Deliberate Mild Hypothermia Research Articles

Comparison of propofol versus sevoflurane on thermoregulation in patients undergoing transsphenoidal pituitary surgery: A preliminary study

Purpose:General anesthesia causes inhibition of thermoregulatory mechanisms. Propofol has been reported to cause more temperature fall, but in case of deliberate mild hypothermia, both sevoflurane and propofol were comparable. Thermoregulation is found to be disturbed in cases of pituitary tumors. We aimed to investigate which of the two agents, sevoflurane or propofol, results in better preservation of thermoregulation in patients undergoing transsphenoidal excision of pituitary tumors.Methods:Twenty-six patients scheduled to undergo transsphenoidal removal of pituitary adenomas were randomly allocated to receive propofol or sevoflurane anesthesia. Baseline esophageal temperature was noted. Times for temperature to fall by 1°C or 35°C and to return to baseline were also comparable (P>0.05). After that warmer was started at 43°C and time to rise to baseline was noted. Duration of surgery, total blood loss, and total fluid intake were also noted. If any, side effects such as delayed arousal and recovery from muscle relaxant were noted.Results:The demographics of the patients were comparable. Duration of surgery and total blood loss were comparable in the two groups. The time for temperature to fall by 1°C or 35°C and time to return to baseline was also comparable (P>0.05). No side effects related to body temperature were noted.Conclusion:Both propofol and sevoflurane show similar effects in maintaining thermal homeostasis in patients undergoing transsphenoidal pituitary surgery.

Direct effect of mild hypothermia on the coronary vasodilation induced by an ATP-sensitive K channel opener, a nitric oxide donor and isoflurane in isolated rat hearts

Deliberate mild hypothermia (MHT) is applied for cerebroprotection after cardiopulmonary resuscitation and during cardiac surgery. MHT has been shown to alter both contractility and relaxation of blood vessels in the brain. However, the effects of MHT on drug-induced vasodilation are not fully understood. The aim of this study was to clarify the effects of MHT on the coronary vasodilation induced by cromakalim (an ATP-sensitive K channel opener), S-nitroso acetyl-penicillamine (SNAP; a nitric oxide donor), and isoflurane in isolated rat hearts. Male SD rat hearts were isolated and perfused with Krebs-Henseleit buffer. Coronary flow was measured with the coronary perfusion pressure kept at 60 mmHg, and coronary vascular resistance (CVR) was calculated. After cardiac arrest was induced by tetrodotoxin, the hearts were allocated to one of three temperature groups: 37, 34, and 31 degrees C (n = 7 for each). All groups received 0.01, 0.1, and 1.0 microM of either cromakalim or SNAP or were exposed to isoflurane at 1MAC and 2MAC. Finally, 50 mM of adenosine was administered to obtain maximal coronary vasodilation. CVR significantly increased after cardiac arrest, but did not change after the application of each temperature. Cromakalim, SNAP and isoflurane significantly decreased CVR in each temperature group. There were no significant differences in CVR among the three temperature groups with any of the test drugs. These results indicate that cromakalim-, SNAP-, and isoflurane-induced coronary vasodilation are not affected by MHT.

Hypothermie et hypertension intracrânienne

There is a large body of experimental evidence showing benefits of deliberate mild hypothermia (33-35 degrees C) on the injured brain as well as an improvement of neurological outcome after cardiac arrest in humans. However, the clinical evidence of any benefit of hypothermia following stroke, brain trauma and neonatal asphyxia is still lacking. Controversial results have been published in patients with brain trauma or neonatal asphyxia. Hypothermia can reduce the elevation of intracranial pressure, through mechanisms not completely understood. Hypothermia-induced hypocapnia should have a role on the reduction of intracranial pressure. The temperature target is unknown but no additional benefit was found below 34 degrees C. The duration of deliberate hypothermia for the treatment of elevated intracranial pressure might be at least 48 hours, and the subsequent rewarming period must be very slow to prevent adverse effects.

IHAST II and the response of neuroanaesthetists

Deliberate mild hypothermia was first used in 1955 as an intraoperative technique to ameliorate new neurological deficits following cerebral aneursym clipping, and subsequently was also used following neonatal asphyxia, head trauma and cardiac arrest. The Intraoperative Hypothermia for Aneurysm Surgery Trial (IHAST II) randomized control trial was designed to determine the effectiveness of mild hypothermia to decrease neurological deficits following aneurysm surgery. No overall benefit was demonstrated in the hypothermic group versus normothermic group (67% versus 63% good outcome; p = 0.32), with a higher rate of bacteraemia in the hypothermic group (5% versus 3%; p = 0.05). We undertook a survey of Australasian and Asian neuroanaesthetists to determine whether their thermal management of patients undergoing cerebral aneursym clipping had changed in response to the IHAST II trial results.

