Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1989
Comparative StudyTime-courses of zones of differential sensory blockade during spinal anesthesia with hyperbaric tetracaine or bupivacaine.
The purposes of this study were twofold: to compare bupivacaine and tetracaine spinal anesthesia with regard to the zones of differential sensory blockade and to evaluate the time-courses of the widths of the zones of differential sensory blockade during spinal anesthesia. In 51 patients, the most rostral levels of sensory denervation to light touch, pinprick, and temperature discrimination were measured. There was no statistically significant difference in the height of sensory blockade in the 29 patients given bupivacaine and in the 22 patients given equipotent doses of tetracaine. ⋯ The width of the zones of differential blockade also remained unchanged within each group during onset, maintenance, and regression of anesthesia. Changes in, and absolute levels of, blood pressure and heart rate were similar with both bupivacaine and tetracaine throughout. We conclude that zones of differential sensory blockade are essentially the same with tetracaine and bupivacaine, that the widths of the zones of differential sensory blockade remain constant during onset, maintenance, and offset of spinal anesthesia, and that bupivacaine and tetracaine are associated with similar changes in heart rate and blood pressure during spinal anesthesia.
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Anesthesia and analgesia · Sep 1989
Randomized Controlled Trial Clinical TrialA cost/benefit analysis of randomized invasive monitoring for patients undergoing cardiac surgery.
The aim of this study was to determine the effect of choice of invasive monitoring on cost, morbidity, and mortality in cardiac surgery. Two hundred and twenty-six adults undergoing elective cardiac surgery were initially assigned at random to receive either a central venous pressure monitoring catheter (group I), a conventional pulmonary artery (PA) catheter (group II), or a mixed venous oxygen saturation (SvO2) measuring PA catheter (group III). If the attending anesthesiologist believed that the patient initially randomized to group I should have a PA catheter, that patient was then reassigned to receive either a conventional PA catheter (group IV) or SvO2 measuring PA catheter (group V). ⋯ Further, mean monitoring and laboratory costs in Group II were statistically significantly (P less than 0.05) less than those in Group III ($1128 +/- 759). Patients in group IV incurred mean total costs of $986 +/- 578, while those in group V had mean total costs of $1126 +/- 382 (NS). There were no significant differences between any of the groups with respect to length of stay in the intensive care unit, morbidity, or mortality.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Sep 1989
Randomized Controlled Trial Comparative Study Clinical TrialEffects of thoracic epidural anesthesia on systemic hemodynamic function and systemic oxygen supply-demand relationship.
The effects of thoracic epidural anesthesia (TEA) on total body oxygen supply-demand ratio are complex due to potential influences on both O2 delivery (QO2) and consumption (VO2). One hundred and five patients undergoing abdominal aortic surgery were randomly assigned to one of three groups to compare the cardiovascular and metabolic responses associated with (1) thoracic epidural anesthesia plus light general anesthesia (group TEA); (2) general anesthesia with halothane (group H); and (3) neuroleptanalgesia (group NLA). Values of cardiac index (CI) and QO2 were less intraoperatively in the TEA group than in the H or NLA groups, while VO2 values were similar. ⋯ Heart rate was slowest intraoperatively during TEA, and stroke work was less with TEA than with NLA. As cardiac filling pressure and systemic vascular resistance did not differ among the three groups, reduced adaptation of CI to tissue O2 needs during TEA was attributed to negative inotropic and chronotropic effects of the sympathetic blockade. We conclude that in patients undergoing abdominal aortic surgery, TEA has no apparent advantage over general anesthesia.
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Anesthesia and analgesia · Sep 1989
Myocardial and cerebral drug concentrations and the mechanisms of death after fatal intravenous doses of lidocaine, bupivacaine, and ropivacaine in the sheep.
This paper reports the cardiovascular effects of intentionally toxic intravenous doses of lidocaine, bupivacaine, and ropivacaine and the mechanisms of death. Fatal doses of lidocaine, bupivacaine, and ropivacaine were established in sheep treated with successive daily dose increments of each drug. The mean fatal dose of lidocaine (+/- SD) was 1450 +/- 191 mg (30.8 +/- 5.8 mg/kg), that of bupivacaine was 156 +/- 31 mg (3.7 +/- 1.1 mg/kg), and that of ropivacaine was 325 +/- 108 mg (7.3 +/- 1.0 mg/kg); thus the ratio of fatal doses was approximately 9:1:2. ⋯ Three out of five animals given ropivacaine died in a manner resembling the fatal effects of lidocaine-treated animals, but unlike the lidocaine-treated animals, in all three sheep there were also periods of ventricular arrhythmias. The remaining two ropivacaine-treated sheep died as a result of the sudden onset of ventricular tachycardia/fibrillation. The mean percentages of the fatal dose found in the myocardium was 2.8 +/- 0.7 for lidocaine-treated animals, 3.3 +/- 0.9 for bupivacaine-treated animals, and 2.2 +/- 1.4 for ropivacaine-treated animals; the corresponding percentages in whole brain were, respectively, 0.71 +/- 0.01, 0.71 +/- 0.21, and 0.89 +/- 0.27.