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

Due to budgetary concerns, the TSC decided it best to adjust sample size as there was sufficient data to assess feasibility. Recruitment was terminated early.

The Physicians' Services Incorporated Foundation, The Ottawa Hospital, Canadian Institutes of Health Research (CIHR), Sainte Justine Hospital Research Institute

The ultimate objective is to test the hypothesis that an 'accelerated titration' protocol for labour augmentation with oxytocin reduces the risk of caesarean births relative to a 'gradual titration' protocol. The aims of this pilot feasibility are: To assess the feasibility of a large multi-centre randomized control trial comparing the two above oxytocin protocols (accelerated titration versus gradual titration for correction of dystocia). More specifically, to identify potential challenges in the study implementation, particularly with respect to patient recruitment, randomization, blinding, and compliance/adherence to the labour management guidelines and study protocols. To obtain preliminary data on the acceptability of the accelerated oxytocin titration protocol among obstetrical providers and participants.

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.

The proportion of patients who are eligible and thus meet inclusion/exclusion criteria at time of labour onset The proportion of eligible participants who consent to participate and are randomized

a) The proportion among those randomized of deviation from study protocol with regards to duration of oxytocin augmentation prior to operative intervention

Pain score on visual analog scale during labour and delivery North Bristol modified Mackey childbirth satisfaction rating scale

Rate of tachysystole and hyperstimulation Rate of abnormal FHR pattern Composite index of adverse fetal outcome (cord arterial pH < 7.1, base deficit ≥ 12 mmol/L, 5 minute Apgar score ≤ 7) Admission of a term infant to the neonatal intensive care unit Proportion requiring unblinding of protocol

From admission to the hospital for delivery until discharge of the baby from the neonatal intensive care unit (up to 4 weeks after birth)

Inclusion Criteria: Capability of participant to comprehend English and/or French and to comply with study requirements ≥ 18 years of age at time of consent Nulliparity Singleton pregnancy Cephalic Presentation No contraindications to trial of labour or vaginal birth Term pregnancy (37+0 to 42+0 weeks gestation) Spontaneous onset of labour In the ACTIVE phase of the FIRST stage of labour. Active labour is defined as: The presence of regular uterine contractions Cervical dilatation of ≥ 3 cm Cervical effacement of at least 80% (cervical length < 1cm) DYSTOCIA in the ACTIVE phase of FIRST stage of labour established by the Physician. Cervical change of < 0.5 cm/hour over four hours OR NO cervical change in 2 hours Ruptured amniotic membranes of at least 30 minutes Normal fetal heart rate pattern at the time of randomization Exclusion Criteria: Serious medical condition (severe cardiac, pulmonary, or renal disease) Known fetal anomaly Known sensitivity to oxytocin Contraindications to labour or vaginal birth (uterine scar) Induced labour (using any method) Oxytocin use prior to randomization Second stage of labour Suspected IUGR (<5th percentile) Suspected macrosomia at term (>4500 grams) Oligohydramnios (no 2x2 pocket of fluid on ultrasound prior to rupture of amniotic membranes) Abnormal FHR pattern at the time of randomization Suspected chorioamnionitis Severe pre-eclampsia Suspected placental abruption