Journal of neurosurgical anesthesiology
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Hydroxocobalamin is a powerful cyanide antidote that prevents sodium nitroprusside-induced cyanide toxicity. The pharmacokinetics of an i.v. bolus of hydroxocobalamin (70 and 140 mg/kg) were studied in conscious dogs (n = 6). Plasma hydroxocobalamin concentrations were measured using derivative spectrophotometry. ⋯ At 70 mg/kg, which is the recommended dose in acute cyanide poisoning, the elimination half-life was 7.36 +/- 0.79 h, the volume of distribution was 0.49 +/- 0.10 L/kg, and the total clearance 0.58 +/- 0.11 L/h. At high doses, hydroxocobalamin has a short elimination half-life and a limited volume of distribution that exceeds blood volume. These results could be useful in elaborating guidelines for the administration of hydroxocobalamin, when repetitive bolus and/or continuous infusion is required.
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J Neurosurg Anesthesiol · Jan 1994
Case ReportsVenous air embolism after craniotomy closure: tension pneumocephalus implicated.
The authors present a case of venous air embolism occurring immediately upon skin closure after craniotomy in the prone position. This 5-year-old patient had a third ventricle tumor resected with bipolar cautery via a frontal trans-collosal approach into the lateral ventricle and through the foramen of Monroe. Doppler monitoring was utilized during the case since the patient's head was extended upwards in 10 degrees reverse Trendelenburg position. ⋯ The ventricles were filled with saline presumably displacing air, prior to dural closure. However, with an increase in nitrous oxide from 55 to 68% prior to skin closure, venous air embolism was subsequently detected by Doppler and confirmed by end-tidal/arterial pCO2 gradient. The authors speculate that tension pneumocephalus caused the venous air embolism and describe the probable route of entry into the venous system.
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J Neurosurg Anesthesiol · Jan 1994
Incidence and clinical significance of hemidiaphragmatic paresis in patients undergoing carotid endarterectomy during cervical plexus block anesthesia.
This study was designed to investigate the incidence and clinical consequences of hemidiaphragmatic paresis in patients undergoing carotid endarterectomy using cervical plexus block anesthesia. In 28 patients, diaphragmatic motion was evaluated by fluoroscopy 20 min after cervical plexus block with 1% mepivacaine. ⋯ These motion anomalies were associated with a statistically significant elevation of PaCO2. Gender, age, and whether the block was on the left or right side did not appear to affect the incidence of motion abnormalities after cervical plexus block anesthesia.
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J Neurosurg Anesthesiol · Jul 1993
Randomized Controlled Trial Clinical TrialClonidine premedication for craniotomy: effects on blood pressure and thiopentone dosage.
The purpose of this study was to determine whether oral clonidine premedication improves cardiovascular stability and/or reduces the requirements for drugs used to control systolic blood pressure (SBP) during elective craniotomies. We performed a double blind randomized trial involving 77 normotensive, ASA physical status I or II adults. Clonidine 4 micrograms/kg or placebo was given as oral premedication. ⋯ Two subgroups were analyzed, based on the study groups mean age and baseline SBP. Three-way analysis of variance revealed that the blood pressure effects of clonidine were almost entirely confined to patients older than 45 years. Baseline SBP had no independent effect.(ABSTRACT TRUNCATED AT 250 WORDS)
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J Neurosurg Anesthesiol · Jul 1993
Comparative StudyAirway pressure monitoring as an aid in the diagnosis of air embolism.
We designed a prospective study to compare the validity of airway pressure (AWP) monitoring with that of end-tidal CO2 (ETCO2) monitoring for early detection of air embolism. Subjects included 76 patients of both sexes who underwent neurosurgery in the sitting position. Anesthesia was maintained with O2, N2O, narcotics, pancuronium, and intermittent positive pressure ventilation (IPPV). ⋯ Murmur was noted in four patients and air aspiration in six patients. Only six patients of the 16 had an increase in AWP along with the decrease in ETCO2. We conclude that AWP monitoring is neither a sensitive nor reliable indicator of air embolism.