British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Remifentanil inhibits muscular more than cutaneous pain in humans.
In experimental studies, drug-induced analgesia is usually assessed by cutaneous stimulation. If analgesics act differently on cutaneous and deep nociception, the results of these studies may not be entirely applicable to clinical pain involving deep structures. We tested the hypothesis that opioids have different abilities to inhibit cutaneous and muscular pain. ⋯ Pain thresholds were recorded. Remifentanil caused a higher increase in the muscular pain thresholds than in the cutaneous pain thresholds (P = 0.035). We conclude that opioids inhibit muscular pain more strongly than cutaneous pain in humans.
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Multicenter Study Clinical Trial
Ropivacaine pharmacokinetics after caudal block in 1-8 year old children.
We studied the pharmacokinetics after caudal block of ropivacaine (2 mg ml-1, 1 ml kg-1) performed in 20 children aged 1-8 yr undergoing subumbilical surgery, in this open, non-comparative, multicentre study. Venous blood samples were collected up to 12-36 h. The mean (SD) peak plasma concentration, 0.47 (0.16) mg litre-1, was achieved after 12-249 min. ⋯ Clearance was 7.4 (1.9) ml min-1 kg-1 and the terminal half-life 3.2 (0.8) h. Thus, the free plasma concentrations of ropivacaine were well below those associated with toxic symptoms in adults and the capacity to eliminate ropivacaine seems to be well developed in this age group. In this open study of 20 patients, ropivacaine was well tolerated and provided satisfactory postoperative pain relief without observable motor block.
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Pulmonary artery catheters are widely used in intensive care, but evidence to support their widespread use in sparse. Some published data suggest that greater mortality is associated with use of these catheters. ⋯ Using a propensity score to account for severity of illness, the odds ratio for mortality in those patients receiving a pulmonary artery catheter was 1.08 (95% confidence interval 0.87-1.33). We believe that continued use of the pulmonary artery catheter is safe; a large randomized controlled trial examining outcome is unlikely to provide an adequate answer.
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Surgical correction of craniosynostosis in infants is a very haemorrhagic procedure. The aim of this study was to determine whether the perioperative use of the continuous autotransfusion system (CATS) would reduce homologous transfusion during repair of craniosynostosis. ⋯ Use of CATS was associated with a significant decrease in the median (95% confidence interval) volume of homologous blood transfused [413 (250-540) ml in the control group versus 317 (150-410) ml in the CATS group, P = 0.02] and in the median (95% confidence interval) number of packed red cell units transfused [2 (1-2) in the control group versus 1 (1-2) in the CATS group, P = 0.04] in the perioperative period. Use of CATS is associated with a reduction in homologous transfusion during the surgical correction of craniosynostosis in infants.
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The plasma concentration of the neuromuscular blocking drug, succinylcholine, is difficult to measure. We have measured concentrations of the breakdown product of succinylcholine, choline, to assess whether choline concentration gives an accurate measure of succinylcholine concentration. Choline concentration was measured by HPLC and electrochemical detection in two blood or plasma samples, one in which succinylcholine hydrolysis was inhibited by 10(-5) M physostigmine and another in which succinylcholine was completely hydrolysed in 20 min by 200 mU butyrylcholinesterase at 37 degrees C. ⋯ Choline standard curves were linear from 156 pmol ml-1 to 200 nmol ml-1. Within-day and between-day mean coefficients of variation for succinylcholine hydrolysis were small (mean (SD) 3.7% (1.2%) and 3.8% (1.6%), respectively). We conclude that this method of measuring succinylcholine concentration in blood is accurate, repeatable and relatively easy.