Hypothermia during saturation diving in the North Sea.

We recently suggested after laboratory experiments' that undetected hypothermia might account for unexplained casualties during working dives in the North Sea. At depths greater than 50 m in the North Sea water temperature is below 10°C. Heat is usually supplied by flooding the diving suit continuously with warm water pumped from the surface via the diving bell; its temperature is monitored at the bell, but not at the diver, and is regulated mainly on the basis of the diver's report of feeling hot or cold. We found that simulation of this with warm water at 290C around a thin man could produce progressive hypothermia with cardiac irregularities but without any serious sensation of cold. We are now reporting the body temperatures of divers during saturation diving operations using the conventional heating system at a depth of 130-145 m in the North Sea in August-November 1979. The divers breathed helium and oxygen throughout. Their urine tempera-tures2 were measured within eight minutes of their return to the bell after working dives with a maximum-reading Digitron thermistor with a response time of under 10 seconds in at least 50 ml of urine flowing through the outlet of a perforated funnel. This volume had been found with this apparatus to yield readings accurate to within 0 2'C. Skinfold thicknesses were measured with Harpenden callipers.3 The table shows that the thinnest diver in the group developed hypothermia at 34 70C during a dive lasting only 55 minutes. He had felt a little cold and shivered at one point during the dive, but when the temperature of the warm-water supply, measured at the bell, was increased by 4'C he had stopped feeling cold. Two of the other divers cooled to near hypothermia with temperatures below 35 5'C at the end of 4-44 hour dives, in one of which the warm-water system had failed for the last hour. That diver felt cold and shivered, but the other did not. In contrast, one relatively fat diver had a normal body temperature even after a one-hour failure of the warm-water supply; he reported considerable shivering and sensation of cold at that time. Body temperature after other dives was usually normal; in one instance it was a little high at 38 3°C. Physical characteristics and body temperatures of divers, temperatures of warm water, and duration of dives Approximate Body temperature temperature Height Body Skinfold of warm Duration at end of …