Active phase slow labour management: a review of the evolutionary history of the 2 hours and 4 hours oxytocin augmentation treatment
AbstractContext: Currently, slow labour is treated with oxytocin augmentation after delay of either 4 hours or 2 hours but there is debate as to whether the 2 hours or 4 hours delay is better to adopt especially for tertiary centre labour ward. Randomized controlled studies which have been conducted to resolve this issue have yielded conflicting reports because the studies used as primary outcome measures caesarean section rate or mode of delivery and perinatal outcome which are also affected by other confounding variables not related to the oxytocin augmentation. The debate as to which is better between the 4 hours and 2 hours delay before augmentation is still on.
Objective: In order to identify the appropriate primary outcome measure to assess the 4 hours and 2 hours delay before augmentation, a historical review has been undertaken of the evolution of the 4 hours and 2 hours delay in order to identify the aim of treatment of the slow labour progress in active phase. This is to reveal what dependable primary outcome measure that can be used to assess which of 4 hours or 2 hours can better prevent prolonged labour which is the original aim of treating the slow labour with oxytocin augmentation. This is the way to end the debate.
Sources of materials used: Information was obtained from Journals, medline, W.H.O. publications, Cochrane database systematic reviews and reputable textbooks using publications from 1969 to 2009.
Materials: In active management of labour, it is the aim to prevent prolonged labour through a strategy to identify slow labour progress and institute immediate oxytocin augmentation hence the need for hourly vagina examination in the original concept by O'Driscoll and associates. Because this regimen required a large compliment of persons with good obstetric knowledge and materials, implementation was difficult hence there were modifications. This was first by Phillpott who designed oxytocin augmentation after 4 hours delay and later 2 hours and 3 hours by other
workers before oxytocin augmentation when slow labour occurred. In spite of these delay the results were comparable to what O'Driscoll obtained with immediate augmentation and hourly vagina examinations. Presently,
oxytocin augmentation is often after 4 hours or 2 hours delay after slow labour occurs. In a bide to know the better option, between 4 hours and 2 hours of delay, there have been randomized controlled studies in which the primary outcome measures assessed, were caesarean section rate or mode of delivery and perinatal outcome with conflicting results. The conflicting report is because mode of delivery and perinatal outcome following treatment of slow labour with oxytocin augmentation, is dependent more on the cause of the slow labour and state of the feto-placenta function before the augmentation. Hence, mode of delivery and perinatal outcome are not dependable outcome measures to assess which is the better option of 4 hours and 2 hours delay before augmentation. Since the aim of treating slow labour progress, is to restore progress to the normal 1cm per hours, cervical dilation rate, the appropriate outcome measure to assess in any comparative studies of the 4 hours and 2 hours are cervical dilation rate, duration of labour and reduction of prolonged labour rate.
Conclusion: It is concluded that the appropriate outcome measure to assess randomized comparative studies of 4 hours and 2 hours delay before oxytocin augmentation, is cervical dilation rate, duration of labour and reduction of prolonged labour rate. This will produce reproducible results and help identify whether 4 hours or 2 hours delay before augmentation contribute more to preventing prolonged labour.
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