Anesthesiology
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Randomized Controlled Trial Clinical Trial
Thermoregulatory thresholds for vasoconstriction in pediatric patients anesthetized with halothane or halothane and caudal bupivacaine.
The thermoregulatory threshold for vasoconstriction has been studied in infants and children given isoflurane, but not in those given halothane anesthesia. More importantly, the effect of vasoconstriction on central temperature in pediatric patients remains unknown. Also unknown is the effect of caudal analgesia on vasoconstriction thresholds. ⋯ In the second part of this study we evaluated the effect of caudal analgesia on the thermoregulatory threshold for vasoconstriction. Children undergoing hypospadias repair were anesthetized with halothane (0.9%) and oxygen. Following induction, they were randomly assigned to caudal analgesia (n = 7) or penile nerve block (n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)
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To determine the induction and maintenance characteristics of desflurane in pediatric patients, the authors anesthetized 206 infants and children aged 1 month to 12 yr with nitrous oxide plus desflurane and/or halothane in oxygen. Patients were assigned to one of four groups: anesthesia was 1) induced and maintained with desflurane after premedication with an oral combination of meperidine, diazepam, and atropine; 2) induced and maintained with desflurane; 3) induced with halothane and maintained with desflurane; or 4) induced and maintained with halothane. An unblinded observer recorded time to loss of consciousness (lid reflex), time to intubation, and clinical characteristics of the induction and maintenance of anesthesia. ⋯ Intraoperatively, heart rate greater than 120% of baseline was more common with desflurane; blood pressures were similar for the two anesthetics. The authors conclude that the high incidence of airway complications during induction of anesthesia with desflurane limits its utility for inhalation induction in pediatric patients. Anesthesia can be safely maintained with desflurane if induced with a different anesthetic.
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Elimination half-life is the pharmacokinetic parameter used most commonly to describe duration of pharmacologic action, including that expected of intravenous anesthetic drugs administered by continuous infusion. Little consideration has been given, however, to the relevance of elimination half-life in describing plasma (central compartment) drug concentrations in the context of relevant infusion durations. Therefore, simulations were performed with multicompartment pharmacokinetic models for six intravenous anesthetic drugs. ⋯ The half-times were explained by posing each pharmacokinetic model in the form of a hydraulic model. These simulations demonstrate that elimination half-life is of no value in characterizing disposition of intravenous anesthetic drugs during dosing periods relevant to anesthesia. We propose that context-sensitive half-times are a useful descriptor of postinfusion central compartment kinetics.