The Zetar Hypothesis

by David Bartell

David Bartell is a scuba divemaster with a degree in astrophysics; in this article, he explores how humans and diseases respond to unusual nitrogen and oxygen mixes and pressures. Although he focuses on treatment in hyperbaric chambers, the discerning reader will find diverse applications and jumping-off points for original science fiction - especially stories set underwater or in outer space.

There is an episode of Star Trek: The Original Series called "The Lights of Zetar" in which shimmering alien entities invade the body of a woman and make it their home. Lawrence M. Krauss makes passing reference to the Zetarians in his book, The Physics of Star Trek, pointing out that as creatures made of pure energy, they should not be able to sit still, but ought to be careening around at the speed of light.

Krauss stops there, but he might have had a more compelling gripe had he pointed out that as creatures of energy, the means of their defeat makes no sense at all. In the end of the episode, the crew of the starship Enterprise exorcised these evil beings using compressed air in what amounted to a hyperbaric (high pressure) chamber. The pressure was deadly to the entities, and they fled.

There are any number of ways that energy can be converted to forms more static than the electromagnetic, so I'm not sure I agree with Krauss's nitpicking. But how can air pressure drive out energy? That's an even bigger stretch.

As an astronomy undergraduate, I noticed that while many students of my generation were inspired by science fiction such as Star Trek, the older professors seemed oddly disinterested in it. They knew what I soon learned: most of the science in TV and movie science fiction has almost no basis in fact. Or does it?

The Zetar Hypothesis

Hopefully your own body is not possessed by aliens from Zetar, but it is host to legions of microorganisms. One alarming estimate claims that our bodies contain more non-human cells than human ones. If that is true, we are, in a sense, more "alien" than human! There are millions of germs living in you, such as the chicken pox virus (varicella-zoster) that hides dormant in the nerves along the spinal cord waiting for a chance to strike again as "shingles." There are also millions of "good germs" that have called you home since your infancy, such as those essential to my digestive processes. Other nasty things thrive inside us from bacteria and viruses to cancer cells and worms.

Aliens of pure energy aside, is there any potential to the idea of treating real infections and parasites with high pressure? Let us formulate the Zetar Hypothesis as follows:

A hyperbaric chamber can be used to destroy invading organisms without harming the human host.

Certainly, the harsh environment of high pressure can be deadly to living tissue. For example, those familiar with scuba diving know the potential dangers of breathing compressed gas. Too much nitrogen under pressure can cause nitrogen narcosis, a "euphoria of the deep". Deep divers may experience symptoms ranging from complacence to elation, which can impair judgement.

A more immediate problem can arise if a diver ascends too quickly: the bends. Breathing pressurized air at depth dissolves more gas into the blood than it can sustain at sea level. Surfacing rapidly causes the gas to separate out of the bloodstream faster than the lungs can off-gas. The resultant bubbles in the blood can cause pain and even death.

Advanced divers may face yet another problem. Special air mixes include a higher percentage, or partial pressure, of oxygen. Breathing oxygen-enriched air under high pressure can cause oxygen toxicity (OXTOX) in which the hyperbaric oxygen actually poisons the body.

The risk to properly trained and equipped divers is actually quite small, so long as divers follow proper guidelines. They use tables and underwater gauges and computers to plan dives, to monitor dive parameters, and to sound alarms. Millions of people dive recreationally without problems.

But what's happening to the microorganisms inside these divers? If nitrogen and especially oxygen can be deadly to humans under high pressure, can the same conditions also be deadly to these other organisms? What effect does hyperbaric pressure have on bacteria, viruses, cancer cells, parasites, blood cells, the immune system, etc? Are some of these more susceptible to oxygen toxicity than human tissues?

Let us suppose a certain bacterium is more sensitive to OXTOX than the human body. If so, could a controlled treatment of hyperbaric oxygen destroy the germ before the patient is injured? This might be analogous to radiation and chemotherapy in cancer patients, where potentially deadly treatments are administered under controlled conditions in a race to destroy the rapidly dividing cancer cells before the healthy cells are killed.

I am a scuba divemaster, and I often dive at over four times atmospheric pressure for about twenty minutes at a stretch. Then I surface, decompressing as I go. A few observations during such dives go some way in answering my questions. For more complete answers, I consulted several leaders in the field of hyperbaric medicine.

First, what were my own observations? Well, while I never dive when my head is congested for fear of barotrauma to my ears, I have gone diving with a mild cold, not to mention the germs that cause bad breath. After the dive, my cold was still there, and my breath did not magically freshen because the germs all died under the water. I have never witnessed anyone else emerging from a dive cured from the flu, a cold, shingles, or any other ailment.

