Anesthesia and analgesia
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Anesthesia and analgesia · Dec 1986
Epidural anesthesia with lidocaine and bupivacaine: effects of epinephrine on the plasma concentration profiles.
The effects of epinephrine on the plasma concentrations and derived pharmacokinetic parameters were studied after epidural administration of lidocaine and bupivacaine. Addition of epinephrine to the local anesthetic solutions reduced the mean peak plasma concentrations of lidocaine and bupivacaine from 2.2 to 1.7 micrograms/ml (23%) and from 0.73 to 0.53 microgram/ml (28%), respectively, but did not alter the times at which the peak concentrations were reached. Epinephrine also did not alter the terminal half-lives or the total plasma clearances. The results suggest that addition of epinephrine to minimize plasma concentrations is as relevant with bupivacaine as it is with lidocaine.
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Anesthesia and analgesia · Dec 1986
Pulse oximetry and circulatory kinetics associated with pulse volume amplitude measured by photoelectric plethysmography.
Through a catheter placed in a superficial vein on the finger, we observed a pulsatile venous pressure. To delineate the relationship between the pulsatile venous pressure and the pulse volume amplitude (PVA) recorded by photoelectric plethysmography (PEPG), both tracings were simultaneously recorded. When the PVA changed acutely or gradually, the venous pulse pressure and mean venous pressure simultaneously followed the same trend. ⋯ Also, the PVA detected by the pulse oximeter followed the same trend as %SaO2. This finding was explained by venous congestion in the dependent finger. On the basis of the high venous pressure, the behavioral trends between the PVA and venous pressure, the high PVO2, and the low %SaO2 and PVA in the dependent finger, we conclude that the PVA of the PEPG is determined mainly by venous pulse volume generated by shunting of arterial pulse via open arteriovenous (AV) anastomoses in the cutaneous circulation.
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Anesthesia and analgesia · Nov 1986
Randomized Controlled Trial Clinical TrialPreoperative oral fluids: is a five-hour fast justified prior to elective surgery?
The effects of preoperative oral administration of 150 ml fluid were studied prospectively in 140 unpremedicated, ambulatory outpatients presenting for first trimester therapeutic abortion. Intraoperative gastric fluid volume, pH, and rate of gastric emptying were measured in the four groups to which patients were randomly assigned. At an average time of 2 1/2 hr preoperatively all patients received either oral ranitidine, 150 mg, or a placebo tablet, with the nonabsorbable marker dye bromosulphthalein (BSP, 50 mg in 10 ml water, followed by either 150 ml water or no further fluid. ⋯ Mean pH values were significantly higher in the two ranitidine groups (5.52 +/- 1.79, 5.03 +/- 1.79) than in the two placebo groups (1.75 +/- 0.94, 1.92 +/- 1.27). The combination of a residual volume of 25 ml and pH less than 2.5 was found in 46% of patients given only BSP with placebo, in 23% of those given 150 ml water with placebo, and in no patient given ranitidine. There was no correlation between the gastric volume or pH values with the ingestion-surgery interval in patients given 150 ml water.
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Anesthesia and analgesia · Nov 1986
Isoflurane decreases the cortisol response to cardiopulmonary bypass.
Eighteen patients with normal left ventricular function scheduled for elective myocardial revascularization were anesthetized with fentanyl (52-58 micrograms/kg). At the beginning of hypothermic cardiopulmonary bypass (CPB) they were assigned to a control (C) group (n = 6) that did not receive further anesthesia, or to a group given either 1% isoflurane (n = 6) or 2% isoflurane (n = 6). Blood samples for measurement of total plasma cortisol concentrations were obtained before, during, and after CPB. ⋯ Patients in group C required higher infusion rates of sodium nitroprusside (P less than or equal to 0.05) and patients given 2% isoflurane received more phenylephrine (P less than or equal to 0.05) to keep mean arterial pressure at 50 +/- 10 mm Hg during CPB. Isoflurane caused a dose-related decrease in total plasma cortisol concentrations during and after CPB. We conclude that increased depth of anesthesia attenuates the cortisol (stress) response to cardiopulmonary bypass.