Correspondence  |   July 2019
Hypotension and Stroke in Cardiac Surgery: Comment
Author Notes
  • University of California, San Diego, San Diego, California; and Veterans Affairs Medical Center, San Diego, California. jdrummond@ucsd.edu
  • (Accepted for publication April 1, 2019.)
    (Accepted for publication April 1, 2019.)×
Article Information
Correspondence
Correspondence   |   July 2019
Hypotension and Stroke in Cardiac Surgery: Comment
Anesthesiology 7 2019, Vol.131, 216-217. doi:https://doi.org/10.1097/ALN.0000000000002786
Anesthesiology 7 2019, Vol.131, 216-217. doi:https://doi.org/10.1097/ALN.0000000000002786
I have long been concerned that anesthesiologists, at least occasionally, are unwittingly accepting intraoperative mean arterial pressures (MAPs) that may bring the central nervous system very close to the thresholds for ischemic injury.1  The recent report by Sun et al. offered a caution about intraoperative hypotension and was therefore a result that I was inclined to welcome.2  They reported, on the basis of a retrospective examination of a large electronic database, an association between MAPs less than 65 mmHg before, during, or after cardiopulmonary bypass (CPB) and the occurrence of postoperative stroke. However, in spite of my biases, I found myself with some uncertainties about the strength of their observations. I am concerned about unmeasured (or merely unreported) covariates. In part, the prompt for that concern was the nearly simultaneous publication of an investigation by Vedel et al. (about which Sun et al. inevitably had no opportunity to comment).3  Vedel et al. assigned cardiac surgery patients to MAPs of either 40 to 50 or 70 to 80 mmHg on CPB. The investigation was randomized and prospective. The CPB parameters, which were reported in detail, were common to the two groups, with the exception of pressors and inotropes in the latter group. The primary endpoint was the volume of new diffusion weighted imaging lesions in the postoperative period. There were no differences between the groups in that endpoint or in several secondary endpoints. While relatively small numbers (98 and 99 patients per group) might be suspected of having resulted in type II statistical errors, every trend (diffusion weighted imaging lesion volume, stroke, cognitive dysfunction at the time of discharge, mortality) was in favor of the low pressure group.