Hyperbaric Oxygen Therapy

Richard: There's increasing evidence that hyperbaric oxygen is useful in inflammatory diseases, for example, ulcerative colitis or Crohn's disease. There's actually a trial going on to confirm the benefit of hyperbaric oxygen in possibly other inflammatory diseases as well.

Brent: Welcome to the Life Lab by Dethklok. I'm your host, Brent Franson. And the mission of Dethklok is to help 100 million people live ten years longer. Today, we speak with Doctor Richard Moon about hyperbaric oxygen therapy. Doctor Moon is the medical director of the Duke Center for Hyperbaric Medicine and Environmental Physiology. He's been in that role since 1989.

Brent: He's a professor of anesthesiology and medicine at Duke University, and he's the past president of the Undersea and Hyperbaric Medical Society. He's been an anesthesiologist studying hyperbaric oxygen therapy and its role primarily in clinical settings. It's used for wound healing. It's used in cases of carbon monoxide poisoning. But it's increasingly a part of the longevity conversation. Bryan Johnson is famous for using a hyperbaric oxygen chamber regularly and touting its benefits at increasing telomere length, and so we ask him about it in that context.

Brent: He's also a fascinating person. He is the go-to phone call if you are scuba diving and you get really bad decompression sickness. He's a really wonderful guest for helping us understand what hyperbaric oxygen therapy is, what it isn't, and where the science is.

Brent: Doctor Richard Moon, welcome to the show.

Richard: Thank you. Glad to be here.

Brent: So today we're going to be speaking about hyperbaric oxygen therapy, and I'm excited to do that. I feel like this is something that's been talked about increasingly in longevity circles. I'm interested in separating fact from fiction and getting your perspective on that.

Brent: What's the shorthand for hyperbaric oxygen therapy?

Richard: We tend to say HBOT here, but others say HBO or HBO2.

Brent: Okay, great, HBOT. Before we get into all things HBOT, can you give us a sense of your background and day job?

Richard: Yes. I am trained as a physician in pulmonary medicine, critical care, and anesthesiology. I do anesthesia several days a month and hyperbaric oxygen therapy. I also evaluate people for safety in diving—people who have various conditions and want to know whether they should dive or not. Of course, the hyperbaric part is that I take care of both patients with wounds of various kinds as well as critically ill patients with carbon monoxide poisoning.

Richard: Gas embolism, usually decompression sickness, those sorts of things.

Brent: And when you say diving, you're referring to scuba diving, correct? Maybe the first question that comes to mind is: is there a relationship between anesthesia and HBOT, hyperbaric oxygen therapy? Do you think of those two things as connected, or were you trained as an anesthesiologist and then became interested in HBOT separately?

Richard: I was interested in hyperbaric oxygen for a long time, primarily diving-related. There is a connection in the sense that in anesthesia we deal with gases—carbon dioxide, oxygen, and what have you—which we also do in hyperbaric medicine. Some practitioners come from emergency medicine, others are internists or pulmonologists. There's a range of people with different specialties.

Brent: Let's start with the very basic question of what it is and how we are using it in clinical settings.

Richard: Hyperbaric oxygen is administration of 100% oxygen at increased ambient pressure. Here in North Carolina, currently I'm almost at sea level, so that's one atmosphere or 760 mmHg. In a hyperbaric chamber, we commonly treat people at two atmospheres and sometimes three atmospheres. Somebody getting 100% oxygen to breathe at elevated ambient pressure increases the oxygen content in their blood.

Richard: That has several effects. One, for example, is that in patients with carbon monoxide poisoning, carbon monoxide is a toxic gas that binds to hemoglobin and displaces oxygen from blood. Breathing 100% oxygen at high pressure essentially forces carbon monoxide off the blood and other proteins, facilitating the recovery of patients with carbon monoxide poisoning.

Richard: It also reduces the risk of long-term complications of severe carbon monoxide poisoning. We also treat patients with certain types of wounds that are not healing due to insufficient blood supply. Another indication is certain bacterial infections that are susceptible to high oxygen, as well as bubble disease, which occurs sometimes in scuba divers related to nitrogen or helium if they happen to be breathing it.

