Low-dose oxytocin - a safe strategy in postpartum hemorrhage

Dear Sir,

A randomized controlled trail titled “Ten units intravenous oxytocin over 2–4 h is as effective as 30 units over 8–12 h in preventing postpartum hemorrhage after cesarean section: A randomized controlled trial” by Cecilia et al.[1] is an excellent sincere work by the team. Nearly one-quarter of maternal mortality in India is due to postpartum hemorrhage (PPH).[2] This article had given deep insights into the management of PPH in general and specially after cesarean delivery (CD). Oxytocin is considered as a drug of choice to treat and prevent the PPH. In this study, the role of oxytocin in the management of PPH covered comprehensively, especially in differentiating higher dose and lower dose. Recently, the Government of India has banned over-the-counter use of oxytocin.[3] This study will help in preventing the reckless use of oxytocin and maintain the stock of the oxytocin in the stores. According to the prestigious American College of Obstetricians and Gynecologists (ACOG) practice bulletin issue of October 2017, information regarding the range of dose that could be used is provided. It recommends the use in the range of 10–40 units per 500–1000 mL either as a continuous infusion or as 10 units by intramuscular injection.[4]

In the current study, the comparison between high-dose and low-dose continuous infusions proved that both of these regimens were equally effective in the prevention of postoperative CD PPH. This is because of receptor saturation at lower dose, and there will not be any response if we use higher doses. However, the rationality in designing the study to the use of high dose and low dose is not clearly defined. If we refer to the ACOG practice bulletin October 2017,[4] it is assumed that the dose is progressively increased based on the response. This brings us a dilemma that when the lower dose cannot control the bleeding adequately, then we should either increase the dose or choose alternative uterotonic. This will help the readers to understand well in study design.

The outcomes of this study were defined clearly. The primary outcomes in the postoperative period were assessed the additional need of uterotonic medications to control hemorrhage and the assessment of vital signs for any major deterioration by the rate of pulse and the blood pressure (BP). The secondary outcome assessed the blood volume difference between preoperative and postoperative packed cell volumes and its significance is shown if the difference ≥10% and its probable need for blood transfusion. These outcomes give a clear picture on the chances of PPH in the study group. However, in defining the exclusion criteria, patients with intraoperative atonicity of the uterus requiring additional uterotonics or severe intraoperative blood loss requiring blood transfusion are not taken in this study. The above exclusion criteria contradict with the primary and secondary outcomes. This might be affected the study difference between higher and lower doses. Another primary outcome in the postoperative period was the measurement of significant or the major deterioration of vital signs that was being assessed by the pulse rate (PR) and by BP. This primary outcome had a vital role in continuous monitoring the patients and timely intervention. However, the range of PR and BP has not defined in this study. Because their range varies with study design and population, therefore defining range helps in good assessment.

In this study, the use of lower doses is preferred because higher doses are associated with headache, nausea, vomiting, flushing, cardiovascular signs, and symptoms such as chest pain, hypotension, myocardial ischemia, electrocardiography changes in ST- and T-wave segment changes, and pulmonary edema water intoxication associated with seizures. In this study, safety parameters are not considered in the overall evaluation in both groups. This should be considered as this article serves as a good reference from our Indian scenario setup.

In this study, the incidence of uterine atony in the low-dose group was 0.7% and in the high-dose group 5.1%; the difference is statistically significant. It indicates that higher dose can cause uterine atony. Yamaguchi et al.[5] observed that higher doses of oxytocin can cause receptor desensitization resulting ineffective action on uterine myometrium. In this study, the duration of the administration of oxytocin drip in the high-dose group was 8–12 h. Receptors became insensitive resulting the higher incidence of uterine atony in the high dose group with the longer duration of infusion the receptors became insensitive that will cause the uterine to be atony.

To conclude, it is an excellent study as it could able to observe a findings of no difference in the regular dose (10 units) and high-dose groups. Instead in the high-dose group, the incidence of uterine atony is significantly high. As low dose is better tolerated and similar efficacy, low dose of oxytocin is preferred over the high dose.

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Conflicts of interest

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