In Over His Head
Ed.'s note: This regular column presents the anatomy of a scuba diving accident and the lessons to be learned from it. The incidents described are real. Names of locations and people have been changed or deleted.
Setting the StageA couple from New York was vacationing in Hawaii as a break from their stressful and sedentary lives. After finding a brochure on snorkeling, the husband decided to try it out and visited the dive operation located by the hotel's swimming pool to rent a mask, snorkel and fins.
The DiveAt the pool, the husband decided to make a test dive before heading off to the ocean. After adjusting the gear, he began swimming around in the pool, which was empty of any other guests. Having heard of hyperventilation, but with no understanding of it, he took several breaths, ducked under the water and swam for the deep end. There, alone and unsupervised, he blacked out and settled to the bottom of the pool.
The RescueOne of the underwater instructors who worked at the dive operation just happened to walk by the pool and spot the snorkeler not moving on the bottom. She immediately summoned aid, jumped in, pulled him from the water and began CPR. By the time the EMTs arrived, she had the victim breathing on his own. He was rushed to the hospital where after a few days he was released.
Thank You Very MuchBack home in New York, the snorkeler filed a lawsuit which claimed the instructor who had saved his life, the dive operator who had rented him the equipment and the hotel where he was staying were all negligent for failing to warn him of the dangers of snorkeling, to supervise him adequately, to prevent his accident and to rescue him promptly. He also claimed mental distress and residual medical problems. The case went all the way to trial before a Hawaiian court.
The prosecution was dealt its first setback during jury selection. It is common to challenge the selection of any person involved in the activity at issue in the trial, in this case snorkeling. The jury pool of almost all native Hawaiians grew up playing and snorkeling in the waters of Hawaii. After much argument, the judge ruled that snorkeling experience would not prevent a juror from serving. Thus, nearly all jurors selected had snorkeling experience.
During the trial, defense medical experts made it clear that the plaintiff had nothing wrong with him that was not wrong with him before the accident. The plaintiff's diving expert failed to articulate any compelling reason why the defendants should be responsible for the snorkeler's accident. After a short deliberation, the jury returned a verdict for the defense, releasing all defendants from responsibility.
Shallow-Water Blackout One of the greatests threats to snorkelers is shallow-water blackout: the sudden loss of consciousness due to oxygen starvation. It happens quickly, without warning and usually above 15 feet of depth. The blackout occurs when the partial pressure of oxygen drops below the level needed to maintain consciousness. Hyperventilation - increasing the rate and depth of respiration - is often a factor.
Hyperventilating just before a free dive allows you to stay down longer because the huffing and puffing decreases the amount of carbon dioxide in your blood (the buildup of which triggers your urge to breathe). As you dive down, Boyle's Law comes into effect: increasing water pressure elevates the partial pressure of oxygen. But because hyperventilation has created an artificial deficit of carbon dioxide, you are able to hold your breath longer than you normally can. And that's when the trouble starts: you don't feel the urge to breathe until the partial pressure of oxygen drops below the level to maintain consciousness. Bingo: blackout.
Lessons For LifeTo avoid shallow-water blackout, snorkelers and free divers should:
- Limit hyperventilations to three or four deep breaths only.
- Rest several minutes between dives.
- Start to the surface as soon as the urge to breathe is felt.
- Free dive with a buddy.
- Avoid endurance dives and timing long breath-hold swims in pools. They give a sense of security, but the shallow depths can still cause blackout.