Anesthesiology
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Randomized Controlled Trial Comparative Study Clinical Trial
Pharmacologic EEG suppression during cardiopulmonary bypass: cerebral hemodynamic and metabolic effects of thiopental or isoflurane during hypothermia and normothermia.
We have determined the effects of thiopental or isoflurane upon cerebral blood flow (CBF) and the cerebral metabolic rate for oxygen (CMRO2) when these agents are used in sufficient dose to attain a deep burst suppression pattern on the electroencephalogram (EEG) during hypothermic and normothermic cardiopulmonary bypass (CPB). Thirty-one patients undergoing coronary artery bypass graft surgery were anesthetized with fentanyl 0.1 mg X kg-1, and were randomly allocated to one of three groups: control (no further anesthetics during bypass and continuous EEG activity), thiopental treatment (EEG suppression), or isoflurane treatment (EEG suppression). Hypothermia (25-29 degrees C) was routinely induced at onset of nonpulsatile cardiopulmonary bypass. ⋯ Pharmacologic EEG suppression with either isoflurane or thiopental was associated with lower cerebral metabolic rate than control values during both hypothermic and normothermic bypass. However, only thiopental-induced EEG suppression was associated with lower cerebral blood flow than control. Cerebral blood flow during isoflurane-induced EEG suppression was similar to control values in spite of the reduced cerebral metabolic rate.
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Patients chronically receiving anticonvulsants have been reported to be resistant to the long-acting competitive neuromuscular blockers. This study examines the effects of atracurium and vecuronium on 100 neurosurgical patients; 50 receiving chronic phenytoin therapy (group I) and 50 controls (group II). During O2/N2O/halothane anesthesia, five patients in each group were given a bolus of vecuronium 0.1 mg/kg, and a different five patients in each group were given atracurium 0.5 mg/kg, to produce neuromuscular blockade in excess of 95%. ⋯ Using analysis of covariance, the slopes and elevations for atracurium were found to be essentially identical in the two groups; as were the calculated ED50 and ED95. Patients receiving chronic phenytoin therapy were resistant to vecuronium-induced neuromuscular blockade. With vecuronium, the dose-response curves for the two groups were parallel; the curve for phenytoin patients was shifted to the right.(ABSTRACT TRUNCATED AT 250 WORDS)
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Endotracheal tube (ETT) fire has been reported secondary to laser and electrocautery ignition. The flammability of polyvinylchloride (PVC), silicone (Si), and red rubber (RR) ETTs in oxygen (O2) and/or nitrous oxide (N2O) in nitrogen was determined and compared by means of the O2 and N2O indices of flammability. The O2 index of flammability is the minimum O2 fraction in nitrogen that will support candle-like flame using a standard ignition source. ⋯ Flammability is a valid method of comparing safety of various endotracheal tube materials. There is a need for new endotracheal tube material with a higher index of flammability. The significance of these findings and the clinical applications are discussed.