Anesthesia and analgesia
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Anesthesia and analgesia · Dec 1998
Randomized Controlled Trial Clinical TrialThe use of metoprolol and glycopyrrolate to prevent hypotensive/bradycardic events during shoulder arthroscopy in the sitting position under interscalene block.
Sudden profound hypotensive and/or bradycardic events (HBE) have been reported in >20% of patients undergoing shoulder arthroscopy in the sitting position under interscalene block anesthesia. Retrospective studies suggest that the administration of beta-blockers is safe and may decrease the incidence of these episodes. We performed a randomized, prospective study to evaluate prophylaxis of these events. One hundred fifty patients were randomized to one of three groups (placebo; prophylactic metoprolol to achieve a heart rate <60 bpm or a maximal dose of 10 mg; or prophylactic glycopyrrolate to achieve a heart rate >100 bpm or a maximal dose of 6 microg/kg) immediately after the administration of the interscalene block. Blood pressure control was achieved with IV enalaprilat as needed. The incidence of HBE was 28% in the placebo group versus 5% in the metoprolol group (P = 0.004). The rate of 22% in the glycopyrrolate group was not significantly different from placebo. Preoperative heart rate and arterial blood pressure, intraoperative sedation score, IV fluids, and enalaprilat use were similar in those patients who had a HBE compared with those who did not. Many aspects of this clinical setting are similar to tilttable testing for patients with recurrent vasovagal syncope, in which beta-adrenergic blockade with metoprolol has also been shown to be effective. We conclude that the Bezold-Jarisch reflex is the most likely mechanism for these events. ⋯ Episodes of acute hypotension and bradycardia occur during shoulder arthroscopy in the sitting position under interscalene block. In this study, we demonstrate that metoprolol, but not glycopyrrolate, markedly decreases the incidence of these episodes when given prophylactically immediately after the administration of the block.
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Anesthesia and analgesia · Dec 1998
Randomized Controlled Trial Comparative Study Clinical TrialPreoperative preparation programs in children: a comparative examination.
We sought to determine whether an extensive behavioral preparation program for children undergoing surgery is more effective than a limited behavioral program. The primary end point was child and parent anxiety during the preoperative period. Secondary end points included behavior of the child during the induction of anesthesia and the postoperative recovery period. Several days before surgery, children (n = 75) aged 2-12 yr randomly received either an information-based program (OR tour), an information + modeling-based program (OR tour + videotape), or an information + modeling + coping-based program (OR tour + videotape + child-life preparation). Using behavioral and physiological measures of anxiety, we found that children who received the extensive program exhibited less anxiety immediately after the intervention, in the holding area on the day of surgery, and on separation to the operating room. These findings, however, achieved statistical significance only in the holding area on the day of surgery (44[10-72] vs 32[8-50] vs 9[6-33]; P = 0.02). Similarly, parents in the extensive program were significantly less anxious on the day of surgery in the preoperative holding area, as assessed by behavioral (P = 0.015) and physiological measures (P = 0.01). In contrast, no differences were found among the groups during the induction of anesthesia, recovery room period, or 2 wk postoperatively. We conclude that children and parents who received the extensive preoperative preparation program exhibited lower levels of anxiety during the preoperative period, but not during the intraoperative or postoperative periods. ⋯ The extensive behavioral preoperative program that we undertook had limited anxiolytic effects. These effects were localized to the preoperative period and did not extended to the induction of anesthesia or the postoperative recovery period.
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Anesthesia and analgesia · Dec 1998
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of 0.5% bupivacaine, 0.5% ropivacaine, and 0.75% ropivacaine for interscalene brachial plexus block.
The onset time and duration of action of ropivacaine during an interscalene block are not known. The potentially improved safety profile of ropivacaine may allow the use of higher concentrations to try and speed onset time. We compared bupivacaine and ropivacaine to determine the optimal long-acting local anesthetic and concentration for interscalene brachial plexus block. Seventy-five adult patients scheduled for outpatient shoulder surgery under interscalene block were entered into this double-blind, randomized study. Patients were assigned (n = 25 per group) to receive an interscalene block using 30 mL of 0.5% bupivacaine, 0.5% ropivacaine, or 0.75% ropivacaine. All solutions contained fresh epinephrine in a 1:400,000 concentration. At 1-min intervals after local anesthetic injection, patients were assessed to determine loss of shoulder abduction and loss of pinprick in the C5-6 dermatomes. Before discharge, patients were asked to document the time of first oral narcotic use, when incisional discomfort began, and when full sensation returned to the shoulder. The mean onset time of both motor and sensory blockade was <6 min in all groups. Duration of sensory blockade was similar in all groups as defined by the three recovery measures. We conclude that there is no clinically important difference in times to onset and recovery of interscalene block for bupivacaine 0.5%, ropivacaine 0.5%, and ropivacaine 0.75% when injected in equal volumes. ⋯ In this study, we demonstrated a similar efficacy between equal concentrations of ropivacaine and bupivacaine. In addition, increasing the concentration of ropivacaine from 0.5% to 0.75% fails to improve the onset or duration of interscalene brachial plexus block.
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Anesthesia and analgesia · Dec 1998
Randomized Controlled Trial Clinical TrialOral clonidine premedication enhances the pressor response to ephedrine during spinal anesthesia.
Clonidine premedication enhances the pressor effects of ephedrine in awake and anesthetized patients. To test the hypothesis that clonidine augments the pressor response to ephedrine during spinal anesthesia, 48 ASA physical status I or II patients were randomly assigned to either the clonidine group (n = 23), receiving oral clonidine approximately 5 microg/kg 90 min before spinal anesthesia, or the control group (n = 25), receiving no clonidine. Spinal anesthesia was performed at either the L2-3 or the L3-4 interspace using 0.5% hyperbaric tetracaine solution 1.4-3.0 mL. Blood pressure (BP), heart rate, and the upper dermatomal level of analgesia were determined at 1-min intervals with the patient in the supine position after tetracaine injections. When systolic BP decreased to <80% of the prespinal value or <100 mm Hg, IV ephedrine 0.2 mg/kg was administered as a bolus. There were no differences in the duration until the first dose of ephedrine after tetracaine injections, and the upper level of analgesia between groups (control group 8.5+/-3.7 min, T5; clonidine group 7.7+/-2.7 min, T6). Although prespinal and preephedrine BP values were higher in the control group, the magnitude of increases in mean BP after ephedrine was significantly greater in the clonidine group (P < 0.05). We conclude that oral clonidine premedication augments the pressor response to IV ephedrine during spinal anesthesia. ⋯ The pressor effect of ephedrine is enhanced in patients given oral clonidine premedication during spinal anesthesia.