Anesthesia and analgesia
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Anesthesia and analgesia · Nov 2000
Perianesthetic risks and outcomes of pheochromocytoma and paraganglioma resection.
Pheochromocytomas and paragangliomas are often surgically curable. However, resection of these tumors can be life threatening. We undertook this study to determine the frequency of, and risk factors for, perioperative complications in patients undergoing resection of pheochromocytoma or paraganglioma. We retrospectively reviewed the medical records of patients during 1983-1996 who underwent surgical resection of catecholamine-secreting pheochromocytoma or paraganglioma. Preoperative risk factors, adverse intraoperative events, and complications occurring in the 30 days after operation were recorded. Blood pressures were collected from manual records. The ranked sum test and Fisher's exact test were used for analyses. Adverse perioperative events or complications occurred in 45 of 143 patients (31.5%; exact 95% confidence interval, 24.0% to 39.8%). Of these 45 patients, 41 experienced one or more adverse intraoperative events. The most common adverse event was sustained hypertension (36 patients). There were no perioperative deaths, myocardial infarctions, or cerebrovascular events. Preoperative factors univariately associated with adverse perioperative events included larger tumor size (P: = 0.007), prolonged duration of anesthesia (P: = 0.015), and increased levels of preoperative urinary catecholamines and catecholamine metabolites: vanillylmandelic acid (P: = 0.019), metanephrines (P: = 0.004), norepinephrine (P: = 0. 014), and epinephrine (P: = 0.004). Despite premedication of most patients with phenoxybenzamine and a beta-adrenergic blocker, varying degrees of intraoperative hemodynamic lability occurred. ⋯ Few patients who had pheochromocytoma or paraganglioma resection experienced significant perioperative morbidity and none died in the largest retrospective study on this topic to date. This study confirms the very good perioperative outcomes demonstrated in smaller studies on this high-risk population, and identifies several risk factors for adverse outcomes.
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Anesthesia and analgesia · Nov 2000
Randomized Controlled Trial Multicenter Study Comparative Study Clinical TrialPostoperative nausea and vomiting after sevoflurane with or without ondansetron compared with propofol in female patients undergoing breast surgery.
We studied 180 female patients undergoing breast surgery. The patients were randomly allocated to receive one of three anesthetic techniques. Compared with either propofol or sevoflurane alone, sevoflurane with ondansetron resulted in a decreased incidence of postoperative nausea and vomiting. Sevoflurane with ondansetron prophylaxis is a good alternative to propofol with respect to avoiding postoperative nausea and vomiting.
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Anesthesia and analgesia · Nov 2000
Comparative Study Clinical TrialThromboelastography as a perioperative measure of anticoagulation resulting from low molecular weight heparin: a comparison with anti-Xa concentrations.
Low molecular weight heparin (LMWH) is commonly used to prevent postoperative thromboembolism. Currently, there is no convenient test to measure the degree of anticoagulation from LMWH. This prospective study examines the relationship of thromboelastography and serum anti-Xa concentration in patients treated with enoxaparin. Twenty-four adult patients scheduled for orthopedic surgery using epidural anesthesia were enrolled. Epidural catheters were removed the morning after surgery before the commencement of subcutaneous enoxaparin 30 mg twice daily. Venous blood samples were obtained at 1) the induction of anesthesia (baseline), 2) immediately before the third dose of enoxaparin postoperatively (Day 2-trough), 3) 4 h after the third dose postoperatively (Day 2-peak), and 4) immediately before the fifth dose postoperatively (Day 3-trough). Whole blood samples were obtained for thromboelastography, activated clotting time, and anti-Xa level analyses at each of the four time intervals. At the four sample intervals, the r time (mean +/- SEM). (20 +/- 1, 25 +/- 2, 51 +/- 6, 31 +/- 3 mm) and the k time (9 +/- 0. 7, 12 +/- 1, 27 +/- 5, 14 +/- 2 mm) of the thromboelastograph were significantly correlated with the expected peak and trough levels of LMWH and serum anti-Xa levels (P: < 0.05). At the Day 3-trough, thromboelastograph r times exceeded the normal range in 6 of 25 patients (25%). Prolongation of r time and k time on postoperative Day 3 may indicate an exaggerated response to LMWH. Thromboelastography is a test that could potentially correlate with the degree of anticoagulation produced by low molecular weight heparin. ⋯ Thromboelastography is a test that could potentially correlate with the degree of anticoagulation produced by low molecular weight heparin. The r time from the thromboelastogram correlates with serum anti-Xa concentration.
