We appreciate the comments by Drs. Pollard and Fisher. Dr. Pollard points out the wide variability in estimated incidence of cardiac arrest in spinal anesthesia. Depending on the data examined, interpretation of data, and definition of cardiac arrest, the incidence could certainly be as common as 1:1,000. We agree with Dr. Pollard that clinicians must maintain vigilance during spinal anesthesia. Dr. Pollard also recommends prophylactic treatment with atropine to reduce sudden baroreflex activity and prevent cardiac arrest in high-risk patients. Although a reasonable suggestion, this intervention has not been definitively studied, and efficacy is unclear. In fact, the cited reference (8) concluded that it was very difficult to prospectively identify patients at risk for sudden increase in baroreflex activity associated with sudden bradycardia and hypotension.
Dr. Fisher's comments on data presentation are appreciated. The figure was reproduced with permission from a previous publication in Anesthesiology by other investigators. Because we were not involved in the statistical analysis and editorial process for the original publication, we have no additional insight to offer.