Canadian journal of anaesthesia = Journal canadien d'anesthésie
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The actions of desflurane, isoflurane and halothane on regional tissue perfusion were studied using radioactive microspheres in dogs chronically instrumented for measurement of arterial and left ventricular pressure, global (left ventricular dP/dtmax) and regional (percent segment shortening) contractile function, and diastolic coronary blood flow velocity. Systemic and coronary haemodynamics and regional tissue perfusion were measured in the conscious state and during anaesthesia with equihypotensive concentrations of desflurane, isoflurane, and halothane. All three volatile anaesthetics (P < 0.05) increased heart rate and decreased mean arterial pressure, left ventricular systolic pressure, and left ventricular dP/dtmax Myocardial perfusion was unchanged in subendocardial midmyocardial, and subepicardial regions by the administration of either dose of desflurane. ⋯ Concomitant decreases in hepatic resistance were observed during administration of desflurane and isoflurane. Dose-related decreases in intestinal and skeletal muscle blood flow were observed during halothane and isoflurane but not desflurane anaesthesia. The results suggest that desflurane maintains myocardial, hepatic, intestinal, and skeletal muscle blood flow while halothane and isoflurane decrease regional tissue perfusion in these vascular beds to varying degrees during systemic hypotension in the chronically instrumented dog.
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Although the surgical advantages of laparoscopic cholecystectomy (LC) have been reported, the anaesthetic problems associated with this new technique have not been well described. For the first 101 patients undergoing laparoscopic cholecystectomy at our institution, we prospectively documented intraoperative critical observations and adverse outcomes in the PACU (Post-Anaesthetic Care Unit). In order to put the magnitude of these problems into perspective, we compared, in an identical manner, the anaesthetic management and outcomes of two more familiar surgical groups, cholecystectomy by laparotomy (C), and laparoscopy for gynaecological examination (LG). ⋯ We have documented considerable postoperative anaesthetic benefits for patients undergoing laparoscopic cholecystectomy compared with conventional cholecystectomy. However, there is still considerable perioperative morbidity compared with gynaecological laparoscopies. Now that specific problems have been identified, they may be amenable to specific anaesthetic interventions.
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It has been previously demonstrated that the output of calibrated vaporizers is influenced by the concentration of nitrous oxide in the carrier gas. This study was performed to determine whether helium in the carrier gas affects the output of modern calibrated vaporizers. A factorial design was used to determine the influence of carrier-gas helium concentration, carrier-gas flow rate and vaporizer dial setting on the output of four vaporizers: Ohio Calibrated Enflurane, Ohio Calibrated Isoflurane, Ohmeda Isotec 4, and Dräger Vapor 19.1 Isoflurane. ⋯ There was an effect of helium concentration on vaporizer output in all models. None of these changes was clinically important, since vaporizer output did not vary by more than +/- 10%, except at high flows and at high helium concentrations with the Ohmeda Isotec 4. It is concluded that these vaporizers can be used safely with helium.