From the Guidelines
Pit breaks are not a recommended intervention for patients with inadequate MVUs in labor with obesity, as the current evidence suggests that oxytocin augmentation is a more effective approach to managing inadequate uterine contractions. When managing labor in obese patients with inadequate MVUs, it is essential to consider the potential impact of obesity on uterine contractility and oxytocin pharmacokinetics 1. Key considerations in the management of these patients include:
- Starting with a low dose of oxytocin (1-2 mU/min) and increasing gradually every 30-60 minutes until adequate contractions are achieved, typically not exceeding 20-40 mU/min depending on institutional protocols 1.
- Close monitoring of both contraction strength and fetal heart rate is essential, with intrauterine pressure catheters potentially being valuable in obese patients to accurately measure contraction strength 1.
- Recognizing that obesity can affect oxytocin pharmacokinetics, potentially requiring higher doses to achieve adequate uterine activity, with studies suggesting that obese women may need 30-40% higher oxytocin doses to achieve similar clinical effects 1.
- Considering alternative delivery methods such as cesarean section if oxytocin augmentation fails to produce adequate contractions (at least 200 MVUs) after several hours of maximum dosing, especially if there is no progress in cervical dilation or fetal descent 1. The most recent and highest quality study on this topic, published in the American Journal of Obstetrics and Gynecology in 2023 1, provides guidance on the diagnosis and management of protracted active phase labor, including the use of oxytocin augmentation in obese patients.
From the FDA Drug Label
CLINICAL PHARMACOLOGY Oxytocin injection (synthetic) acts on the smooth muscle of the uterus to stimulate contractions; response depends on the uterine threshold of excitability. PRECAUTIONS General All patients receiving intravenous oxytocin must be under continuous observation by trained personnel with a thorough knowledge of the drug and qualified to identify complications.
The FDA drug label does not answer the question.
From the Research
Pit Breaks in Patients with Inadequate MVUs in Labor with Obesity
- There is limited research directly addressing the effectiveness of pit breaks in patients with inadequate MVUs (Montevideo Units) in labor with obesity.
- However, studies have investigated the use of oxytocin augmentation in labor, which may be relevant to understanding the management of inadequate MVUs in labor with obesity 2, 3, 4.
- Oxytocin augmentation is commonly used to enhance uterine contractions in labor, but its effectiveness can be influenced by maternal factors such as obesity 3, 4.
- Research suggests that obese women may require higher doses of oxytocin to achieve adequate uterine contractions and vaginal delivery 3, 4.
- A study published in 2017 found that maternal BMI explained 16.56% of the variance in hourly oxytocin doses received by obese women in labor, indicating that obesity may affect the response to oxytocin augmentation 3.
- Another study published in 2020 found that obese women were more likely to require oxytocin rates >20 mU/min to achieve vaginal delivery, and had a longer duration of oxytocin exposure and higher maximum rates of oxytocin compared to normal weight women 4.
- The assessment of uterine contractions in labor is crucial for managing inadequate MVUs, and various methods are available, including manual palpation, external tocodynamometry, and intrauterine pressure monitoring 5.
- However, the effectiveness of pit breaks in patients with inadequate MVUs in labor with obesity is not directly addressed in the available research, and further studies are needed to investigate this specific question.