Anesthesiology
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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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Desflurane, an inhaled anesthetic, may be useful for outpatient procedures in pediatric patients because its blood solubility (similar to that of nitrous oxide and less than that of commercially available potent inhaled anesthetics) may facilitate emergence and recovery from anesthesia. Although the MAC of desflurane without nitrous oxide has been determined in pediatric patients, it is likely that clinicians will administer desflurane with nitrous oxide. To determine the potency of desflurane administered with 60% nitrous oxide in pediatric patients, the authors determined the minimum alveolar concentration that prevents movement in 50% of subjects (MAC) in 12 infants aged 17 weeks-12 months and 12 children aged 1-5 yr. ⋯ Following surgical incision, anesthesia was maintained with nitrous oxide, desflurane, and fentanyl, 4 +/- 1 micrograms/kg (mean +/- SD). MAC, determined using a modification of Dixon's "up-and-down" technique, was 7.5 +/- 0.1% (mean +/- SE) for infants and 6.4 +/- 0.2% for children; similar values were obtained using logistic regression (7.5 +/- 0.01% and 6.3 +/- 0.03%, respectively). Time from discontinuation of anesthesia to eye-opening and tracheal extubation was 5.4 +/- 3.6 min (mean +/- SD).(ABSTRACT TRUNCATED AT 250 WORDS)
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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.
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Randomized Controlled Trial Clinical Trial
Intravenous diclofenac coupled with PCA fentanyl for pain relief after total hip replacement.
Postoperative pain relief immediately after major surgery cannot be achieved with opioids alone in all patients without respiratory depression or other significant side effects. This investigation was conducted to determine whether the need for opioids and the incidence of side effects can be reduced while maintaining the quality of pain relief using a nonsteroidal antiinflammatory drug as an adjuvant to an opioid. The analgesic efficacy and safety of patient-controlled analgesia using fentanyl with and without intravenous diclofenac were compared after total hip replacement. ⋯ The diclofenac group showed a significant reduction in the amount of fentanyl administered during the first 16 h postoperatively as compared to the placebo group (0.65 mg +/- 0.2 vs. 1.08 mg +/- 0.4 respectively, P less than 0.01), and also reported less pain at 16 h (median score on visual analogue scale 0.75 vs. 2.4 respectively, P less than 0.05)). There were no differences in side effects, postoperative blood loss, plasma activated partial thromboplastin time, or Ivy bleeding time between the groups. In conclusion, the addition of diclofenac led to a reduction in fentanyl requirement but did not have any other significant advantages in the treatment of pain following major orthopedic surgery.
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Randomized Controlled Trial Clinical Trial
Epidural clonidine after cesarean section. Appropriate dose and effect of prior local anesthetic.
Epidurally administered clonidine represents a new approach to postcesarean section pain therapy, yet the appropriate bolus dose and infusion to provide effective pain relief have not been defined. In addition, whether 2-chloroprocaine, a commonly used local anesthetic for intraoperative anesthesia, interferes with clonidine's analgesia, as it does with that of opioids, has not been examined. In this study, using a randomized, blinded design, 63 women received either bupivacaine or 2-chloroprocaine for epidural anesthesia for cesarean section and then received, upon request for analgesia in the recovery room, epidural clonidine 400 micrograms or 800 micrograms bolus, each followed by a 24-h infusion of 40 micrograms/h, or an equivalent volume bolus and infusion of saline. ⋯ Clonidine did not alter resolution of residual local anesthetic sensory blockade, as measured by 2- or 4-segment regression following either local anesthetic, but did prolong duration of motor blockade in women receiving bupivacaine. Clonidine produced small decreases in heart rate and blood pressure. One patient received iv fluids for hypotension; one had asymptomatic bradycardia resolving without therapy; and one had mild hypoxemia with snoring during clonidine-induced sedation, responding to supplemental oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)