
00:39:22,440 --> 00:39:26,880
In a severe life threatening 
silent chest scenario where no 

843
00:39:26,880 --> 00:39:30,360
air is moving, small doses of 
epinephrine can be life saving. 

844
00:39:30,400 --> 00:39:33,240
OK, let's talk about a very 
specific surgical scenario that 

845
00:39:33,240 --> 00:39:36,040
comes up all the time, 
laparoscopic surgery in a 

846
00:39:36,040 --> 00:39:40,240
patient with severe COPD. 
This feels like a double whammy 

847
00:39:40,240 --> 00:39:41,600
of problems. 
It is one of the most 

848
00:39:41,600 --> 00:39:44,320
challenging scenarios we face. 
First, you have the 

849
00:39:44,320 --> 00:39:46,640
pneumoperitoneum. 
The surgeon insufflates the 

850
00:39:46,640 --> 00:39:49,880
abdomen with carbon dioxide. 
This pushes the diaphragm up 

851
00:39:49,880 --> 00:39:52,520
into the chest, splitting it, 
and it compresses the lung 

852
00:39:52,520 --> 00:39:54,720
bases. 
This dramatically worsens 

853
00:39:54,720 --> 00:39:57,240
atlactasis. 
And second, you have CO2 

854
00:39:57,240 --> 00:39:59,400
absorption. 
The CO2 from the belly is 

855
00:39:59,400 --> 00:40:01,480
absorbed directly into the 
patient's bloodstream. 

856
00:40:02,000 --> 00:40:04,120
So you have a patient who is 
already struggling to exhale 

857
00:40:04,120 --> 00:40:06,640
their own CO2 because of their 
COPD, and now you are 

858
00:40:06,640 --> 00:40:09,480
systemically loading them with 
extra CO2 from the surgery. 

859
00:40:09,520 --> 00:40:12,480
The end title CO2 on the monitor
is just going to skyrocket. 

860
00:40:12,680 --> 00:40:15,480
It will, and your natural 
instinct as a junior 

861
00:40:15,480 --> 00:40:19,160
anaesthetist is to see a high 
CO2 and want to increase the 

862
00:40:19,160 --> 00:40:21,840
ventilation to blow it off. 
Increase the rate. 

863
00:40:22,440 --> 00:40:24,800
But you can't. 
If you increase the rate you 

864
00:40:24,800 --> 00:40:27,600
cause auto peep. 
If you increase the tidal volume

865
00:40:27,880 --> 00:40:30,120
you get dangerously high keek 
airway pressures. 

866
00:40:30,360 --> 00:40:32,040
You are trapped. 
So what do you do? 

867
00:40:32,040 --> 00:40:34,760
What's the strategy? 
One, you stick to your guns on 

868
00:40:34,760 --> 00:40:38,360
permissive hypercapnia, you let 
that CO2 rise as long as the pH 

869
00:40:38,360 --> 00:40:42,000
is safe. 2 Communication. 
You must speak to the surgeon. 

870
00:40:42,360 --> 00:40:44,240
Ask them to lower the 
insufflation pressure. 

871
00:40:44,560 --> 00:40:47,080
Can they operate at 12 millimill
HG instead of 15? 

872
00:40:47,840 --> 00:40:50,480
Three, positioning. 
You had to avoid extreme 

873
00:40:50,480 --> 00:40:53,360
trendlenberg the head down 
position as that makes the 

874
00:40:53,360 --> 00:40:55,160
diaphragmatic splinting even 
worse. 

875
00:40:55,720 --> 00:40:58,520
And for conversion, if you 
simply cannot ventilate the 

876
00:40:58,520 --> 00:41:01,160
patient safely, you have to be 
brave enough to tell the surgeon

877
00:41:01,160 --> 00:41:03,600
that they need to convert to an 
open procedure for the patient's

878
00:41:03,600 --> 00:41:05,680
safety. 
That communication point is so 

879
00:41:05,680 --> 00:41:08,320
key for the oral exam. 
You have to show that you are 

880
00:41:08,320 --> 00:41:09,760
the captain of the ship in that 
room. 

881
00:41:09,760 --> 00:41:11,840
Absolutely. 
The anesthetist is the guardian 

882
00:41:11,840 --> 00:41:14,400
of the patient's Physiology. 
You have to advocate for it. 

883
00:41:14,560 --> 00:41:17,120
Let's just touch on regional 
anesthesia one more time with a 

884
00:41:17,120 --> 00:41:21,880
specific block, a brachial 
plexus block, specifically an 

885
00:41:21,880 --> 00:41:24,040
interscaling block for shoulder 
surgery. 

886
00:41:24,600 --> 00:41:27,200
Is that safe in a patient with 
severe COPD? 

887
00:41:27,320 --> 00:41:31,040
You need to be extremely 
careful, and interscaling block 

888
00:41:31,200 --> 00:41:34,000
because of where the local 
anesthetic spreads, almost 

889
00:41:34,040 --> 00:41:37,560
always causes a temporary frenic
nerve palsy on the same side. 

890
00:41:37,880 --> 00:41:40,160
This means you paralyze that 
hemidiophram. 

891
00:41:40,560 --> 00:41:42,960
A healthy person can tolerate 
losing 50% of their 

892
00:41:42,960 --> 00:41:44,440
diaphragmatic function just 
fine. 

