Effects of xenon on hemodynamic responses to skin incision in humans

BACKGROUND: The authors evaluated the hemodynamic suppressive effects of xenon in combination with sevoflurane at skin incision in patients undergoing surgery. METHODS: Forty patients were assigned randomly to receive one of the following four anesthetics: 1.3 minimum alveolar concentration (MAC) sevoflurane, 0.7 MAC xenon with 0.6 MAC sevoflurane, 1 MAC xenon with 0.3 MAC sevoflurane, or 0.7 MAC nitrous oxide with 0.6 MAC sevoflurane (n = 10 each group). Systolic blood pressure and heart rate were measured before anesthesia, before incision, and approximately 1 min after incision. RESULTS: The changes in hemodynamic variables in response to incision were less with sevoflurane in combination with xenon and nitrous oxide than with sevoflurane alone. Changes in heart rate (in beats/min) were 19+/-11 (+/- SD) for sevoflurane alone, 11+/-6 for 0.7 MAC xenon-sevoflurane, 4+/-4 for 1 MAC xenon-sevoflurane, and 8+/-7 for nitrous oxide-sevoflurane. Changes in systolic blood pressure were 35+/-18 mmHg for sevoflurane alone, 18+/-8 mmHg for 0.7 MAC xenon-sevoflurane, 16+/-7 mmHg for 1 MAC xenon-sevoflurane, and 14+/-10 mmHg for nitrous oxide-sevoflurane. CONCLUSIONS: Xenon and nitrous oxide in combination with sevoflurane can reduce hemodynamic responses to skin incision compared with sevoflurane alone. One probable explanation may be that xenon has analgesic properties similar to those of nitrous oxide, although the exact mechanism is yet to be determined.