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Danger in the Depths - the sad side to the SA Coelacanth Discovery
After the first filming of the South African Coelacanths disaster struck this group of dedicated divers. At high pressure, nitrogen can become dissolved in water, or the water in blood. Hence the blood becomes nitrogenated, in a similar way to the way a soda-stream machine carbonates cool drink using pressure. As with carbonated cooldrink, if you reduce the pressure of blood with nitrogen dissolved in it, the gas will form bubbles leading to a condition known as decompression sickness (the bends), or embolism. This condition can be fatal. In deep diving, ascent rate and decompression stops are carefully calculated to ensure that divers do not suffer from decompression sickness.
As the coelacanth discovery team began their slow ascent Venter and Gunn noticed that Christo Serfontein was having some difficulties with his equipment. Dennis Harding went to assist him and they both disappeared from view in an uncontrolled ascent. Serfontein was unconscious when he surfaced but with the assistance of Pieter Smith he regained consciousness and was able to immediately descend to a depth of 32 metres where he resumed his decompression schedule. After 134 minutes in the sea Serfontein was taken to the beach, administered oxygen and transported to Richard's Bay where he spent the next 6 hours in a recompression chamber. In this chamber, the diver is able to be gradually returned to normal atmospheric pressure.
Harding, however, lost consciousness soon after he surfaced, was not in a fit state to undergo stage decompression and was rushed to the beach where every effort to resuscitate him was unsuccessful.
As a result of this tragedy and the adverse media interest it generated, and as a mark of respect for the loss of one of their close-knit team, the expedition was promptly terminated.
Things were not to go smoothly for the dive team: in a sad prologue to the problems they were later to face, Erna Smith, wife of Pieter Smith and an accomplished dive partner in the group, died from an undiagnosed heart condition following a routine training dive in a Badplaas sinkhole on the 3rd February 2001. (See the note on this below).
Erna Smith and her undiagnosed heart problem:
Approximately 30% of the human population have some form of a patent foramen ovale (foetal shortcut between left and right ventricles) that has not closed properly. At worst, the venous/arterial admixture causes a systemic hypoxia, and these cases are picked up and treated surgically. At best, the hole is closed over by a flap of tissue that is held in place by a much higher pressure on the systemic side. This condition is usually asymptomatic, even in divers, under normal conditions. It is also difficult to detect.
What happened to Erna Smith was unusual, but has happened before. Something must have caused her to cough during her decompression stop at precisely the moment that the ventricle contracted. This would
have momentarily raised the pulmonary pressure enough to raise the flap over the foramen, allowing some decompression gas bubbles to enter the pulmonary circulation and enter the arterial circulation. From the aorta these bubbles would have gone straight up the carotids to her brain. There was absolutely nothing anybody could have done to save her.
The dive plan was a standard 50m bounce dive on air, with only a brief decompression stop at 2m. Erna was an experienced diver and had made many, very much deeper dives, on Trimix and nitrox, with no prior hint that she had any problem. This unfortunate tragedy does not, therefore, reflect negatively on the conduct, training, safety standards, equipment or dive procedures of this Trimix group.
Edited by Garth Cambray
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