In Response

Abstract

We measured the blood pressure of each subject in the studies and did not find significant differences among the spinal anesthesia, spinal plus isoflurane anesthesia, and spinal plus desflurane anesthesia groups.1 We did not include the blood pressure data in the manuscript, because it has been shown that although hypotension may contribute to postoperative delirium,2 it may not contribute to postoperative cognitive dysfunction,3 which is different from postoperative delirium. We do agree that including minimum alveolar concentration multiples may be a more accurate measure of anesthetic depth and may include this in future studies. Finally, Kinoshita et al. questioned whether the cognitive tests were valid to the subjects in the studies who spoke Chinese.3 Previous studies4 have shown that cognitive tests can be translated into the different languages (e.g., Danish, Dutch, French, German, Greek, and Spanish), and tests that might be culturally sensitive (e.g., the verbal learning tests) can be validated in those languages. We therefore believe the cognitive tests in our current studies were valid in subjects who spoke Chinese. Also all subjects were native Mandarin Chinese speakers and were tested in their native language. Finally, and as described in the Methods section of our paper, we did not rely on normative data, but rather subtracted subjects' raw scores at baseline (preoperatively) from their raw scores postoperatively because we were most interested in their performance following spinal plus isoflurane anesthesia versus spinal plus desflurane anesthesia. The same methodology was used in testing subjects in both groups so that their performances could be validly compared. Bin Zhang, MD, PhD Department of Anesthesia Beijing Friendship Hospital and Capital Medical University Beijing, China Janet Sherman, PhD Psychology Assessment Center Massachusetts General Hospital and Harvard Medical School Boston, Massachusetts Zhongcong Xie, MD, PhD Department of Anesthesia Critical Care and Pain Medicine Massachusetts General Hospital and Harvard Medical School Charlestown, Massachusetts [email protected]