The consequences of complement activation and the symptoms of decompression sickness are similar. Consequently, the relation between the sensitivity of individuals to complement activation by air bubbles and their susceptibility to decompression sickness has been examined. Plasma samples from 34 individuals were incubated with air bubbles, and the concentration of the fluid phase metabolites of complement activation C3a, C4a, and C5a were measured with radioimmunoassays. It was found that both the anaphylatoxins C3a and C5a were produced by the presence of air bubbles but that the anaphylatoxin C4a was not. This finding indicates that air bubbles activate the complement system by the alternate pathway. One group of individuals was found to be particularly sensitive to complement activation by this pathway. They produced 3.3 times more C3a and 5.3 times more C5a in their plasma samples incubated with air bubbles as did the other group. Sixteen individuals were subjected to a series of pressure profiles that were severe enough to produce bubbles in their circulatory system that could be detected by Doppler ultrasonic monitoring. The group of individuals that had been identified as being more sensitive to complement activation by the alternate pathway was also found to be more susceptible to decompression sickness.

1A hospital-based drug information system has been used to assess the time for which patients treated with warfarin were outside the range of Thrombotest values 5-10% and 5-15% and to examine possible contributory factors in situations where anticoagulation fell outside these ranges. 2 Anticoagulant control varied with the age of the patient and with concomitant drug therapy but not with patient sex or indication for anticoagulation. 3 Most patients were 'under-anticoagulated' at some stage but patients over 70 years spent significantly longer in the 5-10% range than those in the age range 30-59 years and Thrombotest values of less than 5% were found predominantly in the older group. 4 Patients given drugs known to interact with warfarin spent least time in the defined Thrombotest ranges. Those on drugs known to potentiate warfarin effect had significantly lower Thrombotest values than the other patients studied.

No abstract