1 00:00:00,040 --> 00:00:04,760 Welcome back to the Deep Dive. Today we are shifting gears 2 00:00:04,760 --> 00:00:06,800 pretty significantly. We're entering what we're 3 00:00:06,800 --> 00:00:09,640 calling exam mode. The hot seat. 4 00:00:09,880 --> 00:00:12,360 Exactly. We're simulating that's, you 5 00:00:12,360 --> 00:00:15,840 know, high pressure environment of the MD anesthesiology finals. 6 00:00:15,840 --> 00:00:19,040 And we're going to get very specific with a focus on the 7 00:00:19,040 --> 00:00:22,520 Gujarat University context. We got a whole stack of sources 8 00:00:22,520 --> 00:00:26,120 here, Morgan and Mikhail Miller's stolting various 9 00:00:26,120 --> 00:00:30,040 guidelines, and our mission is to tackle what I think is one of 10 00:00:30,040 --> 00:00:32,759 the most daunting topics in the whole syllabus. 11 00:00:32,800 --> 00:00:35,400 Oh, it is the anesthetic management of lobectomy and 12 00:00:35,400 --> 00:00:36,800 pneumonectomy. That's the one. 13 00:00:36,880 --> 00:00:40,040 It's daunting for a reason. I mean, this topic is probably 14 00:00:40,040 --> 00:00:42,720 the ultimate test of an anesthesiologist grasp of 15 00:00:42,720 --> 00:00:44,200 Physiology. It really is. 16 00:00:44,240 --> 00:00:45,760 How so? Well, think about what you're 17 00:00:45,760 --> 00:00:47,400 doing. You're taking a patient who, 18 00:00:47,800 --> 00:00:50,000 let's be honest, probably already has compromised lungs to 19 00:00:50,000 --> 00:00:52,240 begin with. A smoker, usually COPD. 20 00:00:52,480 --> 00:00:55,040 Usually then you put them in a position lateral that just 21 00:00:55,040 --> 00:00:57,840 completely defies how gravity normally helps the lungs work. 22 00:00:58,280 --> 00:01:01,680 Then you deliberately collapse one of those lungs, and then you 23 00:01:01,680 --> 00:01:03,600 open the chest to the atmosphere. 24 00:01:03,760 --> 00:01:06,080 It sounds like a list of things you should never do to a lung. 25 00:01:06,080 --> 00:01:08,920 It's a physiological trespass. That's the term for it, a 26 00:01:08,920 --> 00:01:11,920 trespass of the highest order. Physiological trespass. 27 00:01:12,840 --> 00:01:15,360 I like that. It sounds appropriately 28 00:01:15,360 --> 00:01:18,640 terrifying. So for this deep dive, I'm going 29 00:01:18,640 --> 00:01:21,600 to be the postgraduate student. You know, sweating it out. 30 00:01:21,600 --> 00:01:23,960 And I'll be the senior faculty examiner, pen in hand. 31 00:01:24,000 --> 00:01:25,840 Perfect. We need to cover everything. 32 00:01:25,840 --> 00:01:30,440 The long case presentation, the short notes, those really tricky 33 00:01:30,480 --> 00:01:32,480 Viva questions. We will, and you have to 34 00:01:32,480 --> 00:01:35,680 remember in the exam this topic can pop up anywhere. 35 00:01:35,680 --> 00:01:39,160 It's not just one question. You might get a long case, you 36 00:01:39,160 --> 00:01:43,520 know a 65 year old man with COPD and carcinoma of the lung posted 37 00:01:43,520 --> 00:01:46,760 for a section. Or you get a short note, write 38 00:01:46,760 --> 00:01:51,520 about one lung ventilation or discuss hypoxic pulmonary 39 00:01:51,520 --> 00:01:56,840 vasoconstriction HPVHPV exactly. Or my personal favorite, the 40 00:01:56,840 --> 00:01:59,760 Table V Viva where they just hand you a double lumen 2 and 41 00:01:59,760 --> 00:02:02,400 say talk. Or a chest X-ray with a total 42 00:02:02,400 --> 00:02:03,280 whiteout. Precisely. 43 00:02:03,280 --> 00:02:05,280 You have to be ready for all of it from all angles. 44 00:02:05,280 --> 00:02:07,640 OK, let's do it. We're following a really strict 45 00:02:07,640 --> 00:02:10,400 structure today, so we hit every single marking point. 46 00:02:11,039 --> 00:02:13,960 Let's start with part A, introduction and exam framing. 47 00:02:14,040 --> 00:02:16,160 Good place to start. So I'm in the exam hall. 48 00:02:16,320 --> 00:02:19,440 First question, define the procedures. 49 00:02:19,760 --> 00:02:21,960 I can't just say cutting out a piece of lung, can I? 50 00:02:22,400 --> 00:02:24,000 I need to be more precise. You do. 51 00:02:24,000 --> 00:02:25,840 Precision is everything. So let's start with the 52 00:02:25,840 --> 00:02:28,640 definitions. A lobectomy is the surgical 53 00:02:28,640 --> 00:02:31,040 removal of a single lobe of the lung. 54 00:02:31,120 --> 00:02:33,600 Simple enough. OK, but here's the nuance. 55 00:02:33,760 --> 00:02:35,720 This is the bit that gets you the extra marks. 56 00:02:36,600 --> 00:02:40,440 Physiologically, in the immediate acute post operative 57 00:02:40,440 --> 00:02:44,600 phase, a lobectomy behaves like a functional pneumonectomy. 58 00:02:44,680 --> 00:02:46,920 Whoa, hang on. A functional pneumonectomy. 59 00:02:46,920 --> 00:02:47,960 Can you unpack that? Sure. 60 00:02:48,000 --> 00:02:49,840 I mean, you still have other lobes on that side, right? 61 00:02:49,920 --> 00:02:51,320 Right. I take out the right upper lobe. 62 00:02:51,600 --> 00:02:53,240 The middle and lower lobes are still there. 63 00:02:53,360 --> 00:02:55,920 Anatomically, yes, they are. But are they working? 64 00:02:56,400 --> 00:02:59,040 Oh, immediately after the surgery, Those remaining lobes 65 00:02:59,040 --> 00:03:01,560 are, frankly, a mess. They've been compressed by 66 00:03:01,560 --> 00:03:03,400 retractors. They're edematists from being 67 00:03:03,400 --> 00:03:05,160 handled. They're often filled with 68 00:03:05,160 --> 00:03:07,200 secretions. They aren't really contributing 69 00:03:07,200 --> 00:03:10,320 much to gas exchange at all. So they're present but not 70 00:03:10,320 --> 00:03:11,560 participating. Exactly. 71 00:03:11,560 --> 00:03:15,040 So functionally, for a short period, you've essentially lost 72 00:03:15,040 --> 00:03:18,240 that entire side. It's a concept examiners love 73 00:03:18,240 --> 00:03:21,160 because it shows you're thinking about the acute recovery phase, 74 00:03:21,400 --> 00:03:24,240 not just the anatomy. OK, that's a brilliant point. 75 00:03:24,320 --> 00:03:27,640 Functional pneumonectomy. Got it and a pneumonectomy 76 00:03:27,640 --> 00:03:29,920 itself. That's the removal of the entire 77 00:03:29,920 --> 00:03:31,560 lung. No ambiguity there. 78 00:03:32,000 --> 00:03:34,720 And you must state that this carries A significantly higher 79 00:03:34,720 --> 00:03:39,560 mortality and involves a massive permanent physiological shift. 80 00:03:39,560 --> 00:03:41,360 And we'll get into that shift later, I imagine. 81 00:03:41,480 --> 00:03:44,200 Oh yes, particularly the strain on the right heart. 82 00:03:44,400 --> 00:03:45,560 We'll spend a lot of time on that. 83 00:03:45,680 --> 00:03:47,600 OK, So what about the indications? 84 00:03:47,600 --> 00:03:49,960 Why are we even doing these major procedures? 85 00:03:50,040 --> 00:03:51,880 Right. If you look at the standard 86 00:03:51,880 --> 00:03:56,280 Western textbooks like Morgan or Miller, the list is very clear. 87 00:03:56,520 --> 00:03:58,840 Number one by a long shot is malignancy. 88 00:03:58,960 --> 00:04:03,040 Bronchogenic carcinoma. The most common, yes, but, and 89 00:04:03,040 --> 00:04:06,040 this is absolutely crucial for your exams, for the Gujarat 90 00:04:06,040 --> 00:04:10,040 University context, you must mention infection high up on 91 00:04:10,040 --> 00:04:11,640 that list. You mean tuberculosis? 92 00:04:11,800 --> 00:04:16,399 I mean tuberculosis, absolutely. Post tubercular Bronchiectasis, 93 00:04:16,720 --> 00:04:21,600 a destroyed lung from chronic infection, lung abscesses, even 94 00:04:21,600 --> 00:04:24,080 fungal infections like Aspirgaloma. 95 00:04:24,160 --> 00:04:27,600 These are common cases we see. They are very common exam cases 96 00:04:27,600 --> 00:04:30,240 in your region. You simply cannot give a list of 97 00:04:30,240 --> 00:04:33,360 indications in an Indian exam without putting infection right 98 00:04:33,360 --> 00:04:35,840 up there with malignancy. It shows you know your local 99 00:04:35,840 --> 00:04:39,040 pathology. Good tip and trauma I suppose. 