Anesthesiology
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Comparative Study
Amide local anesthetic alterations of effective refractory period temporal dispersion: relationship to ventricular arrhythmias.
The hemodynamic and electrophysiologic effects of bupivacaine, etidocaine, mepivacaine, and lidocaine were investigated in 32 pentobarbital-anesthetized adult mongrel dogs. Following equipotent dosing, all four agents produced similar hemodynamic effects: decrease in stroke volume and cardiac output, heart rate slowing, increase in systemic vascular resistance, and increases in pulmonary arterial pressure (PAP) and pulmonary capillary wedge pressure (PCWP). The effects of the various agents on the ECG were different. ⋯ Six of seven bupivacaine, six of seven etidocaine, two of eight mepivacaine, and none of eight lidocaine animals sustained a polymorphic, undulating ventricular tachycardia similar to Torsades de Pointes following burst ventricular pacing. The results of this study suggest that bupivacaine, etidocaine, and occasionally mepivacaine can result in a Torsades de Pointes-like syndrome following intravenous administration. The magnitude of ERP temporal dispersion differences between the various agents appears to explain their differential arrhythmogenicity.
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This study was designed to determine the nephrotoxic potential of prolonged anesthesia with enflurane or isoflurane in obese and nonobese Fischer 344 rats. Weight-paired rats received either a regular chow diet or Potter's high fat diet for 16 weeks. The chow-fed (nonobese) rats gained 20% in body weight compared with 45% for the Potter's-fed (obese) rats. ⋯ Exposure of nine pairs of rats to 1.4% isoflurane for 4 h produced significantly elevated peak serum F-levels (27 +/- 8 microM vs. 9 +/- 0.4 microM; P less than 0.001) in obese compared with nonobese rats and subclinical nephrotoxicity in obese rats manifested by significantly decreased creatinine and urea nitrogen clearances, but without polyuria. This study suggest that obese patients may be at risk of developing F(-)-induced nephrotoxicity following prolonged enflurane anesthesia. Isoflurane may have significant potential for subclinical F(-)-induced nephrotoxicity in obese patients, to a degree that might affect renal clearance of some drugs in the postoperative period.