[MUSIC] Patrick Colby is a employee with Duke Life flight, when I was in E M T with Duke University E M S. Duke Life flight was the company that more or less allowed are kind of on campus E M S agency to function. And so Patrick here, is an expert in a variety of fields, including critical care. And emergency evacuation methods as used by both life light and for his work with the United States Armed Services. He's a lieutenant Colonel who has over three deployments, most recently in 2019 and 2020, he was in Afghanistan. And so in that role he functioned as a tactical critical care evacuation on the evacuation team there. And so he knows a lot about if you're in a hot zone or you're an area where someone, a wounded soldier needs to be rescued. Well if you're using an air vehicle to evacuate someone that's going to cause a lot of complications, taking them into different elevations, causing all the accelerations. And that's what he's here to talk about hopefully applying a lot of the lessons we have started to develop. And use a lot of the vocabulary like shock that we've also started to talk about here. So without further ado, I'll let Patrick say a little bit more about himself. But then also he'll be presenting on a lot of really interesting gas laws and starting to also talk about some interesting cases. >> Welcome everybody and thanks for inviting me yeah, I think that was a good summation of what I do have been with life flight since 1990. And, three combat deployments and I've got two wonderful sons, so we'll keep on going from there. If you have questions, please ask them I appreciate the dialogue so that I know that I'm getting stuff that you want to hear about. So we're going to talk about stresses of flight we're going to talk about some altitude physiology near the end. And we're going to start talk about gravitational forces and G forces and the effect on the body. And then that's going to tie into there's a 2018 accident involving one of their folks in the Thunderbirds. We're going to talk about negative Gs and positive Gs and how that affected the body and probably led to the crash there, right. And so we'll get started, so we're going to talk about gas laws, Boyle's law, B O Y L E S law. If you think I want to think about this, I'm just a guy, I try to keep it simple Boyle's Law has to do with the word we use with that as a balloon. And when we think about Boyle's Law as we climb in altitude, the pressure decreases, the pressure of the atmosphere decreases. So all right, so that all sounds well and good, but how does that affect? So if you have a balloon at sea level and it's one m across as you climb in altitude. Because you have an enclosed object here as you climb in altitude balloon will actually expand because the pressure and the volume within the balloon stays the same. But as you climb, the pressure outside of the balloon is less, so this balloon wax, they expand. So you can also this effect actually does not require a lot of altitude, I took my voice up to the mountains in North Carolina a couple years ago. So where I lived about 500 ft above sea level and the mountains we were going up over, we're only 2500 ft. But we had a bag of potato chips that we took from here and as we went over the ridge. My son looked at the potato chip bag and it was just round instead of being a little mylar looking bag? It was big and round and I said, well that's Boyle's law so okay, daddy explained that one. So we were explain how that all worked, and then the opposite side is also true. We left a bag and we were there for a couple of days and by then the pressure equalized between the two. So when we left the mountains, the bag was back to normal size and by the time we got back to Raleigh. It has shrunk and you can see all that conform to the shape of the potato chips on the inside so you're asking, okay, so how does this affect us? So any enclosed gas that you have in the body when you get out to do is going to start to expand. So some of the enclosed places where we have gas in the body, the big ones that affect the crew are. Your sinuses are relatively there's not a whole lot of gas flow there, your ears. You also have issues with bowel gas those are not easily vented, so if you don't want to call a flower gas producing me, you don't want to hit the Mexican restaurant. Before the day before you're flying because you will not be a fun one to fly with. So what happens to the crew is when you get the altitude some days, if you've got a nasal congestion, so you've got a little bit of a cold. You got a runny nose, you start to get this pressure here and behind your eyes and it's very uncomfortable It's not a fun day to fly. Some days you can't clear your ears and that's not a fun day to fly because that affects them equilibrium. We'll talk a little bit about how you maintain straight level, but you need your ears to do all that all right. So it affects not only the crew but also affects our patients if a patient has a small pneumothorax on the ground when we take them up to altitude. That pneumothorax is going to expand and what would be not a life threatening issue on the ground now becomes a big problem at altitude. Because that collapsed part of that, the collapse part expands and all that does is compress the lung. So they have less lung tissue to ventilate and talks to me and now we have a bigger gap there. It also has to do if we have patients who are intubated at the end of our if they're on a ventilator at the end of the tube. There's a small cup and that prevents the air from going out around the tube, you went all the the ventilator. You want all that respiration to occur within the tube well, this cuff expands and you get the altitude. So you have to make sure you have proper pressure there, so that doesn't cause any necrosis in the trade. So, I question there but I saw a questionnaire about needling the chest and that's a great question. So yes, that's possible and you can do that and so when we pick up patients, especially from a hospital. And if they have a pneumothorax, that's greater than 25% were required to put a chest tube in before we leave. Anything less than 25% probably is not going to cause you problems, but 25% we have to put a chest tube in. So, I like it somebody's thinking great question all right so, we've got those we also we have devices called a balloon pump. Somebody saying cardiogenic shock will go back to that we talked about that earlier. Somebody is having a heart attack, the heart is not working well or somebody over a period of time has had a lot of cardiac disease and the heart is