However, my experience in observing bacteria under pressure was necessarily limited, and so I turned to the experts. To my surprise, I discovered that there are almost no scientific studies on just this topic. Hyperbaric medicine is a fairly new field, hampered by the impracticalities of testing on human subjects. That said, hyperbaric chambers are routinely used to treat health problems such as the bends, smoke inhalation, and carbon monoxide and cyanide poisoning.

Exorcising Aliens with HBO

Hyperbaric Oxygen Therapy, also called Hyperbaric Oxygenation (HBO), is a common treatment for a number of ailments. In these treatments, the patient repeatedly visits a hyperbaric chamber into which mixes of up to 100% pure oxygen are pumped at high pressure. While there is a risk of OXTOX, hyperbaric treatment is far safer than diving under similar oxygen pressures because of the controlled environment, constant monitoring, and presence of medical personnel. And, of course, the threat of drowning is absent.

The results of HBO are painless, dramatic, and diverse. There are over a dozen uses of HBO, as listed by the Committee on Hyperbaric Oxygenation of the Undersea and Hyperbaric Medical Society (UHMS). As such, there are many dozens of hyperbaric facilities in the US - seven in Virginia alone. Most are treatment centers which commonly assist healing of crush injuries, burns, smoke inhalation, radiation tissue damage, surgical wound complications, grafting, and gas gangrene.

Other facilities specialize in dive injury therapy; these tend to be located near dive sites, such as the Florida coast, and Navy bases. Divers sometimes buy diver insurance that covers hyperbaric treatment, and may even airlift to the nearest facility. There are other esoteric and experimental uses of HBO, including treatments for anemia, blood loss, diabetic foot ulcers, neural hearing loss, venous ulcers, and complications arising from radiation therapy of the head and neck.

That's an interesting and diverse list, but is there any treatment for microorganisms? Yes. There are many organisms to which oxygen is toxic.

For example, oxygen is lethal in any dose to obligate anaerobes such as Archaea bacteria. Some of these are familiar, such as the microbe that causes botulism. Other Arahaea bacteria add some of the color to sulfur pots in Yellowstone National Park, and thrive without energy from the Sun near rift vents at the bottom of the sea. They have been found in miles-deep oil deposits and gold mines, where they might derive their energy from radioactivity in the rocks. Obligate anaerobes live in the digestive systems of cows, termites, and marine organisms, and could even be living on Mars.

These most ancient organisms are not really bacteria, and may even be our oldest ancestors. Since they (and some true bacteria) evolved before photosynthesis did, and the oxygen in our air is said to have come from photosynthesis, they began in an oxygen-free environment. The environment changed, and now obligate anaerobes are confined to the most hermetic prisons on the planet.

Consistent with this, HBO has been helpful in combating a few dangerous organisms, including the notorious flesh-eating Ebola virus that has been in the headlines during the last few years.

Another disease, infection of the bone (osteomyelitis), is illustrative of HBO's effects. HBO elevates the partial pressure of oxygen even inside the bones, killing or slowing the growth of the infectious organisms. In some cases, this occurs because the excess oxygen produces radicals toxic to the infection, and in other cases the effect is indirect, - death is dealt by white blood cells super-charged by the oxygen. Finally, in combination therapy, HBO gives a boost to some antibiotics.

This sounds promising, but there is a catch.

The antibacterial effect of HBO applies only to anaerobic organisms, those that thrive in low-oxygen environments. Hyperbaric oxygen has no ill effect on aerobic organisms, those that prefer higher concentrations of oxygen. On the contrary, these germs may benefit from the extra oxygen, multiplying more quickly. This is hardly the desired result. HBO is not selective; it can not target certain organisms while avoiding others. So HBO may kill anaerobic germs, while helping aerobic ones to multiply. (In the latter case, both aerobic organisms and white blood cells are similarly strengthened, so the reinforced white blood troops keep the reinforced aerobes in check.)

There are other complications as well. Facultative anaerobes such as some bacteria and yeasts metabolize oxygen when it is available, but can switch to an anaerobic metabolism when oxygen is scarce. And don't forget those "good germs" that your body needs to function properly. Might not HBO kill them, making the cure worse than the disease? Studies show that HBO has little effect on the "good" bacteria that aid digestion. That's good news, at least.

Not so good is that HBO has little or no effect on viruses. In fact, HBO is not recommended for patients with viral infections. There has been some research regarding HIV, but no benefits of HBO were found. After all, viruses are not even cells - just "uncivilized bits of protein" as Dr. Eric Kindwall at the University of Wisconsin calls them.

