Change in anaesthesia practice and postoperative sedation shortens ICU and hospital length of stay following coronary artery bypass surgery.

We randomized prospectively 144 patients, undergoing elective coronary artery bypass surgery, to either early or to routine extubation [mechanical ventilatory support for 4-7 h (Group A), or 8-14 h (Group B)]. Anaesthesia was modified for both groups. The groups were well matched in terms of sex, age, NYHA class, preoperative left ventricular ejection fraction, bypass time and aortic cross-clamp time, number of grafts used, and blood units transfused. All patients had normal preoperative respiratory, renal, hepatic and cerebral functions. Mechanical ventilatory support (mean +/- SD) was 6.3 +/- 0.7 h for Group A and 11.6 +/- 1.3 h for Group B. Mean ICU stay was 17 +/- 1.3 h for Group A and 22 +/- 1.2 h for Group B, while the mean hospital stay was 7.3 +/- 0.8 days and 8.4 +/- 0.9, respectively. There were no statistically significant differences in the frequency of all postoperative complications among the two groups. There were no reintubation, readmission to the ICU or death in either group. We concluded that change in anaesthesia practice and early postoperative sedation in patients undergoing elective coronary artery bypass graft (CABG) surgery resulted in earlier tracheal extubation, shorter ICU and hospital length of stay without organ dysfunction or postoperative complications. Early extubation was only possible due to the modification of anaesthesia and ICU sedation regime.

Dose-response curves for edrophonium, neostigmine, and pyridostigmine after pancuronium and d-tubocurarine.

To determine the potencies of neostigmine, pyridostigmine, and edrophonium in reversing pancuronium and d-tubocurarine blockade, dose-response curves were established for first twitch height recovery and train-of-four ratio. One hundred and twenty ASA physical status I or II patients scheduled for elective surgery received either 0.06 mg/kg pancuronium or 0.36 mg/kg d-tubocurarine during a thiopental-nitrous oxide-enflurane anesthetic. Train-of-four stimulation was applied every 12 s, and the force of contraction of the adductor pollicis muscle was recorded. When first twitch height had recovered spontaneously to 10% of its initial value, neostigmine (0.005, 0.01, 0.02 or 0.05 mg/kg), pyridostigmine (0.02, 0.04, 0.1, or 0.2 mg/kg), or edrophonium (0.1, 0.2, 0.4 or 1 mg/kg) was injected by random allocation. Recovery was measured 10 min after the injection of the antagonist. First twitch ED50's were 0.013, 0.085, and 0.17 mg/kg after pancuronium, and 0.017, 0.11, and 0.27 mg/kg after d-tubocurarine, for neostigmine, pyridostigmine, and edrophonium, respectively. The ED50 for pyridostigmine and edrophonium obtained after d-tubocurarine was significantly larger (P less than 0.05) than that after pancuronium. The train-of-four dose-response curves were significantly flatter for edrophonium than for the other two agents, indicating a greater ability of edrophonium to antagonize fade at low doses. It is concluded that the potency of reversal agents may be different for different relaxants, and that potency ratios might depend upon the end-point chosen as full neuromuscular recovery.

Potency of pancuronium at the diaphragm and the adductor pollicis muscle in humans.

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. The force of contraction of the adductor pollicis muscle was measured with a force-displacement transducer and compared with the diaphragmatic electromyogram (EMG). Pancuronium cumulative dose-response curves for both muscles were determined in 10 ASA Class I adults. The mean dose (+/- SEM) required to depress adductor pollicis and diaphragm responses to first twitch stimulation (ED50) was 29.5 +/- 3.5 micrograms/kg and 59.5 +/- 7.0 micrograms/kg, respectively. 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.