Noted Expert Benumof Also Suggests Possible Negative Pressure Cause; Urges Extubation Caution

Jonathan L. Benumof, M.D.

More on Pulmonary Edema

Editor’s Note: In the Spring issue, there was a letter to the Editor describing an unusual series of cases of postoperative pulmonary edema following appendectomies. Two follow-up letters appeared in the Summer issue and two more are published here.

To the Editor

As a clinician with a special interest in/commitment to respiratory physiology, and in response to Dr. Garner’s letter (APSF Newsletter, Spring 1993), 1 am aware of several other cases of bilateral pulmonary edema occurring in young otherwise healthy patients shortly after endotracheal tube extubation. My guess as to the etiology of the observations of Dr. Garner’s group as well as those of other anesthesiologists, is that it may take only one very vigorous descent of the diaphragm against an obstructed airway to produce the edema.

In a young healthy patient, pleural pressure may become minus 100-200 mm Hg (although the transmural pressure across pulmonary vessels will be much less, it will still be significantly increased). Consequently, I can envision the transudation of fluid following just one sustained, vigorous, but unsuccessful, breath. The suppurative process described in the patients of Dr. Garner’s group may have increased the permeability of the alveolar capillary membrane and thereby increased the risk of negative pressure pulmonary edema.

Based on all of the cases that I have heard of, I do not think the occurrence of this complication is as rare as may have been thought in the past. My take-home message is that the patency of the airway following extubation must be closely guarded (jaw thrust, oropharyngeal airway, etc.) for every breath until the patient can spontaneously maintain the patency of the airway. I would like to emphasize that these thoughts are only a guess, and I share the wish of Dr. Garner to know the thoughts of others.

Jonathan L. Benumof, M.D. Professor of Anesthesia

University of California, San Diego Medical Center