Nitrous oxide administration in presence of venous
air embolism results in its volume augmentation. The present case report of a 50-year old patient undergoing
posterior fossa tumor excision in the sitting position demonstrates the hazards of
nitrous oxide in presence of venous
air embolism. Administration of 66%
nitrous oxide 140 minutes after the incidence of
air embolism resulted in a significant decrease of end-tidal
carbon dioxide tension, moderate
hypotension, and
tachycardia, suggesting volume augmentation of the
air embolism. The results of our case report are in contrast to that by Shapiro et al who noted that
nitrogen washout following administration of 100%
oxygen was complete 65 minutes after the occurrence of venous
air embolism. Shapiro and colleagues suggest the use of
nitrous oxide challenge as a diagnostic aid in deciding when lung excretion of intravascular air is complete. However, our case report implies that
nitrogen washout was not complete 140 minutes after venous
air embolism incidence. Accordingly, we recommend to stop
nitrous oxide administration once
air embolism is suspected and to refrain from its re-administration throughout the rest of surgery.