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 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.
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Anesthesia and analgesia · Jan 1994
Randomized Controlled Trial Comparative Study Clinical TrialComparisons of tetracaine spinal anesthesia with clonidine or phenylephrine in normotensive and hypertensive humans.
To compare the hemodynamics and anesthetic effects of spinal tetracaine containing either clonidine or phenylephrine administered to normotensive or hypertensive patients, we studied 75 patients allocated to one of three groups, each of which included nine hypertensive patients: clonidine group (n = 25) received 2 mL of 0.5% tetracaine (10 mg) containing clonidine (0.15 mg); phenylephrine group (n = 25) received 2 mL of 0.5% tetracaine (10 mg) containing phenylephrine (3 mg); and control group (n = 25) received 2 mL of 0.5% tetracaine (10 mg) alone. Analgesic levels and the intensity of motor block obtained did not differ significantly among the three groups. ⋯ Mean blood pressure (MBP) in both hypertensive and normotensive patients given tetracaine-clonidine remained approximately 20% lower than that in the control group for as long as 7 h after the injection (P < 0.05). We conclude that the inclusion of clonidine can provide similar effects to that of phenylephrine with respect to prolongation of hyperbaric tetracaine spinal anesthesia, but could cause more hypotension, without bradycardia, in both normotensive and hypertensive patients for a prolonged time (i.e., 420 min).
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Anesthesia and analgesia · Jan 1994
Multicenter Study Comparative StudyThe postoperative interview: assessing risk factors for nausea and vomiting.
Most studies of postoperative nausea and vomiting have concentrated on single etiologic factors and have not detailed the method of assessing these symptoms. This study used postoperative interview data from patients at four teaching hospitals during 1988-89, to determine 1) risk factors for nausea/vomiting, 2) whether the type of surgery affected the rate of nausea/vomiting among female patients, 3) whether differences in rates across hospitals were due to differences in patient case-mix, and 4) whether there were differences in the rate of nausea/vomiting among the patients of individual anesthesiologists. Research nurses performed 16,000 interviews (59% of all inpatients) from a closed-question standardized format. ⋯ We found marked variations in the rate of nausea/vomiting across hospitals (range, 39% to 73%), and these variations were not explained by the case-mix of patients. The rate of nausea/vomiting varied substantially across anesthesiologists in each hospital and the differences were not explained by differences in the patients they managed. Thus in the time period immediately preceding the introduction of newer antiemetic drugs, we found that the rates of this common problem were persistently high as perceived from the patients' point of view.
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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.