Abstract
A mixture of 50% nitrous oxide and 50% oxygen was compared with methoxyflurane (Penthrane) in analgesic concentrations during labour. Both drugs were self-administered, nitrous oxide by demand flow through face masks, and methoxyflurane through a spscial inhaler (Analgizer). The patients used both drugs in succession, with an interval of one labour pain between the two drugs, and were then asked which drug they preferred. The order in which the drugs were given, was decided at random.
Of 63 patients significantly more chose nitrous oxide than methoxyflurane. Both drugs gave excellent or good analgesia in 92% of the cases. Side effects in the mother were in the same order of magnitude for the two drugs. No adverse effects could be detected in the children, by clinical examination. The more frequent choice of nitrous oxide is likely to be due to the differences in the inhalation procedure for the two drugs in this trial, rather than to their analgesic properties. Both can be recommended for pain relief during labour.