To the Editor:-Bar-Joseph et al.  are to be commended for their report of tension pneumothorax during apnea tests for brain death. We are aware of no previous reports of this complication. We believe that our case of "thoracic inflation"  was a result of tension pneumothorax; however, we did not prove that diagnosis by chest radiography or needle thoracotomy. Perhaps because of this omission, our recommendation for using a small-diameter cannula to prevent barotrauma has not found its way into published practice guidelines. 
Bar-Joseph et al. recommended an oxygen flow rate of no higher than 6 l/min. We used a rate of 15 l/min in our study  and in more than 400 subsequent adult apnea tests with no additional occurrences of barotrauma. This rate does not cause CO2washout, and, in the absence of cannula wedging, it does not seem to cause tension pneumothorax. However, based on available data, this rate may be no more effective than 6 l/min.
We share the suspicion of Bar-Joseph et al. that tension pneumothorax is not rare in apnea tests. The lack of reports is probably due to an understandable reluctance to publish bad results. We strongly recommend that practice guidelines for apnea tests in brain death be revised to include the technique reported by Bar-Joseph et al.
James Zisfein, M.D.
Stephen J. Marks, M.D.
Department of Neurology; New York Medical College; Bronx, New York 10451;email@example.com
(Accepted for publication March 18, 1999.)