Richard: That's due to the formation of bubbles from supersaturation. For example, when you open a carbonated beverage and pour it into a glass, it bubbles because carbon dioxide is dissolved at high pressure. The high pressure is maintained while the bottle or can is closed. As soon as it's opened, the excess carbon dioxide in the liquid forms bubbles.

Richard: The same thing can happen with inert gas when divers breathe nitrogen or helium.

Brent: Basically, it is a therapy in which I am breathing 100% oxygen at some increased pressure. I'm in Colorado, so the air is a little thinner up here. You're at sea level, so you're at one atmosphere, and you're putting somebody in a chamber brought to two atmospheres. You can go up in elevation and the air gets thinner, or you can go down and the air pressure increases.

Brent: Can you help me visualize it? Is it a steel chamber I'm walking into—basically a small room that is closed and sealed, with oxygen pumped in until the air pressure reaches two atmospheres on average? What would the experience look like?

Richard: There are two types of hyperbaric chambers. There's a monoplace chamber, called that because one person fits inside (or a parent and a small child). Those chambers are transparent, made of Plexiglas. The door is closed, and then 100% oxygen is pumped in until it reaches the target pressure.

Richard: Another type is a steel chamber, called a multiplace chamber. That is a small room in which the pressure is increased by pumping in air. We administer oxygen to patients either with a tight-fitting mask, or more commonly with a head tent—a device that fits over the head.

Richard: There's a rubber collar going around the neck to seal it, and then a transparent hood that looks like a space helmet into which oxygen is blown to increase the concentration to 100%.

Brent: The air that we breathe normally is 78% nitrogen, 21% oxygen, and 1% other gases. Nitrogen is inert, so breathing 100% oxygen without nitrogen or other gases is physiologically fine for our bodies?

Brent: Our bodies are fine with that.

Richard: Our bodies are fine with that up to a point. If you breathe 100% oxygen at sea level with a tight-fitting mask for a long time—several hours or a day or two—eventually the lungs get damaged and you get oxygen toxicity, which causes inflammation in the lungs.

Richard: The lungs start weeping fluid, developing pulmonary edema. Oxygen is toxic to all tissues in the body, but the lung is the first organ to experience it because it sees the highest partial pressure. Hyperbaric oxygen therapy protocols have to account for avoiding oxygen toxicity. While the lung becomes toxic first, the brain can also experience toxicity.

Richard: The manifestations are variable: it can cause nausea, tingling in the hands, or seizures similar to an epileptic seizure. There are no lasting ill effects from it, but nevertheless it's something we try to avoid. That is related to the pressure and the fraction of oxygen.

Richard: This was discovered back in the 1920s and remained an uninteresting fact until World War II, when the navies of Italy, Great Britain, and the United States started developing special forces who could sneak into enemy harbors and place mines on ships. When doing that, you don't want bubbles giving away your position.

Richard: These divers were breathing 100% oxygen in a closed-circuit system with a counter-lung and a carbon dioxide absorber. It was discovered during testing that if divers went deeper than about 20 to 30 feet, there was a real risk of having a seizure.

Richard: That is a problem for a diver, because if someone has a seizure underwater, their mouthpiece comes out. When the seizure ends and they take a breath, they inhale water and drown. Oxygen toxicity was a big feature of special forces diving and still is. However, on dry land in hyperbaric oxygen therapy, it is much safer.

Richard: The brain's tolerance to high oxygen levels is much greater on dry land. We routinely treat patients at two atmospheres absolute, and we hardly ever see a seizure. As you go higher in pressure, seizures become slightly more common.

Richard: We occasionally see seizures at higher pressures. Again, as long as they are breathing oxygen or air on dry land, there is no long-term damage, but it does indicate toxicity.

