Anesthesiology
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Inhalational anesthetics produce differential effects on hepatic blood flow and oxygenation that may impact hepatocellular function and drug clearance. In this investigation, the effects of sevoflurane on hepatic blood flow and oxygenation were compared with those of enflurane, halothane, and isoflurane in ten chronically instrumented greyhound dogs. Each dog randomly received enflurane, halothane, isoflurane, and sevoflurane, each at 1.0, 1.5, and 2.0 MAC concentrations. ⋯ A somewhat greater reduction in portal venous blood flow occurred during 2.0 MAC sevoflurane (P less than 0.05 compared to control and 1.0 MAC values for sevoflurane). Enflurane reduced portal venous blood flow at 1.0, 1.5, and 2.0 MAC compared to control. Halothane produced the greatest reduction in portal venous blood flow (P less than 0.05 compared to sevoflurane).(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial
Oral ketamine preanesthetic medication in children.
The authors sought to define a dose of oral ketamine that would facilitate induction of anesthesia without causing significant side effects. Forty-five children (ASA Physical Status 1 and 2; aged 1-7 yr) were assigned randomly in a prospective, double-blind fashion to three separate groups that received either 3 mg/kg, 6 mg/kg, or no ketamine mixed in 0.2 ml/kg cola-flavored soft drink. They also were evaluated preoperatively and postoperatively for acceptance of oral ketamine as a premedicant, reaction to separation from parents, emotional state, and emergence phenomena. ⋯ The 3 mg/kg dose did not always cause sedation and calm separation from parents. Neither dose of ketamine increased the incidence of laryngospasm, prolonged recovery times, or caused emergence phenomena. The authors conclude that an oral dose of 6 mg/kg ketamine is easily administered and well accepted in young children and provides predictable, satisfactory premedication without significant side effects.
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Opioids are known to affect the MAC of inhalational anesthetics. We have determined the interaction between fentanyl and desflurane, following a bolus injection of fentanyl at induction in 134 adult patients. Five groups of patients were studied. ⋯ Recovery was faster in patients who received desflurane than in those who received isoflurane. The authors conclude that the MAC of desflurane is significantly reduced 25 min following a single dose of 3 micrograms/kg of fentanyl and that increasing the fentanyl dose to 6 micrograms/kg produces little further decrease in MAC. Desflurane is also associated with faster recovery from anesthesia than is isoflurane.
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The increased metabolic and respiratory demand during naloxone recovery from opioid-based anesthesia could be related to the return of thermoregulation in hypothermic patients and thus be avoided by preventing intraoperative hypothermia. In this study, we measured O2 uptake (VO2) during naloxone-induced recovery in two groups of patients to determine the effect of intraoperative heat loss on postoperative VO2 changes. In seven patients, intraoperative hypothermia was prevented (normothermic group), whereas hypothermia was allowed to develop in seven other patients (hypothermic group). ⋯ VO2 was integrated throughout the recovery period to calculate recovery energy expenditure. Recovery energy expenditure and intraoperative heat loss were highly correlated (r = 0.88; P less than 0.01). This study demonstrates that the metabolic and respiratory stresses associated with naloxone-induced recovery from opioid-based anesthesia depend on the intraoperative heat loss and can therefore be reduced by preventing intraoperative hypothermia.
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Letter Biography Historical Article
An American dentist pioneered anesthesia in Spain.