British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Quantitative and selective assessment of sensory block during lumbar epidural anaesthesia with 1% or 2% lidocaine.
We have examined sensory block during lumbar epidural anaesthesia using a cutaneous current perception threshold (CPT) sensory testing device in 20 patients who received 10 ml of either 1% or 2% lidocaine (lignocaine). CPT at 2000, 250 and 5 Hz stimulation at the trigeminal (V), ninth thoracic (T9) and second lumbar (L2) dermatomes, and dermatomal levels of block to light touch, temperature and pinprick discrimination were measured before and every 5 min until 60 min after epidural lidocaine. There were significant differences between 1% and 2% epidural lidocaine in all CPT at T9 and L2, in addition to maximal cephalad spread of the three sensory modalities. ⋯ Maximal level of loss of touch sensation after 1% lidocaine was significantly lower than that of cold and pinprick sensations. We conclude that the dose of lidocaine affected intensity of sensory block during lumbar epidural anaesthesia. In addition, differential neural block resulting from epidural anaesthesia appeared to be associated with a differential effect on nerve fibres of different sizes.
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Airway closure and the formation of atelectasis have been proposed as important contributors to impairment of gas exchange during general anaesthesia. We have elucidated the relationships between each of these two mechanisms and gas exchange. We studied 35 adults with healthy lungs, undergoing elective surgery. ⋯ There was no significant correlation between CV-ERV and atelectasis. We conclude that in anaesthetized adults with healthy lungs, undergoing mechanical ventilation, both airway closure and atelectasis contributed to impairment of gas exchange. Atelectasis and airway closure do not seem to be closely related.
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Randomized Controlled Trial Comparative Study Clinical Trial
Effect of i.v. ketamine in combination with epidural bupivacaine or epidural morphine on postoperative pain and wound tenderness after renal surgery.
We studied 60 patients undergoing operation on the kidney with combined general and epidural anaesthesia, in a double-blind, randomized, controlled study. Patients were allocated to receive a preoperative bolus dose of ketamine 10 mg i.v., followed by an i.v. infusion of ketamine 10 mg h-1 for 48 h after operation, or placebo. During the first 24 h after surgery, all patients received 4 ml h-1 of epidural bupivacaine 2.5 mg ml-1. ⋯ There were no significant differences in pain (VAS) at rest, during mobilization or cough, PCA morphine consumption, sensory block to pinprick, pressure pain detection threshold assessed with an algometer, touch and pain detection thresholds assessed with von Frey hairs, peak flow or side effects other than sedation. The power of detecting a reduction in VAS scores of 20 mm in our study was 80% at the 5% significance level. We conclude that we were unable to demonstrate an (additive) analgesic or opioid sparing effect of ketamine 10 mg h-1 i.v. combined with epidural bupivacaine at 0-24 h, or epidural morphine at 24-48 h after renal surgery.
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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of the analgesic potency of xenon and nitrous oxide in humans evaluated by experimental pain.
We have compared the analgesic potency of MAC-equivalent concentrations of xenon (10, 20, 30 and 40%) and nitrous oxide (15, 30, 45 and 60%) in humans using a multimodal experimental pain testing and assessment technique. We tested 12 healthy volunteers in a randomized, single-blind, crossover study. The following experimental pain tests were used: nociceptive reflex to repeated stimuli; pain tolerance to maximal effort tourniquet ischaemia; electrical stimulation; mechanical pressure; and cold. ⋯ There was no difference in MAC-equivalent concentrations of xenon and nitrous oxide. Both increased reaction time in a similar manner. Xenon and nitrous oxide evoked nausea and vomiting in a large number of volunteers.
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Randomized Controlled Trial Clinical Trial Controlled Clinical Trial
Evaluation of routine tracheal extubation in children: inflating or suctioning technique?
We studied prospectively the effects of the technique of tracheal extubation on arterial haemoglobin oxygen saturation (SpO2) in 120 ASA I-III children, mean age 5.3 (range 0.25-16.9) yr. At completion of surgery, tracheal extubation was performed when spontaneous ventilation had resumed, children were fully awake and SpO2 was 99-100%. Children were allocated randomly to receive a single lung inflation manoeuvre with 100% oxygen before tracheal extubation (group I; n = 59) or to have the tracheal tube removed while applying suction through the tube (group S; n = 61). ⋯ We conclude that tracheal extubation greatly impaired oxygenation and therefore administration of oxygen was appropriate. This impairment was more marked when suction was used, and in young children. Lung inflation with 100% oxygen before removal of the tracheal tube is advised before routine tracheal extubation in children.