クリッピング後再発脳動脈瘤の手術

We report our experience in surgical clipping of 7 patients with a recurrent intracranial aneurysm previously treated by neck clipping. All were treated under deliberate mild hypothermia for protection from ischemia during intraoperative temporary vessel occlusion. Surgical approaches were the same as previous in 5, extended in 1 and different in the 7th, which made it possible to expose the entire length of the previous clip. Intraoperative temporary vessel occlusion was necessary in 5 cases and the maximum occlusion time of each case was 7 to 15 minutes. Clipping was successfully completed without surgical complications in all but 1 case, which suffered transient mild hemiparesis with small infarction in the territory of the perforating artery due to intraoperative temporary vessel occlusion. Adequate selection of surgical approach and sharp dissection around the aneurysm were essential. We emphasize the usefulness of intraoperative mild hypothermia for protection from ischemic insults during temporary vessel occlusion in territory supplied with the cortical artery.

Jugular Bulb Oxygen Saturation Under Propofol or Sevoflurane/Nitrous Oxide Anesthesia During Deliberate Mild Hypothermia in Neurosurgical Patients

Jugular Bulb Oxygen Saturation Under Propofol or Sevoflurane/Nitrous Oxide Anesthesia During Deliberate Mild Hypothermia in Neurosurgical Patients

Update on Deliberate Mild Hypothermia for Neurosurgical Procedures

Update on Deliberate Mild Hypothermia for Neurosurgical Procedures

*Comparison of the Effects of Sevoflurane and Propofol on Cooling and Rewarming During Deliberate Mild Hypothermia for Neurosurgery

*Comparison of the Effects of Sevoflurane and Propofol on Cooling and Rewarming During Deliberate Mild Hypothermia for Neurosurgery

Comparison of the effects of sevoflurane and propofol on cooling and rewarming during deliberate mild hypothermia for neurosurgery.

Background Because the time available for cooling and rewarming during deliberate mild hypothermia is limited, studies of the rate of the cooling and rewarming are useful. The decrease in core hypothermia caused by heat redistribution depends on the anaesthetic agent used. We therefore investigated possible differences between sevoflurane and propofol on the decrease and recovery of core temperature during deliberate mild hypothermia for neurosurgery. Methods After institutional approval and informed consent, 26 patients were assigned randomly to maintenance of anaesthesia with propofol or sevoflurane. Patients in the propofol group (n=13) received propofol induction followed by a continuous infusion of propofol 3–5 mg kg−1 h−1. Patients in the sevoflurane group (n=13) received propofol induction followed by sevoflurane 1–2%. Nitrous oxide and fentanyl were also used for anaesthetic maintenance. After induction of anaesthesia, patients were cooled and tympanic membrane temperature was maintained at 34.5°C. After surgery, patients were actively rewarmed. Results There was no difference in the rate of decrease and recovery of core temperature between the groups. There was also no difference in skin surface temperature gradient (forearm to fingertip), heart rate and mean arterial blood pressure between the groups. Conclusions Sevoflurane-based anaesthesia did not affect cooling and rewarming for deliberate mild hypothermia compared with propofol-based anaesthesia.

Comparison of the effects of sevoflurane and propofol on cooling and rewarming during deliberate mild hypothermia for neurosurgery

BackgroundBecause the time available for cooling and rewarming during deliberate mild hypothermia is limited, studies of the rate of the cooling and rewarming are useful. The decrease in core hypothermia caused by heat redistribution depends on the anaesthetic agent used. We therefore investigated possible differences between sevoflurane and propofol on the decrease and recovery of core temperature during deliberate mild hypothermia for neurosurgery.MethodsAfter institutional approval and informed consent, 26 patients were assigned randomly to maintenance of anaesthesia with propofol or sevoflurane. Patients in the propofol group (n=13) received propofol induction followed by a continuous infusion of propofol 3–5 mg kg−1 h−1. Patients in the sevoflurane group (n=13) received propofol induction followed by sevoflurane 1–2%. Nitrous oxide and fentanyl were also used for anaesthetic maintenance. After induction of anaesthesia, patients were cooled and tympanic membrane temperature was maintained at 34.5°C. After surgery, patients were actively rewarmed.ResultsThere was no difference in the rate of decrease and recovery of core temperature between the groups. There was also no difference in skin surface temperature gradient (forearm to fingertip), heart rate and mean arterial blood pressure between the groups.ConclusionsSevoflurane-based anaesthesia did not affect cooling and rewarming for deliberate mild hypothermia compared with propofol-based anaesthesia. Because the time available for cooling and rewarming during deliberate mild hypothermia is limited, studies of the rate of the cooling and rewarming are useful. The decrease in core hypothermia caused by heat redistribution depends on the anaesthetic agent used. We therefore investigated possible differences between sevoflurane and propofol on the decrease and recovery of core temperature during deliberate mild hypothermia for neurosurgery. After institutional approval and informed consent, 26 patients were assigned randomly to maintenance of anaesthesia with propofol or sevoflurane. Patients in the propofol group (n=13) received propofol induction followed by a continuous infusion of propofol 3–5 mg kg−1 h−1. Patients in the sevoflurane group (n=13) received propofol induction followed by sevoflurane 1–2%. Nitrous oxide and fentanyl were also used for anaesthetic maintenance. After induction of anaesthesia, patients were cooled and tympanic membrane temperature was maintained at 34.5°C. After surgery, patients were actively rewarmed. There was no difference in the rate of decrease and recovery of core temperature between the groups. There was also no difference in skin surface temperature gradient (forearm to fingertip), heart rate and mean arterial blood pressure between the groups. Sevoflurane-based anaesthesia did not affect cooling and rewarming for deliberate mild hypothermia compared with propofol-based anaesthesia.