not beating effectively. We can have a device place that actually assists with pumping the blood. But again it's it's driven by helium gas which also expands and you get to altitude. So when you get to altitude we have to repeat, recalibrate the machine in order to compensate for the pressure. And then again when we land we have to calibrate it again, also we sometimes you have will measure arterial blood pressure. Any transducers that we have, we have to recalibrate them when we get altitude, yeah So most people think that, just we are always flying to 2500 feet. So most of the time we only fly half a mile up in the air, but the pressure changes and the volume changes are the greatest, the ratio is the greatest in the first 5000 feet above sea level. So it's not a huge issue for most patients, healthy patients, it's not a big deal, but remember we're taking patients that are very sick. And so especially this plays out a little bit with our Covid patients now because the Covid disease for most of these folks that affects their lungs and they're very, very, very difficult to oxygenate. We have to have huge ventilator support for these folks on the ground even to the point where we roll them on their prone, we roll them on their stomachs so we can carry different parts of the lung, and so they're very tenuous. So just climbing 20 to 20500 feet has huge effects on a lot of these patients and so we have to stay diligent and maximize whatever we can do. And sometimes it's a guessing game of just really what's going to work when you get to altitude. But so far we've been able to compensate and to find ways to keep them at least oxygenated well enough that we can get him to Duke and then we can provide further therapy. So that's how we do it here, bigger issues, when I was in Afghanistan, we flew out of Bagram, which starts out at 5000 feet, so we're already everybody's hypoxic. So it's like living in phoenix or it's like living in Denver all the time, we had to climb over the mountains and some of the peaks, we had a flyover, we're 20,000 feet. So we grabbed pick patients up and have to fly over that same 20,000 feet and most of the folks we transported were recent trauma, they had been injured within the last hour. And so you don't know the full extent of their injuries because we picked a lot of them up actually out at the point of injury. So it was about remaining diligent, keeping all these things in the back of your mind, right? So that was Boylston. Remember Boyle's law is like a balloon, the higher you go up the balloon expands, right the next we have to do with is Charles law and Charles law. What we remember about that is centigrade because Charles law has to do with temperature. And essentially every time you increase your altitude, the temperature drops there are weather phenomena that mitigate this a little, bit but for the general purposes for every 1000 ft that you climb, the temperature drops 2°C. Right? So in the summertime in North Carolina we try to fly a little bit higher because it's amazing how much more pleasant it is for the crew and for the patient when it's not 90° in the back of the helicopter. We do have air conditioning but it takes a little bit for the air conditioning to get working correctly. There we go, we got our law at the bottom, thank you very much. So what this has to do for your patients in the summertime, it's really nice, we climb and then it gets a little bit cooler for everybody. It also means that the aircraft, the wings and the flight surfaces all work better with cooler air, the aircraft is much, much more efficient with cooler air. The engine is and the blades and the wings also, so it's great, we've climbed up sometimes we'll fly 5000 feet just to get a little bit of cooler air. Yeah, unfortunately the opposite is true in the winter time, helicopters are not completely sealed just by the simple fact that there's so much vibration from the engines and all so we cannot go pressurized in a helicopter. So there's a fair bit of Indian air from the outside that flows through in the wintertime, we have to work hard and we have measures in place to try to keep our patients warm. So we don't fly at such high altitudes whenever we unless we absolutely have to, we try to stay a little bit closer to the ground. Alright, so a Charles law that has to do with temperatures. Boyle's law has to do with balloons and now we're going to get into some of the, this will play a little bit India. You've talked about hypoxia in the past, is that correct? If you talk about hypoxic hypoxia and history toxic and all those fabulous, we're good to go then. All right, So, now, we're going to talk about Dalton's Law. So, what do you know? All right, let me back up. Let's go over Henry's law, first, Henry's law has to do with Heineken, okay. So how does that play in here? Solutions, including your blood gasses dissolved in them? So how this things out if you can think about your favorite adult beverage, like a Heineken? All right, you have there's gas that's dissolved in there, when you pop the top, you get this foam on the top. The same thing happens if you're drinking Coke or Pepsi when you release the pressure above that liquid, all the gasses and they're starting to come out, which is why your soda goes flat after a couple of days. All that carbonation and all that, all those things that are dissolved in the fluid amount of solution and then they're off gas into the atmosphere. So, what does that have to do with us? Well, the prominent gas in the atmosphere is nitrogen. Alright, 78% of the atmosphere and 78% of the air that we breathe is nitrogen. So each one of us has about a leader of nitrogen stored in our body tissues right now. The blood, the muscles, most of it is okay. Yeah, we'll get the Dolphins law in a second, thank you. Good call, so you've got this nitrogen, it's very well stored in adipose tissue. So when we go to altitude we no longer have as much pressure on the outside, we talked about that, so all of a sudden now all these gasses want to come out of solution. So it's not such a big deal for us when we go to altitude for the average person, if you have a lot of adipose tissue is a greater threat, however, people who die for scuba dive. As soon as you go 33 feet down, you pick up a whole another atmosphere. So 33 feet you're at one atmosphere, if you go down 66 feet you go down to two atmospheres and if you go down to 99 feet, you're down to three atmospheres. So you have three times the pressure on your body when you go down, so what you do is you absorb that much more nitrogen, and that gets