The View From the Other Side of the Microscope

By Karl Shreeves

Zzzaaaaappp! It didn’t really make that sound, but I felt that a chest x-ray should, as cancer-inducing subatomic particles streamed in on one side of my lungs to make a picture of the other. All in the name of science and good health. Maybe they were using a silencer.
“See, that wasn’t hard, was it?” commented the physician, one of the researchers in the hyperbaric study I was participating in.
“No,” I agreed, keeping to myself that, had I known I’d be getting a free physical, I’d have spared myself the one I had a month earlier.
Such was the price of participating in this research project. Having been involved in several research dive projects, I usually know what to expect. But this time I was not working as para-scientist extending the arms of a biologist, archaeologist or geologist. My role was to be a rodent, extending and multiplying human knowledge of decompression theory as a test subject in a week-long hyperbaric study.
“Alfalfa?” one of my guinea mates whispered to me.
“Don’t call me that,” I hissed back.
“I’m asking if you want any.”
Basically, three other divers and I would dive in a chamber at the Institute of Applied Physiology and Medicine (IAPM) in Seattle several times daily for a week. After each session, IAPM physiologist Dr. Michael R. Powell (now with NASA) would use a Doppler ultrasound flowmeter to listen for bubbles moving through our hearts. Pretty cool, huh?
After the medical came the lecture. Though I don’t remember the exact words, it went something like this:
“This is a research study in a hyperbaric chamber, which has inherent risks including bent lung expansion injury, sudden chamber failure, explosive decompression suffocation, carbon dioxide poisoning, bad air or complications if the chamber attendant falls asleep. Other risks include gagging for an hour if someone eats baked beans before we lock you in the chamber, or if a supply tank ruptures, launching you into orbit but, unfortunately, not in one piece. While you’re in here, we own you: we will tell you when to get up, when to sleep, when to eat, when to eliminate and what the dives will be. No alcohol for the duration. [What!? That wasn’t in the fine print when we signed up!] But you can pick the station on the chamber television. In summary, you risk paralysis, being maimed, excruciating pain, permanent neurological damage and a slow, agonizing death. Here’s a waiver.”
“Cool,” we agreed, “where do we sign?”
The next day, the four of us dutifully climbed into IAPM’s chamber for the first of many, many dives. If you’ve never done it before, the first couple chamber rides are a novelty. We inflated balloons and sealed film canisters then watched the pressure shrink and crush them respectively. We did the same at depth and watched them pop and expand respectively as we ascended. We made paper airplanes and watched how they performed in the dense air. There was even a phone where we could call our friends, none of whom recognized our Donald Duck voices.
After each dive, Dr. Powell would put a Doppler meter over our hearts and listen for bubbles at specified intervals, dutifully recording the data. Someone suggested a “bubble pool,” betting on who would have the most after each dive, but that brainstorm fizzled since there just weren’t that many bubbles. (Not a bad thing in retrospect.)
It was really entertaining—for about the first half a day. By the end of day one, all of us in the Guinea Crew were plagued by a malady not recited during the lecture: terminal tedium. During the dives, we just lay around, reading, watching TV or sleeping (they had to wake us up for depth changes in case we held our breath in our sleep). Outside, we saw the attendants suffering the same. After all, the schedule ran us to say, 60 feet, and then we would just sit there for about an hour, the periodic chamber venting (to keep the air fresh) our only interruption. Being young, creative but not entirely mature men, we agreed something had to be done.
Our chance came when they locked lunch into the chamber during a stay at 40 feet. Through the chamber windows, we could see major lethargy outside, and by now we knew every inch of our iron prison. One interesting feature was a tiny tube that dangled from a port on the wall. Dr. Powell had explained that an infinitesimal flow went through it to various sensors, telling the chamber operator the oxygen and carbon dioxide content of our air.
“Here’s an idea,” said someone (not me, I swear), taking a half-finished bottle of Coke and shaking it. Too low to fizz over, but lots of CO2 bubbles—he deftly slipped the bottle opening over the air-sampling tube.
Hee-hee-hee. From inside, we watched the chamber attendant slumped idly in a chair, semi-comatose. Behind him, the carbon dioxide readout began to tick steadily upward.
No one had told us about an alarm. The chamber operator catapulted to the controls just as he glimpsed four laughing faces through the eight-inch porthole. He killed the alarm.
“OK, guys. Very funny,” he said over the chamber phone. Well, it broke the tedium. Only four days to go.
In the end, we were the first of several guinea teams participating in the first (and so far only) major multi-day, repetitive, no-decompression dive study. The data told researchers many things about that kind of diving, one of the most noteworthy being that bubble development varied from some of the predictions. This led to modified theories about gas formation in the body following repetitive dives.
For me, I learned that being a volunteer in this type of project is both interesting and boring. Since you’re not researching but being researched, you don’t always feel like you’re doing much. But your contribution is essential—without the guinea pigs there could be no research.

Karl Shreeves is Vice President, Technical Development for DSAT and PADI. He still doesn’t like alfalfa, and never call him that.