British journal of anaesthesia
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This study investigated the possible analgesic effect of midazolam as a result of interruption of those spinal cord pathways taken by pain afferents. Experiments were performed on 15 male Wistar rats with chronically implanted lumbar subarachnoid catheters. ⋯ We also performed experiments on frog sciatic nerves which showed that midazolam did not have a local anaesthetic action. We conclude that intrathecal midazolam causes spinally-mediated analgesia by binding to benzodiazepine receptors in the spinal cord.
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Randomized Controlled Trial Comparative Study Clinical Trial
Intrathecal sufentanil as a supplement to subarachnoid anaesthesia with lignocaine.
The combination of low-dose sufentanil with lignocaine for subarachnoid anaesthesia was studied in a double-blind comparative trial in 40 urological patients. Patients were allocated randomly to two groups and received 5% heavy lignocaine 1.5 ml together with either 1.5 ml of sufentanil 5 micrograms ml-1, or physiological saline 1.5 ml. ⋯ There was no significant difference in the number of patients requiring supplementary analgesics. Side-effects were similar in both groups.
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The influence of fresh gas flow (FGF) setting on rebreathing was investigated in 15 infants and children (weight 3.5-21.8 kg) during balanced anaesthesia with mechanically controlled ventilation using a T-piece (Mapleson E) system and a Nuffield ventilator 200. Tidal volume (VT), minute volume (VE), maximal inspired (PICO2) and end-tidal (PE'CO2) carbon dioxide tensions and airway pressure were measured. VE, set to produce a PE'CO2 of about 4.5 kPa and measured at a high FGF (minimal rebreathing), was unchanged throughout the study and the regression equation for VE and weight was: VE (ml min-1) = 146 x kg + 482, r = 0.92. ⋯ At FGF:VE ratios equal to 1.0, alveolar rebreathing was more pronounced and hypercapnoea occurred with a PE'CO2 (mean +/- 1 SD) of 5.89 +/- 0.53 kPa. At this FGF setting, change in I:E ratio from 1:2 to 1:1 did not influence the level of alveolar rebreathing. A minimal FGF (ml min-1) setting of 1.5 x VE (that is, 1.5 (146 x kg + 482), approximated to the expression (200 x kg + 1000) is recommended for controlled ventilation to avoid hypercapnoea when using the T-piece system in children weighing less than 20 kg.
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Somatosensory evoked responses after median nerve stimulation were recorded in 21 patients during hypothermic cardiopulmonary bypass. During hypothermia a significant linear correlation (P less than 0.001) was found between evoked potential latency and temperature. Correlation was best for tympanic membrane temperature during cooling and for perfusate temperature (arterial, venous) during rewarming. ⋯ The slopes of the regression lines were different during cooling and rewarming, when latencies were related to patient (tympanic, nasopharyngeal, rectal) temperature, but identical when arterial or venous blood temperature was used as the reference. No correlation was found between latency and perfusion pressure. We conclude that sophisticated temperature measurement is required to aid the interpretation of evoked responses used during hypothermia.
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Randomized Controlled Trial Clinical Trial
Extradural bupivacaine with sufentanil for vaginal delivery. A double-blind trial.
The combination of sufentanil with bupivacaine plus adrenaline given extradurally for pain relief during labour was studied in a double-blind trial. One hundred and twenty patients were randomly divided into three groups and received a 10-ml extradural injection of sufentanil 15 micrograms + bupivacaine 12.5 mg + adrenaline 12.5 micrograms, sufentanil 7.5 micrograms + bupivacaine 12.5 mg + adrenaline 12.5 micrograms, or bupivacaine 12.5 mg + adrenaline 12.5 micrograms (control group). A second injection, which was given upon request, was identical to the first. ⋯ Moreover, the quality of analgesia was better and less bupivacaine was required, resulting in less motor blockade at delivery. There were no differences between the three groups in regard to Apgar scores. The only side effect of sufentanil was pruritus.