Episode 26: Richard Moon discusses deep-sea and high-altitude medicine
// Dec 6, 2016
Dr. Richard Moon had an unusual inspiration to practicing medicine: a television show, in black and white, entitled, “Medicine in the ‘60s.” He remembers being blown away by watching live surgeries performed on the show. This eventually led him to a career in the operating room—not as a surgeon, but an anesthesiologist.
Like many STEM-Talk guests, Moon wears many hats. In addition to being a physician, he is a renowned researcher in the hyperbaric and diving medicine. He is currently a professor of anesthesiology and medicine at Duke University, and the Medical Director of Duke’s Center for Hyperbaric Medicine and Environmental Physiology. http://anesthesiology.duke.edu/?page_id=828766
In this episode, Host Dawn Kernagis, herself a rising research scientist in undersea medicine, as well as a highly experienced diver—earlier this year, she was inducted to the Women Divers Hall of Fame—talks with Moon, one of her mentors. Dawn met Moon when she participated in one of his research projects as a diver, and she went to him with research ideas as a potential research intern. She eventually became one of his graduate students at Duke University.
In this lively and informative mentor-mentee discussion, Dawn and Moon talk about the history of hyperbaric medicine, including the establishment of Duke’s world-renowned Center for Hyperbaric Medicine and Environmental Physiology. They talk about medical conditions that can occur in deep sea diving, such as high pressure nervous syndrome and immersion pulmonary edema, as well as high-altitude sickness.
Moon shares insights about his experiments in both high altitude and deep sea medicine, as well as his own expedition in climbing Mount Everest.
Check out Moon’s home page at Duke: http://anesthesiology.duke.edu/?portfolio=richard-moon-md ; as well as his lecture at IHMC last January: “From the Ocean Depths to the Mountain Tops: How Do Humans Adapt?” https://www.ihmc.us/lectures/20160121/
00:15: Dawn introduces Ken and describes Moon as a world-renowned physician and researcher who works in hyperbaric and diving medicine.
00:40: Dawn says she was “very lucky to have Dr. Moon as a mentor.” She participated in his research projects, as a diver. She then went to him with research ideas, and he accepted her as a graduate student, and he’s been a mentor and colleague ever since.
1:45: Ken reads a five-star iTunes review from “GTG2010” called “Exploding Kid:” “Dear STEM-Talk, I like your show. The super telescope looking at asteroids is cool. I like it so much I’m going to explode. Love, Griffin, age 6.”
2:38: Dawn runs through Moon’s bio. He holds an M.D. and a C.M. from McGill University in Canada, and a Master’s degree in biomedical engineering from the University of Toronto. He is a member of the Royal College of Physicians of Canada, as well as the American Board of Internal Medicine. He has authored hundreds of peer-reviewed publications.
3:48: Dawn welcomes Moon to the podcast.
4:06: Moon describes what sparked his interest in medicine when he was in high school. He watched a television show, in black and white, called “Medicine in the ‘60s.” “It showed operations. It was mind-blowing, so I decided that I had to go into medicine.”
4:49: In medical school, Moon’s first interest was in pulmonary medicine—simply because in the first-year lecture series on organ systems, the one on the pulmonary system was the best. Yet, he felt compelled to do something different and took a couple of years off to study biomedical engineering.
6:20: Moon went to Duke University with a fellowship in pulmonary medicine as well as an opportunity to undergo scientific training in diving physiology. One of his mentors, Enrico Camporesi, encouraged him to go into anesthesiology.
7:20: “Eventually he [Camporesi] won me over. That’s where I am today.”
7:46: Moon’s interest in diving physiology initially came from the television program “Sea Hunt.” He also read the Jacque Cousteau books, which talked about decompression sickness and carbon monoxide poisoning. “When it came time to figure out where I was going to go after internal medicine, since Duke had this mega lab, the best in the world, and some leading lights in diving physiology, I just couldn’t resist.”
8:48: Dawn comments that the F.G. Hall Laboratory, which is now part of the Center for Hyperbaric Medicine and Environmental Physiology “is considered to be one of the best and prestigious environmental physiology labs in the world. Especially back then, there was research being done that wasn’t being done and hasn’t been done anywhere else in the world.”
9:18: Moon talks about the history of the lab. People have always asked, ‘How did this undersea lab get to be in a place that isn’t near the ocean?’ “It was a confluence of interests at Duke at the time. Herb Salzman was a pulmonologist interested in diving; F.G. Hall had been of an earlier generation and interested in altitude physiology; a surgeon named Ivan Brown was interested in cardiac surgery under hyperbaric conditions. This was an era before heart and lung machines were developed. So, the notion of drenching the tissue with oxygen was very appealing – if you could hyperoxygenate tissues in a hyperbaric chamber during surgery, you would have longer available time to perform surgery.”
