Anesthesia and analgesia
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Anesthesia and analgesia · Oct 1993
The direction dependence of thermoregulatory vasoconstriction during isoflurane/epidural anesthesia in humans.
We tested the hypothesis that once thermoregulatory vasoconstriction is triggered at a given core temperature during isoflurane anesthesia, redilation starts at a substantially higher core temperature. To avoid direct perception of cutaneous cooling and warming, we used epidural anesthesia and limited our thermal manipulations to the blocked area. Seven volunteers were anesthetized with isoflurane/epidural anesthesia (approximately T9 dermatomal level). ⋯ The difference between the two thresholds defined the direction-dependent hysteresis. Vasoconstriction occurred at 35.2 +/- 0.6 degrees C and vasodilation at 36.2 +/- 0.5 degrees C (P < 0.01, paired t-test); consequently, the hysteresis was 1.0 +/- 0.6 degrees C. The observed hysteresis suggests that thermoregulatory responses during combined isoflurane/epidural anesthesia are not determined simply by instantaneous thermal input to central controllers, but may also depend on the direction of core temperature change.
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Anesthesia and analgesia · Oct 1993
Clinical pharmacology of mivacurium in pediatric patients less than off years old during nitrous oxide-halothane anesthesia.
We determined the dose-response relationship of mivacurium in infants 2-6 and 7-11 mo of age during nitrous oxide-halothane anesthesia. The neuromuscular and cardiovascular effects of a bolus dose of mivacurium larger than the ED95 in infants and young children from 2-23 mo of age were observed. The infusion rate of mivacurium required to maintain approximately 95% neuromuscular block was determined. ⋯ The time to onset of maximum block was 1.6 +/- 0.3 (0.7-2.7) (mean, SEM [range]) min, and time to recovery to 25% of T1 (T25) was 7.5 +/- 0.7 (5.5-11) min after 150 micrograms/kg in these patients. A bolus dose of 200 micrograms/kg mivacurium in infants and young children (7-23 mo) produced 100% depression of T1 in 14 of 17 patients, 97% depression in 2, and 90% depression in 1. The time to onset of maximum block was 1.5 +/- 0.1 (0.8-3) min and T25 was 10.3 +/- 1.5 (4.8-30.5) min after 200 micrograms/kg in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Oct 1993
Blood conservation during pediatric cardiac surgery: ultrafiltration of the extracorporeal circuit volume after cardiopulmonary bypass.
After separation of pediatric patients from cardiopulmonary bypass (CPB), the authors salvaged red blood cells (RBCs) from the extracorporeal circuit by ultrafiltration and reinfused them to the patients. The purposes of this study were to determine 1) the effects of infusion of hemoconcentrated RBCs on hemoglobin, plasma free hemoglobin, and activated clotting time, and 2) the incidence of perioperative homologous RBC transfusion. Data were collected prospectively from 200 consecutive infants and children undergoing CPB during correction of congenital heart defects. ⋯ Intraoperative transfusion was more frequent in small infants who were more hemodiluted by the clear CPB priming solution. Postoperative transfusion was more frequent in patients who had operation for cyanotic heart disease. Hemoconcentration by ultrafiltration after CPB is an effective and safe means of salvaging RBCs and reducing homologous RBC transfusion.
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Anesthesia and analgesia · Oct 1993
Predictive accuracy of continuous alfentanil infusion in volunteers: variability of different pharmacokinetic sets.
To evaluate the variability of the predictive accuracy of alfentanil by using different pharmacokinetic data sets, eight healthy young male adult volunteers were given the same alfentanil infusion for 4 h. Nineteen venous blood samples were taken from each volunteer, and alfentanil concentrations were titrated by radioimmunoassay. For each volunteer, the pharmacokinetic variables of a two-compartment model were calculated, averaged, and considered as a reference set. ⋯ The reference set had the best predictive accuracy (MDAPE, 23.6%). Five sets from the literature also showed a reliable predictive accuracy but four other sets with a clearance more than 5 mL.kg-1.min-1 and derived from a large bolus injection were inaccurate (MDAPE > 50%) as they underestimated the alfentanil concentrations. We conclude that pharmacokinetic sets derived from large bolus should not be selected to accurately predict alfentanil infusion.