into the tissues. So if you come up slowly, if you have a slower sent, everything is good, you blow that off as that nitrogen comes out of the tissues and comes out of solution, you can blow that off. However, if you climb too quickly, then what happens is that the nitrogen especially comes out, and it forms bubbles in your blood, which is very, very bad. What happens is those little bubbles get caught in the small capillaries, especially in the lungs, and then the second place they like to go is the small capillaries in the brain. Both of those are very bad because they impede blood flow at that point, so if they get stuck in the lungs then you end up with a pulmonary emboli and you have a part of the lung that's not doesn't have any blood flow through it. And which is a huge problem if you get stuck in the brain, then you end up having a stroke, so if you're going to scuba dive, if you dive, you do what you called table dive. So your send you stop, you make sure you off gas, you send some more and you spend a certain amount of time there and then your final stop is usually about 15 feet below the deck of the boat. And usually hang out there for about five or 10 minutes and then everything's good, but we every year we have a couple of people that don't do their table dives and usually there's some kind of alcohol involved with this which is always a bad thing Diving and alcohol don't mix and they don't do their table dive correctly, so they end up getting the bends.. So this also presents itself, so then they call, well, we need Duke's got great hyperbaric chambers. And so it's a great place to bring these people because the treatment for the bands is to take them back down to pressure. The trouble is that they've now got problems with these. They've all gassed this nitrogen, so you don't want to take some very high up in altitude that just makes it worse. So, again, that's to do. The best thing to do for Henry's Law and for the bends is to, if you're going to dive to your table dives the way that you're supposed to do that. All right, my cinema didn't too sorry, I jumped around Dalton's Law, that was kind of fun. The partial pressures of all the gasses, every gas that you have, nitrogen, the oxygen, all the rare gasses and all the minute gasses. No matter what altitude you go to, the percentage of that guess always stays the same. At that sea level, you're always going to have 78% nitrogen, 21% oxygen, when you go to 20,000 ft, it's still 78% nitrogen, 21% oxygen. The issue becomes when the air becomes thinner, the percentage stays the same, but the number of molecules is less. So how that plays out it at sea level, let's just say we take a sample, we've got 100 molecules of air. And in that you're going to have 78 molecules of nitrogen and you have 21 molecules of oxygen, which is at pressure. When you go up to 20,000 ft because of the drop in pressure, you don't have as many molecules at this point, You only have 10 molecules of oxygen. So you had 20,000 ft, you've got less than half the amount of oxygen that you're able to breathe. So what does that mean for us? Anytime pilots for the most part, when you get above 12,000 ft, you get on supplemental oxygen. You can be above 12,000 ft, there are certain guidelines for a certain amount of time. But when you get over 20,000 ft you have to be in a pressurized aircraft so that you have adequate oxygen to breathe. Otherwise you get into all that hypothesis stuff that you have already talked about. So that's why you get lightheaded at 5000 ft, there's just not enough oxygen available what you used to on the ground. So when you go to Colorado and you say, well, I flew in this morning, I'll act like made it today and we're going to take a short hike. And we're going to do one of those 14,000 peaks tonight, I can promise you, that's a very, very bad idea, do not do that. It will take you at least a day to acclimate to the 5000 ft. And if you want to do your 1st 14,000 peak, you might do it tomorrow but I would make it an easy one. Do not make it a strenuous trail, do not make it a fast take up. And so I give you, my personal one is we flew into Bagram at 5000 ft. Now we're already tired because we've flown halfway around the world and so there's jet lag and all that kind of stuff that goes with it. And I'm pretty good shape, It took me about a week to 10 days to really get well acclimated to the altitude. Now we flew our first mission three days after we got there, but it took us a week to really get the good feeling. We did our first mission because we were first ones up and we did it and everything was good, but I'm glad we waited to our third day. The 3rd day is about when we started to feel good again you don't have any, you don't have any appetite. You don't really feel good about what you're doing, you're just tired and you just want to go sleep. So again, go hike all the heights you want to in Colorado. It's beautiful out there and hike as many 14 thousands as you want to, just be a little bit smart with the first lines, right? So a couple other things about guest lost, Armstrong's line. Did you talk about that the other day? Okay, so Armstrong's line is a line at 63,000 ft, and when you're at sea level we measure pressure by millimeters of mercury. At sea level it's one bar or it's £15 per square inch, or it's 700 and 60 millimeters of mercury, all those are perfectly fine way to measure at Armstrong's line. I remember on the ground where 760 millimeters of mercury when you get to Armstrong flying at 63,000 ft, it's only 47 millimeters mercury. So it's about 7% of the pressure that we have on the ground, and how that plays out because you have less pressure. Let's back up a second. If you go out, anybody live at altitude and try to cook. Anybody here live in Denver or live at 5000 ft and try to cook. Okay, nobody's fighting on that one. If you read your recipes on the back, there's always a disclaimer for if you live at altitude, you have to alter your recipes because water boils at a much lower temperature at altitude. The higher you get the water boils at a much much lower temperature, there you go. There you go, so when you make your pancakes in the morning, If you're not careful, you got to burn them and they're going to end up being real nasty. And that has to do with pressure changes, at 63,000 ft. Your blood will boil at 98.6, so if you happen to get a ride with one of these folks that are doing all the nice space shots now. When you get to 63,000 ft, don't take a spacewalk without a suit, it's just an interesting tidbit but your blood boils at 63,000 ft. All right, so