Central venous bubbles and mixed venous nitrogen in goats following decompression.

Decompression of awake goats from saturation at 1, 2, and 3 ATA of air has been carried out using ultrasonic Doppler bubble detection, central venous blood inert gas measurement, and cardiac output measurement. The results of these experiments indicate that the decrease in nitrogen elimination rate as an apparent result of decompression cannot be due to excessive cardiac output or mass transport of a large amount of inert gas to the lungs as bubbles. Rather, the rapid drop in mixed venous nitrogen content is consistent with a generalized decrease in tissue-to-blood nitrogen elimination. This in turn appears to be due to a cardiovascular response to the decompression insult as was previously reported for dogs (D'Aoust et al., J. Appl. Physiol. 41: 348--355, 1976) at 1, 2, and 3 ATA; addition of ultrasonic Doppler monitoring and cardiac output in the present studies allowed measurement of the degree of latency in the appearance of bubbles at a central venous location. This time period includes that required...