Brent: Why is there a Goldilocks zone pressure-wise—meaning two atmospheres is better than one atmosphere, but also better than four atmospheres in terms of oxygen toxicity? Why does pressure matter in terms of the body's ability to tolerate it?

Richard: It's because of partial pressure. At one atmosphere, breathing 21% oxygen means the partial pressure of oxygen is 0.21 atmospheres. In Colorado, because your atmospheric pressure is lower, it's slightly less than 0.21 atmospheres.

Richard: Humans and other animals evolved under roughly the same atmospheric pressure and oxygen fraction over millions of years, so the body tolerates it. At higher pressures, the partial pressure of oxygen increases, which is when toxicity begins. You're right about the Goldilocks zone: we want to treat people with hyperbaric oxygen at the right pressure—not too low and not too high—to avoid toxicity.

Brent: Let's talk about why it's actually helpful. If you breathe 100% oxygen for too long, it's toxic. But if you have a wound or carbon monoxide poisoning, it has a medicinal, healing purpose that helps you recover faster.

Brent: Setting aside diving for a second, if a patient is in a hospital and recommended hyperbaric oxygen therapy for a wound or carbon monoxide poisoning, what is it doing? Why is it helpful?

Brent: What what is it doing? Why is it helpful?

Richard: We don't use it for all wounds—most wounds heal fine on their own. But in individuals with vascular disease, such as atherosclerosis, there isn't sufficient blood supply to the wound.

Richard: Or they may have had past radiation therapy that thinned out blood vessels. While blood supply might keep the skin and muscle intact, healing a wound requires additional blood supply and oxygen that may not be sufficient on its own.

Richard: Adding hyperbaric oxygen increases the amount of oxygen in the bloodstream while the person is in the chamber, which can be sufficient once or twice a day to elicit healing.

Brent: So the combination of two issues becomes a problem—for example, having vascular disease and getting a wound from a cut or car accident. The rate at which the wound heals is impacted by the vascular disease, so hyperbaric oxygen therapy is used to help it heal. Is that right?

Brent: And so the combination of these two things, we would say, all right, in order to help the wound heal, that is unrelated to the heart disease, but the the rate at which it's it's healing or not healing is related to the heart disease. We're going to use, hyperbaric oxygen therapy, is that right?

Richard: That's exactly right. Yes.

Brent: What do you think about HBOT for general longevity and preventative health? Are you skeptical or optimistic? Do you believe spending time regularly in a chamber to prevent disease is beneficial, even without a specific clinical indication?

Richard: I have an open mind, but currently we don't have enough evidence to say one way or the other. There have been studies looking at parameters associated with aging. For example, chromosomes contain DNA and program cells in our body.

Richard: Chromosomes have protective caps called telomeres, and aging is associated with a decrease in telomere length. Studies have looked at what happens to telomeres in individuals receiving hyperbaric oxygen.

Richard: Evidence so far, at least in some cells, suggests that it causes an increase in telomere length. That parameter of aging appears to be reversed to some degree by hyperbaric oxygen. The question is whether that is just an interesting phenomenon or if it actually protects cells against aging or reverses it.

Richard: Many changes occur with aging: blood vessels become more rigid, muscle mass decreases, hair turns gray, and skin wrinkles. Dying your hair back to its natural color doesn't increase longevity.

Richard: Could hyperbaric oxygen be lengthening telomeres without actually increasing lifespan? Additionally, other interventions reduce the rate of telomere shortening, such as exercise, healthy diet, and maintaining a healthy weight.

Richard: Those lifestyle factors decrease the rate at which telomeres shorten. We don't yet know for sure where hyperbaric oxygen fits in.

Richard: Some studies show these changes, but we need more data.

Brent: The limited data available isn't conclusive, but some studies show an actual increase in telomere length rather than just a slower rate of shortening.

Brent: With hyperbaric oxygen therapy, are they actually increasing the length of telomeres rather than just slowing the shortening rate?

Richard: Yes, there is published data showing that, which is very interesting. As with anything in science, we look for replication from independent sources to verify if the result applies broadly.

