Anesthesia and analgesia
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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.
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Anesthesia and analgesia · Sep 1989
Hemodynamic and central nervous system effects of intravenous bolus doses of lidocaine, bupivacaine, and ropivacaine in sheep.
Lidocaine hydrochloride (HCl) (80-320 mg), bupivacaine HCl (20-80 mg), and ropivacaine HCl (30-120 mg) were administered as intravenous bolus doses to conscious sheep (n = 18; average body weight 45 kg) that had previously placed intravascular cannulae for hemodynamic monitoring and for obtaining blood samples. The mean convulsive doses and arterial blood concentrations were approximately 110 mg and 40 mg/L, respectively, for lidocaine HCl, 45 mg and 14 mg/L for bupivacaine HCl, and 60 mg and 20 mg/L for ropivacaine HCl. ⋯ Ventricular fibrillation caused death in two sheep after bupivacaine (80 mg) and in two sheep after ropivacaine (90 and 120 mg) administration. With sublethal doses, the hemodynamic responses to these agents were qualitatively and quantitatively similar when compared with their local anesthetic potencies.
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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
Nitrogen-sparing effect of epidural administration of local anesthetics in colon surgery.
A nitrogen-sparing effect of epidural anesthesia has been clearly demonstrated in gynecological and lower abdominal surgery. To determine if epidural anesthesia also has a protein-sparing effect during major upper or mid-abdominal surgery, postoperative nitrogen balance and 3-methylhistidine urinary excretion (an index of skeletal muscle protein catabolism) were measured for 6 days in 28 patients who had undergone colon resection for cancer with general anesthesia (N2O-O2-1% enflurane) either supplemented with low dose fentanyl plus intermittent systemic pentazocine for postoperative pain (n = 13), or the same general anesthetic plus epidural injection of either etidocaine 1% intraoperatively and bupivacaine 0.25% postoperatively (n = 8) or meperidine (n = 7) for 48 hr after skin incision. ⋯ There was a significant correlation between the daily urinary excretion of 3-methylhistidine and the daily nitrogen balance in the three groups. This study suggests that in colon surgery, epidural analgesia with local anesthetics in the postoperative period improves nitrogen balance and this effect takes place partly in the muscle.
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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)