100 00:04:39,040 --> 00:04:42,440 Trauma bullish disease, sure, but let's stick with cancer for 101 00:04:42,440 --> 00:04:45,000 a second because it's so common. If you have a patient with lung 102 00:04:45,000 --> 00:04:48,480 cancer, there's a mnemonic you absolutely must know for 103 00:04:48,480 --> 00:04:51,440 assessing the disease itself. OK, it's the four Mims, the. 104 00:04:51,480 --> 00:04:54,320 Four Mims. I think I've seen this in KANA. 105 00:04:54,600 --> 00:04:57,600 This isn't about the patient's fitness for surgery, right? 106 00:04:57,800 --> 00:05:00,080 This is about the tumor's impact on the body. 107 00:05:00,200 --> 00:05:01,800 Correct. It's a framework to make sure 108 00:05:01,800 --> 00:05:04,240 you don't miss any of the systemic effects of the cancer. 109 00:05:04,320 --> 00:05:04,840 Right. What are they? 110 00:05:05,240 --> 00:05:08,720 First, M is for mass effects. This is the tumor itself 111 00:05:08,720 --> 00:05:11,600 physically pushing on things. Like SVC syndrome? 112 00:05:11,840 --> 00:05:17,600 Exactly superior vena cava syndrome or Pancos tumors up in 113 00:05:17,600 --> 00:05:21,400 the apex of the lung compressing the brachial plexus, causing arm 114 00:05:21,400 --> 00:05:22,880 pain and weakness. Corners. 115 00:05:23,400 --> 00:05:27,480 Coroner syndrome Yes, and nerve palsies, specifically the 116 00:05:27,480 --> 00:05:30,920 recurrent laryngeal nerve or the phrenic nerve if a patient comes 117 00:05:30,920 --> 00:05:33,360 to you pre op and they're hoarse. 118 00:05:33,360 --> 00:05:35,680 You have to worry about the recurrent laryngeal nerve. 119 00:05:35,760 --> 00:05:37,600 And not just because they've lost their voice. 120 00:05:37,640 --> 00:05:40,520 It means they've lost a vocal cord, which has huge 121 00:05:40,520 --> 00:05:43,360 implications for airway protection after extubation. 122 00:05:43,560 --> 00:05:45,320 It's a major red flag. Got it. 123 00:05:45,920 --> 00:05:47,920 Mass Effects. What's the second M? 124 00:05:48,000 --> 00:05:51,320 The second is metabolic effects. These are the perineoplastic 125 00:05:51,320 --> 00:05:54,360 syndromes, weird things, the tumor secrets that affect the 126 00:05:54,360 --> 00:05:55,960 whole body. Like SIADH. 127 00:05:55,960 --> 00:05:57,600 SIADH. So you need to check their 128 00:05:57,600 --> 00:05:59,400 sodium. Yeah, hypercalcemia. 129 00:05:59,400 --> 00:06:02,040 And the big one for us is Lambert Eaton, Myasthenic 130 00:06:02,040 --> 00:06:03,320 syndrome. Right, that's the one that looks 131 00:06:03,320 --> 00:06:06,080 a bit like myasthenia gravis, but their strength actually gets 132 00:06:06,080 --> 00:06:08,240 better with activity. That's the one often associated 133 00:06:08,240 --> 00:06:10,600 with small cell carcinoma. And why do we care? 134 00:06:10,640 --> 00:06:13,560 Muscle relaxants. They are incredibly sensitive to 135 00:06:13,560 --> 00:06:16,680 non depolarizing relaxants. If you missed that in the 136 00:06:16,680 --> 00:06:20,840 history and give a standard dose of say, rocaronium, you might 137 00:06:20,880 --> 00:06:24,360 have a patient who is paralyzed for hours and hours in the ICU. 138 00:06:24,360 --> 00:06:28,480 It's a classic Viva trap. OK, mass metabolic third M. 139 00:06:28,480 --> 00:06:33,360 Metastases, lung cancer, loves to travel, liver, bone, brain, 140 00:06:33,360 --> 00:06:34,920 adrenals. You need to know these have been 141 00:06:34,920 --> 00:06:38,120 looked for and ruled out. And the fourth medications these 142 00:06:38,120 --> 00:06:41,960 patients are often getting or have had chemotherapy and some 143 00:06:41,960 --> 00:06:44,640 of those drugs are notorious. The big one is bleomycin. 144 00:06:45,040 --> 00:06:47,040 Bleomycin Lung Pulmonary fibrosis. 145 00:06:47,040 --> 00:06:48,560 Yes. And what's the specific 146 00:06:48,560 --> 00:06:51,360 anesthetic implication of bleomycin toxicity? 147 00:06:51,360 --> 00:06:53,800 They're very sensitive to high concentrations of oxygen. 148 00:06:53,800 --> 00:06:56,720 Exactly, Bleomycin induced lung injury is made worse by 149 00:06:56,720 --> 00:06:59,200 hyperoxia. So for a patient with a history 150 00:06:59,200 --> 00:07:02,520 of bleomycin, you want to use the lowest possible FIO 2 to 151 00:07:02,520 --> 00:07:05,000 keep their Sats safe. So you're aiming for, say, 152 00:07:05,280 --> 00:07:07,760 9092%, not 100. Percent precisely. 153 00:07:08,080 --> 00:07:11,760 The other chemo drug to remember is doxorubicin or adriamycin. 154 00:07:11,760 --> 00:07:14,680 It causes cardiomyopathy, so you need to have a very close look 155 00:07:14,680 --> 00:07:17,920 at their heart function. That's a great framework mass 156 00:07:18,040 --> 00:07:22,120 metabolic metastasis medications that covers the disease. 157 00:07:22,120 --> 00:07:23,720 It does. OK, let's move on. 158 00:07:24,400 --> 00:07:28,240 Part B Preoperative assessment. This feels like the part of the 159 00:07:28,240 --> 00:07:31,320 long case where the examiner can just keep digging and digging. 160 00:07:31,600 --> 00:07:34,960 This is where you pass or fail. This is absolutely the core of 161 00:07:34,960 --> 00:07:37,280 the exam. If you can't properly assess the 162 00:07:37,280 --> 00:07:39,200 patient's fitness, the rest doesn't matter. 163 00:07:39,480 --> 00:07:42,160 The framework we use, which you'll find in Miller and all 164 00:07:42,160 --> 00:07:45,680 the standard texts, is the three legged stool approach. 165 00:07:45,760 --> 00:07:49,360 The three legged stool, OK. You need to assess 3 distinct 166 00:07:49,440 --> 00:07:53,040 but related areas to see if the patient can survive having a big 167 00:07:53,040 --> 00:07:55,800 piece of their lung removed. If any one of the legs is weak, 168 00:07:55,800 --> 00:07:57,960 the stool falls over. And the three legs are 169 00:07:58,240 --> 00:08:01,880 respiratory mechanics, lung prank malfunction and cardio 170 00:08:01,880 --> 00:08:03,360 pulmonary reserve. Correct. 171 00:08:03,600 --> 00:08:06,240 Let's take them one by one. First, respiratory mechanics. 172 00:08:06,240 --> 00:08:09,280 This is all about airflow. Can they move air in and out? 173 00:08:09,520 --> 00:08:11,880 We start with the history, dyspnea, cough, sputum. 174 00:08:12,280 --> 00:08:14,720 But the huge topic here, of course, is smoking. 175 00:08:14,800 --> 00:08:18,880 The classic Viva question Doctor The patient is a heavy smoker. 176 00:08:19,120 --> 00:08:21,320 Should we ask them to stop before surgery? 177 00:08:21,480 --> 00:08:23,160 And the answer needs to be nuanced. 178 00:08:23,800 --> 00:08:25,240 It's not just a simple yes or no. 179 00:08:25,240 --> 00:08:26,840 You have to break it down by time. 180 00:08:27,040 --> 00:08:31,680 OK, short term cessation, we're talking 12 to 48 hours is always 181 00:08:31,680 --> 00:08:32,760 beneficial. Always. 182 00:08:32,919 --> 00:08:34,400 Why is that? It's all about 183 00:08:34,400 --> 00:08:37,320 carboxyhemoglobin. Carbon monoxide binds to 184 00:08:37,320 --> 00:08:40,600 hemoglobin about 200 times more tightly than oxygen does. 185 00:08:40,840 --> 00:08:42,919 It just hogs all the seats on the bus, right? 186 00:08:43,360 --> 00:08:46,840 By stopping smoking for just a day or two, you clear out that 187 00:08:46,840 --> 00:08:49,440 Co. This shifts the oxygen 188 00:08:49,440 --> 00:08:52,400 dissociation curve back to the right where it should be and 189 00:08:52,400 --> 00:08:54,600 improve the delivery of oxygen to the tissues. 190 00:08:54,680 --> 00:08:57,600 That is always a good thing. But that doesn't really help 191 00:08:57,600 --> 00:09:00,240 their lungs, does it? The coughing and the phlegm. 192 00:09:00,240 --> 00:09:03,360 No, for that you need longer for the significant pulmonary 193 00:09:03,360 --> 00:09:04,800 benefits. We're talking reduced 194 00:09:04,800 --> 00:09:08,080 secretions, improve mucosillary transport, less airway 195 00:09:08,080 --> 00:09:10,600 reactivity. You need 4 to 8 weeks of 196 00:09:10,600 --> 00:09:12,040 cessation. That's the ideal. 