Brent: What is the downside of experimentation? We know exercise, sleep, and diet matter significantly, so focusing time on heavily researched areas makes sense.

Brent: If someone is already running, eating well, and sleeping enough, and wants to sit in a hyperbaric oxygen chamber as well—setting aside financial cost, is there a physical risk that regular sessions could cause harm?

Brent: And I will acknowledge that the you know, the research is not quite definitive, but I don't know, telomere lengthening sounds pretty good. And what's the downside if we set aside just a cost downside. But is there some risk if I'm if I'm doing it at some regularity, that I'm going to harm myself and have the opposite of the intended consequence.

Richard: The risk is low, but anytime you perform a medical procedure, there is some risk. If it is beneficial, how much treatment is needed? Do you need one course of 40 treatments, or repeat courses every six months?

Richard: Ideally, to study this, you would divide a large group into two: one receiving regular hyperbaric oxygen and the other receiving a sham control treatment.

Richard: In a sham setup, participants think they receive hyperbaric oxygen, but pressure is increased only slightly. You would then follow them for life to see who lives longest, but a 20- to 30-year human trial isn't feasible.

Richard: To test the hypothesis, animal studies using mice or rats can track lifespan naturally from birth to death.

Richard: Comparing rats given hyperbaric oxygen versus a sham treatment would show if lifespan increases, as mechanisms would likely translate across species.

Brent: I presume that study hasn't been done yet and the topic remains understudied?

Richard: Yes, it is understudied. However, one of my colleagues recently obtained a grant to investigate this, and I look forward to the results.

Brent: If those study results turn out positive, why would that be? What mechanism in general health would cause breathing 100% oxygen at two atmospheres to be beneficial?

Brent: Why would, some frequency out breathing 100% oxygen at two atmospheres? Why would that be good for me?

Richard: There are a few theories. One theory proposes that aging is caused by oxidative stress. Oxygen creates oxygen free radicals, which can damage DNA and cell components.

Richard: The body uses antioxidants for defense. Giving hyperbaric oxygen on a long-term basis might induce higher levels of protective antioxidant defense mechanisms against oxidative stress.

Richard: That is just a theory at present, but it represents one plausible explanation.

Richard: I have no idea whether that's the case or not, but that's one possibility.

Brent: What about the bear case—if a definitive study shows no preventative benefit?

Brent: I don't know. Is it just the opposite of that. It's just some other theory. I mean, why would that be the case?

Richard: Proponents currently observe reversed markers of aging without fully proven explanatory mechanisms. If it isn't effective, it could mean the dose was wrong or the concept was incorrect.

Richard: But that's of course, that would be the next step if it's helpful. What's the mechanism? If it's not helpful, why wasn't it? Do we pick the wrong dose? Or maybe the whole idea is is garbage. Anyway, We'll see.

Brent: How do clinicians in this field view their personal relationship to it? As a leading expert who relies on rigorous research, do you or your colleagues personally experiment with hyperbaric oxygen therapy in anticipation of positive findings?

Brent: But do then do do you or do your colleagues then say, well, actually I believe in where this is going. And so for me personally, I'm going to spend some time in hyperbaric oxygen, oxygen therapy, because I think that research is going to prove positive. And so it'd be irresponsible for me to say it, you know, broadly recommend it.

Brent: But actually, for me, I'm willing to experiment on myself. I'm optimistic enough about it to show people, you know, you can speak about yourself personally or not. You know you'll choose what you want to do. But do people in the space who are close to it, are they experimenting on themselves at all or no, the science is too early.

Brent: They want to do the real experiments and they're not really thinking about it for themselves.

Richard: I don't know of anyone close to the science experimenting on themselves. Given established interventions like exercise, diet, weight management, and treating hypertension, researchers are waiting for confirmed trial results.

Richard: Even if 40 treatments are beneficial, open questions remain about frequency—whether treatments must be repeated daily, annually, or every five years.

Richard: Or can you do it once a year or once every five years? I mean, these are open questions.

