Canadian journal of anaesthesia = Journal canadien d'anesthésie
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Venous air embolism is a well-recognized complication of central venous catheterization. Although previous reports have documented venous air embolism occurring in a number of ways, including during initial catheterization, when catheters crack or are disconnected, and after catheter removal, no reports mention the possibility of air embolism occurring when a guide wire without a catheter was in place. ⋯ It is postulated that a previously described gasp reflex or some sort of sustained negative pressure manoeuvre caused venous air embolism around the guide wire and accounted for the patient's signs and symptoms. During central venous catheter placement, a high index of suspicion for venous air embolism should be maintained, pulse oximetry should be used, the skin entrance site should be kept covered by an occlusive dressing, and the patient should be positioned head-down.
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Randomized Controlled Trial Clinical Trial
Tussive effect of a fentanyl bolus.
The aim of this study was to investigate the incidence of pre-induction coughing, after an iv bolus of fentanyl. The study sample was 250 ASA physical status I-II patients, scheduled for various elective surgical procedures. The first 100 were randomly allocated to receive 1.5 micrograms.kg-1 fentanyl via a peripheral venous cannula (Group 1), or an equivalent volume of saline (Group 2). ⋯ Fentanyl, when given through a peripheral cannula, provoked cough in a considerable proportion of patients. This was not altered by premedication with atropine or midazolam, but was reduced after morphine (P less than 0.01). Coughing upon induction of anaesthesia is undesirable in some patients, and stimulation of cough by fentanyl in unpremedicated patients may be of clinical importance.
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Comparative Study
Comparison of integrated evoked EMG between the hypothenar and facial muscle groups following atracurium and vecuronium administration.
In 17 healthy patients undergoing O2. N2O.isoflurane anaesthesia, following atracurium or vecuronium administration, we compared simultaneous integrated evoked electromyograms (IEEMGs) during spontaneous recovery of the adductor digiti minimi (ADM) and orbicularis oris (OOM) muscle groups in response to train-of-four (TOF) stimulation of the ulnar and facial nerves, respectively. ⋯ When the OOM attained a T4/T1 = 0.70 +/- 0.01, the simultaneous T4/T1 in the ADM was 0.29 +/- 0.15 (P less than 0.05) in the atracurium group and 0.41 +/- 0.16 (P less than 0.01) in the vecuronium group. We conclude that (1) the facial muscles (OOM) recover earlier than the hypothenar muscles (ADM) and (2) an EMG T4/T1 = 0.70 in the facial muscles may not indicate adequate recovery of neuromuscular function.
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Comparative Study
Time-cycled inverse ratio ventilation does not improve gas exchange during anaesthesia.
Inverse ratio ventilation (IRV) has been reported to improve oxygenation at lower peak airway pressures in patients with respiratory failure. Therefore we hypothesised that IRV might also improve oxygen exchange during anaesthesia. Conventional ratio ventilation (CRV) and IRV were compared in 24 low-risk surgical patients who were paralysed and whose lungs were ventilated with air/O2 by a non-rebreathing circuit and a Siemens 900-C servo ventilator. ⋯ Multivariate models were tested to identify variables which predicted O2 exchange during CRV. Patient age was the only predictor consistently significant in all models. We conclude that age is an important determinant of impaired pulmonary oxygen exchange during anaesthesia, and that increasing mean AWP by TC-IRV has no beneficial effects on pulmonary mechanics or gas exchange.
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This study examined the effect of flumazenil, a benzodiazepine antagonist, on aqueous humour pressure in dogs receiving either midazolam or no benzodiazepine. Twenty-four halothane-anaesthetized dogs were assigned to one of four groups. Group I (n = 6) received saline iv at 0, 45 and 90 min. ⋯ In Groups 3 and 4, midazolam decreased aqueous humour pressure from 18 +/- 2 mmHg (mean +/- SD) to 14 +/- 3 mmHg (P less than 0.001) and from 34 +/- 5 mmHg to 31 +/- 3 mmHg (P less than 0.01) respectively. Flumazenil given during continuous infusion of midazolam produced increases of aqueous humour pressure of 2 +/- 1 (P less than 0.01) to 5 +/- 2 mmHg (P less than 0.01) that lasted less than or equal to 12 min. It is concluded that at both normal and elevated aqueous humour pressures flumazenil produces statistically significant but clinically unimportant increases of aqueous humour pressure in anaesthetized dogs receiving midazolam, but not in dogs given no benzodiazepine.