11:07: One of the chambers at the Duke Hyperbaric Center was built as a hyperbaric operating room. Enough money was put together to create the facility. By the time the chamber was open, heart and lung machines were in place, so the whole concept of surgery in a hyperbaric chamber was out of date; however, the Duke Hyperbaric Center remained a nice facility to treat patients.
12:03: In 1968, after the nuclear submarine disaster, the Navy realized that it didn’t have a facility to do deep diving. So, Saltzman was asked to develop a deep diving program for salvage operations at 1000 feet of seawater.
12:35: In the late ‘60s through mid-70s, there was a perceived expiration of oil. Several labs were created around the world (two labs in the U.S. (University of Pennsylvania, Duke), one lab in Europe, and one lab in Japan) to study the physiology of humans during exposure to relevant depths for oil exploration (1000-2000 feet). Several problems were identified for humans at these extreme depths, including high pressure nervous syndrome (HPNS, where a diver gets tremors, difficulty standing up, nausea, vomiting).
14:08: Part of the Duke endeavor, called the Atlantis Dive Series, was to work out how HPNS could be overcome. One idea: to put a little bit of narcotic gas (nitrogen) in the helium-oxygen breathing mix; it was felt this might offset HPNS. It did work, but it had other effects such as an increase in breathing gas density.
15:00: With an increase in gas density, did lung work to provide enough oxygen to the tissues and remove carbon dioxide? Duke was the first to measure blood gases, such as oxygen, and pH under those conditions. They found that the lungs actually worked pretty well breathing a denser gas, contrary to common belief. The Duke researchers provided the boundaries on what the lungs could do under those circumstances.
16:15: To get to 2,000 feet, it takes several days: one way to offset HPNS is to add nitrogen to the mix, Decompression is slow – it takes 2-3 weeks to get people to the surface from depth due to decompression issues.
17:10: The Atlantis Dive Series conducted four experiments—each with three male study participants living inside the chamber. “They were stuck inside. If one of them had developed an acute illness, say appendicitis, it would have taken us three weeks to get him out.” They were also in tight quarters and slept in bunks in layers. Food had to be locked in.
18:10: Our part of the experiment was to have each person exercise on an exercise bicycle. The other guys had to place an arterial catheter in the wrist. The blood samples then had to be analyzed in a blood gas machine. “It was an adventure not only in biology, but also in engineering. “
19:10: Dawn compares it to telemedicine, and asks about the psychological issues of the men in the experiment.
19:40: Moon says there were areas of friction: “Three is worse than two or four because one person is always the fall guy. It was a challenge. They were carefully chosen, and they were up to it, and ultimately did a great job.”
20:00: Dawn mentions linking to Duke University’s F.G. Hall Center: http://anesthesiology.duke.edu/?page_id=1061
20:48: One of the benefits of Duke’s chamber is that it is actually within a hospital. “We can expose people to high or low pressure to simulate altitude and have all the accoutrements of medicine available.” Moon adds they’ve been able to do some very interesting studies. He mentions one, led by Dr. Jake Freiberger, which looks at nitrogen narcosis and any cognitive effects of additional carbon dioxide.
22:21: Another study is looking at immersion pulmonary edema, which is basically “drowning from the inside,” or when divers’ or swimmers’ lungs fill up with fluid. They’ve shown: People who are susceptible to pulmonary edema have higher pressures for a given amount of exercise than others. This issue reached public consciousness because Navy Seals have experienced this malady. “These are young, healthy, exceptionally fit individuals who start coughing up fluid/blood in the middle of what would otherwise be a normal swim.”
24:00: Moon explains that the hearts of people susceptible to pulmonary edema are normal, but just a little bit different. Their left ventricle is a little stiffer than normal when the heart fills up with blood. Therefore, in order to fill it, the pressure is a little bit higher; adding to that is extreme exertion, which raises the pressure even higher. That’s enough to break the barrier between the blood within the lung and the air spaces within the lung, and cause fluid to leak.
25:18: To deal with it, a lot of people (including the Navy) have recommended pushing fluids. Dehydration is a bad thing; overloading with fluid tends to make the problem worse. Some potential drugs could be taken.
26:10: Navy SEALs tend to get it; and triathletes—especially during the swim part of the race – can also experience it. “Triathletes are go-go people; want to win the race. They often see it, not as a health problem so much as something that just slows them down.”
26:54: Commercial break: STEM-Talk is an educational service of the Florida Institute for Human and Machine Cognition, a not-for-profit research lab pioneering ground-breaking technologies aimed at leveraging human cognition, perception, locomotion and resilience.