Brent: Cost is a key consideration. Home hyperbaric chambers cost around $50,000, require oxygen refills, and carry fire risks. Even if recommended, 40 yearly sessions would be cost-prohibitive for most.

Brent: Everybody should be doing 40 sessions, I don't know, once per year. It's going to be a little bit cost prohibitive.

Richard: Yeah. But that's exactly right.

Brent: What about pulse oximeters? Should consumers use fingertip pulse oximeters for monitoring general health?

Richard: Pulse oximeters aren't very useful at sea level for healthy individuals because readings sit at 98% to 100%. At high altitude, readings are lower.

Richard: Evidence that moderate high altitude reduces longevity is sparse, and cancer risks in high-altitude areas like Colorado are lower than in some sea-level regions.

Richard: Slightly lower oxygen saturation at moderate altitude isn't proven detrimental, and using home oxygen tanks to raise it offers no documented benefit.

Brent: You've been to Everest Base Camp and seen low-oxygen environments firsthand. What happens in the body at extreme altitudes, and what is supplemental oxygen's role?

Brent: And you know, what it's doing in terms of oxygen saturation.

Richard: At extreme altitudes, blood oxygen drops significantly, hindering physical activity. Oxygen saturation can fall to the 60% range, making supplemental oxygen necessary.

Richard: At moderate altitudes like Everest Base Camp (~17,000 feet), the body adapts by growing muscle capillaries and increasing mitochondria. Sherpas have physiological adaptations allowing normal activity at that elevation.

Richard: And, and some people, some groups, for example, the Sherpas, they have all kinds of adaptive mechanisms, and they can, you know, do almost anything at 17,000ft that most of us can do at sea level. So obviously, if you if you're going to live at 17,000ft for whatever reason, you got a summer job at base camp, at Everest, working there for whatever reason, doing science or something else.

Richard: Carrying oxygen tanks at 17,000 feet isn't necessary unless exerting heavily, as the human body can adapt to that altitude.

Brent: Is oxygen toxicity a concern when climbing Everest, or is oxygen pressure too low at 25,000 feet for toxicity to matter?

Brent: Or I already have such low oxygen that it doesn't matter?

Richard: No, oxygen toxicity is dependent on partial pressure. At the summit of Everest, ambient pressure is roughly one-third of sea level, so 100% oxygen equates to 33% oxygen at sea level and will not cause toxicity.

Richard: There are three main altitude illnesses: Acute Mountain Sickness (AMS), High Altitude Pulmonary Edema (HAPE), and High Altitude Cerebral Edema (HACE). AMS causes headaches and nausea, resolving in a few days with acclimatization.

HAPE causes fluid accumulation in the lungs, severely lowering blood oxygen and posing a life-threatening risk. HACE causes dangerous brain swelling.

Richard: Redeem your lungs, fill up with fluid and of course, what that does is it makes your oxygen level in your blood go down even more than it was just from the altitude itself. And, high altitude edema can kill you. There's another very poorly understood type of altitude illness called high altitude cerebral edema, where the brain swells up and we know almost nothing about the about the physiology of it.

Richard: If someone develops HAPE or HACE, giving oxygen and descending immediately is essential.

Richard: I also if you see those individuals, you got to get them off the mountain or you've got to give them oxygen for sure.

Brent: What do you think of recreational canisters sold at ski resorts for altitude headaches? Are they effective or a gimmick?

Brent: They've got these little tanks that have basically what looks like a, you know, a breather. It's like a mouth guard on it. And you can you can consume, you can breathe just straight oxygen. Do you think those are good for the tourists or is that a is that a sham?

Richard: Small oxygen canisters contain very little oxygen and only last a couple of breaths, making them essentially ineffective for treating altitude illness.

I had a scary experience running out of air diving off Monterey at age 15. What happens physically during decompression sickness, and how does hyperbaric oxygen therapy resolve it?

