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February 2001 Vol. 27, No. 2   RSS Feed for Undercurrent Issues
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Arm Wrestling, Whalesharks, Ghostly Visions

Events behind DCS

from the February, 2001 issue of Undercurrent   Subscribe Now

DAN recently analyzed one thousand DCS cases that occurred between 1987 and 1997. Compared with 1987, divers injured in 1997 were older, dived more frequently, were more often female, used dive computers more often, and were more likely to dive in locations remote to the US. Delays to treatment were shorter. Diving injury severity decreased as evidenced by less reported paralysis, unconsciousness, bladder problems, embolism, and residual symptoms.

Of 427 divers who successfully achieved complete relief of their symptoms, 71 percent of those who received oxygen before recompression had complete relief; of those who did not receive oxygen before recompression, 64 percent had complete relief.

The British also studied DCS cases. They found that in 69 percent, the divers were less than 100 feet. Twenty-nine percent of the cases involved rapid ascents. 21 percent miscalculated repeat diving, and 14 percent missed decompression stops. While the British found that the number of incidents resulting in DCS were down, uncontrolled ascents accounted for a higher proportion of incidents than ever before.

We have gathered cases from DAN, the British Sub Aqua Club and the South Pacific Medical Society to illustrate how diver error leads to serious consequences.

DCS and the flying ascent

Fully understanding BC operation and features is essential. New BC’s and rental BC’s are common causes of diving accidents.

In Britain, a diver was
bent when she shot to
the surface from 35
feet after her weightbelt
slid around her
body and the buckle
popped open when it
hit her tank.

In this case, an experienced 45- year-old American woman made her third dive to 88 feet with a multilevel ascent. At 30 feet and 30 minutes, a strong current pulled her upward. Unfamiliar with her new BC, she had difficulty reaching the dump valve. Before reaching the surface, she felt weak and was unable to move her legs, then lost consciousness after surfacing. She awoke partially paralyzed from the waist down. She was recompressed locally within an hour and had some improvement, then received a second treatment but remained paralyzed. After air evacuation to the U.S., she underwent an additional 57 hours of recompression; a year after her injury, she still had weakness and numbness in her legs.

Two divers completed a dive to 125 feet, then began their ascent. One had serviced his BC himself and had failed to connect the wire that operated the dump valve. As he rose, he operated the dump and when no air escaped he assumed it was empty. At 20 feet he lost control of his buoyancy and shot to the surface. It took him three trips to the chamber to eliminate his DCS symptoms. Of course, this diver had the other option — usually the first — to dump air from his inflator valve. Ignoring that option cost him .

Two divers descended a line to a wreck. At 90 feet one signaled he had a problem. Hanging onto the line, he fumbled with his inflator, but it wasn’t connected and he couldn’t reattach the hose. His buddy tried to help, but when the troubled diver released the line he began to ascend, because he had dropped his weightbelt. Despite attempts to control their ascent, both divers rose rapidly. The buoyant diver required recompression, which cleared his symptoms. Had he remained calm and held the line, his buddy could have easily solved the problem if he could not.

In Britain, a diver was bent when she shot to the surface from 35 feet after her weightbelt slid around her body and the buckle popped open when it hit her tank. A sliding weight belt is common as the body’s soft tissues squeeze on descent, giving you the waistline you’ve always wanted. Tighten up the belt on the way down, but don’t forget to loosen it back up as your belly sadly returns to normal.

Horsing Around

One way to bring on bends symptoms when they otherwise may not appear is to exercise after diving. This Brit engaged in an evening of serious arm wrestling after a week of diving (on his last day, one to 135 feet for 30 minutes and the second, four hours later, to 85 feet for 39 minutes). After his he-man games, he complained of increasing severe pain in the shoulder, elbow and wrist joint of his wrestling arm. It took recompression to eliminate that pain.

While divers joke about getting narked, it can be a serious problem. To some, the effect is similar to alcohol ingestion, while others say it is similar to a nitrous oxide high, one legally obtained in a dentist’s chair. Some people speculate that individuals who have experienced and handled either are better suited to deal with similar problems underw ater.

Two divers descended to a wreck at 50 meters. At the bottom, one diver saw two other divers and believed they had joined him and his buddy. He felt fine, but when he looked again he could see three divers. When the three images began moving as one, he realized he had a problem. He gave the “something is wrong” signal and let air into his d rysuit to ascend. He managed to make it to the surface, but on the boat he suffered some loss of feeling in one foot; with the help of oxygen, the symptoms disappeared.

Ignoring Symptoms

First, we have a 52-year-old female, who had made more than 300 dives, then performed 17 in six days, some to 120 fsw. On the fifth day she began with a dive to 110 fsw, followed by a shallower dive. On the third dive, she inadvertently followed a whale shark to 147 fsw, then made decompression stops as required by her dive computer. On the sixth day she made three more dives, all within the limits of her computer. After 48 hours, she flew home and became dizzy midway into the flight. At home, she went to bed. The next day her dizziness continued, and she noticed tingling and numbness in her left arm. The following day she had to support herself when standing. On the fifth day, she received recompression treatment. Her symptoms resolved completely within 30 minutes.

This diver, a healthy 31-year-old male, had made only 20 dives and none for two years. On a five-day vacation he made seven dives, his first to 50 fsw. During the next three days, he made one to two dives per day to 70-80 fsw, all with a safety stop. On his last day, he made a multilevel computer dive to 90 fsw for 40 minutes. The dive was complicated by rapid ascent from the 15 fsw safety stop, but there were no symptoms. Twenty hours after his last dive, he noticed discomfort in both elbows, then his wrists; later pain appeared in his knees and ankles. Thirty-six hours after his last dive and 16 hours after symptom onset, he flew home, his symptoms present throughout the flight. After a day at home and four days after symptom onset, he was recompressed twice in two days with complete relief.

Next we have a 24-year-old male with fewer than 10 dives. During a Caribbean vacation, he made 14 dives in five days without a problem and did safety stops on all dives. On the last day, he made a single dive to 65 fsw for 45 minutes, exiting the water mid-morning. Eight hours after his final dive, he felt mild knee pain and the following morning, pain in his hands and fingers. He flew home 27 hours after his last dive, where his symptoms increased. After a day at home with no change in his symptoms, a single recompression gave him complete relief.

Finally, not all symptoms produce serious consequences, thank fully. This diver, after beginning his first open- water training dive, barely submerged when he began to panic. Returning to the surface, he removed his mask and regulator, continuing to panic while complaining he couldn’t breathe. His instructor helped him ashore. The diver took himself to a hospital, but no problems were found. The conclusion: his wetsuit was too tight.

--Ben Davison

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