Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Oct 1998
Randomized Controlled Trial Clinical TrialModulation of somatosensory evoked potentials under various concentrations of desflurane with and without nitrous oxide.
Continuous measurement of somatosensory evoked potentials (SEP) by means of characteristic changes in the signal pattern makes it possible to identify cerebral or spinal cord ischemia during critical phases of the operative procedure. A correct interpretation of the measurements is only possible, however, if the influence of drugs acting on the central nervous system is known. The authors were able to show that inhaled anesthetics have an impact on latencies and response amplitudes. ⋯ When nitrous oxide is added, there were marked reductions in amplitude (p<0.01) of the cortical stimulus response (1.5 MAC = 2.4 +/- 0.9; 1.5 MAC/N2O = 1.1 +/- 1). It can therefore be recommended that supplementation with N2O should be avoided in the presence of low initial amplitudes. Based on the study's results, the use of desflurane (up to 1.0 MAC) seems to be compatible with intraoperative monitoring of median somatosensory evoked potentials.
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J Neurosurg Anesthesiol · Jul 1998
Randomized Controlled Trial Clinical TrialTranscranial Doppler sonography mean flow velocity during infusion of ultrapurified bovine hemoglobin.
A number of studies have shown that polymerized bovine hemoglobin (HBOC-201) does not cause clinically significant side effects. This has been demonstrated in spite of the fact that a primary increase in oxygen extraction ratio has been associated with an increase in systemic vascular resistance (SVR) and a decrease in cardiac index (CI). The current study investigated the effects of HBOC-201 on cerebral circulation. ⋯ Cardiac indices were significantly lower in Group 1 (1.7-1.8 l/minute x m(-2)) than in Group 2 (2.4-2.7 l/minute x m(-2)) after PM 3. After hemodilution, mean flow velocity showed an insignificant increase in both groups, ranging from 39 to 46 cm/second. Although SVR increased significantly following HBOC-201 -infusion, the results of this study did not reveal changes in cerebral blood flow that establish significant group-to-group differences.
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J Neurosurg Anesthesiol · Oct 1997
Randomized Controlled Trial Comparative Study Clinical Trial7.5% hypertonic saline versus 20% mannitol during elective neurosurgical supratentorial procedures.
This prospective randomized clinical study was designed to compare the effects of equal volumes of 7.5% hypertonic saline solution (HS) or 20% mannitol (M) on brain bulk and lumbar cerebrospinal fluid pressure (CSFP) during elective neurosurgical procedures (aneurysm, arteriovenous malformation, or tumor). After informed consent, 50 American Society of Anesthesiologists physical Status I (ASA I) patients were randomly assigned to M (n = 25) or HS (n = 25) groups. Anesthesia protocol was identical for both, and variables monitored included mean arterial blood pressure (MAP), heart rate (HR), central venous pressure (CVP), CSF pressure (CSFP), arterial blood gases (PaCO2 30-35 mm Hg), serum sodium, potassium, and osmolality, and diuresis. ⋯ During the study, brain bulk was always considered satisfactory. CSFP was not different between M and HS groups and significantly decreased overtime (p = 0.0056) with no difference between treatments. The results of the present study demonstrate that hypertonic saline is as effective as mannitol in reducing the brain bulk and the CSFP during elective neurosurgical procedures under general anesthesia.
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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.