Anesthesiology
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Arterial tonometry is a technique used to measure arterial blood pressure noninvasively. The authors developed a new tonometer system containing an array of 15 piezoresistive pressure transducers, a mechanical positioning system, signal conditioning and multiplexing electronics, and a display and control console. The authors evaluated the accuracy, reliability, and clinical acceptability of this system by comparing tonometric blood pressure measurements with intraarterial blood pressure measurements in 60 anesthetized patients. ⋯ Mean absolute values of error (precision) for the systolic, mean, and diastolic measurements did not differ significantly among the five systolic, five mean, and four diastolic pressure groups and ranged from 3.6 to 6.6 mmHg, with negligible bias, with intraarterial pressure used as the reference. Bias for the various pressure groups was small: -0.9-3.6 mmHg for systolic; -3.0-0.7 mmHg for mean; and -2.1-4.5 mmHg for diastolic. The "limits of agreement" (mean difference +/- two standard deviations) were within an acceptable range for clinical anesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Comparative Study Clinical Trial
Effect of propofol on the incidence of postoperative vomiting after strabismus surgery in pediatric outpatients.
Vomiting is a common problem after strabismus surgery in pediatric outpatients. We compared the effects of propofol with and without N2O and droperidol to the effects of a conventional regimen consisting of halothane-N2O-droperidol on the recovery characteristics and the incidence of postoperative emesis after strabismus surgery in 120 ASA physical status 1 or 2 children. After induction of anesthesia with halothane-N2O, patients were randomly assigned to one of four groups. ⋯ Patients in group B had more episodes of intraoperative oculocardiac reflex responses than patients in group A, but had shorter times to extubation, oral intake, ambulation, and discharge, as well as a lower incidence of postoperative emesis (P less than 0.05). The addition of N2O to the propofol anesthetic regimen (group C) was associated with an increased incidence of emesis (P less than 0.05), whereas the addition of droperidol to the propofol-N2O regimen (group D) did not affect the incidence of emesis compared to the other three groups. We conclude that maintenance of anesthesia with a total intravenous regimen using propofol results in a more rapid recovery and less postoperative emesis than with a halothane-N2O-droperidol regimen.(ABSTRACT TRUNCATED AT 250 WORDS)
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Randomized Controlled Trial Clinical Trial
The neuromuscular effects of ORG9426 in patients receiving balanced anesthesia.
In searching for a nondepolarizing muscle relaxant with intermediate duration but more rapid onset of action than the presently available compounds, the neuromuscular and circulatory effects of ORG9426 were investigated in two studies in humans receiving fentanyl, droperidol, thiopental, and nitrous oxide-oxygen anesthesia. Eighty patients, randomly assigned to one of four groups of 20 each, received 0.12, 0.16, 0.20, or 0.24 mg/kg ORG9426. In the first study, the doses (in milligrams per kilogram) of ORG9426 that caused 50% (ED50), 90% (ED90), or 95% (ED95) neuromuscular block were determined by the individual dose-response method; they were 0.170, 0.268, and 0.305 mg/kg, respectively. ⋯ After the administration of 0.6 mg/kg ORG9426, maximal neuromuscular block developed in 1.5 +/- 0.12 min in group 1 and in 1.2 +/- 0.14 min in group 2. Patients tracheas were intubated after development of the maximal neuromuscular effect of the intubating dose and after the recording of heart rate and systolic and diastolic blood pressure. There was no difference in the clinical duration of the intubating doses, which were 40.0 +/- 3.2 (15-73) min in group 1 and 39.3 +/- 2.4 (19-57) min in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study
Dose-response for atropine and heart rate in infants and children anesthetized with halothane and nitrous oxide.
The dose recommendations for atropine in anesthetized children vary, and the dose-response for heart rate has not been defined. We determined the dose-response for atropine and heart rate in 181 healthy children anesthetized with halothane and nitrous oxide. After induction of anesthesia, atropine in a dose of 5, 10, 20, 30, or 40 micrograms.kg-1 was administered by rapid intravenous infusion of each subject. ⋯ Subjects less than 6 months old had higher control and peak heart rates than did subjects greater than or equal to 2 yr old, but the older subjects had greater change in heart rate after atropine. For subjects greater than or equal to 2 yr old, all doses of atropine produced a significant increase in heart rate. The same was true for younger subjects, less than 6 months old, except that 5 micrograms.kg-1 did not increase heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study
Direct vasodilation by sevoflurane, isoflurane, and halothane alters coronary flow reserve in the isolated rat heart.
Direct vasodilation of coronary resistance vessels by anesthetics may reduce coronary flow reserve and interfere with myocardial flow-metabolism coupling. This study was performed to evaluate the potential for the halogenated anesthetic agents sevoflurane, isoflurane, and halothane to alter the regulation of coronary flow via a direct action on coronary resistance vessels. Coronary flow and flow reserve were measured in the quiescent isolated perfused rat heart at anesthetic concentrations between 0 and 3 x MAC. ⋯ At high concentrations (3.0 x MAC), coronary flow reserve was abolished by halothane and was decreased to near zero by isoflurane; however, flow reserve was reduced only 48% from control by sevoflurane. This difference among anesthetics is explained primarily by variations in the magnitude of direct coronary vasodilation produced by each anesthetic, rather than by effects on maximal vasodilator capacity. These data show that sevoflurane's intrinsic vasodilator action on coronary resistance vessels differs substantially from that of halothane and isoflurane.