197 00:09:12,040 --> 00:09:13,560 Okay, but. Here's the trap I've heard 198 00:09:13,560 --> 00:09:16,520 about. What if they stop smoking, say 2 199 00:09:16,520 --> 00:09:20,360 weeks before the operation? The famous exam trap, and it's a 200 00:09:20,360 --> 00:09:22,560 good one. There is some evidence, though 201 00:09:22,560 --> 00:09:25,360 it's a bit controversial, that stopping smoking in that one to 202 00:09:25,360 --> 00:09:28,800 two week window might actually increase your risk of pulmonary 203 00:09:28,800 --> 00:09:30,480 complications. How could that be? 204 00:09:30,800 --> 00:09:33,280 Well, the theory is that the volume of sputum they're 205 00:09:33,280 --> 00:09:36,840 producing hasn't had time to decrease yet, but the cessation 206 00:09:36,840 --> 00:09:39,640 might temporarily increase sputum viscosity, make it 207 00:09:39,640 --> 00:09:43,080 thicker, or increase airway irritability without the full 208 00:09:43,080 --> 00:09:45,800 benefit of improved clearance mechanisms kicking in. 209 00:09:45,840 --> 00:09:49,120 So you get thick sticky plugs. You might it can lead to mucus 210 00:09:49,120 --> 00:09:51,360 plugging. So while we always, always 211 00:09:51,480 --> 00:09:54,480 encourage cessation, you have to be aware of this controversial 212 00:09:54,480 --> 00:09:57,520 window. The ideal is 48 weeks. 213 00:09:57,880 --> 00:10:01,200 Short term, 48 hours is good. That two week zone is 1 to be 214 00:10:01,200 --> 00:10:03,000 wary of. OK, that's a great clinical 215 00:10:03,000 --> 00:10:04,760 parole. Now let's move to actually 216 00:10:04,760 --> 00:10:07,040 testing their mechanics. We're talking pulmonary function 217 00:10:07,040 --> 00:10:10,000 tests, PFTS. What are the numbers I need to 218 00:10:10,000 --> 00:10:12,520 have memorized? Spirometry is your main tool 219 00:10:12,520 --> 00:10:15,000 here, and the headline number, the one you look at first, is 220 00:10:15,000 --> 00:10:18,360 the FEV one. Forced excretory volume in one 221 00:10:18,360 --> 00:10:19,000 second. OK. 222 00:10:19,040 --> 00:10:21,920 Fev One. Historically we used to use 223 00:10:21,920 --> 00:10:25,080 absolute cut offs and you should know them just in case. 224 00:10:25,320 --> 00:10:28,160 Who were they? If the FEV 1 is greater than two 225 00:10:28,160 --> 00:10:30,560 liters, the patient was generally considered safe for a 226 00:10:30,560 --> 00:10:33,640 pneumonectomy. If the FEV one was greater than 227 00:10:33,640 --> 00:10:36,720 1.5 liters, they were considered safe for a lobectomy. 228 00:10:36,760 --> 00:10:39,600 But wait, absolute numbers can be a bit misleading, can't they? 229 00:10:39,600 --> 00:10:44,040 I mean if 2 liter fev one in a huge 6 foot 5 athlete is 230 00:10:44,040 --> 00:10:47,960 terrible, but in a tiny 5 foot elderly woman it might be 231 00:10:47,960 --> 00:10:50,000 fantastic. You are absolutely right and 232 00:10:50,000 --> 00:10:51,720 that's exactly why we moved away from them. 233 00:10:51,800 --> 00:10:54,400 We prefer percentages now and FEV. 234 00:10:54,440 --> 00:10:57,480 One greater than 80% of the predicted value for their age, 235 00:10:57,480 --> 00:11:00,080 sex and height is generally considered safe. 236 00:11:00,360 --> 00:11:03,680 But what if it's not? What if their FEV 1 is say 60% 237 00:11:03,680 --> 00:11:05,240 predicted? Does that mean we cancel the 238 00:11:05,240 --> 00:11:06,680 surgery? Not necessarily. 239 00:11:06,680 --> 00:11:07,960 This is where the real work begins. 240 00:11:07,960 --> 00:11:10,760 We have to calculate the predicted post operative FEV 1, 241 00:11:10,760 --> 00:11:13,120 the pipo FEV 1. Right, this is the formula you 242 00:11:13,120 --> 00:11:14,360 have to be able to write down in the view. 243 00:11:14,360 --> 00:11:16,000 You have to you must know it cold. 244 00:11:16,120 --> 00:11:21,920 The formula is PIPO FEV 1% equals the preoperative FEV 1% * 245 00:11:21,920 --> 00:11:24,680 1 minus the percentage of functional the lung tissue being 246 00:11:24,680 --> 00:11:26,440 removed divided by 100. OK. 247 00:11:26,440 --> 00:11:29,440 So to do that you need to know how much lung you're removing. 248 00:11:29,720 --> 00:11:33,120 And for that you need to know the anatomy, the segments. 249 00:11:33,240 --> 00:11:34,960 Yes. For the most precise 250 00:11:34,960 --> 00:11:38,320 calculations, which you'll see in major texts like Miller, we 251 00:11:38,320 --> 00:11:41,080 use a total of 42 sub segments in the lungs. 252 00:11:41,120 --> 00:11:44,520 The right lung has about 20, two of these and the left has 20. 253 00:11:44,680 --> 00:11:47,040 So you kind of how many segments the surgeon is taking. 254 00:11:47,040 --> 00:11:48,720 Out exactly. Let's say you're removing the 255 00:11:48,720 --> 00:11:51,640 right upper lobe. That's roughly six of those 42 256 00:11:51,640 --> 00:11:53,760 segments. When you do the math, you 257 00:11:53,760 --> 00:11:56,520 calculate what percentage of the total that is and you plug it 258 00:11:56,520 --> 00:11:58,400 into the formula and. What do you do with the number 259 00:11:58,400 --> 00:12:00,520 you get? This brings us to the crucial 260 00:12:00,520 --> 00:12:04,560 4030 rule. If the resulting PIPO FEV 1 is 261 00:12:04,560 --> 00:12:07,880 greater than 40%, the patient is considered low risk. 262 00:12:08,360 --> 00:12:10,360 You can generally proceed with confidence. 263 00:12:10,360 --> 00:12:14,480 OK if the PIPO FEV 1 is less than 30%, they are high risk. 264 00:12:15,040 --> 00:12:17,560 Spirometry alone is not enough to clear this patient. 265 00:12:17,680 --> 00:12:19,800 You absolutely must do further testing. 266 00:12:19,840 --> 00:12:22,840 And what about that Gray zone in between 30 to 40%? 267 00:12:22,880 --> 00:12:25,440 That's the zone where you need to look very, very carefully at 268 00:12:25,440 --> 00:12:28,520 the other two legs of the stool. Your clinical judgment really 269 00:12:28,520 --> 00:12:30,680 comes into play. Okay, which brings us to the 270 00:12:30,680 --> 00:12:33,640 second leg of the stool. Lung parenchymal function. 271 00:12:34,040 --> 00:12:35,160 This isn't about airflow anymore. 272 00:12:35,160 --> 00:12:37,200 This is about gas exchange. Precisely. 273 00:12:37,240 --> 00:12:40,640 You can have a patient with brilliant airflow, a great FEV 274 00:12:40,720 --> 00:12:43,920 one, but their lungs are terrible at getting oxygen into 275 00:12:43,920 --> 00:12:46,240 the blood. Think of emphysema, where the 276 00:12:46,240 --> 00:12:48,800 alveolar walls are just destroyed, or pulmonary 277 00:12:48,800 --> 00:12:50,760 fibrosis, where they're thick and stiff. 278 00:12:51,080 --> 00:12:53,280 And the test for this is the DLCO. 279 00:12:53,280 --> 00:12:57,360 DLCO diffusing capacity of the lung for carbon monoxide. 280 00:12:57,360 --> 00:13:00,920 You must mention this. DLCO is an independent predictor 281 00:13:00,920 --> 00:13:04,120 of mortality. A low DLCO is a huge warning 282 00:13:04,120 --> 00:13:07,960 sign even if the FEV 1 looks OK. And we calculate a predicted 283 00:13:07,960 --> 00:13:10,960 post operative DLCO 2. The exact same way you use the 284 00:13:10,960 --> 00:13:14,720 same formula As for the FEV 1. And again, a tipo DLCO of less 285 00:13:14,720 --> 00:13:18,320 than 40% is a major red flag for high perioperative risk. 286 00:13:18,480 --> 00:13:19,800 OK. So we've checked mechanics with 287 00:13:19,880 --> 00:13:23,480 FEV 1 and parenchyma with DLCO. The third leg is cardio 288 00:13:23,480 --> 00:13:25,920 pulmonary reserve, the link between the heart and lungs. 289 00:13:26,080 --> 00:13:28,720 This is what you test when the first two legs are looking a bit 290 00:13:28,720 --> 00:13:32,160 wobbly. If your patient is in that 3040% 291 00:13:32,160 --> 00:13:37,640 Gray zone for either PPOFE V1 or PPODLCO, you have to assess 292 00:13:37,640 --> 00:13:40,000 their reserve. You need to know if their heart 293 00:13:40,000 --> 00:13:43,040 can actually pump enough oxygenated blood to the tissues 294 00:13:43,040 --> 00:13:45,920 when their lungs are severely compromised by the surgery. 295 00:13:46,080 --> 00:13:49,520 And the gold standard test for this is CPECP. 296 00:13:49,520 --> 00:13:52,320 E Cardio pulmonary exercise testing. 297 00:13:52,880 --> 00:13:55,840 You put them on a treadmill or a bike with a mask on and you 298 00:13:55,840 --> 00:13:59,320 measure their VO2 Max, their maximum oxygen consumption now. 299 00:13:59,320 --> 00:14:02,160 I have to be honest, I suspect most hospitals, even big 300 00:14:02,160 --> 00:14:05,600 teaching ones, don't have ACP lab that's readily available for 301 00:14:05,600 --> 00:14:08,280 every single thoracic case. That's true, it's often not 302 00:14:08,280 --> 00:14:10,600 available, but for the exam you have to know the numbers. 