Doctors I spoke with at the Mount Vernon Hospital Hyperbaric Unit call Kindwall "the mind" on such matters. HBO itself was caught up in something of a rage back in the 1960s, at the same time that Star Trek and the race to the Moon were capturing the imagination of the public. HBO was proposed as a potential treatment for a wide variety of problems, including cancer, heart attacks, senility, stroke, and multiple sclerosis.

A few of the treatments suggested have proven effective. A few others, such as leprosy treatment, are still promising. However, most research failed. The results did not live up to the hype, precipitating widespread skepticism that lingers today. HBO has been called a therapy in search of diseases.

Certainly Dr. Kindwall is not taken to flights of fancy, and warns of dangerous HBO side effects. These include OXTOX, seizures, inner ear trauma and infection, finger numbness, deteriorating myopia, and possible cataract acceleration. The potentially good side effect of lessening farsightedness is not remotely worth the risks. Researchers today harbor no false hopes, and are busy methodically testing treatments whose benefits are logically predicted by detailed analysis.

Let us make an in-progress scorecard for HBO. Efficacy in treating bacteria: pros and cons balance it to a zero sum. Viruses: no effect. But what about parasites?

Pregnant women are discouraged from scuba diving. There is no empirical reason for this; to the contrary, there is evidence from a study in the former Soviet Union that women treated with HBO in any stage of pregnancy produced normal children. Nevertheless, expectant mothers are heeding the warnings and are not diving.

Since there will be no reasonable sample of pregnant divers from which to gather statistics, let us assume the worst: that the fetus may be harmed by absorbing high concentrations of air. If diving can harm a dependent organism like a fetus, what about other organisms that live off the body of a host? What about parasites such as tapeworms or head lice? When I asked Dr. Kindwall whether there were any data on this, he compared such hypothetical research to counting angels on the head of a pin. Why do it? There are numerous other treatments for such parasites that are simpler and far less expensive. Besides, he said, tapeworms are very hardy organisms, and there is no reason to believe this treatment would be effective.

Duke University, in South Carolina, is another habitat for hyperbaric experts, since it is home to DAN, the Divers Alert Network, a non-profit research and assistance organization. Duke is a major HBO research center, of which there are several. Duke even does hypobaric experiments - low pressure tests with applications such as astronautics - a very understudied field.

At Duke, Dr. Guy Dear echoed Dr. Kindwall. Though it remains to be proven, HBO might actually help tumors to grow, he noted. "Not a good idea." The bottom line seems to be that HBO helps some organisms, hurts some, and has no appreciable effect on others. Since the human body has a large number of both good and bad germs, the result is a wash. HBO is not a magic disinfectant for the body, although it is an effective treatment for some specific problems.

A Cure Just Around the Bends?

So far we have focused on Hyperbaric Oxygenation, but oxygen toxicity is only one of the hazards of breathing compressed air. Most people have heard of the bends, a condition caused when divers ascend toward the surface too quickly. As pressure decreases, nitrogen comes out of solution, forming harmful bubbles in the bloodstream. Pressurization in a hyperbaric chamber, distinct from HBO treatment, forces excess nitrogen back into solution. Then the patient is decompressed slowly, under controlled conditions. The nitrogen is gradually exhaled normally.

Current theory indicates that these harmful bubbles start as micro-bubbles, tiny pockets of air that accumulate into larger ones. These are also called silent bubbles, because they have been detected in the bloodstream of symptom-free subjects. This indicates that all divers have silent bubbles. Getting the bends is just a matter of extent.

(Ironically, "silent" bubbles are detected in a laboratory using Doppler ultrasound devices. There is research on portable devices to detect bubbles in the blood of astronauts during spacewalks. Since the pressure of spacesuits is below that of the spacecraft, astronauts can get the bends during extravehicular ventures. Perhaps someday divers will swim using a sort of sonar, not to detect objects in the water column, but to ping for bubbles in their own blood.)

In terms of pure physics, the parameters that cause the bends are depth, dive duration, and rapidity of ascent. Many other factors can contribute as well, such as fatigue, age, cold, and alcohol. Experiments show that motion of the limbs can induce bubble formation in certain crabs (Pachygrapsus crassipes) subjected to rapid decompression. This lends credence to the belief that physical exertion contributes to the bends in humans, and helps explain why the bends causes pain in the joints.