what do you do to minimize the effects of altitude? All right, so number one is you stay in good shape. The better cardiovascular shape you're in, you can manage the hypoxic effects much better. Less adipose is a big help, and the big thing has to do with your cardiovascular health is you're much more efficient at using the oxygen. So when you have an oxygen debt, you don't have as much oxygen available to you. Your body has tolerated that because you're in such good shape. And when you're on your marathons, you do your swimming or you do your hit training or you do your crossfit, spend some time in hypoxic. Sometimes you're borderline hypoxic as you do that if you put the pulse ox on your finger, your sats might drop a little bit. So that's the best way that you can minimize the effects of altitude. All right, we're all good with that so far with gas laws. All right, man the times just cruise along so I'm going to go through the next stresses pretty quick. So I don't want to get to the case study, how about that? Right, so stretches of flight are things that you have to deal with. Again, we talked about the pressure stuff already, so when we want to next, you have already talked about hypoxia. So I'm not going to go over that one again. The case that is thermal, we talked about that a little bit. Just know that the effects of one thing to remember is that their effects of all these stressors and all these gas laws are cumulative. So you're hot, you got vibration, you're up at altitude, you've got all these other pressures. The hypothesis that these all just accumulate and add on to each other. So it's not just one thing or another. Next thing you come up with is humidity and dehydration Increased altitude. The air is much dryer when you're flying an aircraft. When you're up in an airplane flying commercial, the humidity in the air up there is about less than 5%. So what that means to you is that your sinuses dry out. All the, secretions that you have are all dried out there hard to remove. They don't filter the air as efficiently as they would normally. Your eyes start to dry out and they get real uncomfortable when you're flying. So what does that mean for us and for you as you go up in the air, it means you have to stay hydrated, and so never passed up a good opportunity to drink a half liter of water and to go to the bathroom. And so when we're walking around at our base both here and when I was deployed, you're constantly drinking and you're constantly going to the bathroom. If you get behind the hydration power curve, it's going to be a very bad day. All right, Next one is noise aircraft are all noisy helicopters noisy c one third. So noisy. Even if you're flying a 747 unless you've got the real nice Bose noise canceling headphones. It's a noisy place to be. And the big factor that there is, it just, it over stimulates the nervous system. It increases your metabolism, increases your heart rate and makes you fatigued. Alright, vibration has the same effect. It over stimulates the nervous system and just the inherent vibration in the aircraft with the engines turning and the blades turning and all that, that has a market effect on fatigue if you have another, a lot of renewal is in the air and it's a bumpy day that's magnified hugely. It just wears you out. So this also not only does the fatigue you, but it also dehydrates you. So the dehydration is a big key and that's a dehydration or staying hydrated is and staying in shape for the two keys to being able to manage altitude. All right, the next one is spatial disorientation, spatial disorientation is the number one cause of aircraft accidents. And essentially what it is is you try to manage, you have three ways that we keep our balance and try to figure out where we are and how we are in relation to our environment, our eyes, our middle ear with our vestibular semicircular canals. And then we've got barrow receptors throughout our body that sense changes in pressure. And those are the three ways that sometimes you say I'm flying by the seat of my pants. Well, it's how your head feels when you're that you're flying straight and level and your body also senses some of that and we've all had times when you're your nose a little bit clogged up and your sinuses a little bit stuffed up and you're walking around like this and you say I feel like I'm walking straight, but I know that I'm not. My eyes are telling me that I'm tilted, but I know that I'm not. And that happens again. We talked about your sinuses get dried up, noise, vibration, you get fatigued. And so this is a big problem because your eyes sense that you're, they know where the horizon and you're looking at your gauges, but the rest of your body is telling you that you're in a turn. All right. So, this gets worse as you do a lot of turning and we get into that when we're trying to make a landing, sometimes we have to turn one way, then turn another. Or if we're flying by instruments, a lot of the approaches have a right turn and a left turn and then a descent and then a left turn and a right turn and a descent. Also comes into problems when you really can't see the horizon. Summertime in north Carolina, there's a lot of haze in the air so you can't always see the horizon. So it's very difficult to get a fixed point for your eyes to tell you what's going on. And in the meantime, every time the wind blows you and you start doing this back and forth, your eyes cannot square up again with where you're going and so this just becomes cumulative and then you end up, people fly perfectly good aircraft into the ground thinking that they're flying straight and level, but they're actually in a turn. They think that's what happened to, Kennedy a couple years ago when he crashed off the coast of, of Massachusetts use flying in, is still legal to fly visually, but there's enough Hayes and I think it was in the early evening and it's very easy to lose the horizon and you're over the water. He was a fairly low time pilot flying a, a pretty high performance aircraft. And I'm not, I'm not picking on him, but this just happens, you get in over your head and your usually way behind the power curve by the time you realize you're in trouble. So what you have to do, the hardest part of all the ego also plays into this. Pilots. There are no old bold pilots. But a lot of pilots do have egos. We all have a little bit of an ego, but, the first part of all this is recognizing that, I'm spatially disoriented. What do I got to do now? So you have to trust your instruments. That is the way out of all this. Your instruments don't lie. You've