British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of the pharmacodynamics and pharmacokinetics of an infusion of cis-atracurium (51W89) or atracurium in critically ill patients undergoing mechanical ventilation in an intensive therapy unit.
We have studied 12 critically ill, sedated patients who required a neuromuscular blocking drug to assist mechanical ventilation in an intensive care unit. Patients were randomized to receive an infusion of cis-atracurium 0.18 mg kg-1 h-1 (group 1, n = 6) or atracurium 0.6 mg kg-1 h-1 (group 2, n = 6) preceded, if necessary, by a bolus dose of 2 x ED95 of the same drug (cis-atracurium 0.1 mg kg-1 or atracurium 0.5 mg kg-1). Neuromuscular block was monitored using an accelerograph and the infusion rate adjusted regularly so that it was possible to detect the first response to train-of-four (TOF) stimulation of the ulnar nerve at the wrist. ⋯ Using the NONMEM program, a single compartment pharmacokinetic model was fitted to the plasma concentrations of cis-atracurium and the cis-cis, cis-trans and trans-trans isomers of atracurium. The mean population pharmacokinetic values for cis-atracurium were: volume of distribution (V) = 21,900 (SEM 416) ml; clearance (Cl) = 549 (79) ml min-1; half-life (T1/2) = 27.6 (3.6) min; and for the three groups of atracurium isomers were: cis-cis, V = 15,100 (720) ml, Cl = 449 (42) ml min-1, T1/2 = 23.4 (1.2) min; cis-trans, V = 18,000 (667) ml, Cl = 1070 (43) ml min-1, T1/2 = 11.7 (0.1); trans-trans, V = 13,100 (1280) ml, Cl = 1560 (55) ml min-1, T1/2 = 5.8 (0.4) min. Plasma laudanosine concentrations were lower in the cis-atracurium (peak value 1.3 micrograms ml-1) than in the atracurium (maximum 4.4 micrograms ml-1) group.
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Randomized Controlled Trial Clinical Trial
Delayed forced air warming prevents hypothermia during abdominal aortic surgery.
We have evaluated the efficacy of the delayed forced air warming during abdominal aortic surgery in 18 patients. Patients were allocated randomly to one of two groups: the control group (n = 9) received no intraoperative warming device; the Bair-Hugger group (n = 9) had active skin surface warming with an upper body cover. ⋯ In the control group, core temperature continued to decrease until the end of surgery, whereas in the Bair-Hugger group, the reduction in core temperature stopped after 1 h of warming, and then rewarming began. At the end of surgery, core temperature in the Bair-Hugger group was similar to core temperature before induction, and was higher than core temperature in the control group (P < 0.003).
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Randomized Controlled Trial Clinical Trial
Effect of isoflurane and sevoflurane on the magnitude and time course of neuromuscular block produced by vecuronium, pancuronium and atracurium.
We have compared the ability of equipotent concentrations of isoflurane and sevoflurane to enhance the effect of non-depolarizing neuromuscular blocking drugs. Ninety ASA I and II patients of both sexes, aged 18-50 yr, were stratified into three blocker groups (Vec, Pan and Atr), to undergo neuromuscular block with vecuronium (n = 30), pancuronium (n = 30) or atracurium (n = 30), respectively. Within each group, patients were allocated randomly to one of three anaesthetic subgroups to undergo maintenance of anaesthesia with: (1) alfentanil-nitrous oxide-oxygen (n = 10); (2) alfentanil-nitrous oxide-oxygen-isoflurane (n = 10); or (3) alfentanil-nitrous oxide-oxygen-sevoflurane (n = 10) anaesthesia. ⋯ In the Vec and Pan groups, a total dose of 40 micrograms kg-1 of vecuronium or pancuronium, respectively, was given, and in the Atr group a total dose of atracurium 100 micrograms kg-1. Each blocker was given in four equal doses and administered cumulatively. We showed that 0.95% isoflurane and 1.70% sevoflurane (corresponding to 0.8 MAC of each inhalation anaesthetic, omitting the MAC contribution of nitrous oxide) augmented and prolonged the neuromuscular block produced by vecuronium, pancuronium and atracurium to a similar degree.
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Case Reports
Reducing the potential morbidity of an unintentional spinal anaesthetic by aspirating cerebrospinal fluid.
We describe two cases where we attempted to reduce the adverse effects of inadvertent spinal anaesthesia by aspirating local anaesthetic-contaminated cerebrospinal fluid (CSF). Analysis of this CSF for its local anaesthetic concentration revealed that we were able to recover 51% and 39% of the administered lignocaine. It is suggested that such aspiration may be a helpful additional measure to the supportive management of this complication.
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Clinical Trial Controlled Clinical Trial
Radial artery tonometry: moderately accurate but unpredictable technique of continuous non-invasive arterial pressure measurement.
Radial artery tonometry provides continuous measurement of non-invasive arterial pressure (CNAP) by a sensor positioned above the radial artery. An inflatable upper arm cuff enables intermittent oscillometric calibration. CNAP was compared with invasive radial artery pressure recordings from the opposite wrist in 22 high-risk surgical patients with an inter-arm oscillometric mean arterial pressure difference < or = 10 mm Hg. ⋯ Individual accuracy of oscillometry was good or acceptable in all 22 patients. The trend in CNAP changes (difference between consecutive measurements) was sufficiently accurate during induction of anaesthesia, as only 47 (7.6%), 14 (2.3%) and 27 (4.4%) of 616 systolic, diastolic and mean CNAP values differed by more than 10 mm Hg of invasive pressure trends. We conclude that: intermittent oscillometry provides accurate arterial pressure monitoring; CNAP measurements offer a reliable trend indicator of pressure changes during induction of anaesthesia and may be considered an alternative to invasive pressure measurements, should arterial cannulation be difficult in an awake patient; and accuracy of absolute CNAP values is only moderate and unpredictable, thus radial artery tonometry should not replace invasive monitoring in high-risk patients during major surgical procedures.