When the heart stops: a review of cardiac arrest in pregnancy.

Cardiac arrest is a rare occurrence in pregnancy and may be related to obstetric or medical causes. Pregnancy is associated with profound physiologic changes that prepare the gravida for the challenges of labor and delivery, and resuscitation of the pregnant patient needs to take these changes into consideration. Cardiac output and plasma volume increase in pregnancy and distribute differently with the uterine circulation receiving approximately 17% of the total cardiac output. On the other hand, cardiac output is sensitive to positional changes in the second half of pregnancy but may improve with a lateral tilt of the gravida. Both oxygen reserve and upper airway size decrease in pregnancy, leading to difficulties surrounding airway management. Changes in the volume of distribution, renal and hepatic clearance may impact drug effects and need to be recognized. This review will discuss an overview of pregnancy physiology that is relevant to cardiac resuscitation, detail the challenges in the various resuscitative steps including a synopsis on perimortem delivery, and describe obstetric and nonobstetric causes of mortality and cardiac arrest in pregnancy.