got an artificial horizon in front of you, you've got to get your links, get your wings straight and level, let your ears and let the rest of your body reactivate the straight level and then you can get out of this. But, this is a big problem and it continues to be a big problem and, it's a matter of education and just being aware that this can happen. I've been with pilots when they get into the specialty, which is why we ride up front and both times were flying in the clouds and it was just a yucky day and the wind is blowing us all around and the helicopters doing all this stuff and it's like being a cork in the ocean. And they looked at me and said I'm starting to feel a little bit funny. It's like okay, we're doing great. They're still flying the aircraft and I just had to give them a sense of assurance is like just look at the gauges, the gauges are all great and and we're doing fine. I've been up in the front before when I've been especially disoriented and you get, and you do you're looking funny and you're looking at this and you're looking at the, at the gauges like this is what it feels like. This is really bad. So you get squared up all right, so I think we're about down. Yeah. Hyperglycemia? It's an issue if you're expending late day flying, you get the hypoglycemic and the last one will cover is the acronym DEATH and that has to do with drugs, exhaustion alcohol, tobacco and hypoglycemia. And those should all be pretty much self explanatory if you're going to fly, it's not a good time to go partying the night before unless you really want to get sick between flying commercial or any other time. Alright so now we're going to we're going to end up talking about the thunderbirds crash a couple years ago but we set it up with those and there's one more thing you want to set us up with and that's G forces. So those are gravitational forces and specifically we're just going to talk about two of them. We're going to talk about negative Gs and positive Gs. So did I miss a question of the Karman line? Okay you can have that that I'll keep on going. Okay. All right. So as you're flying along positive Gs. RX by definition G forces have to do with acceleration but we kind of extrapolated into when you have positive chief forces. It means you're putting additional weight onto the body because of a maneuver that you're doing most of the time. That has to do with climbing. As in the seated position. When the aircraft starts to climb you can feel yourself sinking down into the seat. You might get a little bit lightheaded if the GSR high enough or if the acceleration And the climb is high enough. Those are positive Gs because there's more gravitational force and we measure those by how many gravitational forces there are upon the body. When you're sitting here at the ground, you have 1G. If you had 0GS, you're free falling. When you're free falling, you jump out of an airplane and you're skydiving, you're at 0Gs because you're just falling. When you sit on the ground, you've got one gravitational force on your body. If A 2G turn or 2G climb is not a big deal. To put some of this in perspective. If you go to an amusement park and you're at one a super fast with what they do, cool beams, roller coasters. They max out at about 5Gs. So, the wildest one you're going to get on this 5Gs. If you're on one of the old wooden roller coasters, you might get up to 2.5 maybe. All right, the average person on you and I can tolerate about 5Gs before we pass out. Hi. So that's about all you can do and that's positive Gs that has to do mostly with climbing. You also have negative Gs. Which is where you're in a car driving fast and someone goes over the railroad tracks and go over a bump and you can kind of feel your step stomach coming up into your throat is the way we always name that those are negative G's. So, you have that when a pilot goes up and you go over the top and you come down the other side or in dissent, you've got negative Gs. Although for the most part they're not perceptible because the descent is so gradual. Humans do not tolerate negative Gs very well. And negative Gs to blood flow all comes up to the head and we don't like that a whole life. Two negative Gs is all we can handle maybe up to three at that point your lower eyelid actually starts to come up cover your eyes and so you get this red sensation. Everything you see is all just red because the blood is all coming up this way, as opposed to when you're having positive Gs and you're doing these inside loops. It goes through you get hypoxic, here's that word again because the blood flow to your brain and your eyes particularly is diminished. And so, those are both organs that require a lot of oxygen. So, they don't work very well when they're not confused at all. So, the first thing you end up with doing is you'll get a real quick, you'll get a headache when you're in positive Gs, remember positive Gs, the blood is all starting to go towards your legs. The first thing you do is you going to get a headache, then you're going to start to lose all the color. All right, because the receptors the nerves and the eyes that sense the colors they're very oxygen sensitive. So right away you get the black and white vision. The next thing you do is you get this tunnel vision and then things start to come in and it starts to get black on the outside that comes in. Next thing happens is you black out, you're still conscious and you can talk but you can't see a thing because the ice has shut down. And the last thing you do then you get into G lock, which is gravitational loss of consciousness, right? And so, for us again for us, 5G is about all we can take and and most of us pass out and you do this kind of thing. Right? So, that's not good because we have fighter pilots. We have fighter aircraft that can handle lots and lots and lots of Gs. So, the United States are fighter pilots train and you have to be able to withstand 9Gs. All right, so they put you in the center feuds and they spin you around, make sure you can tolerate nine Gs. And so, they all have to go through training and they get checked on this from time to time. Let me back up once. So, everybody follows formula one, high performance racing top of the line, world's fastest world's best at maximum braking. The driver is subject to 6.3Gs. The brakes are locked up. It's as fast as that thing will slow down. The highest recorded G level of any human, was a guy named Kenny Brack,a couple years ago, he was in a wreck in Indianapolis at the speedway and it's a pretty violent crash. But he hit end up airborne, hit the catch fence