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11.17.2015

UHealth Cardiologists Contribute to Groundbreaking Document on Cardiac Arrest in Pregnancy

Two UHealth cardiologists — Robert J. Myerburg, M.D., professor of medicine and physiology, and the American Heart Association Chair in Cardiovascular Research, and Maureen H. Lowery, M.D., professor of medicine and Director of the Noninvasive Cardiovascular Laboratory at University of Miami Hospital — have written a commentary in response to the first-ever Scientific Statement on cardiac arrest in pregnancy published by the American Heart Association.

The AHA document, “Cardiac Arrest in Pregnancy: A Scientific Statement from the American Heart Association,” was published in the journal Circulation. The commentary by Drs. Myerburg and Lowery was published in Practice Update – Cardiology.

Despite the fact that 800 maternal deaths occur each day worldwide, cardiac arrest in pregnancy, and the proper response to it, is one of the least-discussed areas of cardiology. Although most methods of resuscitating a pregnant woman are similar to those of standard adult resuscitation, there are additional considerations because of the numerous potential causes of the arrest, and the fact that the responder is dealing with two patients — the mother and the fetus.

“It is interesting that the AHA has never produced a document on this topic before now, because cardiac arrest in pregnancy has very unique and specific requirements for responders,” said Myerburg. “There is a very limited discussion in the 2010 and 2015 American Heart Association Guidelines Updates for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care, but the Scientific Statement is much more thorough and comprehensive, addressing issues not covered in the Guidelines. In addition, I spoke to a number of people in various disciplines, and none of them had ever seen anything prior to the AHA statement, or were even aware of the specifics of the problem.”

The problem, although relatively uncommon, has been growing. According to the AHA Scientific Statement, the Centers for Disease Control and Prevention documented a steady increase in maternal mortality from 7.2 deaths per 100,000 live births in 1987 to 17.8 deaths per 100,000 live births in 2009 in the U.S. It also states, however, that “knowledge deficits and poor resuscitation skills could be major contributors to poor outcomes once cardiac arrest has occurred … further justifying appropriate training and preparation for such events despite their rarity.”

The Scientific Statement goes on to address the important factors in maternal arrest, including maternal physiology as it relates to resuscitation, pre-event planning of the critically ill pregnant patient, risk stratification during pregnancy, management of the unstable pregnant patient, basic life support (BLS) in pregnancy, advanced cardiovascular life support (ACLS) in pregnancy, neonatal considerations, emergency medical service care, cause of maternal arrest, point-of-care instruments, immediate post-arrest care, medico-legal considerations, and knowledge translation, training and education recommendations.

In their commentary, Myerburg and Lowery write that “it is curious that one area that has received very limited attention is the management of cardiac arrest in pregnancy, labor and delivery. Estimates of incidence place the risk at a level higher than that in the general age-related population — in the range of 1/15,000 to 1/30,000 — with maternal survival rates as low as 7 percent reported.… The AHA document is an outstanding example of a scientific statement addressing a low-frequency but important part of the realm of cardiac arrest. The document is particularly important because it makes up for the absence of any mention of the pregnant cardiac arrest victim in the BLS/ACLS teaching modules used for training of both professional and lay responders, despite the fact that a number of the response techniques are uniquely specific to the pregnant victim.”

The cardiologists go on to highlight the major points in the scientific statement that are relevant to the practitioner. Among the most relevant are some modifications of CPR unique to late pregnancy. Because of aorto-caval compression by the gravid uterus, BLS/CPR includes displacement of the uterus to the left (LUD) during BLS to relieve this impairment to circulatory support. Thus, if only two responders are available initially, the second responder is probably better advised to perform LUD, along with hands-only compressions by the first responder, until more responders are on site.

In addition, because of respiratory constraints in advanced pregnancy, and the fact that the pregnant victim is more dependent on O2 support during CPR, initial respiratory support is recommended to employ 100 percent O2 BMV before attempting intubation, which can be more difficult and time-consuming in this setting. There are no special requirements for chest compression techniques or defibrillator energy levels for shocks in the pregnant patient in VF, because there are no data suggesting arcing from the chest electrodes to the fetus.

Myerburg and Lowery also emphasized the need for more research. They pointed out that among the 79 recommendations in the AHA Scientific Statement, all but four are based on Level of Evidence C; the remainder were B. Based on incidence, adequately powered studies by single centers or small groups of institutions are unrealistic goals. However, the establishment of a carefully constructed and managed national data repository for cardiac arrests during pregnancy, as part of the general recommendation for national reporting of both out-of-hospital and in-hospital cardiac arrests in a recent Institute of Medicine report, appears warranted. These data sources can be used both for research purposes and for individual institutions to compare and modify their policies and procedures to national practices and outcomes.

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