303 00:14:10,600 --> 00:14:12,720 You have to be able to talk about the gold stearic numbers. 304 00:14:13,000 --> 00:14:16,000 AVO 2 Max greater than 20 molecule Jimin is generally 305 00:14:16,000 --> 00:14:17,400 safe. They have good reserve. 306 00:14:17,880 --> 00:14:21,680 AVO 2 Max less than 10 molecule. Edumen represents a prohibitive 307 00:14:21,680 --> 00:14:24,600 risk. The mortality is extremely high. 308 00:14:24,880 --> 00:14:26,600 You should probably not be doing the surgery. 309 00:14:26,600 --> 00:14:30,080 That's a hard stop. It's a hard stop and that 1015 310 00:14:30,080 --> 00:14:34,600 mil collision range is that high risk Gray zone again where you 311 00:14:34,600 --> 00:14:37,520 have a very serious discussion with the surgeon in the family. 312 00:14:37,560 --> 00:14:42,320 OK, and if we don't have C Pete, which is most of the time, we 313 00:14:42,320 --> 00:14:44,600 fall back on the poor man's C Pete. 314 00:14:45,240 --> 00:14:48,760 The stair climbing test. It sounds so simple, almost 315 00:14:48,760 --> 00:14:52,200 rudimentary, but it correlates surprisingly well with VO2 Max. 316 00:14:52,200 --> 00:14:55,000 So what's the metric? If the patient can climb three 317 00:14:55,000 --> 00:14:57,440 flights of stairs without stopping for breath, they can 318 00:14:57,440 --> 00:15:00,040 likely tolerate a lobectomy. And for a pneumonectomy? 319 00:15:00,200 --> 00:15:01,720 You want to see them climb five flights? 320 00:15:01,720 --> 00:15:04,600 A flight is usually about 20 steps, and as an examiner, I 321 00:15:04,600 --> 00:15:05,760 always like to add a little joke. 322 00:15:05,880 --> 00:15:07,960 Make sure they're actually climbing the stairs, doctor, not 323 00:15:07,960 --> 00:15:09,240 just telling you they took the lift. 324 00:15:09,240 --> 00:15:10,680 Right. And one last thing before we 325 00:15:10,680 --> 00:15:14,680 leave pre op, the heart, specifically the right heart. 326 00:15:14,800 --> 00:15:17,240 Absolutely vital. You cannot forget this, 327 00:15:17,240 --> 00:15:19,360 especially for a pneumonectomy. Think about it. 328 00:15:19,600 --> 00:15:22,680 The surgeon is about to clamp the main pulmonary artery on one 329 00:15:22,680 --> 00:15:24,560 side. OK, that means the right 330 00:15:24,560 --> 00:15:27,160 ventricle. The RV suddenly has to pump the 331 00:15:27,160 --> 00:15:30,480 entire cardiac output through only 50% of the pulmonary 332 00:15:30,480 --> 00:15:33,480 vascular bed. The resistance must skyrocket. 333 00:15:33,720 --> 00:15:35,840 It does the pulmonary vascular resistance. 334 00:15:35,840 --> 00:15:39,720 PVR goes way up. Now if the patient already has 335 00:15:39,720 --> 00:15:43,080 pre-existing pulmonary hypertension, PHTN or a weak 336 00:15:43,120 --> 00:15:47,080 failing RV, what we call core pulmonale, that clamp could be 337 00:15:47,080 --> 00:15:49,480 the final straw. It could send them into acute 338 00:15:49,480 --> 00:15:52,960 right heart failure and cardiac arrest right there on the table. 339 00:15:53,120 --> 00:15:56,560 So you have to get an echo. You must get an echocardiogram 340 00:15:56,560 --> 00:15:59,800 to look at the RV function and estimate the pulmonary artery 341 00:15:59,800 --> 00:16:01,760 pressures. The PA pressures are 342 00:16:01,760 --> 00:16:03,840 significantly elevated. The surgery might be 343 00:16:03,840 --> 00:16:05,640 contraindicated. It's that serious? 344 00:16:05,640 --> 00:16:09,200 OK, that pre op assessment is locked in four Ms. for the 345 00:16:09,200 --> 00:16:11,920 tumor, the three legged stool for the patient, mechanics, 346 00:16:12,440 --> 00:16:15,160 pericoma. Reserve the 4030 rule for your 347 00:16:15,160 --> 00:16:18,280 calculations and a specific check of the right heart. 348 00:16:18,360 --> 00:16:20,760 That's a very solid summary. Let's move to part C. 349 00:16:21,000 --> 00:16:23,000 Physiological changes during lung resection. 350 00:16:23,120 --> 00:16:25,560 This is where things get really interesting with gravity and 351 00:16:25,560 --> 00:16:27,880 positioning. Yes, the exam question here is 352 00:16:27,880 --> 00:16:31,240 often framed as doctor describe the changes in ventilation 353 00:16:31,240 --> 00:16:34,360 perfusion matching when you turn an anesthetized paralyzed 354 00:16:34,360 --> 00:16:36,200 patient into the lateral position. 355 00:16:36,360 --> 00:16:38,680 OK, let's break that down. Start with the awake patient. 356 00:16:38,960 --> 00:16:40,920 I'm lying on my side, breathing on my own. 357 00:16:41,120 --> 00:16:44,600 What's happening? So in an awake, spontaneously 358 00:16:44,600 --> 00:16:48,160 breathing person in the lateral position, things are actually 359 00:16:48,160 --> 00:16:50,640 pretty good. Gravity pulls most of the blood 360 00:16:50,640 --> 00:16:53,160 down to the dependent lung, the lower lung. 361 00:16:53,200 --> 00:16:55,200 OK. So perfusion is greatest in the 362 00:16:55,200 --> 00:16:56,160 dependent lung. Right. 363 00:16:56,400 --> 00:16:59,680 And what about ventilation? The diaphragm on that lower side 364 00:16:59,680 --> 00:17:02,680 is pushed up by the weight of the abdominal contents, but 365 00:17:02,680 --> 00:17:05,640 because it's a muscle and it's stretched, it's on a more 366 00:17:05,640 --> 00:17:08,359 favorable part of its contraction curve, so it 367 00:17:08,359 --> 00:17:11,520 contracts more efficiently. The lower lung gets the most 368 00:17:11,520 --> 00:17:14,960 blood and the most ventilation. So V&Q are matched. 369 00:17:15,720 --> 00:17:19,200 The key matching is pretty good, everything is fine, but then we. 370 00:17:19,200 --> 00:17:20,960 Give them anesthesia and paralyze them. 371 00:17:20,960 --> 00:17:23,520 And all that beautiful Physiology goes out the window. 372 00:17:23,760 --> 00:17:25,839 Chaos ensues. What happens first? 373 00:17:26,240 --> 00:17:29,560 Well, you've paralyzed them so that heavy mediastinum, the 374 00:17:29,560 --> 00:17:33,160 heart and great vessels just slumps down with gravity 375 00:17:33,320 --> 00:17:36,800 compressing that lower lung. The abdominal contents are still 376 00:17:36,800 --> 00:17:39,960 pushing up against the lower diaphragm, but now the diaphragm 377 00:17:39,960 --> 00:17:42,800 is paralyzed. It's just a floppy sheet, it 378 00:17:42,800 --> 00:17:45,240 can't push back. So the lower lung gets squashed 379 00:17:45,240 --> 00:17:46,920 from both sides. It gets squashed. 380 00:17:47,000 --> 00:17:50,080 The dependent lung, the good lung that's getting all the 381 00:17:50,080 --> 00:17:53,200 blood flow from gravity, becomes compressed and starts to develop 382 00:17:53,200 --> 00:17:55,280 atelectasis. And what's happening to the 383 00:17:55,280 --> 00:17:57,120 upper lung, the non dependent one that's. 384 00:17:57,120 --> 00:18:00,920 The lung we're about to operate on, it's up high, so gravity is 385 00:18:00,920 --> 00:18:03,480 pulling blood away from it. And because the chest is 386 00:18:03,480 --> 00:18:05,680 eventually opened, it becomes very compliant. 387 00:18:06,240 --> 00:18:09,240 The ventilator finds it very easy to push air into it. 388 00:18:09,240 --> 00:18:11,000 It's the path of least resistance. 389 00:18:11,000 --> 00:18:15,400 So you have a situation where the lower lung is perfused but 390 00:18:15,400 --> 00:18:17,200 not well ventilated. That's a shunt. 391 00:18:17,480 --> 00:18:20,040 And the upper lung is ventilated but not well perfused. 392 00:18:20,040 --> 00:18:23,040 That's Dead Space. It's the perfect recipe for a 393 00:18:23,040 --> 00:18:26,960 severe VQ mismatch and hypoxia. And then, just to make things 394 00:18:26,960 --> 00:18:30,720 even worse, we deliberately stop all ventilation to that upper 395 00:18:30,720 --> 00:18:32,520 lung. We start one lung ventilation. 396 00:18:32,600 --> 00:18:35,160 Exactly. Now we've created a massive 397 00:18:35,160 --> 00:18:38,280 intentional shunt. We've collapsed the non 398 00:18:38,280 --> 00:18:40,480 dependent lung. Blood is still flowing through 399 00:18:40,480 --> 00:18:43,280 it thanks to gravity, but it's picking up 0 oxygen. 400 00:18:43,280 --> 00:18:46,520 It's a huge right to left shunt. Which should cause profound 401 00:18:46,520 --> 00:18:49,520 hypoxemia, but it often doesn't because the body has a trick up 402 00:18:49,520 --> 00:18:50,920 its sleeve. It does. 403 00:18:50,920 --> 00:18:53,080 It has a crucial defense mechanism. 