Cardiac arrest during pregnancy: ongoing clinical conundrum

While global maternal mortality has decreased in the last 25 years, the maternal mortality ratio in the United States has actually increased. Maternal mortality is a complex phenomenon involving multifaceted socioeconomic and clinical parameters including inequalities in access to health care, racial and ethnic disparities, maternal comorbidities, and epidemiologic ascertainment bias. Escalating maternal mortality underscores the importance of clinician preparedness to respond to maternal cardiac arrest that may occur in any maternal health care setting. Management of maternal cardiac arrest requires an interdisciplinary team familiar with the physiologic changes of pregnancy and the maternal resuscitation algorithm. Interventions intended to mitigate obstacles such as aortocaval compression, which may undermine the success of resuscitation interventions, must be performed concurrent to standard basic and advanced cardiac life support maneuvers. High-quality chest compressions and oxygenation must be performed along with manual left lateral uterine displacement when the uterine size is ≥20 weeks. While deciphering the etiology of maternal cardiac arrest, diagnoses unique to pregnancy and those of the nonpregnant state should be considered at the same time. If initial basic life support and advanced cardiac life support interventions fail to restore maternal circulation within 4 minutes of cardiac arrest, perimortem delivery is advised provided the uterus is ≥20 weeks’ size. Preparations for perimortem delivery are best anticipated by the resuscitation team for the procedure to be executed opportunely. Following delivery, intraabdominal examination may reveal a vascular catastrophe, hematoma, or both. If return of spontaneous circulation has not been achieved, additional interventions may include cardiopulmonary bypass and/or extracorporeal membrane oxygenation. Simulation and team training enhance institution readiness for maternal cardiac arrest. Knowledge gaps are significant in the science of maternal resuscitation. Further research is required to fully optimize: relief of aortocaval compression during the resuscitation process, gestational age and timing of perimortem delivery, and other interventions that deviate from nonpregnant standard resuscitation protocol to achieve successful maternal resuscitation. A robust detailed national and international prospective database was recommended by the International Liaison Committee on Resuscitation in 2015 to facilitate further research unique to cardiac arrest during pregnancy that will produce optimal resuscitation techniques for maternal cardiac arrest.

Introduction

The last decade has heralded a paradigm shift in perceptions regarding maternal collapse and cardiopulmonary resuscitation (CPR). Historically, survival was described as poor, and resuscitation futile, because “the causes of cardiac arrest are fatal.”1, 2 But new evidence indicates high survival, with a significant proportion of cases attributed to a reversible etiology of arrest. This unique population of young, yet critically ill women can respond to appropriate treatment and may be more salvageable than most patients requiring CPR.³

While the global maternal mortality ratio (maternal deaths/100,000 live births) has decreased in the last 25 years from 281.5-195.7, the maternal mortality ratio has actually increased from 16.9-26.4 in the United States. More robust ascertainment systems likely explain some, but not the majority, of this increase. Maternal mortality is a complex multifaceted phenomenon with each etiology of maternal death influenced by population health, comorbid conditions, access to health care, and socioeconomic, racial, and ethnic inequalities. Regardless, cardiac arrest separates survival from death for many forms of maternal critical illness and comorbidities. Institutional preparation for maternal CPR represents an opportunity to optimize maternal survival in many health care settings.⁴

In this article, we aim to provide a comprehensive review of cardiac arrest in pregnancy and outline a practical management algorithm for the clinician in the trenches. Recent guidelines from the Society for Obstetric Anesthesia and Perinatology (SOAP), the American Heart Association (AHA), and the International Liaison Committee on Resuscitation (ILCOR) are reviewed.

Due to the low prevalence and the circumstances of cardiac arrest during pregnancy, randomized clinical trials do not exist to guide management; therefore, we have extrapolated data from simulation studies, expert opinions, small case series, and cohort studies, including new prospectively reported data on maternal cardiac arrest (MCA).5, 6 Given the low frequency of maternal resuscitation, optimal resuscitation practices are poorly described. Most recommendations are based on expert opinion, case reports, and case series. To encourage further research in maternal resuscitation science, this review also highlights existing knowledge gaps.