Non-obstetric causes of cardiac arrest in pregnancy include sepsis, trauma, myocardial infarction, aortic dissection, anaphylaxis, status asthmaticus, and pulmonary embolism (PE). The most common cause of cardiac arrest in pregnancy in the United States is PE [9]. PE complicates 1 in 1,000 pregnancies, and pregnant women are up to ten times more likely to have a venous thromboembolism than nonpregnant women [10, 11]. When PE is the cause of cardiac arrest, standard advanced cardiac life support (ACLS) therapies are less likely to be effective, necessitating early recognition of this pathology [12]. Clues to PE as the etiology of cardiac arrest include pulseless electrical activity as the initial rhythm as well as a dilated right ventricle on bedside ultrasound [13, 14]. Treatment includes standard ACLS protocol and fibrinolytic therapy. Fibrinolytic options include recombinant tissue plasminogen activators, or synthetic derivatives such as streptokinase and urokinase [15]. A recent meta-analysis of hemodynamically unstable pregnant patients with PE showed the risk of major bleeding following fibrinolysis was low, and the fetal demise rate was only 2.6% [16]. There have been multiple case reports of successful use of fibrinolytic therapy in unstable pregnant women with massive PE, including patients at 26 weeks and 32 weeks with good outcomes [17–19]. Another somewhat novel therapeutic option is extracorporeal membrane oxygenation (ECMO). There have been several case reports showing the use of ECMO for PE with favorable outcomes for both mother and fetus [20, 21].

Iatrogenic causes of maternal cardiac arrest include anesthesia-related arrest (both general and regional anesthesia) and medication induced, specifically magnesium toxicity. Anesthesia-induced cardiac arrest is the seventh leading cause of maternal death in the United States [22], although mortality rates are declining [23]. The decline in maternal deaths related to general anesthesia has been attributed to increase the use of pulse oximetry and capnography and utilization of difficult intubation algorithms including the use of supraglottic airway devices. The reduction in maternal deaths from local anesthesia is likely due to using a lower concentration of anesthetics, an increase in general awareness regarding anesthetic toxicity, and an overall emphasis on safety practices [22].

Pregnant patients with systemic anesthetic toxicity present with respiratory and cardiovascular depression, which can eventually lead to complete cardiopulmonary collapse. Treatment is supportive and centered on early recognition, fluid resuscitation, and airway management. Prevention of hypoxia and metabolic acidosis is critical [22]. For patients with complete cardiopulmonary collapse refractory to standard resuscitative measures, lipid emulsion therapy can be considered, though a recent review was inconclusive regarding the efficacy of lipid emulsion therapy for systemic anesthetic toxicity [24].

Another cause of iatrogenic cardiac arrest in pregnancy is magnesium toxicity. Magnesium is a standard therapy for patients with preeclampsia and eclampsia, and there is a risk of cardiopulmonary collapse if toxic levels are reached [25]. Fortunately, toxicity is now rare, as many hospitals have protocols in place to monitor for overdose; however, the possibility still exists and was addressed in recent guidelines from the American Heart Association (AHA) on cardiac arrest [26]. Toxic levels are reached at levels greater than 3.5 mmol/L, although the exact dosing to reach this level is unclear [27]. Symptoms of magnesium toxicity include loss of deep tendon reflexes, respiratory depression, somnolence, and cardiac arrest. If magnesium toxicity is suspected, the infusion should be stopped immediately, and 10 mL of 10% calcium gluconate can be administered [28, 29].

ACLS algorithms are generally the same in pregnancy including defibrillation doses and medical management. However, three important differences exist when resuscitating a pregnant patient: (1) positioning of the patient, (2) airway management and anticipation of a difficult airway, and (3) early consideration of perimortem cesarean delivery (PMCD). Additionally, intravenous access should be obtained above the diaphragm in pregnant patients.