Anesthesia and analgesia
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Anesthesia and analgesia · Dec 1998
Randomized Controlled Trial Comparative Study Clinical TrialRocuronium versus succinylcholine: are they equally effective during rapid-sequence induction of anesthesia?
The purpose of our study was to assess the onset and quality of muscle paralysis and intubation conditions with succinylcholine (Sch) or rocuronium (Roc) during rapid-sequence induction. Patients were randomly assigned to receive thiopental (5 mg/kg) and Sch (1.5 mg/kg) or thiopental (5 mg/kg) and Roc (1.2 mg/kg). The anesthesiologists performing the endotracheal intubation were blinded by standing with their back to the patient. Thirty seconds after drug administration, laryngoscopy was performed. Intubating conditions were scored, the clinical onset of apnea was noted, and a train-of-four monitor recorded data. All patients were ASA physical status I-III and scheduled for emergency procedures; both groups were demographically similar. Thirteen patients received Roc and 13 received Sch. There was no significant difference between the two groups in the number of patients receiving excellent intubating scores (P = 0.41) or in the combined number of patients receiving good and excellent scores (P = 1.0). There was no significant difference in time of onset of apnea for Sch (22+/-13 s) versus Roc (16+/-8s). The return of the first twitch response was significantly faster with Sch (5.05+/-2.5 min) compared with Roc (17.3+/-21.7 min) (P = 0.0001). ⋯ In pediatric patients scheduled for emergency surgery, thiopental 5 mg/kg and rocuronium 1.2 mg/kg provided conditions for the completion of intubation in <60 s comparable to those provided by thiopental 5 mg/kg and succinylcholine 1.5 mg/kg. We conclude that rocuronium is a reasonable substitute for succinylcholine in children for rapid-sequence intubation when a rapid return to spontaneous respiration is not desired.
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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 Comparative Study Clinical TrialIs the bispectral index useful in predicting fast-track eligibility after ambulatory anesthesia with propofol and desflurane?
This study was designed to test the hypothesis that outpatients with higher electroencephalographic (EEG) Bispectral Index (BIS) values at the end of anesthesia achieve a modified Aldrete score of 10 and satisfy fast-track eligibility criteria more rapidly after ambulatory surgery. Sixty consenting women undergoing laparoscopic tubal ligation procedures were studied. After premedication with midazolam 2 mg IV, anesthesia was induced with propofol 2 mg/kg IV, fentanyl 1.5 microg/kg IV, and succinylcholine 1 mg/kg IV and was initially maintained with either desflurane 4% (n = 31) or a propofol infusion 100 microg kg(-1) min(-1) (n = 29), in combination with nitrous oxide 65% in oxygen. Subsequently, the inspired desflurane concentrations (2%-6%) and propofol infusion rates (50-150 microg.kg(-1) min(-1) were varied to maintain a clinically acceptable depth of anesthesia. The average BIS value during the 3-min interval immediately before the discontinuation of the maintenance anesthetics was recorded. Emergence times and modified Aldrete scores were assessed from the end of anesthesia until patients were considered fast-track-eligible. The BIS values at the end of anesthesia were significantly correlated with the time to reach fast-track eligibility in both the desflurane (r = -0.68) and propofol (r = -0.76) groups. We concluded that the EEG-BIS value at the end of anesthesia is useful in predicting fast-track eligibility after laparoscopic tubal ligation procedures with either a desflurane- or propofol-based anesthetic technique. ⋯ In outpatients receiving either desflurane and propofol anesthesia for laparoscopic tubal ligation surgery, the times to achieve criteria for bypassing the recovery room (i.e., fast-tracking) correlated with the electroencephalographic-Bispectral Index values at the end of anesthesia.
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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 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.