British journal of anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Peripheral lidocaine but not ketamine inhibits capsaicin-induced hyperalgesia in humans.
We examined the effect of the subcutaneous infiltration of ketamine, lidocaine and saline before injury on capsaicin-induced pain and hyperalgesia. Twelve healthy volunteers participated in two separate, randomized, double-blind, placebo-controlled crossover experiments. In experiment 1, 100 micrograms capsaicin was injected intradermally in one volar forearm 10 min after the skin had been pretreated with lidocaine 20.0 mg in 2.0 ml or 0.9% saline 2.0 ml at the capsaicin injection site. ⋯ Pain scores and areas of hyperalgesia were not affected when the contralateral site was infiltrated with ketamine or lidocaine. Lidocaine produced no side-effects, whereas ketamine produced paraesthesia, dizziness and sleepiness in six out of 24 (25%) cases. Blocking peripheral sodium channels with locally administered lidocaine reduces spontaneous pain and capsaicin-induced hyperalgesia but local block with the NMDA-type glutamate receptor antagonist ketamine has no effect on capsaicin-induced pain and hyperalgesia.
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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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Randomized Controlled Trial Comparative Study Clinical Trial
Comparison of intubating conditions following propofol and succinylcholine with propofol and remifentanil 2 micrograms kg-1 or 4 micrograms kg-1.
We evaluated the intubating conditions, haemodynamic responses and duration of apnoea in 60 healthy adult patients after propofol 2 mg kg-1 combined with either a bolus of remifentanil 2 micrograms kg-1 or 4 micrograms kg-1, or succinylcholine 1 mg kg-1. Patients intubated following remifentanil showed dose-dependent intubating conditions, similar at 4 micrograms kg-1 to the conditions produced with succinylcholine. Post-induction mean arterial pressure decreased from baseline values by 21% (P < 0.0001), 28% (P < 0.0001) and 8% (P > 0.05) in the remifentanil 2 micrograms kg-1, remifentanil 4 micrograms kg-1 and succinylcholine 1 mg kg-1 groups, respectively. The mean (SD) duration of apnoea following induction was 9.3 (2.6) min and 12.8 (2.9) min in the remifentanil 2 micrograms kg-1 and 4 micrograms kg-1 groups, and 6.0 (0.9) min in the succinylcholine group (P < 0.001 between groups).
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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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The lower inflection point (LIP) of the inspiratory limb of a static pressure-volume (PV) loop is assumed to indicate the pressure at which most lung units are recruited. The LIP is determined by a static manoeuvre with a PV-history that is different from the PV-history of the actual ventilation. ⋯ Volume-dependent dynamic compliance suggested a PEEP reduction (to 15 (13-18) cm H2O). Pulmonary gas exchange remained satisfactory and this change resulted in reduced mechanical stress on the respiratory system, indirectly indicated by volume-dependent compliance being consistently great during the entire inspiration.