Canadian journal of anaesthesia = Journal canadien d'anesthésie
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In a retrospective one-year study, we documented respiratory failure or prolonged neuromuscular blockade in eight of 65 patients with chronic renal failure who had received either vecuronium (four of 29 patients) or atracurium (four of 36 patients) during anaesthesia for kidney transplantation. We reviewed the charts of the patients and recorded all aspects of medication and anaesthesia to try to determine whether there might be a single factor associated with this high incidence (12 per cent) of respiratory failure. Anaesthesia for all patients was induced with thiopentone, isoflurane, and N2O/O2. ⋯ Neuromuscular blockade was reversed with edrophonium (0.75-1 mg.kg-1) or neostigmine (0.06-0.08 mg.kg-1). The eight patients with prolonged neuromuscular blockade received ventilatory support for one to three hours after operation. Respiratory failure was significantly more frequent in patients who received cyclosporine (P less than 0.05).
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Comparative Study
Neuromuscular and cardiovascular effects of pipecuronium.
Pipecuronium bromide (Arduan) is a bisquaternary, steroid-type neuromuscular blocking agent in clinical use in Eastern Europe. Before its introduction into clinical practice in the USA, in the first phase of this study the neuromuscular potency of pipecuronium was determined under "balanced" and enflurance anaesthesia by the cumulative log dose-response method in 30 patients each. In the second phase the intubation and onset times, clinical duration of the first and repeated doses, spontaneous recovery index, reversibility of its residual neuromuscular effect by an anticholinesterase and its effect on heart rate and blood pressure was compared with the same variables observed in patients, anaesthetized with identical techniques but who had received vecuronium or pancuronium. ⋯ Following the administration of 2 x ED95 doses there were no clinically significant differences in the intubation or onset times of pipecuronium, vecuronium and pancuronium. Under balanced anaesthesia the clinical duration of 2 x ED95 dose of pipecuronium (110.5 +/- 0.3 min) or pancuronium (115.8 +/- 8.1 min) were similar and about three times longer than that of vecuronium (36.3 +/- 2.1 min). The recovery indices of pipecuronium (44.5 +/- 8.2 min) and pancuronium (41.3 +/- 4.2 min) were also similar and about three times longer than that of vecuronium (14.3 +/- 1.4 min).(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study
Occurrence of gastroesophageal reflux on induction of anaesthesia does not correlate with the volume of gastric contents.
In an attempt to explain the discrepancy between the high number of patients said to be at risk of aspiration pneumonitis and the low reported incidence of this anaesthetic complication, 100 ASA physical status I-II elective surgical patients were studied. The volume of fluid present in the stomach at the time of induction of anaesthesia was correlated with gastroesophageal reflux (GER) detected by visual inspection of the pharynx and by continuous measurement of upper oesophageal pH. Mean gastric volume was 30 +/- 28 ml (range 0-210 ml). ⋯ No GER was detected during induction of anaesthesia in our sample of 100 patients. Furthermore, patient age, duration of preoperative fasting, body mass index, cigarette smoking, alcohol consumption, preoperative anxiety, and a history of preoperative GER were not correlated with significant modifications of gastric volume or pH. We conclude that the low incidence of aspiration pneumonitis in elective surgical patients may be explained in part by the very low risk of GER, despite gastric fluid volumes of more than 0.4 ml.kg-1 in a high proportion of this patient population.
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Case Reports
Negative pressure pulmonary oedema: a potential hazard of muscle relaxants in awake infants.
We report two cases of healthy infants who were given an IV intubating bolus of a nondepolarizing muscle relaxant (0.1 mg.kg-1 vecuronium) at the beginning of an inhalational induction of anaesthesia. Shortly after the introduction of low concentrations of gaseous agents, both infants exhibited airway obstruction although inspiratory muscle activity was still vigorous. The airway obstruction was due to approximation of the tongue to the posterior pharyngeal wall, and was easily corrected by insertion of an oral airway. ⋯ It is postulated that paralysis of glossal muscles occurred prior to diaphragmatic paralysis, creating upper airway obstruction while preserving inspiratory muscle activity. This can rapidly lead to negative pressure pulmonary oedema in the small infant. Meticulous attention to the maintenance of an unobstructed upper airway is required if muscle relaxants are administered to the awake infant.
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The changes in the arterial to end-tidal carbon dioxide gradient. P(a-ET)CO2, were studied in postoperative cardiac surgery patients from the time of admission to the intensive care unit, during changing cardiorespiratory support, up to the time of tracheal extubation. Individual factors evaluated for their effects on P(a-ET)CO2 included rate of mechanical ventilation, infusion of vasoactive agents (nitroglycerin, nitroprusside, dopamine, dobutamine, and metariminol), and associated changes in haemodynamic pathophysiology (cardiac index, pulmonary artery pressure, pulmonary vascular resistance index, systemic vascular resistance index, and pulmonary capillary wedge pressure). ⋯ For many of the individual patients, however, the relationship between PaCO2 and ETCO2 did not maintain a significant correlation throughout the study period. In the postoperative cardiac surgery patient population P(a-ET)CO2 follows a normal distribution and PaCO2 and ETCO2 maintain a statistically significant correlation. However, when evaluating individual patients, this relationship has wide variability.