404 00:18:53,320 --> 00:18:56,600 HPV, hypoxic pulmonary vasoconstriction. 405 00:18:56,720 --> 00:19:00,760 HPV is a huge short note topic. Can you define it very clearly? 406 00:19:00,960 --> 00:19:05,360 Is it for a theory paper? Certainly HPV is a unique local 407 00:19:05,360 --> 00:19:08,720 physiological reflex. When the alveoli and a specific 408 00:19:08,720 --> 00:19:11,600 area of the lung become hypoxic, meaning there's low oxygen in 409 00:19:11,600 --> 00:19:14,960 the air sacs, the small pulmonary arterioles supplying 410 00:19:14,960 --> 00:19:17,440 that exact area constrict. It's the opposite of what 411 00:19:17,440 --> 00:19:19,040 happens in the systemic circulation. 412 00:19:19,040 --> 00:19:23,280 It is systemically hypoxia causes vasodilation in the lung. 413 00:19:23,280 --> 00:19:25,440 It causes vasoconstriction. This is smart. 414 00:19:25,640 --> 00:19:28,120 It increases the vascular resistance in the hypoxic 415 00:19:28,120 --> 00:19:31,000 collapsed lung and automatically diverts blood away from it, 416 00:19:31,240 --> 00:19:34,440 rerouting it towards the ventilated, oxygenated dependent 417 00:19:34,440 --> 00:19:36,080 lungs. So it actively tries to reduce 418 00:19:36,080 --> 00:19:37,440 the shunt. It does. 419 00:19:37,480 --> 00:19:40,640 It's remarkably effective. It reduces the shunt flow by 420 00:19:40,640 --> 00:19:43,040 about 50%. It's the main reason when our 421 00:19:43,040 --> 00:19:45,840 patients don't become profoundly cyanotic the second we start 422 00:19:45,960 --> 00:19:48,240 OLV. But as anesthesiologist, we have 423 00:19:48,240 --> 00:19:51,800 a whole arsenal of drugs and techniques that can accidentally 424 00:19:51,800 --> 00:19:54,200 mess this up. This is the classic Viva trap. 425 00:19:54,440 --> 00:19:57,960 The examiner will lean forward and say, doctor, what anesthetic 426 00:19:57,960 --> 00:20:01,440 factors can inhibit this protective HPV reflex? 427 00:20:01,440 --> 00:20:05,920 OK, let's listen. #1 volatile anesthetics, Isoflurane, 428 00:20:05,920 --> 00:20:10,200 subaflurane, desflurane. They're all direct vasodilators. 429 00:20:10,520 --> 00:20:12,960 At concentrations greater than about one MSC, they 430 00:20:12,960 --> 00:20:16,320 significantly inhibit HPV. So the practical take away is 431 00:20:16,320 --> 00:20:20,320 keep your gas low. Keep your MC below 1 or even 432 00:20:20,320 --> 00:20:23,440 better, consider using tyvatotal intravenous anesthesia with 433 00:20:23,440 --> 00:20:26,160 propofol. Propofol does not inhibit HPV, 434 00:20:26,160 --> 00:20:28,680 which is a major advantage in these cases. 435 00:20:28,760 --> 00:20:32,720 OK, what else #2 Vasodilators. Things like nitroglycerin, 436 00:20:32,720 --> 00:20:35,040 sodium nitropresside, calcium channel blockers. 437 00:20:35,480 --> 00:20:37,680 If the patients blood pressure goes up and you treat it with a 438 00:20:37,680 --> 00:20:40,200 systemic vasodilator, you're going to dilate everything, 439 00:20:40,200 --> 00:20:41,960 including the vessels in that collapsed lung. 440 00:20:42,320 --> 00:20:44,360 You'll increase the shunt and the saturation will drop. 441 00:20:44,520 --> 00:20:47,040 So you might be better off deepening the anesthetic rather 442 00:20:47,040 --> 00:20:49,640 than reaching for a vasodilator. Often, yes. 443 00:20:50,160 --> 00:20:52,160 What else? Infection or sepsis? 444 00:20:52,520 --> 00:20:55,360 The inflammatory mediators completely override the 445 00:20:55,360 --> 00:20:57,880 constriction reflex. So in your patient with a lung 446 00:20:57,880 --> 00:21:01,720 Abscess or TB, expect their HPV to be pretty weak from the 447 00:21:01,720 --> 00:21:03,040 start. Anything else? 448 00:21:03,200 --> 00:21:06,760 A couple more hypocapnia. Blowing off too much CO2 causes 449 00:21:06,760 --> 00:21:09,760 a general pulmonary vasodilation, and very high 450 00:21:09,760 --> 00:21:12,680 pressures in the pulmonary artery can mechanically force 451 00:21:12,720 --> 00:21:15,000 open those constricted vessels. OK. 452 00:21:15,040 --> 00:21:18,960 So keep volatiles low. Avoid systemic vasodilators if 453 00:21:18,960 --> 00:21:21,160 you can. Now let's talk specifically 454 00:21:21,160 --> 00:21:23,080 about the Physiology of a pneumonectomy. 455 00:21:23,080 --> 00:21:26,200 You mentioned the RV strain. Yes, this is a huge topic. 456 00:21:26,440 --> 00:21:29,080 With a pneumonectomy, you are instantly and permanently 457 00:21:29,080 --> 00:21:32,240 removing 50% of the entire pulmonary vascular bed. 458 00:21:32,480 --> 00:21:35,360 This causes an immediate and sustained increase in pulmonary 459 00:21:35,360 --> 00:21:38,240 vascular resistance. The RV has to work much, much 460 00:21:38,240 --> 00:21:40,400 harder to push blood through the remaining lung. 461 00:21:40,720 --> 00:21:42,960 If that RV is already weak, it can fail. 462 00:21:42,960 --> 00:21:44,800 And that's when cardiac output plummets. 463 00:21:45,000 --> 00:21:50,360 And you get systemic hypotension and shock postoperatively. 464 00:21:50,360 --> 00:21:53,880 There's also the issue of the empty space that hematorax will 465 00:21:53,880 --> 00:21:56,960 slowly fill with serous sanguinous fluid over days to 466 00:21:56,960 --> 00:21:59,640 wince the media. Steinem will eventually shift 467 00:21:59,640 --> 00:22:02,880 over to fill that space, but acutely we have to be extremely 468 00:22:02,880 --> 00:22:06,280 careful with positioning to avoid sudden, dangerous shifts 469 00:22:06,480 --> 00:22:09,280 that can kink the great vessels. OK, let's move into the 470 00:22:09,280 --> 00:22:11,760 operating room Part D, intraoperative anesthetic 471 00:22:11,760 --> 00:22:13,480 management. We've done our pre op. 472 00:22:13,480 --> 00:22:16,360 We understand the Physiology. Now we have to actually do the 473 00:22:16,360 --> 00:22:19,200 case right, The choice of anesthesia, it has to be general 474 00:22:19,200 --> 00:22:22,120 anesthesia, that's a given. But what about analgesia? 475 00:22:22,480 --> 00:22:25,520 For an open thoracotomy, the thoracic epidural is still the 476 00:22:25,520 --> 00:22:27,320 gold standard. There's really no debate about 477 00:22:27,320 --> 00:22:28,520 that. Why is it so good? 478 00:22:28,720 --> 00:22:32,200 It provides superior analgesia which isn't just about comfort. 479 00:22:32,640 --> 00:22:36,000 Excellent pain relief allows the patient to cough effectively and 480 00:22:36,000 --> 00:22:38,120 take deep breaths post operatively. 481 00:22:38,640 --> 00:22:41,800 This is crucial for clearing secretions and preventing 482 00:22:41,800 --> 00:22:44,480 atelectasis and pneumonia. And where do you place it? 483 00:22:44,720 --> 00:22:47,360 Usually in the mid thoracic region, somewhere around T4 to 484 00:22:47,360 --> 00:22:51,040 T8 and you almost always place it before you induce anesthesia 485 00:22:51,040 --> 00:22:53,400 while the patient is awake and can tell you if they feel any 486 00:22:53,400 --> 00:22:54,440 paresthesia. OK. 487 00:22:54,640 --> 00:22:57,080 And monitoring what's the absolute minimum? 488 00:22:57,160 --> 00:23:00,680 Standard monitors of course, but the one that is non negotiable 489 00:23:00,680 --> 00:23:03,560 is an ulterior line. It is absolutely mandatory. 490 00:23:03,600 --> 00:23:05,000 Why mandatory? Two reasons. 491 00:23:05,360 --> 00:23:08,080 First, you need beat to beat blood pressure monitoring. 492 00:23:08,520 --> 00:23:12,280 The surgeon can easily compress the heart or great vessels or a 493 00:23:12,280 --> 00:23:15,320 sudden mediastinal shift can occur causing catastrophic 494 00:23:15,320 --> 00:23:18,120 hypotension in a heartbeat. You can't wait for a cuff to 495 00:23:18,120 --> 00:23:20,640 cycle. Second, you need it for frequent 496 00:23:20,640 --> 00:23:23,920 arterial blood gases to check your oxygenation and ventilation 497 00:23:23,920 --> 00:23:27,200 during one lung ventilation. And a central line ACVP. 498 00:23:27,360 --> 00:23:30,760 It's more controversial, ACVP reading is not very accurate for 499 00:23:30,760 --> 00:23:33,840 judging fluid responsiveness when the chest is open, but it 500 00:23:33,840 --> 00:23:35,440 can be useful for looking at trends. 