and spun around. He survived had a lot of broken bones but he had a momentary 214 Gs when he hit the fence. So, which is it? Yeah, he had some bad but again intensity and duration. Yeah, a lot of intensity, very short duration, right? So, when you ride the rides you've got three Gs that might last 10 seconds and then you're off and then you've got another three Gs. So you have less Gs a little bit longer. So, yeah, he survived, I just pulled up the Youtube video saw his name and it's pretty cool. He had a couple of fractured vertebrae, ankle, leg but he raced again. He was back in India a couple years later. Pretty interesting guy. So anyway, that's not a badge and I'm going to try to get your good 214. That's all yours pal. So, how do we get our pilots to 9Gs. All right, so number one proper fitness. Definitely plays a role in all that. Number two is there are maneuvers that they do to help to protect them. And the first one they do they learn to do is they bear down. And when they are anticipating this high G maneuver, you tense up every muscle in your body and as they tense up those muscles it also constricts the blood vessels and so it the blood that's in your legs and it pushes it up a little bit. Really, what it does is it just prevents it from all coming down there and pulling you don't get a whole lot of pushback but you just prevent all that blood from coming down into your legs and into your arms and into the rest of the body. The other thing they do and anyway that tensing up that provides them about 3Gs of protection, which is pretty interesting. Okay, so we'll get the split s in a second. Good for you. I like this, you're staying a step ahead of me, which is all good. All right, so, they do this tensing up maneuver. The next thing they do is they do an anti G breathing maneuver. And so, essentially what they're trying to do here is increase the pressure in the chest. And so then, what they do then is by increasing the pressure in the chest, are forcing blood from the heart up to the brain. All right, so what the maneuver is you take a deep breath and you say the word kick at the end of the kick, you close your flights that k sound actually closes the gliders. And so you keep it closed and you keep it closed for about 2.5 seconds. And then you forcefully exhale and immediate land house. So it's a, [SOUND] and they bear down. And so, this whole maneuver takes about four seconds, 4-5 seconds. And by bearing down like that they are forcing the blood from the heart of up to the brain. So, you have to learn to do this time too well if you do it too quickly, you don't give the lungs a chance to get enough oxygen in and the heart doesn't get enough chance to really refill. So, anyway that's the maneuver that they go through, so that gives you about 2Gs of protection. So, if you can do all those things you can do a 9G turn and you're only subject into about 4Gs actually. We also those barrels receptors that we talked about earlier in the body, they provide you about one G of protection. They take a little bit longer. They take about 10 or 15 seconds for them to be implemented, as the barrel receptors in your aorta and in your Carotid artery sense that there's a decrease in blood pressure. It takes about 10 seconds for them to spin up, but then they last about 10 or 15 minutes. So your first maneuver that you go through your prime and those up. Okay we're good, the body sensing all this, my heart rates increased. I get a little bit of a zoo constriction, and so now you're only having to deal with maybe 3Gs in the turn if everything goes well. All right, so now they kind of set us up for where we're at. >> Let me also really quick direct your attention to two really good questions in the chat, okay. >> Sorry, I got on a roll, I wasn't really looking there. >> Sorry, yeah the first is when people tend their bodies do they also not exhale the oxygen. So this whole anti G, strain maneuver in doing so do they not exhale and also just holding the breath make it worse about. >> What they're trying to do when they do the there, you take a deep breath. Then you bear down and that pressure inside the chest is what helps to force the blood out of the heart and then after you do that you forcefully exhale. And you have to forcibly and aggressively inhale your breathing, maneuvering the exhale and inhale has to occur, all that occurs in less than a second. So it's a very quick you have to get back to bearing down again. You have to get back to that straining maneuver. All right, so you do forcefully exhale, and then you inhale again. People that ride along with these stunt teams, they teach them this reflex and invariably most of them don't do it very well, and they pass out when they do it. They passed out of the 16 maneuver because they start off doing that. But it it really takes a lot of practice to get this down. All right, so does that answer the question? They do you do have to exhale, right there you go. But then you have things exhale because if you don't exhale you can't get the pressure oxygen, right? I there we go, okay, a second question. >> Those were the two parts of the question that's holding the ground, make it worse, the second one. >> Okay so we're just going to bring an airplane along. So you have to go with my hand. So the maneuver and question this day yeah the aircraft go up in four, and then they break off. And then they come down and at the bottom they all crisscross again at the bottom. So in climbing again, he's got the positive Gs. But as soon as you peel out now, you're a negative to get my hands down here. So when you peel out now you're upside down, and now you're negative Gs. And as you're falling, you continue to be a negative Gs. But then when you come around the bottom, the positive Gs come on quick. And so this is called the push-pull effect, it's a known problem. And so they tried this maneuver set up so that you don't exceed the parameters of what the pilot can maneuver or what they can handle. So usually what they get into in the negative Gs. Again, its intensity and duration are the two big issues. So when you're at negative Gs, he was like the accident pilot involved, he was a negative maybe two Gs. And there was a period of time that he was -2Gs. When it came down, by all accounts, he was performing and maneuver the way he was supposed to. But when they got down and got into the positive Gs the highest recorded for him was 8.56 Gs. Which is getting close to that 90 threshold. And so he went into G lock at that point and was not able to recover the aircraft and that's why it crashed. So