27:40: Problem with altitude boils down to one thing: low levels of oxygen. Because pressure is lower, the partial pressure of oxygen is lower as well…low oxygen has a variety of effects on human physiology. People who go to high altitude often experience acute mountain sickness, which is nausea, vomiting. It can cause high altitude cerebral edema or high altitude pulmonary edema, where lung fill up with fluid.
29:07: If you go to 10,000 feet and then exercise, you realize at altitude you really can’t do it as well as you can at a lower altitude (e.g., you are short of breath). One of the mysteries of altitude is people who have lived there, such as Sherpas…on Moon’s trek to Mount Everest, they were continually surpassed by Sherpas with 80 kilos on their back. They were small guys—150 pounds at most.
30:50: On their way to Mount Everest, their blood oxygen saturation started off in the 70s when their place landed; they were often down in the 60s. If you ask the average physician what would happen if blood oxygen is in the 60s, they would say brain damage. It’s also difficult to do field research. On the other hand, you can do things in the field that you can’t do in a lab-based facility. “It’s always a balance, and you get incremental pieces of information from each type of research.”
32:27: Moon mentions a study that was propelled by John Andrews, a Green Beret before medical school, who had experienced altitude issues. They studied a new drug, called Riociguat (for people for pulmonary hypertension); they are interested in whether this drug would increase exercise performance at altitude.
33:50: They found that pulmonary pressure did go down; the drug worked as advertised; but, unfortunately, it didn’t change exercise performance or improve oxygenation. Had it worked, it could have been a very useful drug for special forces deployed in mountainous areas throughout the world.
34:40: Moon discusses hyperbaric oxygen therapy, calling it “essentially a dive in a hyperbaric chamber breathing 100 percent oxygen at double the atmospheric pressure.” It has therapeutic applications for diving injuries and carbon monoxide poisoning. You can wake people up more quickly, prevent long-term complications, and make people feel better very quickly. It can also be used to treat gas gangrene—an infection of soft tissues that is highly lethal. Hyperbaric oxygen facilitates the killing of those organisms. It is also therapeutic for healing wounds in people with atherosclerosis and diabetes (related foot injuries).
37:14: Moon talks about career paths for people interested in studying diving or high-altitude medicine. He says there are several routes: one is doing expeditionary medicine in the Armed Forces. Another is going into a related field such as surgery, internal medicinal pulmonary medicine or anesthesia, and using altitude medicine as a sideline.
38:25: To do it full-time, Moon suggests programs at Duke or the University of Pennsylvania; or the military.
38:48: Dawn adds there are close ties (and opportunities) between both academic and military research centers.
39:30: Moon says he has read a lot of books written by people (like Jacque Cousteau) and many of the mountaineers. In terms of the medicine of diving, the book that really got him into it was edited by Peter Bennett and David Elliot. It’s a classic called “The Physiology and Medicine of Diving.” Fred Bove also edited a book called “Diving Medicine” for several editions.
40:41: Moon talks about his own expedition to Mount Everest, first noting that during the earliest “Hillary” expeditions, they had to walk from Katmandu. Now people fly into Lukla (in Nepal), “the most dangerous airport in the world. There’s no second chance for the pilot. You’re flying in with wingtips close to mountains…the runway goes cliff, runway, cliff…You have this little landing strip, so there’s no way to turn the aircraft around if you miss the landing.”
42:00: “The first day, you have to go down 1,000 feet, and then up 1,000 feet. At the end of that day, you think: ‘If this continues, I don’t think I’m going to be able to do it.’ But the scenery is spectacular: It starts off tropical. [Then it becomes] almost like a hike in a U.S. National Park. The higher you go, eventually it becomes barren, as trees drop away. Eventually it is snow and ice. By the time you get to base camp, it’s totally snow. But it also has a huge diurnal variation in temperature. When you wake up, you’ve gone through minus twenty degrees Fahrenheit. By lunchtime, you’re sitting with very little clothing on. Once the sun goes down behind the mountain, it becomes very cold again.”
43:36: “The Sherpas are delightful people. There is usually one room only that is warm; with a stove in the middle burning yak gum. Food is pretty good. “Despite eating like crazy because you’re hiking, and you’re hungry, we lost weight … It seems to be an altitude effect.”
45:00: Dawn observes that whenever they bring the tools of the trade into the field, whether deep divers or free divers, there’s always always a lot of interest peaked in terms of the research being done.
45:31: A British group had a full-blown lab at 12,000 feet at Namche, and another group had one at base camp: they were doing muscle biopsies, exercise tests…that data is still being crunched. “Climbing community is like the diving community: it’s a very elite group of people. Everyone’s got their own theory on how to do it, how best to prepare for it. There’s a relative lack of science because the experimental conditions are so tough.”
46:25: Dawn thanks Moon.
46:37: Dawn commentates on being able to interview her mentor, and Ken calls Moon “a broad and fascinating fellow.”
46:50: Dawn and Ken sign off.