501 00:23:35,440 --> 00:23:37,960 And of course it gives you reliable central venous access 502 00:23:37,960 --> 00:23:39,400 for drugs. OK, now the big one. 503 00:23:39,560 --> 00:23:42,480 The key technical skill, lung isolation. 504 00:23:42,800 --> 00:23:44,920 We have to collapse one lung for the surgeon. 505 00:23:45,040 --> 00:23:47,400 How do we do it? The standard answer, the 506 00:23:47,400 --> 00:23:50,440 workhorse is the double lumen tube, the DLT. 507 00:23:50,680 --> 00:23:52,640 And for the exam I need to know the anatomy. 508 00:23:52,640 --> 00:23:55,880 I remember you saying we almost always prefer a left sided DLT. 509 00:23:55,920 --> 00:23:59,000 Almost always, even if you're operating on the left lung. 510 00:23:59,120 --> 00:24:02,280 Explain that again, why not use a right DLT for a left sided 511 00:24:02,280 --> 00:24:04,000 surgery? It seems more intuitive. 512 00:24:04,040 --> 00:24:05,880 It seems intuitive, but it's a trap. 513 00:24:06,080 --> 00:24:08,880 It's all about the anatomy of the right main bronchus. 514 00:24:08,880 --> 00:24:12,320 It's very short, and crucially, the takeoff for the right upper 515 00:24:12,320 --> 00:24:16,040 lobe bronchus is very high up, sometimes less than 2cm from the 516 00:24:16,040 --> 00:24:17,080 Carina. I see. 517 00:24:17,360 --> 00:24:21,520 If you try to place a right DLT, the blue bronchial cuff very 518 00:24:21,520 --> 00:24:25,640 often inflates over and blocks that right upper lobe orifice, 519 00:24:25,800 --> 00:24:28,720 so you end up with an unventilated RUL which causes 520 00:24:28,720 --> 00:24:32,000 atelectasis and hypoxia. It's very hard to position 521 00:24:32,000 --> 00:24:33,720 correctly. And the left main bronchus is 522 00:24:33,720 --> 00:24:35,440 different. It's much more forgiving. 523 00:24:35,520 --> 00:24:38,600 It's longer, about four to 5 centimeters, and has a simpler 524 00:24:38,600 --> 00:24:40,800 anatomy. So a left DLT gives you a much 525 00:24:40,800 --> 00:24:42,960 bigger margin for error. It's just safer. 526 00:24:43,240 --> 00:24:47,160 The only real indication for a right DLT is if there's a tumor 527 00:24:47,280 --> 00:24:50,760 or a stricture physically in the way of placing a left sided 1. 528 00:24:51,040 --> 00:24:54,880 OK, left DLT it is. And what if you can't get a D, 529 00:24:54,880 --> 00:24:57,600 Lt. N Say a patient with a known 530 00:24:57,600 --> 00:25:00,440 difficult airway or someone with a tracheostomy. 531 00:25:00,880 --> 00:25:04,080 Then your backup plan is a bronchial blocker. 532 00:25:04,600 --> 00:25:07,280 This is essentially a thin catheter with a balloon on the 533 00:25:07,280 --> 00:25:10,240 end that you pass down through a regular single lumen 534 00:25:10,240 --> 00:25:13,360 endotracheal tube and then guide it into the bronchus you want to 535 00:25:13,360 --> 00:25:13,960 block. Right? 536 00:25:14,200 --> 00:25:16,880 But here's the most important point about isolation, and you 537 00:25:16,880 --> 00:25:19,680 have to say this in the exam. Whatever device you use, 538 00:25:20,040 --> 00:25:23,520 auscultation is unreliable. You might listen to the chest 539 00:25:23,520 --> 00:25:25,480 and your breath sounds where you expect them and think you're 540 00:25:25,480 --> 00:25:27,320 perfect position, but you could be wrong. 541 00:25:27,480 --> 00:25:30,160 So what's the gold standard? The gold standard for confirming 542 00:25:30,160 --> 00:25:33,520 the position of your DLT or bronchial blocker is fiber optic 543 00:25:33,520 --> 00:25:36,120 bronchoscopy. You must say I will confirm 544 00:25:36,120 --> 00:25:38,600 correct placement with a flexible bronchoscope. 545 00:25:39,000 --> 00:25:41,720 The examiner needs to hear that you prioritize safety above all 546 00:25:41,720 --> 00:25:42,480 else. OK. 547 00:25:42,800 --> 00:25:46,280 The tube is in position. Confirmed we start one lung 548 00:25:46,280 --> 00:25:48,800 ventilation. How do we set the ventilator? 549 00:25:48,800 --> 00:25:51,240 This seems critical. It is, and the strategy has 550 00:25:51,240 --> 00:25:53,640 really evolved. We've moved completely away from 551 00:25:53,640 --> 00:25:58,720 the old days of using big tidal volumes to try and force oxygen 552 00:25:58,720 --> 00:26:01,240 in. We now use a protective lung 553 00:26:01,240 --> 00:26:03,960 ventilation strategy. What does that mean in practice? 554 00:26:04,200 --> 00:26:06,800 It means low tidal volumes. Your tidal volume should be 555 00:26:06,800 --> 00:26:09,360 between 4:00 to 6:00 millikilograms, and that's based 556 00:26:09,360 --> 00:26:12,200 on their ideal body weight, not their actual weight to avoid. 557 00:26:12,200 --> 00:26:14,560 Blowing up that one good lung. Exactly. 558 00:26:14,720 --> 00:26:17,440 You want to avoid volume trauma and barotrauma. 559 00:26:18,080 --> 00:26:21,240 And what else do we add? Peep Peep is essential. 560 00:26:21,480 --> 00:26:24,960 You need to add about 5 to 10 centimeter H2O of PEEP to the 561 00:26:24,960 --> 00:26:28,360 dependent ventilated lung. This helps to counteract all 562 00:26:28,360 --> 00:26:31,440 that compression we talked about and keeps the alveoli open, 563 00:26:31,440 --> 00:26:33,640 preventing atelectasis. And the respiratory rate? 564 00:26:33,840 --> 00:26:36,760 You adjust the rate to keep the end title CO2 in a reasonable 565 00:26:36,760 --> 00:26:38,880 range. A little bit of hypercapnia is 566 00:26:38,880 --> 00:26:40,480 actually fine. We call it permissive 567 00:26:40,480 --> 00:26:43,560 hypercapnia as long as the patient's pH stays above about 568 00:26:43,560 --> 00:26:46,440 7.25. It's well tolerated and much 569 00:26:46,440 --> 00:26:49,520 safer than trying to normalize the CO2 with huge ventilator 570 00:26:49,520 --> 00:26:51,640 pressures. OK, the surgeon starts working, 571 00:26:51,920 --> 00:26:54,080 the lung is collapsed, everything's going smoothly, and 572 00:26:54,080 --> 00:26:59,240 then suddenly the pulse oximeter starts to drop 9590808580. 573 00:26:59,320 --> 00:27:01,600 The dreaded hypoxia on table scenario. 574 00:27:01,600 --> 00:27:04,240 What's the protocol? I need a step by step drill for 575 00:27:04,240 --> 00:27:06,280 the Viva. This needs to be an automatic 576 00:27:06,280 --> 00:27:08,280 sequential response. You rattle this off without 577 00:27:08,280 --> 00:27:09,200 thinking. Let's hear it. 578 00:27:09,200 --> 00:27:13,600 Step 1 FIO 2 to 100%. Don't hesitate, just crank it up 579 00:27:13,640 --> 00:27:14,720 OK. Step 2. 580 00:27:15,080 --> 00:27:18,080 Check the position of your tube. Grab the bronchoscope. 581 00:27:18,400 --> 00:27:21,160 The DLT very often gets dislodged when the surgeon 582 00:27:21,160 --> 00:27:23,920 manipulates the lung or the patient is repositioned. 583 00:27:24,280 --> 00:27:26,960 This is the most common cause. Fix it if it's moved. 584 00:27:26,960 --> 00:27:28,120 Makes sense? Step 3. 585 00:27:28,120 --> 00:27:31,480 Suction both lungs. A mucus plug can ruin your day. 586 00:27:31,760 --> 00:27:34,560 Suction the ventilated lumen and the collapsed lumen. 587 00:27:35,200 --> 00:27:38,400 Step 4 Perform a recruitment maneuver on the dependent 588 00:27:38,480 --> 00:27:41,680 ventilated lung. A gentle, sustained inflation to 589 00:27:41,680 --> 00:27:45,400 pop open any areas of atelectasis, but only if the 590 00:27:45,400 --> 00:27:48,320 patient is hemodynamically stable enough to tolerate it. 591 00:27:48,400 --> 00:27:49,880 And if the sats are still dropping? 592 00:27:49,920 --> 00:27:53,720 This is Step 5 and this is the high yield money answer for the 593 00:27:53,720 --> 00:27:55,920 exam. You apply CPAP to the non 594 00:27:55,920 --> 00:27:58,680 dependent operative lung. So you're putting oxygen into 595 00:27:58,680 --> 00:28:00,480 the collapsed lung? Exactly. 596 00:28:00,640 --> 00:28:03,800 You connect a CPAP circuit to the lumen going to the collapsed 597 00:28:03,800 --> 00:28:07,400 lung. Even a small amount, say 510 598 00:28:07,400 --> 00:28:11,720 centimeter H2O of C pap is enough to passively insufflate 599 00:28:11,720 --> 00:28:15,040 some oxygen into those alveoli. It helps to oxygenate the 600 00:28:15,040 --> 00:28:17,120 shunted blood that's still flowing through there. 