Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Jan 2002
Bispectral Index (BIS) may not predict awareness reaction to intubation in surgical patients.
Bispectral Index (BIS) has been marketed as a measure of the hypnotic component of anesthesia and is recommended as a guide for the administration of hypnotic drugs during anesthesia. BIS values between 40 and 60 are recommended for surgery under general anesthesia. This study investigates whether a BIS baseline between 50 and 60 prevents awareness reaction to endotracheal intubation. ⋯ Comparison of patients with and without awareness reaction revealed no differences in BIS before or after intubation. This study shows that a BIS value between 50 and 60 prior to intubation is inadequate to prevent an awareness reaction to endotracheal intubation during propofol/alfentanil anesthesia. Because BIS cannot differentiate between patients with and without awareness reaction, its value as a monitor for awareness and a measurement of the hypnotic component of anesthesia must be questioned.
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J Neurosurg Anesthesiol · Jan 2002
Effects of sevoflurane on electrocorticography in patients with intractable temporal lobe epilepsy.
Fentanyl-droperidol technique is the choice for epilepsy surgery. It requires intraoperative electrocorticography (ECoG), but a large dose of fentanyl is needed for this technique. On the other hand, sevoflurane reportedly may be beneficial for intraoperative ECoG. ⋯ The mean number of spikes for 1 minute decreased from 38.3 to 14.1 after 1.5 MAC sevoflurane was induced, which was statistically significant ( P <.05). Our results showed that balanced technique with neurolepto-analgesia (NLA) and sevoflurane is not suitable for epilepsy surgery requiring intraoperative ECoG. When epilepsy surgeries are performed under sevoflurane anesthesia, it is important to consider that sevoflurane may suppress electric activities when it is used with other anesthetic agents.
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To clarify the epileptogenicity of sevoflurane, electrocorticograms were monitored in seven patients with unruptured cerebral aneurysm under sevoflurane anesthesia. They had no history of epilepsy or other complications. Spike activities on electrocorticography were seen in all seven patients at 3.3% end-tidal sevoflurane. These results suggest that further study is required to evaluate the suitability of sevoflurane for neurosurgical procedures.
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J Neurosurg Anesthesiol · Jan 2002
Sedative doses of remifentanil have minimal effect on ECoG spike activity during awake epilepsy surgery.
The use of remifentanil for sedation during awake epilepsy surgery has been described in a case report. However, little information is available regarding the effect of remifentanil on the quality of intraoperative electrocorticography (ECoG). This study was designed to investigate the effect of sedative doses of remifentanil on ECoG interictal spike activity among patients undergoing awake anterior temporal lobectomy for refractory epilepsy. ⋯ Respiratory rates decreased in all patients (mean decrease, 8 breaths/min) and one patient transiently developed a respiratory rate of 4 breaths per minute that elicited a decrease in the rate of remifentanil administration. Remifentanil administered at sedation doses does not adversely affect intraoperatively recorded interictal spike activity. Further investigation of the use of this drug during awake epilepsy surgery is warranted.
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J Neurosurg Anesthesiol · Jan 2002
Phenylephrine increases cerebral perfusion pressure without increasing intracranial pressure in rabbits with balloon-elevated intracranial pressure.
Using a rabbit model of intracranial hypertension, we studied the effects of infusion of phenylephrine on intracranial pressure (ICP) and cerebral perfusion pressure (CPP). Seven New Zealand white rabbits were anesthetized with isoflurane and normocapnia was maintained. An extradural balloon was used to raise ICP to 25 +/- 1 mm Hg. ⋯ The phenylephrine infusion was stopped after 45 minutes and MAP returned to baseline (76 +/- 8 mm Hg). We conclude that phenylephrine increased CPP because of its effect on MAP, but did not alter ICP. Phenylephrine may be used to increase CPP without raising ICP when autoregulation is intact.