Maternal and fetal effects of intravenous patient-controlled fentanyl analgesia during labour in a thrombocytopenic parturient

The use of intravenous (iv) patient-controlled fentanyl analgesia during labour in a parturient with unexplained thrombocytopenia (70 × 10³ · ml^-1) is described. The patient self-administered boluses of 25 μg of fentanyl with a lock-out interval often min. In addition, a concurrent fentanyl infusion of 25 μg · hr^-1 was given. Effective analgesia was achieved during labour and a total of 1025 μg of fentanyl was infused over 11 hr 55 min until delivery of a vigorous infant with Apgar scores of 9 after one and five min. Respiratory depression or undue sedation were not observed in the mother either during labour or in the post-partum period. At birth, maternal total plasma fentanyl concentration was 1.11 ng · ml^-1, whereas neonatal umbilical total plasma fentanyl concentration was 0.43 ng · ml^-1. Newborn plasma protein binding of fentanyl was lower compared to the mother (63% vs 89%). Thus, free fentanyl concentrations (0.16 ng · ml^-1) were identical in the mother and newborn at delivery.