Cumulation and reversal with prolonged infusions of atracurium and vecuronium.

A randomized, double-blind study was undertaken to compare the tendencies for cumulation, and reversal characteristics of atracurium (ATR) and vecuronium (VEC) when administered by continuous infusion for long surgical procedures under balanced anaesthesia. Eligible subjects were between 50 and 75 yr of age and were free of neuromuscular disease. Patients in the ATR group (n = 25) received a loading dose of atracurium 0.25 mg.kg-1, followed by an infusion initially set at 5.0 micrograms.kg-1.min-1. In the VEC group (n = 25) patients received a loading dose of vecuronium 0.05 mg.kg-1, followed by an infusion at 1.0 microgram.kg-1.min-1. During surgery, the infusions of both ATR and VEC were titrated in increments or decrements of 12.5% to maintain first twitch (T1) suppression of 90-95%. Neuromuscular block was measured by recording the integrated evoked electromyographic response (EMG) of the first dorsal interosseous muscle in response to supramaximal TOF stimuli on the ulnar nerve. The durations of infusion were similar for the two groups (164 +/- 42 and 183 +/- 67 min for ATR and VEC, respectively). The infusion rates of ATR (mean +/- SD) remained between 4.0 +/- 0.7 and 5.0 +/- 1.0 microgram.kg-1.min-1 throughout the study period. In contrast, a progressive decrease (P less than 0.05) in the infusion rate of VEC, from 1.0 to 0.47 +/- 0.13 micrograms.kg-1.min-1, was observed during the study period. The number of adjustments required to maintain 90-95% T1 suppression decreased between the second and fourth hours of administration, but were similar at corresponding times when comparing the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Obstetrical anaesthesia and analgesia in chronic spinal cord-injured women.

Improved acute and rehabilitative care and emphasis on integrating patients into society after spinal cord injury is likely to result in increasing numbers of cord-injured women presenting for obstetrical care. Anaesthetists providing care to these women should be familiar with the complications resulting from chronic cord injury and aware that many may be aggravated by the physiological changes of normal pregnancy. These complications include reduced respiratory volumes and reserve, decreased blood pressure and an increased incidence of thromboembolic phenomena, anaemia and recurrent urinary tract infections. Patients with cord lesions above the T5 spinal level are at risk for the life-threatening complication of autonomic hyperreflexia (AH) which results from the loss of central regulation of the sympathetic nervous system below the level of the lesion. Sympathetic hyperactivity and hypertension result in response to noxious stimuli entering the cord below the level of the lesion. Labour appears to be a particularly noxious stimulus and patients with injuries above T5 are at risk for AH during labour even if they have not had previous AH episodes. Morbidity is related to the degree of hypertension and intracranial haemorrhage has been reported during labour and attributed to AH. We report our experience in providing care to three parturients with spinal cord injuries. Two patients had high cervical lesions, one of whom experienced AH during labour and was treated with an epidural block. The second was at risk for AH having had episodes in the past and received an epidural block to provide prophylaxis for AH. In both cases epidural blockade provided effective treatment and prophylaxis for AH.(ABSTRACT TRUNCATED AT 250 WORDS)