Cerebral Oxygenation Under General Anesthesia Can Be Safely Preserved in Patients in Prone Position: A Prospective Observational Study.

BACKGROUND: The effects of prone position (PP) on cerebral tissue metabolism are not well known. The aim of this investigation was to evaluate regional cerebral oxygen desaturation in patients undergoing lumbar spine surgery in PP during routine anesthesia management. MATERIALS AND METHODS: Between July 2013 and October 2013, 50 consecutive patients undergoing lumbar spine surgery under general anesthesia in PP were enrolled. The anesthetic technique was standardized. Using near-infrared spectroscopy, bilateral regional cerebrovascular oxygen saturation was recorded during the surgery. RESULTS: After 30 and 60 minutes of prone repositioning, significant decreases in bilateral regional cerebral oxygen saturation were observed compared with the values in the supine position (from 76.24% to 73.18% at 30 min and 72.76% at 60 min on the right side and from 77.06% to 73.76% at 30 min and 72.92% at 60 min on the left side; P<0.05). These changes were not clinically important and returned to supine values after 90 minutes of prone positioning. Decreases in cerebral oxygen saturation were accompanied by reductions in heart rate and mean arterial pressure (P<0.05). Older age and higher perioperative risk had a significant effect on the reduction of cerebral oxygen values (P<0.05). CONCLUSIONS: The results of our study show that margin of safety against impaired cerebral oxygenation can be maintained in PP. Preventing bradycardia and arterial hypotension is crucial. Older patients and those at higher perioperative risk need more meticulous attention.

Xenon does not modify mivacurium induced neuromuscular block.

PURPOSE: The interaction between mivacurium and inhaled anesthetics is known, with the exception of xenon. We compared the pharmacodynamics of mivacurium during xenon anesthesia vs total iv anesthesia with propofol. METHODS: This randomized controlled trial was carried out in the Aachen University Hospital. Forty-two adult patients ASA I or II, aged 18 to 60 yr, were randomized to receive either xenon or propofol anesthesia. Anesthesia was induced with propofol and remifentanil in both groups (each n = 21). The xenon group received xenon via face mask until an end-expiratory concentration of 60% was reached for one minute. Meanwhile, the acceleromyograph was calibrated and a train-of-four stimulation of the adductor pollicis muscle was started. After stabilization of the signal for five minutes, a single bolus of 0.16 mg.kg-1 mivacurium was injected. Anesthesia was maintained with xenon and remifentanil or with propofol and remifentanil. RESULTS: There were no significant differences between groups with respect to onset time (xenon 180 +/- 64 vs propofol 195 +/- 77 sec; P = 0.39), duration (xenon 16.18 +/- 4.97 vs propofol 15.68 +/- 6.17 min; P = 0.73), recovery index (xenon 5.63 +/- 2.48 vs propofol 5.73 +/- 2.12 min; P = 0.42) and clinical recovery (xenon 8.75 +/- 2.57 vs propofol 9.28 +/- 2.28 min; P = 0.22). CONCLUSION: We conclude that the neuromuscular blocking effects of mivacurium are similar when given during propofol vs xenon anesthesia.

Xenon does not prolong neuromuscular block of rocuronium.

With the exception of xenon, the interaction between muscle relaxants and inhaled anesthetics is known. We therefore compared the pharmacodynamics of rocuronium during xenon anesthesia versus a total IV anesthesia with propofol. Anesthesia was induced with propofol and remifentanil in both the xenon and propofol groups (each n = 20). The xenon group received xenon via face mask until an end-expiratory concentration of 60% was maintained for 1 min. Meanwhile, the acceleromyograph (TOF-Watch SX(R)) was calibrated and a frequent train-of-four stimulation of the musculus adductor pollicis was started. After stabilization of the signal for 5 min, a single bolus of 0.6 mg/kg rocuronium was injected. Anesthesia was maintained with xenon and remifentanil (xenon group) or with propofol and remifentanil (propofol group). There were no significant differences between the groups concerning the onset time (xenon group 125 +/- 33 and propofol group 144 +/- 43 s), duration (xenon group 33.2 +/- 10.8 and propofol group 32.6 +/- 8.4 min), recovery index (xenon group 9.4 +/- 6.6 and propofol group 8.4 +/- 5.3 min), and clinical recovery (xenon group 18.0 +/- 10.2 and propofol group 17.1 +/- 8.5 min). We conclude that the neuromuscular blocking effects of rocuronium are not different when given during propofol versus xenon anesthesia.