By Melanie E. de Wit, JD MPH & Randy Zettle MD LLB, Borden Ladner Gervais LLP, Health Law Group
Patient injury from drug therapy is believed to be the most common type of patient safety event (PSE) that occurs in the inpatient setting.[i] The potential consequences of medication-related PSEs are nowhere more devastating than in the maternal/newborn setting. This leads us to consider the use of oxytocin during labour induction and augmentation. Approximately half of all paid obstetric litigation claims involve allegations of oxytocin misuse.[ii] Misuse of oxytocin is perhaps the most preventable cause of perinatal liability.[iii]
One of the purposes of administering oxytocin is to stimulate a labour pattern that is similar to that seen with spontaneous labour.
In 1998, the US Food and Drug Administration issued a warning about oxytocin, and recommended that it be used only for medically indicated inductions and augmentation of labour.[iv] In 2011, induced or augmented labours accounted for approximately 20% of all American deliveries, two thirds of which were elective.[v] Other studies have shown that oxytocin is used in up to approximately 45% of cases, particularly in first time mothers.[vi] Since 2007, oxytocin has been classified as a 'high alert medication' by the Institute for Safe Medication Practices. High alert medications "bear a heightened risk of causing significant patient harm when they are used in error. Although mistakes may or may not be more common with these drugs, the consequences of an error are clearly more devastating to patients."[vii]
At the risk of oversimplification, inappropriately increasing the dose of oxytocin or not reducing or stopping the infusion in a timely manner in response to hyperstimulation (ie. contractions which are too strong, too long and/or too frequent) and signs of fetal distress can lead to inadequate oxygenation of the fetus. The extent to which intrapartum asphyxia can be prevented is controversial, but several investigations suggest that some proportion can be avoided.[viii]
It is trite to say that oxytocin should be administered only where indicated, for as long as it is indicated, and at the dose indicated, with consideration of its pharmacology (onset of action, half life and steady state), the individual variation in response to the medication, and the condition of the fetus. Close monitoring of a patient receiving oxytocin is imperative.
Oxytocin is a powerful drug, and we should not be lulled into a sense of security because it is so often used. Training, policies and skill building should be mindful of the risks of improperly using oxytocin. Non-adherence to best practices (namely the Society of Obstetricians and Gynecologists of Canada Clinical Practice Guidelines and hospital induction/augmentation protocols) may only uncommonly result in an adverse outcome, but that outcome can be so devastating that the importance of establishing best practices in relation to oxytocin use is essential.
[i] Simpson & Knox, Oxytocin as a high-alert medication: implications for perinatal patient safety. American Journal of Maternal Child Nursing, 2008, 34(1), 8-15.
[ii] Clark SL, Simpson KR, Knox GE & Garite TJ. Oxytocin : New perspectives on an old drug. American Journal of Obstetrics & Gynecology. 2009 Jan. 200(1) 35 e1-6.
[iii] Clayworth S, The nurse's role during oxytocin administration, American Journal of Maternal Child Nursing, 2000 25(2), 80-4.
[iv] Hayes EJ & Weinstein L. Improving patient safety and uniformity of care by a standardized regimen for the use of oxytocin. American Journal of Obstetrics & Gynecology, 2008, 198(6), 622.e.1-7.
[v] Brunton L et al. Goodman & Gilman's The Pharmacological Basis of Therapeutics (12th Ed) 2011, McGraw Hill Medical
[vi] Oscarsson ME et al. Outcome in obstetric care related to oxytocin use: A population-based study, Acta Obstetricia Gynecologica Scandinavica, 2006, 85(9), 1094-8; Bernitz S et al. Oxytocin and dystocia as risk factors for adverse birth outcomes: a cohort of low risk nulliparous women. Midwifery, 2013, 30(3), 364-70
[vii] Institute for Safe Medication Practices, 2007 Survey on High-Alert Medications (May 2007), available at http://www.ismp.org/newsletters/acutecare/articles/20070517.asp
[viii] Jonsson M et al. Metabolic acidosis at birth and suboptimal care – illustration of the gap between knowledge and clinical practice, British Journal of Obstetrics & Gynaecology, 2009 Oct, 116(11), 1453-60.