Comparison of the effects of sevoflurane and propofol on cooling and rewarming during deliberate mild hypothermia for neurosurgery

Because the time available for cooling and rewarming during deliberate mild hypothermia is limited, studies of the rate of the cooling and rewarming are useful. The decrease in core hypothermia caused by heat redistribution depends on the anaesthetic agent used. We therefore investigated possible differences between sevoflurane and propofol on the decrease and recovery of core temperature during deliberate mild hypothermia for neurosurgery. After institutional approval and informed consent, 26 patients were assigned randomly to maintenance of anaesthesia with propofol or sevoflurane. Patients in the propofol group (n=13) received propofol induction followed by a continuous infusion of propofol 3-5 mg kg(-1) h(-1). Patients in the sevoflurane group (n=13) received propofol induction followed by sevoflurane 1-2%. Nitrous oxide and fentanyl were also used for anaesthetic maintenance. After induction of anaesthesia, patients were cooled and tympanic membrane temperature was maintained at 34.5 degrees C. After surgery, patients were actively rewarmed. There was no difference in the rate of decrease and recovery of core temperature between the groups. There was also no difference in skin surface temperature gradient (forearm to fingertip), heart rate and mean arterial blood pressure between the groups. Sevoflurane-based anaesthesia did not affect cooling and rewarming for deliberate mild hypothermia compared with propofol-based anaesthesia.

Jugular Bulb Oxygen Saturation during Propofol and Sevoflurane/Nitrous Oxide Anesthesia during Deliberate Mild Hypothermia for Neurosurgical Procedures

Jugular Bulb Oxygen Saturation during Propofol and Sevoflurane/Nitrous Oxide Anesthesia during Deliberate Mild Hypothermia for Neurosurgical Procedures

Amrinone can accelerate the cooling rate of core temperature during deliberate mild hypothermia for neurosurgical procedures

We investigated the effects of i.v. amrinone on intraoperative changes of core temperature during deliberate mild hypothermia for neurosurgery. The patients in a control group (n=10) did not receive amrinone and patients in the amrinone group (n=10) received amrinone 5 microg kg(-1) min(-1) after a loading dose of 1.0 mg kg(-1). Anaesthesia was maintained with nitrous oxide in oxygen, propofol and fentanyl. After the induction of anaesthesia, patients were cooled and tympanic membrane temperature was maintained at 34.5 degrees C. After completion of the main surgical procedures, patients were rewarmed in the operating room. Tympanic membrane temperatures between 30 and 90 min after cooling were significantly lower in the amrinone group than in the control group. During cooling, the times taken to cool to 35 degrees C and to the lowest temperature were significantly shorter in the amrinone group than in the control group. These results suggest that i.v. amrinone can accelerate the cooling rate of core temperature during deliberate mild hypothermia for neurosurgical procedures.

The Effects of Prostaglandin E1 on Intraoperative Temperature Changes and the Incidence of Postoperative Shivering During Deliberate Mild Hypothermia for Neurosurgical Procedures

The Effects of Prostaglandin E1 on Intraoperative Temperature Changes and the Incidence of Postoperative Shivering During Deliberate Mild Hypothermia for Neurosurgical Procedures

Effects of prostaglandins E1 and F2-alpha on systemic, pulmonary, and splanchnic circulations in dogs.

Effects of prostaglandins E1 and F2-alpha on systemic, pulmonary, and splanchnic circulations in dogs.