Anesthesiology
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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.
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The measurement of force of contraction of the adductor pollicis muscle following supramaximal stimulation of the ulnar nerve has become a standard method to assess the effect of neuromuscular blocking drugs. However, the diaphragm is regarded as resistant to these drugs, and considerable residual respiratory power might still be present after total block of adductor pollicis function. To quantify this differential effect, train-of-four stimulation was applied to the ulnar and the phrenic nerves in patients under N2O-halothane anesthesia. ⋯ Corresponding values for ED90 were 45 +/- 5 micrograms/kg and 95 +/- 11 micrograms/kg, respectively, indicating that the diaphragm required approximately twice as much pancuronium as the adductor pollicis block, the diaphragm was only 24 +/- 4% blocked. It is concluded that the adductor pollicis response might underestimate the degree of diaphragmatic relaxation. On the other hand, the administration of pancuronium in a dose sufficient to produce total paralysis might result in the inability to antagonize neuromuscular block in all muscles.