Now, if nitrogen bubbles in the blood can cause injury and death in people, might not carefully controlled micro-bubbles be able to destroy microorganisms or parasites without harming the patient? Can unwanted tenants be evicted from the body by deliberately inducing a mild case of the bends? Or is the harm inflicted by bubbles only a "macro" effect that does not apply to microscopic life?

The answer: no one knows, because no one thinks it is worth researching. Most experimentation on the bends, called decompression sickness, or DCS, has been conducted on vertebrates in order to simulate human symptoms as closely as possible. When I suggested research on inducing the bends, dive physicians unanimously objected.

Since the damaging bubbles in humans are in the bloodstream, one would not predict damage to bacteria or viruses, which generally do not live in the blood. Parasites such as tapeworms, or those that cause malaria and sleeping sickness, are far simpler organisms than humans. They would probably not be harmed by DCS. In any case, there are already well-established treatments for these internal menaces.

Moreover, inducing the bends is foolish. The bends can be life threatening, and even in the mildest controlled cases, may result in some brain damage. The effect of nitrogen bubbles is not just the mechanical one of interfering with circulation; they can cause cells to burst, kicking off complicated biochemical chain reactions. These side-effects probably have no ill effect on germs or parasites, but are dangerous to the patient.

Therefore, no research has been done in this area. There is no reason to believe inducing the bends can be beneficial, and plenty of reasons to believe the opposite.

Fishy Findings

The Zetar Hypothesis is largely discredited. HBO has a nearly static short list of approved applications. Inducing the bends in hopes of eradicating invading organisms is pointless and exceedingly foolish. If it's any consolation, the jury is out on the efficacy of HBO or the bends on aliens from Zetar. Personally, I'm not worried about them.

As a diver, I ought to be more concerned with avoiding hyperbaric chambers. I can plan my dives, use my dive computer, and avoid risk factors for the bends. And I can keep an eye on a groundbreaking area of research: identifying conditions that help prevent the bends. For example, a recent study has shown that the presence of fish oils reduces the formation of nitrogen bubbles in the bloodstreams of divers. Believe it or not, fish can get the bends, so it is probably no coincidence that they are chemically equipped to prevent it.

It probably is a coincidence that at the same time this result was published, an announcement in the national news stated that eating oily fish is healthy for the heart. Fish oil is the only unsaturated animal fat with omega acids. This is no longer news to health watchers, but the applicability to diving is new science. The cliché is apt: you are what you eat. To swim like a fish, eat fish.

Another new finding was discovered by accident. A research team at the Norwegian University of Science and Technology sought to validate anecdotal evidence that the risk of getting the bends is lower for divers who are more physically fit. They found no such correlation. What they did find was that when animals exercised vigorously the day before a simulated dive in a hyperbaric chamber, the formation of nitrogen bubbles in their blood was greatly reduced. The same was shown for humans by a team at the University of Split School of Medicine in Croatia. Using ultrasound imaging, the average number of bubbles for subjects who ran on a treadmill the day prior was measured to be a fifth that of subjects who did not exercise. The bubbles in the subjects who exercised were much smaller as well.

The reasons for these results are not fully understood, but one theory is that the exercise flushes microbubbles from the blood. Without these "seeds," larger bubbles can not grow. Another explanation is based on the theory that microbubbles lodge in tiny pockets inside the walls of blood vessels. Exercise stimulates the release of nitric oxide (NO), which can smooth the walls of the vessels so that microbubbles don't stick as often. Nitric oxide also dilates blood vessels, again facilitating the flushing of microbubbles. Whatever the mechanism, exercising the day before a challenging dive seems to be an excellent preventative measure for the bends.

Finally, you can't seriously expect advice to exercise often to go unaccompanied by a pharmaceutical alternative, can you? If the theories hold up, it is likely that a drug that produces NO in the blood will soon become available. This has been successfully tested in mice, and while bubbles can form in other tissues, it is bubbles in the blood that cause the most serious risks.

We have pretty much given up on the use of hyperbaric chambers to exorcise infections and parasites, except for some specific cases. Now it looks as though we may also be using them a lot less for the bends, by preventing the bends through exercise and drugs. And since astronauts are sometimes at risk for the bends, such as during spacewalking, maybe they'll be taking those drugs too. Might come in handy when those nasty Lights of Zetar come flashing by.

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© David Bartell

David Bartell is a Scuba divemaster. He has a degree in astrophysics, and is currently a manager at a software company. He has sold three stories (co-authored with Ekaterina Sedia) to Analog, and articles to the national magazines Catalyst, Connecting Link, and The Empty Vessel. He has stories appearing in the upcoming anthologies Mind Scraps and Jigsaw Nation.