The use of Diagnostic Imaging for Identifying Abnormal Gas Accumulations in Cetaceans and Pinnipeds (original) (raw)

Methodology for in situ gas sampling, transport and laboratory analysis of gases from stranded cetaceans

2011

Gas-bubble lesions were described in cetaceans stranded in spatio-temporal concordance with naval exercises using high-powered sonars. A behaviourally induced decompression sickness-like disease was proposed as a plausible causal mechanism, although these findings remain scientifically controversial. Investigations into the constituents of the gas bubbles in suspected gas embolism cases are highly desirable. We have found that vacuum tubes, insulin syringes and an aspirometer are reliable tools for in situ gas sampling, storage and transportation without appreciable loss of gas and without compromising the accuracy of the analysis. Gas analysis is conducted by gas chromatography in the laboratory. This methodology was successfully applied to a mass stranding of sperm whales, to a beaked whale stranded in spatial and temporal association with military exercises and to a cetacean chronic gas embolism case. Results from the freshest animals confirmed that bubbles were relatively free of gases associated with putrefaction and consisted predominantly of nitrogen. G as-bubble lesions have been described in cetaceans stranded in spatio-temporal concordance with military maneuvers 1,2 . Authors described an acute and systemic gas and fat embolic syndrome similar to decompression sickness (DCS) in human divers. These findings raised a number of questions addressing cetacean's ability to avoid hyperbaric conditions like DCS. Two key questions arising from such findings are: a) What are the constituent gases in the bubbles? 3 ; (b) Do we have a robust method for gas analysis in stranded marine mammals?