Anesthesia and analgesia
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Anesthesia and analgesia · Jan 1994
Randomized Controlled Trial Clinical TrialFentanyl or alfentanil decreases the minimum alveolar anesthetic concentration of isoflurane in surgical patients.
The minimum alveolar anesthetic concentration (MAC) is an accepted potency measure for inhaled anesthetics. There is no generally accepted intraoperative measure of opioid potency, partly because of the difficulty in obtaining steady state biophase concentrations. We have studied the relative potency of fentanyl and alfentanil by using computer-assisted continuous infusions (CACI), in terms of reduction of isoflurane MAC. ⋯ The maximum likelihood solution to a logistic regression model showed that fentanyl 0.5 ng/mL (95% confidence intervals [CI], 0-4.6 ng/mL) or alfentanil 28.8 ng/mL (95% CI, 0-70.9 ng/mL) resulted in a 50% isoflurane MAC reduction. In the logistic regression model, age or weight were not significant factors in the model. These results suggest that the comparative intraoperative potency ratio for alfentanil and fentanyl is 58:1, and that this methodology allows for direct intraoperative comparisons of opioid potency.
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Anesthesia and analgesia · Jan 1994
Comparative StudySyringe pumps for infusion of vasoactive drugs: mechanical idiosyncrasies and recommended operating procedures.
Syringe pumps for vasoactive infusions have the advantages of small size and weight, portability, and low cost of the disposable components. However, limited syringe capacity necessitates the use of high drug concentrations, and the accidental delivery of even a small volume of infusate could seriously alter the patient's hemodynamics. To determine the circumstances under which drug delivery might be delayed, or inadvertent boluses could be delivered into the manifold, two brands of commercially available clinical syringe pumps were connected to a stopcock manifold via small-bore tubing and a series of tests were performed. ⋯ When a syringe pump operating at 6 mL/h was turned off, typically an additional 0.05 mL was delivered during the ensuing 2-3 min. Depending upon the method used to flush the tubing prior to use, delays in drug delivery of 2-3 min occurred at an infusion rate of 3 mL/h. These observations emphasize the need for careful equipment setup and proper use of the manifold stopcocks to avoid unintended drug administration or delay in drug administration.
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Anesthesia and analgesia · Jan 1994
Comparative StudyCombined epidural analgesia and general anesthesia induce ischemia distal to a severe coronary artery stenosis in swine.
Epidural analgesia combined with general anesthesia may improve cardiac function and reduce the work of the heart by decreasing the rate pressure product. However, the effect of this combined technique has not been studied in the presence of severe coronary artery stenosis. Therefore, we investigated epidural analgesia combined with general anesthesia in a swine model with a tight coronary artery stenosis. ⋯ Myocardial wall thickening in the LAD bed decreased 31%, although it remained unchanged in the normal myocardium. Epidural bupivacaine added to general anesthesia resulted in moderate hypotension. Distal to the coronary stenosis was a moderate decrease in regional myocardial function and a severe reduction in blood flow.
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Anesthesia and analgesia · Jan 1994
Comparative StudyA comparison of epidural catheters with or without subcutaneous injection ports for treatment of cancer pain.
The aim of this study was to compare the incidence of technical complications of epidural catheters with subcutaneous injection ports to percutaneous epidural catheters without ports, fixed only by adhesive dressing. We reviewed 149 patients who received 250 epidural catheters for treatment of cancer pain during a 3 1/2-yr period from January 1, 1989, to June 30, 1992. Of the 250 catheters, 52 were provided with subcutaneous injection ports and 198 were percutaneous catheters. ⋯ No injection port became infected during the first 70 days of treatment, whereas in the percutaneous group infections occurred as early as the first week. Within the percutaneous group the complication rate in the tunneled epidural catheters was as high as in the nontunneled. We conclude that injection ports reduce the complication rate of epidural catheters, particularly catheter dislodgement and early infections.