Investigation of some problems associated with the Cardiff infusion pump

A multicentre prospective randomized controlled trial of induction of labour with an automatic closed-loop feedback controlled oxytocin infusion system

A randomized prospective controlled trial of an automatic feed-back controlled oxytocin infusion system (AIS) for the induction of labour at term was carried out in three hospitals. In primiparae, a four-fold reduction in the total dose of oxytocin infused, for the same induction-delivery interval, was achieved with the AIS compared with standard labour ward protocols relying on midwife control of oxytocin infusion rate. In multiparae, the total dose of oxytocin infused was almost halved when the AIS was used, while the mean duration of labour was increased by 1.6 h to 7.5 h. There were no differences in the mode of delivery or Apgar scores. It is concluded that the AIS is a safe technique for induction of labour. Its use has demonstrated that term labour can be induced efficiently with a mean oxytocin infusion rate between 2.5 and 3 mU/min (max 8.8 mU/min) and a total oxytocin dose infused of less than 5 U.

Pulsed oxytocin infusion in the induction of labour

A randomized controlled trial was mounted in which induction of labour at term was successfully accomplished in 12 patients by amniotomy and intermittent (or pulsed) oxytocin, compared with 16 patients receiving continuous oxytocin. In the pulsed group, oxytocin was infused for one minute in every ten using a modified Cardiff Infusion System Mark III in the automatic setting. Compared with the control group the induction-delivery and induction-to-full-dilatation intervals were similar but the total dose of oxytocin required was significantly lower in the pulsed group than in the control group.

Experiments in the measurement of intrauterine pressure

A series of experiments investigating the quality of the signals obtained from intrauterine catheters was conducted in the labour rooms and laboratories. Clear evidence of signal attenuation due to partial blockage of catheters was obtained. Some methods which might help to overcome these problems are discribed.