Brent: And running out of air diving is a pretty crazy experience. It's you don't it's not like there's just a little bit of air and you're sucking really hard. It's like you're sucking on a bottle of toothpaste. I mean, there's nothing there. And you, you know, in my case, you haven't taken a full breath. I think when I pictured training for scuba diving, like, you've taken a full breath and you've got time to figure out what's going on, you go to this panic mode and say, okay, I get my, I'm diving with my dad, and we end up.

Brent: I end up getting his, you know, he's got a little spare breather, and we go up slowly. And I avoided the bends. But I thought a lot about the bends, then. And sense it was just. It was a scary experience. But the, you know, the nitrogen bubbles in the blood, that just doesn't sound fun. So can you talk about what's happening in the case of diving, I come up too quickly.

Brent: I get these the the nitrogen bubbles in my blood. And then why does a hyperbaric oxygen chamber actually help resolve that?

Richard: Bubbles form through two mechanisms: missing decompression stops (causing nitrogen to bubble out of solution) or pulmonary barotrauma from breath-holding during ascent.

Richard: And what happens is, let's say, or, you know, down at 30 or 40ft of seawater, you run out of air where unless you think carefully, you may be inclined to rush to the surface holding your breath. And if you do that, your lungs will expand as the ambient pressure decreases. And if you hold your breath, firmly enough.

Richard: Breath-holding causes air sac rupture and arterial gas embolism. Hyperbaric chambers shrink bubble volume using pressure and promote nitrogen diffusion through 100% oxygen breathing.

Richard: Additionally, hyperbaric oxygen acts as an anti-inflammatory, dampening the body's inflammatory response to bubbles blocking blood vessels and tissue.

Richard: And if you were to take a piece of that pneumonia and look at it under a microscope, we all know that bacteria cause it. But you'd be hard pressed to find any bacteria. Most of the problem with pneumonia is the host response, the pulse that's in the lung. The same thing happens with bubbles. Bubbles, block blood vessels.

Richard: They expand and they press on nerves, causing pain, but they also induce inflammation and, hyperbaric oxygen through mechanisms we don't totally understand is an anti-inflammatory. It reduces inflammation. So there are at least 2 or 3 things that go on with, with hyperbaric oxygen and bubble disease or decompression sickness.

Brent: Can severe decompression sickness causing paralysis be completely resolved with hyperbaric oxygen therapy sessions?

Brent: Is that true? I'm doing session after session in these very extreme cases, and I can go from paralysis basically to all good. It's resolved it.

Richard: In a series of nearly 100 severe cases unable to walk for 24 hours, one-third recovered completely, one-third had minor residual symptoms, and only one-third had major lasting deficits.

Richard: So it's it's a remarkable therapeutic, approach for severe decompression sickness.

Brent: Are the decompression sickness cases you treat mostly commercial or recreational divers?

Richard: About 99% of our cases are recreational divers. Commercial operations usually have on-site chambers and dedicated medical staff for rapid treatment.

Richard: And so somebody who has symptoms, they can pop them in very quickly. Occasionally we do get a call from a small commercial operator who maybe, one man or two men, operation, inland, usually. And we'll get a call, but, I would say 99% of the calls and patients we get are, a recreational divers.

Brent: What future applications of hyperbaric oxygen therapy excite you most?

Richard: There is growing evidence for inflammatory diseases such as ulcerative colitis and Crohn's disease, with ongoing clinical trials likely to yield positive results.

Richard: Maybe in other infections that we aren't currently using it for. I don't know about aging. That's that's going to take a while to figure out, but I think, it's here to stay. So far, we we don't have anything to replace hyperbaric oxygen for the diseases that we treat and probably for, diseases, that we will become, we'll we'll be approved for treatment in the near future.

Brent: Dr. Richard Moon, thank you so much for joining us and for your work.

Richard: My pleasure. Thanks for having me.

Brent: The Life Lab by Death Clock is recorded in Boulder, Colorado, and sometimes San Francisco, California. Produced by Patrick Gudino, music by Patrick Lee, and hosted by yours truly, Brent Franson, founder and CEO of Death Clock.