Dive Dry with Dr. Bill

#287: Beam Me Down, Scottie... er, Karl

Most of us carry car insurance, household insurance, liability insurance, life insurance, health insurance, boat insurance, trip cancellation insurance and/or dental insurance. In addition to those, I carry DAN insurance from the Divers Alert Network. As one who dives frequently, occasionally to "unfathomable" depths, it is critical that I carry this insurance to cover treatment in a recompression chamber should I experience an unexpected decompression sickness "hit." In the nearly 50 years I've been submerging, I've never had an incident... but it could happen at any time, and the cost of treatment without insurance would be more than I earn in a year. Come to think of it, the cost of gas these days is more than I earn in a year.

Here on Catalina we are very fortunate to have the Catalina Hyperbaric Chamber at USC's Big Fisherman Cove facility, so close in the event of a diving accident. A fatal dive-related incident here last weekend involved transport from the dive park to the Isthmus. Recently, organizer Ken Kurtis reported the dive community raised over $120,000 on Chamber Day to help support the operation of this critical service, and at the Long Beach SCUBA Show in June chamber program director Dr. Karl Huggins will be honored as the recipient of the California SCUBA Service Award. Although Karl is a relative "newbie" in the dive community, having started diving "just" 31 years ago (just teasing you, Karl), he is noted for his pioneering work in decompression theory and as co-inventor of one of the first commercial dive computers, the EDGE. Under his direction, the Chamber has become one of the most highly regarded facilities in the world.

For those of you who relish statistics, the Chamber at USC is 24 feet long and 9 1/2 feet in diameter. Its size allows more than one diver to be treated at a time and it has held as many as four at once. It is staffed 24 hours a day, 365.25 days a year by a rotating volunteer staff who deserve our thanks! Unlike many other facilities, which may be used to treat other medical conditions like burns or carbon monoxide poisoning, ours is dedicated to treating dive accident victims. Los Angeles County funds operations with a grant of about $108,000 each year but like most universities, USC takes a large percentage of that for administrative overhead. Therefore nearly 40% of the annual operating budget of $185,000 must come from benefits, donations and other sources.

Although many refer to such facilities as "decompression" chambers, I think of them as recompression chambers. Although they treat decompression sickness (DCS), also known as "the bends," they do so by taking the diver "back down" to the higher pressures experienced when they were diving. The word hyperbaric refers to higher pressures, just as a hyperactive child is over rather than under active. Let's look at the reasons why this treatment is used.

DCS results from improper ascents from the depths where the overlying layers of water increase the pressure on a diver. At the ocean surface, we are all subjected to one atmosphere (atm) of pressure from the various gasses extending miles above us. If a diver descends to 33 feet, they experience a total pressure of 2 atm due to the added weight of the water above them. For every 33 feet they descend, the pressure increases by 1 atm. If a diver descends to the maximum recreational depth of 130 ft, they experience a pressure of about 5 atm (1 for the actual atmospheric gas pressure at the surface and four for the water above them).

Now our bodies are largely composed of water which is not compressed significantly under such pressures. However, when gasses are under such pressures they go into solution in the blood and our soft organs and tissues. Divers who use compressed air in their SCUBA tanks like me, have about 21% oxygen and 78% nitrogen in them. As we breathe, these gasses are carried throughout our body and get absorbed in the blood and tissues because they are under pressure. The deeper one goes and the longer one stays down at depth, the greater the amount of dissolved gas in our bodies.

When the diver begins their ascent, the pressure decreases as they move into shallower water. The gasses come out of solution, and are exhausted through our exhalations. However, if a diver ascends too quickly, these gasses are released in higher volume and form bubbles in the blood stream and tissues. Less serious impacts include bubble formation in joints and tissues which cause pain and other symptoms. In serious incidents known as AGE (arterial gas embolism) the formation of bubbles in the blood may block blood circulation to the brain, resulting in stroke-like symptoms and potential death.

When a diver is brought to the Chamber with bubble formation in their blood or tissues, they are taken back down to higher pressures (recompression) causing the gasses to redissolve. Then the diver can be carefully decompressed, with the pressure decreased slowly allowing smaller bubbles to form slowly enough to be exhaled safely. Hopefully there will be no serious lasting effects. However, a diver who experiences a CDS "hit" is more likely to have another in the future than one who hasn't.

According to some statistics, diving deaths average just over 80 per year in the United States and Canada. The majority of these (60%) are due to drowning. It is estimated that 3 to 9 deaths occur each year per 100,000 dives. Now I have no idea how many dives I did between 1961 and June of 2000 when I left the Conservancy. Since I was usually gainfully employed during most of that period, and therefore often stuck in an office, I was diving at much lower frequency than in the current decade. In a few weeks I will have done 2,000 dives this decade. Using the statistics provided earlier, and being conservative, one might expect one death every 11,000 dives. Even at my current rate I'd have to be diving for about 45 more years... until I'm 100+ years old! I sure am glad Karl and the Chamber crew, including our own Lorraine Sadler, will be there for me. You will, won't you?

© 2008 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. Please help me climb out of self-imposed poverty... buy my "Munching and Mating in the Macrocystis," "Great White Sharks of Guadalupe," "Calimari Concupiscence: Mating Squid, " "Playful Pinnipeds: California Sea Lions," "Belize It or Not: Western Caribbean Invertebrates, Fish and Turtles," "Gentle Giants: Giant Sea Bass," "Common Fish and Invertebrates of the Sea of Cortez" or the new "Sharks and Rays of Southern California" DVD's. Yes, take Dr. Bill home with you... we'll both be glad you did!

The hyperbaric chamber facility and the chamber itself; Karl leading a tour for divers off the King Neptune,
a sight I hope I never see shortly after a dive... the inner sanctum!

This document maintained by Dr. Bill Bushing.
Material and images © 2008 Star Thrower Educational Multimedia