Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Apr 1995
Case ReportsPerforation and partial obstruction of an armored endotracheal tube.
Armored endotracheal tubes are often used during cases in which there is a risk of compromise of a polyvinylchloride tube with positioning of a patient's head. The authors describe a case in which partial airway obstruction and perforation of such a tube occurred as a result of biting by a patient. Ways to avoid this complication are discussed.
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J Neurosurg Anesthesiol · Apr 1995
Nitrous oxide increases cerebral blood flow velocity during pharmacologically induced EEG silence in humans.
We examined the effect of nitrous oxide on cerebral blood flow velocity (Vmca), arteriovenous oxygen content difference and cerebral use of glucose during propofol-induced electrical silence of the electroencephalogram (EEG) in 10 patients undergoing anesthesia for nonneurosurgical procedures. Anesthesia was induced with propofol 2.5 mg/kg, fentanyl 3 micrograms/kg (followed by an infusion of 2 micrograms/kg/h), vecuronium 0.1 mg/kg, and maintained with a propofol infusion (250-300 micrograms/kg/min) sufficient to induce EEG silence. A transcranial Doppler was used to measure the Vmca and a jugular bulb catheter was inserted for oxygen saturation and glucose use measurements. ⋯ Nitrous oxide increased Vmca (29 +/- 4 to 35 +/- 4 cm/s, p < 0.01), cerebral use of oxygen (166 +/- 13 to 190 +/- 12 vol%-cm/s, p < 0.05) and glucose (245 +/- 38 to 290 +/- 48 g%-cm/s, p < 0.05) by approximately 20%. Occasional bursts of EEG activity were observed in eight patients studied during the N2O stage. We conclude that in patients with propofol-induced isoelectric EEG, the increase seen in Vmca with the introduction of N2O is mainly due to cerebral stimulation and increase in cerebral metabolic rate.
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J Neurosurg Anesthesiol · Jan 1995
Comparative StudyEffect of intrathecal saline injection and Valsalva maneuver on cerebral perfusion pressure during transsphenoidal surgery for pituitary macroadenoma.
Cerebrospinal fluid pressure (CSFP) was monitored through a lumbar intrathecal catheter in 32 patients undergoing transsphenoidal excision of pituitary macroadenomas. In the first 20 patients, standardized intermittent Valsalva maneuvers were followed by intrathecal saline injections in 2.5-ml increments. Their effects on CSFP, mean arterial pressure (MAP), and therefore, cerebral perfusion pressure (CPP) were compared. ⋯ Peroperative data, including surgical conditions, and post-operative morbidity, with special reference to low-pressure headache and meningeal infection, were analyzed in all 32 patients. Operative conditions produced with intrathecal saline were judged excellent or good in 75% of patients. However, because this technique can decrease the CPP excessively, we recommend that it be used only with continuous CSFP monitoring.
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J Neurosurg Anesthesiol · Jan 1995
Comparative StudyBrain edema and neurologic status with rapid infusion of 0.9% saline or 5% dextrose after head trauma.
We previously reported that intravenous (i.v.) administration of large volumes (0.2 ml/g) of either an isotonic dextrose-free solution or 5% dextrose solution given over 18 h after closed head trauma (CHT) in rats did not significantly affect neurological severity score or brain tissue specific gravity. However, it is possible that with more rapid administration, isotonic or 5% dextrose i.v. solutions may alter neurological outcome after CHT. Our study examined whether neurological severity score, brain tissue specific gravity and water content, and blood composition were significantly altered when 0.25 ml/g of either 0.9% saline or 5% dextrose was given i.v. over 0.5 h (rather than over 18 h) after CHT. ⋯ There were no statistically significant differences in neurologic outcome and brain edema between the untreated and the saline-treated groups. However, 5% dextrose i.v. increased mortality (group 6 and 11, 50 and 0% survivors, respectively), decreased specific gravity in the noncontused hemisphere, and worsened neurologic outcome with and without CHT. Blood osmolality remained stable in comparison to the baseline value of 291.9 +/- 7.4 mOsm/kg (mean +/- SD).(ABSTRACT TRUNCATED AT 250 WORDS)
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Core body temperature is normally rigidly regulated by effective thermoregulatory responses that are triggered by small deviations in core and skin temperature. All general anesthetics so far tested markedly impair thermoregulatory control, increasing the range of temperatures not triggering protective responses by approximately 20-fold. Inhibition of thermoregulatory control--and reemergence of protective responses--are major factors influencing intraoperative temperature. ⋯ Forced air appears to be the most effective clinically practical cooling method. Mild hypothermia is also associated with serious complications including myocardial ischemia, impaired resistance to surgical wound infections, coagulopathies, and postoperative shivering. Consequently, patients deliberately made hypothermic during neurosurgery should subsequently be actively rewarmed.