they're in pretty big loops. I see a question about the loops, the loops, right? The size of loops would have to do with the intensity of the Gs involved. And so I don't know how to correlate that into size, this one this day, they were at 5500 ft. So they were right about a mile above the ground. At the peak of when all this was and when they end up at the bottom there's still four or 500 ft above the ground when they pass each other. So the altitude and the footage there is important, but the bigger issue is the Gs. Involved and effect on the pilot, and so it's interesting. I actually pulled up the crash report and so there's a couple of things about that they actually had listed. The last 20 G maneuvers that this pilot did, and he was subject and too much before that they were doing training, they were getting ready for the season for the acrobatic team. And he had many episodes of positive 7-8Gs. However, this 8.56 was the highest G that he would have encountered. That that was listed in this report. Also of note, so also note that the negative G's wasn't any higher than what he had experienced in the past. He actually had some higher numbers of the negative Gs, but the positive G's. This would have been the highest that he experienced. They also looked to did he actually do this training maneuvers correctly. And so unfortunately there's a camera that they actually have looking at the pilot. And what they'll do is they pull the video after every flight, and you look at it, so you can learn to do things better. It's a training that's not their punitively that it's there to see are you doing this correctly as you're breathing correctly? You're tensing up at the right times. And so as they were back through these flights beforehand, he had done an excellent job with his anti-straining maneuvering with his breathing even through all the turns that he went through before. So while we cannot know for sure what he did on this on the crash of flight, they're going to extrapolate that yes. He was very good at what he did, and he knew how to do this maneuver. Just the fact that he was negative, Jesus went to positive Jesus more than what his body could handle. So that's where that all ends up, unfortunately. So the lesson learned from all that is just to, I don't know that they changed any policies, they still do that maneuver. But just you know it's an awareness kind of a thing and it's just it was just one of those days that that happened, you know it's unfortunate, accident unfortunate that it happened but I don't know that you know the difference between eight and 8.5 Gs as far as controlling the aircraft as such is so small. It really doesn't take that much at all when you're when you're talking about the magnitude of the G forces there, that would you know the difference, okay at the bottom. At the bottom when he came out of his when he leveled off. If you have leveled off 20 ft lower, that would have been the difference between him crashing at him. Him going to G lock and him not going to G lock. And when you're thinking about traveling at 450 mph as he's descending and then pulling out the bottom and then aircraft are so, the movements of the controls are so small. That's absolutely minuscule movement at all. Right questions, so I saw a questionnaire about a split S. And that's actually a very good question because you get into the same issue there with a split S. And a split S, I don't have my I don't have it. You gotta go with my hand again, so split S. Is when they go around, and you start to make a downward maneuver And you turn as you come down so you start off with negative to use, you rotate 180 degrees. So you come out at the bottom, then you're level when you're on top. So you end up with you start off with negative G's, you end up with positive. That's another maneuver where, if you don't make your 180 degree roll or 180 degree y'all, you're going to run into troubles there. So it would be a role, I'm sorry if you don't make your role then you're going to run into trouble. because then you're going to get into the high negative Gs and hopefully you can roll at that point and pull out and get the positive. But again the human body does not tolerate negative Gs very well at all. Right, questions? In case we're talking about the pilot was from the Thunderbirds, I do safety stuff not only for the Air Force but also for life flight. I'm on the safety committee. It's interesting to read the crash report and the details involved because the lessons that we have. And the reason we do a lot of the things we do in aviation, are because of the lessons are all written in blood. Unfortunately, we continue to push the envelope when we go a little bit farther until something happens. And then, we try to figure out why that happened and then we just continue on. Aviation is not inherently dangerous but it's terribly unforgiving, right, questions? >> I think we also had another question up in the chat. Is the holding of breath in the anti G strain maneuver, maintaining the systolic pressure. Usually experienced from the pumping of the heart in a way? Yes, that would be yes, I think that's an accurate way, I don't know how the pressures do. I don't I don't know how you'd actually measure the pressure. Yes, that's exactly what we're doing, we're trying to maintain the blood flow. We're trying to maintain the oxygen in the brain and and so yes, I would say yes, okay? >> And this last comment I think can segway nicely to a question which is. The body so naturally tolerates high positive Gs but not so well high negative Gs. Can you maybe add on on why the human body is an effective at resisting negative Gs. >> Great questions and everything that I read, I went to several sources. Just the body does not tolerate that much blood in the brain very well, the brain is not happy. It's an enclosed area and it's either filled with neurons or blood and fluid. That's it, you got blood, you got cerebral spinal fluid and you've got neurons. And so when you get something else up in there, then the pressure inside your brain increases and that's bad. That's not good, you get a headache and and neurons are not happy, they're very happy with oxygen. That anything that comes up here and start to crowd their space, they are not happy at all. So we run into that when somebody has a head lead, that they have a stroke and you have a blood vessel, the brakes. And you end up with a stroke that increased pressure in the brain is very bad or somebody's got a closed head injury. Again, you get swelling in the brain, all that extra pressure is very bad. Okay, I