Patient-controlled analgesia using remifentanil in the parturient with thrombocytopaenia.

Patient-controlled intravenous remifentanil was used to provide analgesia in labour for three thrombocytopaenic women. The most successful regimen comprised a patient-demand bolus of 0.5 microg x kg(-1) with a lockout period of 2-3 min, allowing for a successful demand with each contraction. There was an initial period during which the patient learned to anticipate the next contraction and to deliver a bolus about 30 s beforehand; subsequently the remifentanil provided excellent analgesia, with a range of consumption of 426-1050 microg x h(-1). Apart from one episode of maternal sedation and fetal heart rate decelerations resulting from an excessive demand bolus, mothers and neonates tolerated the remifentanil without sequelae. Owing to rapid metabolism by tissue esterase, the use of remifentanil allows adequate doses of opioid to be administered to the mother to achieve good analgesia, without its accumulation in the fetus.