Detection of bubbles in decompression sickness

Abstract

AMATEUR diving and industrial demands have changed decompression sickness from being a specialised problem to becoming a health risk for many thousands of people. Rising medical standards and the recognition of bone damage¹ have resulted in increasingly stringent diving regulations, but the devising of suitable decompression schedules is still largely empirical; our best strategy is still to avoid sickness by accepting grave restrictions on diving procedures (such as decompression for a week or more²). It is important to find the earliest events involved, particularly as it is now generally accepted that the condition arises from supersaturated gas separating in the tissues; separation precedes overt symptoms and may remain symptomless³ and experimentally at least, gas does not readily separate without some nucleus^4,5. Methods are required applicable to man which can detect separated gas as such, and not by the physiological effect it produces, as early as possible. Various acoustic methods have been used. Bubbles moving in blood vessels have been successfully detected by the Doppler method^6,7 in experiments confirming their significance and presymptomatic existence³. However, this method cannot recognise stationary bubbles. We describe here a method using ultrasonic imaging that will make it possible to detect moving or static bubbles down to the required limits, in a chosen plane in the body, and hence to study at the earliest stages the location, development and movement of bubbles in a variety of tissues after subjection to decompression procedures.