thought I saw the G light, G force loss of consciousness and that all has to do with. Again, we use the terms that somebody had mentioned here, you don't have enough systolic pressure. To profuse the brain and that's exactly what we're doing, the brain is not getting the oxygen. And we know that the brain and the eyes are very sensitive to the lack of oxygen. And so that's where G lock comes in and you can actually see some of the videos, you can pull it up on YouTube. And you can watch people in the centrifuge and it's funny, you'll sit there and laugh at. because people do all kind of funny things with their head and then you realize, yeah, I wouldn't do any better if I got in there. So I'm not going to laugh too much because each one of us [LAUGH] would be the same way. >> To bring us full circle, the discussion of shock, it's not quite shock because it's not necessarily distributed or widespread. But it's a very specific form of you can't get the blood to the head like it's supposed to. And you then you run into hypoxia of the brain. >> Right, that's a better way to put it, you're not confusing, the brain is not really shocked. But you're not confusing, you're not oxygenating the brain, right? Great questions, great comments. Anybody else? Fine, the blood vessels in the brain, they do have valves, it's actually a very good question. And it's also you're correct, it's almost like a stagnant hypoxia. The blood vessels in the brain, do not have valves similar to what we have in the rest of the body. There are some but not nearly as much as over the rest of the body has. And I'm not sure about why all the physiology that is but I'm going to take a stab at it, so don't hold me, I'm not a profusionist. But the blood supply and the brain is set up that there's a supply that comes in from many places. And it all joins up in one big circle of Willis, there you go, thank you. Absolutely, I love it and it ends up in a circle of Willis and ended distributed again. And the reason is that way is if you include one of the arteries. Then you still have the other arteries that supply the circle of Willis to supply blood to the rest of the brain. And I got pretty sure it probably has something to do with that. So if you think about that way, the circle of Willis this is a holding pool and then, it distributes blood to the rest of the brain. In that way, if you have people get blockages that are corroded arteries and so if you block off one. You still have the second one and you have one in the posterior, you have your vertebral artery that supplies. But if you have two of them get clogged off, then you got a bigger issue because now you only have one artery supplying blood to the brain. Again, that's my best stab at it. >> I think also if you kind of look at it from an evolutionary perspective, right? Humans eventually evolved to be bipedal, so we have those valves in our legs. To help us fight the gravity of pushing blood back up out of the legs. However, our brains have always been above, so we don't need those same kind of valves to let the blood trickle back down. Gravity assists with that. So when you get in and abnormal situation where gravity is no longer assisting, that's where you have those issues. Right, good question on the leggings, that would provide some G tolerance because that's essentially what the suit does. The suit that they wear a G suit, I'm sorry I didn't bring that up before. So they wear a G suit which it's a fabric suits, that they wear from their belly button on down. And when the aircraft senses that they're going into these hygiene maneuvers, it inflates. And so that would be a higher level of the tight leggings that you wear. All right, so that's an automatic response and again for the crash involved. The leggings were certified and you actually there's a great set of checks and balances in a checklist. And you have your crew chief makes sure that all that stuff hooked up and your life support people make sure that all that worked and they confirmed that it was working for the flight. Good question though. >> And really quickly I don't know if we have any other questions but to relate that one actually even more directly to space. There as a engineer from MIT and Dominica, no you might have the name on hand that is in the process of researching and designing an EVA suit that's not nearly as bulky as our current ones. It actually is an incredibly well-made compression suit that provides enough pressure to the body, that it can kind of cover everything that a normal EVA suit would but not be as bulky. And Dominic, you might be able to elaborate a bit on that more. >> Yes I believe her name is David Newman, Dr Newman at MIT and it's effectively a whole rather than using pressure like air or hydro pressure. It actually uses coils and magnetic springs more or less to apply a positive pressure effectively on the whole body. And there's actually a really cool application, I was reading some of the notes on it that this could be used for futuristic tourniquets where you more or less have a coil that will naturally wine. When you apply either a current or a little bit of stimulation, mechanical force then you'll get basically a super tight seal that prevents blood flowing outwards and causing other forms of shock causing hypovolemic shock to to bring things full circle. And Patrick I see you nodding along, I don't know if you have encountered discussions of this technology or. >> I think it's a great idea, I think it's actually very cool because I think yeah there you go. I think we've done well with what we got but we can improve upon all the things that we're doing so far and that's just a great idea to have those coils and then because it's a whole lot less bulky you can implement that right into the fabric. So I also saw a question from Pam, yes. The anti G suit works much like the SCDS that we put on our patients that are in bed. A sequential device that keep people from getting DVDs in their legs. >> All right wonderful. We are past time so I want to be respectful of Patrick's time here. So we're going to go ahead and wrap it up, do we have maybe one last question or we all satisfied? Yeah the suit is really cool, I would highly recommend you go and look at it. It's the different lines are very specific stress points that she is applying pressure to, it's really cool. But if there are no more questions I want to give a big round of applause to Patrick for coming in and giving, of course, his guest lecture wasn't, I guess it was my honor. >> I'm glad to be here, if you need anything else, please give me a call.