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Anesthesia and analgesia · Nov 2000
Multicenter StudyIs there a learning curve associated with the use of remifentanil?
This study prospectively determined whether there was a learning curve with the use of remifentanil, as indicated by decreased hemodynamic variability, improved recovery profile, and decreased incidence of opioid-related adverse events with increasing experience. Patients undergoing diverse surgical procedures (outpatient [n = 1340] and inpatient [n = 560]) were enrolled by investigators (n = 190) who had no previous experience with remifentanil use. Each investigator enrolled 10 patients. A standardized protocol for administration of remifentanil was used. Data were analyzed to determine differences between the first three patients and the last three patients enrolled for each anesthesiologist in the study. There were no differences in hemodynamic variables between the first triad and the last triad in either outpatients or inpatients. Requirements for hypnotic drugs and the doses of remifentanil used were also similar between groups. Analgesic medications administered at the end of surgery and in the postanesthesia care unit (PACU) were similar between groups, except that the last triad in the outpatient group received smaller doses of fentanyl compared with the first triad. Times to response to verbal command, tracheal extubation, and operating room discharge did not differ between groups. However, patients in the last triad undergoing outpatient surgery had shorter times to eligibility for PACU discharge, but times to eligibility for discharge home did not differ. The overall incidence of all adverse events (i.e., hypotension, hypertension, muscle rigidity, respiratory depression, apnea, nausea, and vomiting) was less in the last triad as compared with the first triad. When analyzed separately, only the incidence of vomiting (in the outpatient group) was decreased in the last triad as compared with the first triad. This study suggests that there is a learning curve that aids reduction of minor adverse effects associated with the use of analgesic medications administered at the end of surgery in outpatients, which might have reduced the incidence of postoperative vomiting and the duration of PACU stay. ⋯ This study demonstrated that anesthesiologists rapidly acquire the ability to use remifentanil with limited experience. However, there is a learning curve that aids reduction of minor adverse effects associated with the use of analgesic medications administered at the end of surgery in outpatients, which might have reduced the incidence of postoperative vomiting and the duration of postanesthesia care unit stay.
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Anesthesia and analgesia · Nov 2000
Comparative StudyVentricular arrhythmias with or without programmed electrical stimulation after incremental overdosage with lidocaine, bupivacaine, levobupivacaine, and ropivacaine.
It is unclear whether the mechanism of death from local anesthetic (LA) intoxication is primarily a consequence of cardiac arrhythmias or myocardial contractile depression, and whether LAs might differ in this susceptibility to these two mechanisms. By using programmable electrical stimulation (PES) protocols in anesthetized, ventilated dogs, we compared the arrhythmogenic potential of bupivacaine (BUP), ropivacaine (ROP), levobupivacaine (LBUP), and lidocaine (LIDO). Open-chest dogs were randomized to receive escalating incremental infusions of the four local anesthetics until cardiovascular collapse. We assumed a concentration relationship of 4:1 for LIDO/BUP, LBUP, and ROP. The effective refractory period did not change significantly until the dose increment corresponding to target concentrations of 8 and 32 microg/mL for BUP, LBUP, ROP, and LIDO, respectively. Thirty percent to 50% increases in effective refractory period occurred in surviving dogs at this dose. The incidence of spontaneous or PES-induced ventricular tachycardia and ventricular fibrillation did not differ among groups. Compared with LIDO, the incidence of PES-induced extrasystoles was more frequent for BUP- and LBUP-treated dogs (P: < 0.05). ROP-treated dogs did not differ from LIDO-treated dogs with respect to PES-induced extrasystoles. At the dose increment preceding cardiovascular collapse, all LAs produced significant increases in heart rate and reductions in blood pressure compared with their respective baseline values. The incidence of programmable electrical stimulation-induced ventricular tachycardia and fibrillation with BUP does not differ from the incidence that occurs with the single S:(-) enantiomers LBUP and ROP, providing further evidence against stereoselective arrhythmogenesis as a primary component of local anesthetic-induced cardiotoxicity. ⋯ Progressive bupivacaine intoxication in anesthetized, ventilated dogs does not produce early arrhythmogenic events. The incidence of programmable electrical stimulation-induced ventricular tachycardia and fibrillation with bupivacaine does not differ from the incidence that occurs with the single S:(-) enantiomers levobupivacaine and ropivacaine, providing further evidence against stereoselective arrhythmogenesis as a primary component of local anesthetic-induced cardiotoxicity.