Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Jul 1997
Randomized Controlled Trial Comparative Study Clinical TrialConvection versus conduction cooling for induction of mild hypothermia during neurovascular procedures in adults.
Hypothermia for cerebral protection is usually achieved by administration of intravenous fluids at room temperature, cooling ambient air, ice packs, and a temperature-adjustable circulating water mattress. We compared cooling by conduction by using a water mattress to cool by convection by using a forced-air cooling device. Twenty patients were prospectively randomized to two groups: 10 patients cooled by convection (CC) and 10 patients cooled by traditional methods (TC). ⋯ CC, 142 +/- 21 min). One patient had some arrhythmias on cooling in the convective group, but her preoperative condition may have been responsible. In conclusion, cooling by convection appears to be a safe alternative to conduction cooling.
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J Neurosurg Anesthesiol · Jul 1997
Randomized Controlled Trial Clinical TrialThe use of ketamine or etomidate to supplement sufentanil/N2O anesthesia does not disrupt monitoring of myogenic transcranial motor evoked responses.
Intraoperative monitoring of myogenic transcranial motor evoked responses (tc-MERs) requires an anesthetic technique that minimally depresses response amplitudes. Acceptable results have been obtained during opioid/N2O anesthesia, provided that the concentration of N2O does not exceed 50%. However, this technique may necessitate supplementation with additional agents to achieve adequate depth of anesthesia. ⋯ Administration of ketamine did not significantly change tc-MER amplitudes, whereas etomidate resulted in a transient amplitude depression to 72% of control (p < 0.05) at 2 min after injection. Latency remained unchanged with both drugs. In conclusion, the data suggest that both ketamine (0.5 mg/kg) and etomidate (0.1 mg/kg) can be used to supplement sufentanil/N2O anesthetic without disrupting tc-MER monitoring.
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J Neurosurg Anesthesiol · Jul 1997
Clinical Trial Controlled Clinical TrialThe effects of fentanyl and sufentanil on cerebral hemodynamics.
Our study investigated the effects of moderate doses of fentanyl and sufentanil versus high-dose sufentanil on cerebral hemodynamics by using transcranial Doppler ultrasonography (TCD). Thirty American Society of Anesthesiologists (ASA) II and III patients scheduled for elective coronary artery bypass graft (CABG) were studied after Institutional Review Board (IRB) approval and informed consent. The evening before surgery, all patients received oral flurazepam (1 mg/kg), Atropine (0.4 mg/70 kg s.c.) and a combination of droperidol (70 micrograms/kg s.c.) plus fentanyl (1.5 micrograms/kg s.c.) were given as preanesthetic medication 1 h before induction of anesthesia. ⋯ In contrast, infusion of high-dose sufentanil (group 3) was associated with 27 to 30% decreases in CBFV (p < 0.05). Our results suggest that sufentanil decreases CBFV in a dose-related fashion with a threshold effect. Increases in CBFV and CBF seen in previous studies may be related to an increasing PaCO2 when maintenance of normocarbia is based on only real-time capnography with a constant PetCo2 rather than additional arterial blood gas monitoring.
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J Neurosurg Anesthesiol · Jul 1997
Clinical Trial Controlled Clinical TrialChanges in oxygenation variables during progressive hypothermia in anesthetized patients.
Because deliberate hypothermia is becoming commonly used during neurosurgery, this study was performed to investigate the effects of a progressive reduction of body core temperature (T) on whole body oxygenation variables in patients undergoing elective intracranial surgery. In 13 patients (Hypothermic Group), T was reduced to 32.0 degrees C using convective-based surface cooling. In six patients (Control Group), T was maintained at 35.5 degrees C during the entire study period. ⋯ DO2 remained unchanged in both groups. We conclude that progressive hypothermia in anesthetized patients reduces metabolic rate but does not change DO2. The significant decrease in O2ER may partly be related to a leftward shift of the oxyhemoglobin dissociation curve, as evidenced by the decrease in P50.