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 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 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
Comparative StudyEvaluation of platelet function by Sonoclot analysis compared with other hemostatic variables in cardiac surgery.
Platelet function can be easily measured as time to peak (TP) by Sonoclot Coagulation & Platelet Function Analyzer (Sienco Inc., Morrison, CO) analysis. However a correlation between Sonoclot analysis and platelet aggregation, which is accepted as a test of platelet function, has not been established. In this study, we compared TP and collagen-induced whole blood platelet aggregation in 15 patients undergoing cardiac surgery. Two or three blood samples were randomly obtained from each patient before and after cardiopulmonary bypass (CPB). Sonoclot analysis, collagen-induced whole blood aggregation, and laboratory measurement (including platelet count and coagulation profile) were measured. Seventy-two samples were obtained (35 before CPB and 37 after CPB). TP was correlated with collagen-induced whole blood aggregation (r = -0.652), platelet count (r = -0.671), fibrinogen level (r = -0.598), prothrombin time (r = 0.394), activated partial thromboplastin time (r = 0.486), and use of CPB (r = 0.380). Significant predictors of TP for multiple linear regression modeling were collagen-induced whole blood aggregation, platelet count, and fibrinogen level (r = 0.742). In conclusion, Sonoclot analysis TP predicts approximate platelet function in patients undergoing cardiac surgery. ⋯ Approximate platelet function can be easily measured as time to peak by Sonoclot analysis. In this study, time to peak was predicted by platelet count, whole blood platelet aggregation, and fibrinogen level for multiple linear regression modeling.
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Anesthesia and analgesia · Dec 1998
Hypoxemia decreases the shivering threshold in rabbits anesthetized with 0.2 minimum alveolar anesthetic concentration isoflurane.
Shivering has been proposed as an etiology of postoperative hypoxemia. The difficulty with this theory is that hypoxemia inhibits shivering in unanesthetized cats, rats, and humans. However, anesthesia inhibits many protective reflexes, including the ventilatory response to hypoxemia. We therefore tested the hypothesis that arterial hypoxemia fails to inhibit shivering in lightly anesthetized rabbits. Rabbits were intubated and instrumented during exposure to surgical concentrations of anesthesia, and anesthesia was then maintained with 0.2 minimum alveolar anesthetic concentration isoflurane. The core was cooled at a rate of 2-3 degrees C/h by perfusing water at 10 degrees C through a colonic thermode. Core temperatures were recorded from the distal esophagus. Sustained, vigorous shivering was considered physiologically significant. The core temperature that triggering significant shivering identified the thermoregulatory threshold for this response. Arterial blood was sampled for gas analysis at the shivering threshold in each rabbit. Hypoxemia linearly reduced the shivering threshold from 36.7 degrees C at 130 mm Hg to 35.4 degrees C at 50 mm Hg (threshold = PaO2.0.019 + 34.3; r2 = 0.49). We failed to confirm our hypothesis: instead, even mild hypoxemia reduced the shivering threshold >1 C. A 1 C decrease in the shivering threshold is likely to prevent or stop most postoperative shivering because it exceeds the reduction produced by many effective anti-shivering drugs. These data do not support the theory that shivering causes postoperative hypoxemia. ⋯ Shivering has been proposed as an etiology of postoperative hypoxemia. Our data, in contrast, show that mild hypoxemia inhibits shivering. Shivering is thus unlikely to be a cause of postoperative hypoxemia.