893
00:41:44,440 --> 00:41:48,120
They won't even notice. 
But a patient with severe COPD 

894
00:41:48,120 --> 00:41:50,880
who is already using every 
accessory muscle they have to 

895
00:41:50,880 --> 00:41:53,760
breathe, losing half their 
diaphragm might be the final 

896
00:41:53,760 --> 00:41:56,280
straw that pushes them into 
acute respiratory failure. 

897
00:41:56,720 --> 00:41:59,360
So the standard teaching is to 
strictly avoid interscaling 

898
00:41:59,360 --> 00:42:02,160
blocks in severe COPD. 
You'd want to use a 

899
00:42:02,160 --> 00:42:05,240
supraclavicular approach, though
that has a risk of pneumothorax,

900
00:42:05,240 --> 00:42:07,680
or an axillary approach if the 
surgery allows. 

901
00:42:08,000 --> 00:42:09,800
Fantastic. 
OK, let's do a true or false 

902
00:42:09,800 --> 00:42:12,040
rapid fire around from some of 
these question bangs just to 

903
00:42:12,040 --> 00:42:15,880
submit some of these concepts. 
OK #1 Routine use of 

904
00:42:15,880 --> 00:42:18,720
prophylactic post operative 
mechanical ventilation is 

905
00:42:18,720 --> 00:42:21,200
recommended for all patients 
with severe COPD. 

906
00:42:21,560 --> 00:42:23,680
False. 
The modern approach is to try 

907
00:42:23,680 --> 00:42:26,920
and extubate them as early as 
possible to avoid ventilator 

908
00:42:26,920 --> 00:42:29,200
associated pneumonia and 
ventilator dependency. 

909
00:42:29,480 --> 00:42:32,200
However, we have a very low 
threshold to use prophylactic 

910
00:42:32,200 --> 00:42:35,440
non invasive ventilation. 
So the strategy is extubate to 

911
00:42:35,440 --> 00:42:39,840
NIV or bi PAP, not leave them on
the ventilator. #2 inhaled cell 

912
00:42:39,840 --> 00:42:42,480
butamol can cause hyperkalemia. 
False. 

913
00:42:42,920 --> 00:42:45,800
It causes hypokalemia. 
The beta 2 stimulation drives 

914
00:42:45,800 --> 00:42:48,520
potassium into the cells. 
This can be clinically 

915
00:42:48,520 --> 00:42:51,480
significant, especially if the 
patient is already on diuretics,

916
00:42:51,480 --> 00:42:54,520
which also cause potassium loss.
It can trigger arrhythmias. 

917
00:42:54,600 --> 00:42:58,400
OK #3 Aminopheline is the first 
line drug for treating severe 

918
00:42:58,400 --> 00:43:00,520
intraoperative bronchospasm. 
False. 

919
00:43:00,800 --> 00:43:03,880
It has a very narrow therapeutic
index and a lot of side effects 

920
00:43:03,880 --> 00:43:06,960
like tachycardia and seizures. 
Is very much a second or third 

921
00:43:06,960 --> 00:43:09,520
line agent now. 
The inhaled beta agonists, 

922
00:43:09,520 --> 00:43:13,040
volatile agents, and magnesium 
are all superior and safer. 

923
00:43:13,120 --> 00:43:16,240
Last one, using a larger 
endotracheal tube, for example 

924
00:43:16,240 --> 00:43:20,360
size 8.5 versus A7 point O 
significantly reduces the work 

925
00:43:20,360 --> 00:43:23,280
of breathing during weaning. 
True, absolutely true. 

926
00:43:23,520 --> 00:43:26,960
You have to remember Poiseu's 
law resistance is inversely 

927
00:43:26,960 --> 00:43:29,280
proportional to the radius to 
the power of four. 

928
00:43:29,840 --> 00:43:32,840
A small increase in the tube's 
diameter drastically reduces the

929
00:43:32,840 --> 00:43:35,880
resistance to airflow. 
This can make a huge difference 

930
00:43:35,880 --> 00:43:38,520
for a patient with weak 
respiratory muscles trying to 

931
00:43:38,520 --> 00:43:40,680
wean. 
Expert This has been incredibly 

932
00:43:40,680 --> 00:43:42,320
thorough. 
I feel like we have covered the 

933
00:43:42,320 --> 00:43:45,960
basics, the advanced Physiology,
the pharmacology and the crisis 

934
00:43:45,960 --> 00:43:47,880
management. 
This is the whole package. 

935
00:43:47,880 --> 00:43:50,320
And we've tried to keep an exam 
focused at every step. 

936
00:43:50,840 --> 00:43:54,440
Just remember when you're in 
that exam, define your terms 

937
00:43:54,440 --> 00:43:58,680
clearly, always explain the why 
the underlying Physiology, 

938
00:43:58,920 --> 00:44:01,800
prioritize safety above all 
else, and don't fall for the 

939
00:44:01,800 --> 00:44:04,720
common traps like the hypoxic 
Dr. myth or the smoking 

940
00:44:04,720 --> 00:44:07,040
cessation timing. 
Thank you again for this master 

941
00:44:07,040 --> 00:44:09,400
class. 
To our listeners, you are now 

942
00:44:09,400 --> 00:44:11,680
armed with the knowledge to walk
into that exam hall. 

943
00:44:11,680 --> 00:44:15,200
Take a deep breath, a long 
exhalation preferably, and own 

944
00:44:15,200 --> 00:44:17,560
the room. 
Review your notes, practice 

945
00:44:17,560 --> 00:44:20,440
drawing that bitten sandwich 
loop, and we will see you on the

946
00:44:20,440 --> 00:44:22,640
next deep dive. 
Good luck to all of you.