title: Self-administered mixture of Entonox and isoflurane in labour.
abstract: Entonox (50% nitrous oxide premixed in oxygen) was compared with a mixture of Entonox and approximately 0.25% isoflurane (Entonox-isoflurane) for pain relief in the first stage of labour in 39 mothers. An Oxford Miniature Vaporizer was incorporated as the draw-over vaporizer for adding isoflurane to Entonox. The mixture was self-administered via the Entonox on-demand valve. The two mixtures were given in random sequence for five consecutive contractions of labour to each patient. Linear analogue pain relief scores were significantly higher (P=0.001) with Entonox-isoflurane. Fourteen patients continued using Entonox-isoflurane until delivery. No adverse effect from prolonged use was noted. Entonox-isoflurane is considered worthy of further investigation.
authors.affiliation: Department of Anaesthetics, Aberdeen Royal Infirmary, Foresterhill, Aberdeen, UK.
authors.forename: S
authors.initials: S
authors.lastname: Arora
authors.forename: M
authors.initials: M
authors.lastname: Tunstall
authors.forename: J
authors.initials: J
authors.lastname: Ross