Accelerated Titration of Oxytocin for Nulliparous Patients With Labour Dystocia: ACTION Pilot Study

• Consent Rate [ Time Frame: From screening for eligibility until randomization (up to 5 weeks) ] [ Designated as safety issue: No ]
  1. The proportion of patients who are eligible and thus meet inclusion/exclusion criteria at time of labour onset
  2. The proportion of eligible participants who consent to participate and are randomized
  
  
• Protocol Violation Rate [ Time Frame: From admission to a hospital for delivery until delivery (up to 1 week) ] [ Designated as safety issue: No ]
  a) The proportion among those randomized of deviation from study protocol with regards to duration of oxytocin augmentation prior to operative intervention
  
  
• Maternal satisfaction [ Time Frame: from hospital admission to 4 weeks postpartum ] [ Designated as safety issue: No ]
  1. Pain score on visual analog scale during labour and delivery
  2. North Bristol modified Mackey childbirth satisfaction rating scale
  
  

• Caesarean section rate [ Time Frame: From admission to a hospital for delivery until delivery (up to 1 week) ] [ Designated as safety issue: No ]
  
• Rate of Maternal and Fetal/Neonatal Adverse Events [ Time Frame: From admission to the hospital for delivery until discharge of the baby from the neonatal intensive care unit (up to 4 weeks after birth) ] [ Designated as safety issue: Yes ]
  1. Rate of tachysystole and hyperstimulation
  2. Rate of abnormal FHR pattern
  3. Composite index of adverse fetal outcome (cord arterial pH < 7.1, base deficit ≥ 12 mmol/L, 5 minute Apgar score ≤ 7)
  4. Admission of a term infant to the neonatal intensive care unit
  5. Proportion requiring unblinding of protocol
  
  

There has been a steady increase in the rate of Caesarean births in Canada and worldwide. Almost half of all primary caesarean sections are performed for labour dystocia - when labour is abnormally slow or when there is no further progression in cervical dilatation. When dystocia occurs, oxytocin is used to increase the frequency and intensity of uterine contractions, with the goal of achieving full cervical dilatation and a vaginal birth. The actual dose required to produce a clinical response (progressive cervical dilatation) varies greatly from patient to patient. There is a wide range of oxytocin regimens currently in use. They may be broadly categorized as being of two types: 1) those involving a gradual titration of oxytocin dose (or 'low dose') and 2) those with accelerated oxytocin titration (also called 'high dose').

In fact, the frequently used terms 'low dose' and 'high dose' are to a certain extent misnomers. Both protocols titrate oxytocin dose to achieve the desired 'physiological frequency' of uterine contractions (usually 4 to 5 contractions in a 10 minute interval) that are normally sufficient to result in progressive labour. Thus, the target dose should, theoretically, be identical and independent of the rate of increase of oxytocin. These protocols differ mainly in the rate at which the desired physiologic response is achieved. While most patients achieve a response to stimulation at oxytocin concentrations between 4 and 10 mU per minute, a proportion of nulliparae require higher doses of oxytocin. Accelerated titration protocols are also frequently associated with a higher maximum concentration of oxytocin. While, most Canadian birthing centres currently follow a 'gradual titration' or 'low dose' protocol, there is evidence that 'accelerated titration' or 'high dose' protocols may be more effective in correcting dystocia and in preventing caesarean section. It is postulated that by more rapidly progressing to the required therapeutic dose, cervical dilatation is achieved more rapidly, the likelihood of a spontaneous vaginal birth is increased, and the risk of occurrence of complications resulting from prolonged labour (such as infection and maternal fatigue) is reduced.