601 00:28:17,400 --> 00:28:20,200 It is often the single most effective maneuver to improve 602 00:28:20,200 --> 00:28:23,240 oxygenation, and it usually doesn't inflate the lung enough 603 00:28:23,240 --> 00:28:25,440 to bother the surgeon. That's the magic bullet for the 604 00:28:25,440 --> 00:28:26,520 Viva. It is. 605 00:28:26,520 --> 00:28:29,480 If that doesn't work, step 6 is to increase the PEEP on the 606 00:28:29,480 --> 00:28:32,400 dependent lung. Step 7, if you're really in 607 00:28:32,400 --> 00:28:35,320 trouble, is to tell the surgeon you have to stop and perform 608 00:28:35,320 --> 00:28:37,240 intermittent to lung ventilation. 609 00:28:37,800 --> 00:28:40,080 And finally, the ultimate solution if they're doing a 610 00:28:40,080 --> 00:28:43,080 pneumonectomy is asking the surgeon to clamp the pulmonary 611 00:28:43,080 --> 00:28:45,360 artery. Once that's clamped, the shunt 612 00:28:45,360 --> 00:28:47,480 is gone. That's a great clear protocol. 613 00:28:47,600 --> 00:28:49,800 OK, one more interop topic, Fluid management. 614 00:28:49,800 --> 00:28:51,840 This is another one I hear is a huge exam topic. 615 00:28:51,840 --> 00:28:54,320 It is huge because getting it wrong is lethal. 616 00:28:54,520 --> 00:28:58,600 The rule is simple 3 words restrictive, restrictive. 617 00:28:58,760 --> 00:29:01,520 Restrictive. You can dry as dry as you can 618 00:29:01,520 --> 00:29:04,480 possibly get away with. Fluid overload is one of the 619 00:29:04,480 --> 00:29:07,440 main causes of post pneumonectomy pulmonary edema, 620 00:29:07,440 --> 00:29:10,440 which is a devastating complication with a mortality 621 00:29:10,440 --> 00:29:12,920 rate of over 50%. So where are the actual numbers? 622 00:29:13,120 --> 00:29:17,720 In the 1st 24 hours post op, the total fluids given IV oral 623 00:29:17,720 --> 00:29:21,280 everything should generally be less than 3 liters, or to put it 624 00:29:21,280 --> 00:29:23,480 another way, less than 20 millikilograms. 625 00:29:23,480 --> 00:29:24,880 It's not a lot. It's not. 626 00:29:25,040 --> 00:29:28,000 And you do not chase urine output if their urine output it 627 00:29:28,000 --> 00:29:31,200 is 0.5 millikiliter chart that is perfectly fine. 628 00:29:31,400 --> 00:29:34,480 Do not give a big crystalloid bolus from mild hypotension 629 00:29:34,680 --> 00:29:37,080 unless you are absolutely certain they are hypovolemic 630 00:29:37,080 --> 00:29:39,120 from bleeding. You're much better off using a 631 00:29:39,120 --> 00:29:40,440 small dose of a phase suppressor. 632 00:29:40,520 --> 00:29:41,920 Why are they so sensitive to fluid? 633 00:29:42,080 --> 00:29:44,960 Because the surgery itself massively disrupts the lymphatic 634 00:29:44,960 --> 00:29:47,880 drainage of the lungs, the lungs lose their ability to clear 635 00:29:47,880 --> 00:29:50,400 excess fluid. Any extra crystalloid you give 636 00:29:50,400 --> 00:29:53,040 them just leaks straight out of the capillaries and into the 637 00:29:53,040 --> 00:29:55,080 alveoli of the one remaining good lung. 638 00:29:55,160 --> 00:29:58,120 You are literally drowning them. OK, let's move into party post 639 00:29:58,120 --> 00:30:01,680 operative management. Surgery's over, We're in 640 00:30:01,680 --> 00:30:04,400 recovery or the ICU. We've already said pain control 641 00:30:04,400 --> 00:30:06,960 is king because if it hurts, they don't breathe and they get 642 00:30:06,960 --> 00:30:08,960 pneumonia. We've got our epidural working 643 00:30:09,080 --> 00:30:11,040 right, But let's talk about something specific to 644 00:30:11,040 --> 00:30:13,160 niminectomy positioning. Yeah. 645 00:30:13,640 --> 00:30:15,240 How should the patient be nursed? 646 00:30:15,520 --> 00:30:18,200 This is absolutely critical and a common point of error. 647 00:30:18,760 --> 00:30:23,200 The cardinal rule is you should never turn a fresh pneumonectomy 648 00:30:23,200 --> 00:30:26,360 patient fully onto their unoperated side, so the good 649 00:30:26,360 --> 00:30:28,120 lung should not be done. Why not? 650 00:30:28,360 --> 00:30:30,320 There are two catastrophic reasons. 651 00:30:30,320 --> 00:30:33,800 First, drowning. If the bronchial stump where the 652 00:30:33,800 --> 00:30:36,320 surgeon sewed up the bronchus were to break down into hesens, 653 00:30:36,680 --> 00:30:39,920 all the fluid and blood that's collecting in that empty chest 654 00:30:39,920 --> 00:30:43,680 cavity would immediately drain by gravity straight down into 655 00:30:43,680 --> 00:30:45,920 their only remaining good lung. You would drown them in their 656 00:30:45,920 --> 00:30:48,680 own fluid. Second mediastinal shift. 657 00:30:49,240 --> 00:30:52,520 If you put them good lung down, gravity can cause the entire 658 00:30:52,520 --> 00:30:55,680 mediasynum, the heart and great vessels to shift dramatically 659 00:30:55,680 --> 00:30:58,840 into the empty space. This can kink the superior vena 660 00:30:58,840 --> 00:31:02,560 cava or the pulmonary veins, leading to sudden cardiovascular 661 00:31:02,560 --> 00:31:04,920 collapse and cardiac arrest. So how should they be 662 00:31:04,920 --> 00:31:07,000 positioned? Usually we keep them flat, 663 00:31:07,000 --> 00:31:10,040 supine or slightly turn towards the operated side. 664 00:31:10,280 --> 00:31:12,760 That helps splint the mediastinum and keeps the good 665 00:31:12,760 --> 00:31:15,480 lung up and clear. Let's talk more about these 666 00:31:15,480 --> 00:31:17,680 scary complications. You mentioned cardiac 667 00:31:17,680 --> 00:31:20,320 herniation. That sounds incredibly dramatic. 668 00:31:20,480 --> 00:31:22,840 It is lethal. It's rare, but you have to know 669 00:31:22,840 --> 00:31:24,080 about it. It happens after a 670 00:31:24,080 --> 00:31:26,440 pneumonectomy, more commonly on the right side. 671 00:31:26,440 --> 00:31:29,240 If the surgeon had to open the pericardium and didn't close it 672 00:31:29,240 --> 00:31:31,720 properly. When you move the patient, say, 673 00:31:31,720 --> 00:31:34,640 from the operating table to the bed, the heart can literally 674 00:31:34,640 --> 00:31:37,520 slip through that defect in the pericardium and twist on its 675 00:31:37,520 --> 00:31:39,720 great vessels portion. What are the signs? 676 00:31:39,840 --> 00:31:42,440 Sudden profound cardiovascular collapse. 677 00:31:42,600 --> 00:31:46,840 Shock signs of SVC obstruction. If this happens, there is only 678 00:31:46,840 --> 00:31:49,760 one treatment. Reopen the chest immediately. 679 00:31:50,120 --> 00:31:52,400 Fluids and pressers will not fix a twisted heart. 680 00:31:52,640 --> 00:31:55,800 Another one is bronchoplural fistula or BPF. 681 00:31:56,040 --> 00:31:57,480 The stump leaks. Correct. 682 00:31:57,760 --> 00:32:00,720 The signs are usually a sudden onset of dyspnea. 683 00:32:00,960 --> 00:32:04,480 You might feel subcutaneous emphysema, air crackling under 684 00:32:04,480 --> 00:32:07,760 the skin, and the patient might start coughing up a watery, 685 00:32:07,760 --> 00:32:10,120 serous, sanguinous fluid. What's that fluid? 686 00:32:10,400 --> 00:32:12,880 It's the fluid from the empty pneumonectomy space now 687 00:32:12,880 --> 00:32:16,280 connected to their airway. But there's a pythagnamonic sign 688 00:32:16,280 --> 00:32:18,080 on the chest X-ray. You must know this. 689 00:32:18,720 --> 00:32:22,160 Normally after pneumonectomy, that empty space is half filled 690 00:32:22,160 --> 00:32:25,280 with air and half with fluid. Over the next few days, the 691 00:32:25,280 --> 00:32:28,320 fluid level should slowly rise as the space fills up. 692 00:32:28,600 --> 00:32:31,280 If you take an X-ray and the air fluid level has suddenly 693 00:32:31,280 --> 00:32:32,720 dropped. It means air has gotten in from 694 00:32:32,720 --> 00:32:33,960 the airway, pushing the fluid down. 695 00:32:34,720 --> 00:32:37,000 Or fluid has leaked out and been coughed up. 696 00:32:37,680 --> 00:32:41,080 A drop in the air fluid level on a post pneumonectomy chest X-ray 697 00:32:41,080 --> 00:32:43,680 means a BPF until proven otherwise. 698 00:32:43,920 --> 00:32:45,880 It's a classic exam question. OK. 699 00:32:46,160 --> 00:32:48,560 We've touched on part F analgesia. 700 00:32:48,880 --> 00:32:52,040 Epidural is king. What's the main alternative? 