Anesthesiology
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Randomized Controlled Trial Clinical Trial
The hemodynamic and cardiovascular effects of isoflurane and halothane anesthesia in children.
The hemodynamic and cardiovascular effects of isoflurane and halothane anesthesia were studied in 15 unpremedicated ASA I children using measurements of heart rate, blood pressure and M-mode echocardiography (echo). The children (ages 2 to 7.3 yr) were randomly assigned to receive either isoflurane (N = 8) or halothane (N = 7) with oxygen. End-tidal carbon dioxide concentrations (range 30-44 mmHg) were monitored throughout the study in each child. ⋯ Halothane was associated with a significant dose-dependent decrease in echo-measured left-ventricular shortening fraction and mean velocity of circumferential fiber shortening. These echo measurements were not significantly altered by isoflurane at either end-tidal anesthetic concentration. These alterations suggest halothane is associated with significant myocardial depression in normal children, while myocardial function is well preserved during isoflurane anesthesia.
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Randomized Controlled Trial Clinical Trial
Prolonged antagonism of opioid action with intravenous nalmefene in man.
To identify the opioid antagonist activity of nalmefene and to determine its duration in man, six healthy male subjects were pretreated on separate days with a saline placebo, 0.5 mg, 1 mg, or 2 mg nalmefene intravenously in a randomized double-blind fashion. Opioid challenges with fentanyl, 2 micrograms/kg, then were administered 1, 2, 4, 6, and 8 h afterward. Respiratory depression was monitored by ventilatory and occlusion pressure responses during CO2 rebreathing, while analgesia to experimental pain was identified with the submaximal effort tourniquet ischemia test. ⋯ The antagonist effects of the lowest nalmefene dose, 0.5 mg, persisted for about 4 h, at which time VE60 was 64% of control. Fentanyl administration produced consistent increases in pain tolerance (44-55% above control) throughout the experiment. Nalmefene pretreatment abolished this analgesic response in a dose-related time course that mirrored the respiratory effects almost exactly.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial
Effects of clonidine on narcotic requirements and hemodynamic response during induction of fentanyl anesthesia and endotracheal intubation.
The effects of clonidine, a centrally acting alpha 2-adrenergic receptor agonist, on depth of fentanyl anesthesia and on cardiovascular response to laryngoscopy and intubation were studied. Twenty-four patients undergoing aortocoronary bypass surgery (ACBS) with a history of arterial hypertension, coronary artery disease (NYHA class 3-4), and well-preserved left ventricular function were assigned randomly to either Group 1 (n = 12), who received standard premedication, or Group 2 (n = 12), who received clonidine 5 micrograms X kg-1 po in addition to standard premedication 90 min before estimated induction time. Depth of anesthesia was assessed by on-line aperiodic computerized analysis of the electroencephalogram (Lifescan EEG Monitor). ⋯ By contrast, fentanyl requirements in Group 2 were significantly reduced by 45% when compared with Group 1, i.e., from 110 +/- 23 to 61 +/- 19 micrograms X kg-1 (P less than 0.001). The authors conclude that at a similar anesthetic depth, as assessed by the EEG shift into the lower frequency range (0.5-3 Hz), a markedly reduced fentanyl dose effectively prevented the hyperdynamic cardiovascular response to laryngoscopy and intubation in the group of patients premedicated with clonidine. This is likely explained by the known synergistic inhibitory action of opiates and alpha 2-adrenoceptor agonists on central sympathetic outflow.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of enflurane, halothane, and isoflurane for diagnostic and therapeutic procedures in children with malignancies.
The authors performed a randomized, prospective trial comparing enflurane, halothane, and isoflurane (each administered with nitrous oxide) to establish which inhaled anesthetic produced the fewest complications and the most rapid induction of anesthesia for children undergoing general anesthesia for diagnostic procedures as oncology outpatients. Sixty-six children, ranging from 8 months to 18 years, underwent a total of 124 anesthetics. Induction of anesthesia (time from placement of facemask to beginning of skin preparation) was faster with halothane (2.7 +/- 1.0 min, mean +/- SD, n = 46) than with enflurane (3.2 +/- 0.8 min, n = 43) or isoflurane (3.3 +/- 1.2 min, n = 35). ⋯ During the maintenance of, emergence from, and recovery from anesthesia, coughing occurred most frequently with isoflurane. During the recovery period, headache occurred most frequently with halothane (9%); there were no significant differences in the incidence of nausea, vomiting, hunger, or depressed effect. The authors conclude that the rapid induction and minimal airway-related complications associated with halothane anesthesia make it an excellent anesthetic agent for pediatric patients undergoing short diagnostic procedures.
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Randomized Controlled Trial Comparative Study Clinical Trial
Preanesthetic cimetidine and metoclopramide for acid aspiration prophylaxis in elective surgery.
The effect of preanesthetic cimetidine and metoclopramide on gastric contents in inpatients undergoing elective surgery was studied. One hundred and fifty patients were allocated randomly into six groups with 25 patients in each group. Patients in Group 1 served as control. ⋯ Cimetidine and metoclopramide favorably modified the risk factors in all the experimental groups. This study demonstrated that the three groups receiving cimetidine in the morning (Groups 3, 5, and 6) had significantly greater mean gastric pH than the other groups. Gastric volumes were significantly less in all experimental groups.(ABSTRACT TRUNCATED AT 250 WORDS)