New guidelines for divers?

Carbon dioxide may have a profound influence on the development of gas bubbles in the blood, a fresh doctoral study at the Norwegian School of Veterinary Science (NVH) has shown.

Decompression sickness can develop in both sports and professional divers if the diver surfaces too quickly and nitrogen in the blood does not have sufficient time to re-dissolve and distribute before the diver reaches the surface. Decompression sickness is a painful condition, which at worst may be life-threatening.

Local production of CO2
Previously, nitrogen, helium and similar gasses have been considered to be the primary agents of decompression sickness. Carbon dioxide has been ignored, since this gas is highly soluble in blood and is quickly removed from the body.

The doctoral thesis of Henrik Rasmussen shows, however, that naturally-produced CO2 formed in the caecum of mice and rats is distributed through the entire intestinal wall, creating a state of localised supersaturation at various places in the caecum. Should these animals subsequently be given ultrasound contrast agents, which consist of gas bubbles administered intravenously, the gasses in these agents increase in size as a result of the gas supersaturation, causing damage to the caesium and liver.

Consequences for North Sea divers?
Based on these findings, it is feasible to expect that a corresponding local production of CO2 occurs in North Sea divers, which might influence the creation of bubbles in the blood and thereby contribute to the development of decompression sickness. It is possible that professional divers may develop local increases in the concentration of CO2 in parts of their intestinal tract or in the muscles they use the most. Should seismic operations be conducted nearby, damage from CO2 may be profound, since sonar waves have a potent influence on the growth of bubbles in blood.

This work was carried out in collaboration with researchers from GE Healthcare, the Karolinska Institute in Stockholm, the Rikshospitalet University Hospital in Oslo and the University of Gothenborg, Gothenborg, Sweden.