701 00:32:52,360 --> 00:32:55,040 A para vertebral block is an excellent alternative, 702 00:32:55,360 --> 00:32:58,920 especially if an epidural is contraindicated, for example if 703 00:32:58,920 --> 00:33:02,320 the patient has a Coagulopathy or an infection near the spine. 704 00:33:02,400 --> 00:33:04,920 What are the advantages? It's a unilateral block, so you 705 00:33:04,920 --> 00:33:07,840 get fewer hemodynamic side effects, specifically less 706 00:33:07,840 --> 00:33:10,640 hypotension. It provides very comparable 707 00:33:10,640 --> 00:33:13,280 analgesia to an epidural. And of course you always use a 708 00:33:13,280 --> 00:33:16,920 multimodal approach. Paracetamol and ascites if their 709 00:33:16,920 --> 00:33:18,840 kidneys are good. Gabapentinoids. 710 00:33:19,120 --> 00:33:21,120 Pain control is respiratory therapy. 711 00:33:21,240 --> 00:33:24,440 OK, let's pull it all together in part G comparison and exam 712 00:33:24,440 --> 00:33:27,920 integration. First, a head to head lobectomy 713 00:33:27,920 --> 00:33:30,480 versus pneumonectomy. How would you lay this out in a 714 00:33:30,480 --> 00:33:32,120 table for the exam? Good idea. 715 00:33:32,120 --> 00:33:34,320 Let's make a comparison. So mortality. 716 00:33:34,320 --> 00:33:36,760 Higher in pneumonectomy significantly. 717 00:33:36,760 --> 00:33:40,480 P Physiological risk. In pneumonectomy, it's PHTN and 718 00:33:40,480 --> 00:33:43,920 right ventricular failure. In lobectomy, the main risk is a 719 00:33:43,920 --> 00:33:46,480 persistent air leak from the remaining lung tissue. 720 00:33:46,520 --> 00:33:48,480 Fluid Management. Absolutely critical and 721 00:33:48,480 --> 00:33:51,600 restrictive in pneumonectomy, More liberal but still cautious 722 00:33:51,600 --> 00:33:53,480 in lobectomy. And chest drains. 723 00:33:53,560 --> 00:33:56,560 This is a big difference. It is in a lobectomy. 724 00:33:56,560 --> 00:33:58,640 We usually put the chest drains to suction. 725 00:33:58,920 --> 00:34:01,520 We want to apply negative pressure to help the remaining 726 00:34:01,520 --> 00:34:03,320 lobes re expand and fill the space. 727 00:34:03,880 --> 00:34:06,480 In a pneumoctomy we usually do not use suction. 728 00:34:06,520 --> 00:34:08,719 It's a balanced or underwater sealed drainage. 729 00:34:09,320 --> 00:34:12,280 We want that space to fill up with fluid gradually to 730 00:34:12,280 --> 00:34:15,480 stabilize the mediastinum. Pulling it out with suction can 731 00:34:15,480 --> 00:34:17,480 cause a dangerous mediastinal shift. 732 00:34:17,800 --> 00:34:20,920 That's a fantastic comparison. OK, let's end by running through 733 00:34:20,920 --> 00:34:24,000 the Viva traps one more time. The things students always get 734 00:34:24,000 --> 00:34:24,520 wrong. Happy to. 735 00:34:25,320 --> 00:34:29,679 Trap #1 the fluid trap, the examiner says to you doctor, 736 00:34:29,679 --> 00:34:33,000 your post pneumonectomy patient in the ICU has a blood pressure 737 00:34:33,000 --> 00:34:35,920 of 90 / 60. What is the first thing you do? 738 00:34:36,280 --> 00:34:39,080 And the wrong answer is. The knee jerk wrong answer is I 739 00:34:39,080 --> 00:34:41,760 will give a fluid bolus. The examiner will just write 740 00:34:41,760 --> 00:34:44,120 fail on their sheet. What's the right answer? 741 00:34:44,360 --> 00:34:47,960 The right answer is I will first rapidly assess and rule out 742 00:34:47,960 --> 00:34:50,280 other life threatening causes of hypotension. 743 00:34:51,239 --> 00:34:54,639 Is it bleeding? Is it an arrhythmia like AFEM 744 00:34:54,639 --> 00:34:58,880 which is very common or is it the dreaded cardiac herniation? 745 00:34:59,360 --> 00:35:02,480 You do not give fluid until you know why they are hypotensive, 746 00:35:02,640 --> 00:35:05,000 because fluid overload kills these patients. 747 00:35:05,000 --> 00:35:08,800 OK, trap #2. The extubation question When do 748 00:35:08,800 --> 00:35:11,040 you plan to extubate your pneumonectomy patient? 749 00:35:11,160 --> 00:35:14,920 And the right answer is. On the operating table, we want 750 00:35:14,920 --> 00:35:17,560 them extubated immediately if at all possible. 751 00:35:17,800 --> 00:35:20,880 Every minute of positive pressure ventilation put strain 752 00:35:20,880 --> 00:35:23,320 on that fresh bronchial stump suture line. 753 00:35:23,760 --> 00:35:26,480 We want them breathing spontaneously, creating negative 754 00:35:26,480 --> 00:35:29,880 intrathoracic pressure. The goal is a wash and alert, 755 00:35:30,000 --> 00:35:33,120 warm and comfortable. You do not electively ventilate 756 00:35:33,120 --> 00:35:35,480 them overnight unless they are profoundly unstable. 757 00:35:35,640 --> 00:35:37,800 And a final track. The smoking one we discussed, 758 00:35:37,880 --> 00:35:40,000 the examiner says. The patient proudly tells you he 759 00:35:40,000 --> 00:35:42,200 stopped smoking 10 days ago. Is this good? 760 00:35:42,360 --> 00:35:44,600 And you say? It is potentially problematic 761 00:35:44,600 --> 00:35:47,520 due to the risk of increased speed of viscosity and plugging. 762 00:35:48,160 --> 00:35:50,720 I will ensure aggressive test physiotherapy postoperatively. 763 00:35:50,800 --> 00:35:52,160 Perfect, you've navigated the track. 764 00:35:52,280 --> 00:35:54,320 And for diagrams in the theory paper. 765 00:35:54,440 --> 00:35:57,840 You should be able to draw a basic flow volume loop showing 766 00:35:57,840 --> 00:36:00,120 the scooped out expiratory limb of COPD. 767 00:36:00,160 --> 00:36:03,840 You should be able to draw the West zones of the lung to help 768 00:36:03,840 --> 00:36:07,000 explain the VQ mismatch in the lateral position. 769 00:36:07,280 --> 00:36:11,000 And you must be able to write out the PIPO FEV 1 formula from 770 00:36:11,000 --> 00:36:13,160 memory. Examiners love to see that you 771 00:36:13,160 --> 00:36:15,600 can do the math. This has been a massive, massive 772 00:36:15,600 --> 00:36:18,040 download of information. Let's try and summarize it into 773 00:36:18,040 --> 00:36:20,800 a but a few key high yield takeaways for the exam. 774 00:36:20,800 --> 00:36:22,960 Let's do it. One, your assessment is built on 775 00:36:22,960 --> 00:36:26,200 the three legged stool mechanics parent Chema and reserve. 776 00:36:26,560 --> 00:36:31,360 Two, you must calculate PIPO FEE 1 and pipo DLCO. 777 00:36:31,800 --> 00:36:35,440 The key numbers are 40% for low risk and 30% for high risk. 778 00:36:35,840 --> 00:36:39,000 Reserve is key. AVO 2 Max less than 10 million 779 00:36:39,000 --> 00:36:42,320 kilogram in is a no go. 4 Lung isolation. 780 00:36:42,760 --> 00:36:45,480 The left DLT is your workhorse and you must confirm its 781 00:36:45,480 --> 00:36:47,880 position with a bronchoscope. 5. You have to understand the 782 00:36:47,880 --> 00:36:50,840 Physiology of HPV and the massive shunt created by the 783 00:36:50,840 --> 00:36:54,800 lateral position and OLV. 6. If you get hypoxia your go to 784 00:36:54,800 --> 00:36:57,480 maneuver after the basics is CPAP to the operative lung. 785 00:36:57,640 --> 00:36:59,400 And seven may be the most important. 786 00:36:59,560 --> 00:37:03,560 Restrict fluids less than 3 liters in the 1st 24 hours for a 787 00:37:03,560 --> 00:37:05,280 pneumonectomy. Keep them dry. 788 00:37:05,800 --> 00:37:08,360 And eight. Post op watch like a hawk for 789 00:37:08,360 --> 00:37:11,600 the big killers, cardiac herniation, bronchoplural 790 00:37:11,600 --> 00:37:14,520 fistula and post pneumonectomy pulmonary edema. 791 00:37:14,760 --> 00:37:17,480 Professor, thank you. I genuinely feel much more 792 00:37:17,480 --> 00:37:19,720 prepared for that hot seat now. You're welcome. 793 00:37:19,880 --> 00:37:23,560 It is dense, but it's logical. To our listener, this is the 794 00:37:23,560 --> 00:37:26,440 kind of material you might need to listen to more than once. 795 00:37:26,880 --> 00:37:29,880 Write down those formulas, draw the diagrams, and really try to 796 00:37:29,880 --> 00:37:33,080 visualize the Physiology. This is as high stakes as 797 00:37:33,080 --> 00:37:36,720 anesthesia gets and the exam questions absolutely reflect. 798 00:37:36,720 --> 00:37:38,520 That they do knowledge is safety. 799 00:37:38,640 --> 00:37:41,040 Good luck with your Gujarat University exams. 800 00:37:41,200 --> 00:37:43,680 Go crush that Viva. Indeed, good luck. 801 00:37:43,760 --> 00:37:45,080 We'll see you on the next deep dive.