Anaesthesia
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Randomized Controlled Trial Comparative Study Clinical Trial
Epidural fentanyl in labour. An evaluation of the systemic contribution to analgesia.
In a randomized double-blind trial in the first stage of labour, 20 patients given fentanyl 80 micrograms in the epidural test dose of bupivacaine, were compared with 20 patients receiving an intravenous infusion designed to produce comparable plasma fentanyl concentrations, at the same time as their epidural test dose. Despite slightly higher plasma fentanyl concentrations in the intravenous fentanyl group, epidural fentanyl produced analgesia which was more complete, more rapid in onset and slightly longer lasting. Supplementary doses of bupivacaine were needed to produce analgesia in 75% of the intravenous and 30% of the epidural fentanyl group. It is clear that epidural fentanyl produces satisfactory pain relief when added to the epidural test dose, but that the presence of fentanyl in the systemic circulation makes a negligible contribution to analgesia.
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Comparative Study
The haemodynamic effects of intravenous induction. Comparison of the effects of thiopentone and propofol.
The haemodynamic changes following induction of anaesthesia with equipotent doses of propofol and thiopentone have been compared. Propofol caused a significant fall in arterial blood pressure and total peripheral resistance, with a slight fall in cardiac output. ⋯ Apart from an initial, but statistically insignificant increase in heart rate, similar changes were produced by thiopentone, but to a lesser degree. It is concluded that induction of anaesthesia with propofol results in acceptable haemodynamic changes, but that the agent is more depressant to the cardiovascular system than thiopentone.
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The action of midazolam is influenced by serum protein binding as seen in the relationship between the time of onset of action of a fixed dose of the drug and the plasma albumin. Pretreatment with intravenous aspirin produces a decrease in the in vitro binding of midazolam. ⋯ Probenecid pretreatment will also cause a decrease in the onset time of midazolam. However, this is not due to altered plasma protein binding of the sedative.