In Reply:-We appreciate Dr. Cohen's thoughtful remarks regarding consent in emergency procedures would like to offer a few clarifications in specific reference to our trial.

Dr. Cohen's concern about the waiver of prospective consent focuses on the notion that the complication under treatment in our study (postoperative AF) was not "sudden (or) unanticipated." Although postoperative supraventricular tachycardia is relatively common in cardiac and thoracic surgery patients (rates approach 40%), our study was directed mainly at a general surgical population in which the incidence is far lower. We estimate that less than 2% of the gastrointestinal/genitourinary surgery patients, who comprised our largest subgroup Table 1, developed postoperative atrial fibrillation. Although reasonable people might not agree on exactly what incidence satisfies the criterion for "unanticipated," it would be necessary to interview thousands of patients preoperatively to obtain a worthwhile sample size under these conditions. We would also reaffirm that postoperative atrial arrhythmias do occur suddenly and, in our view, require immediate rate control intervention given the risk of myocardial ischemia with rapid heart rates.

Brian A. Rosenfeld, M.D.

Associate Professor; Anesthesiology, Medicine, and Surgery; The Johns Hopkins University School of Medicine; Baltimore, Maryland

Jeffrey R. Balser, M.D., Ph.D.

Associate Professor; Anesthesiology and Pharmacology; Vanderbilt University School of Medicine; Nashville, Tennessee

(Accepted for publication March 15, 1999.)