what are the causes of cardiac arrest in a pregnant patient?

Cardiac arrest in pregnant patients is a rare but critical emergency, often stemming from unique physiological changes and obstetric complications that differ from non-pregnant cases. Causes are typically categorized into obstetric and non-obstetric factors, with prompt recognition vital for maternal and fetal outcomes.

Primary Causes

Obstetric issues dominate due to pregnancy-specific stressors like increased blood volume and aortocaval compression. Common triggers include:

• Hemorrhage : Often from placental abruption, uterine rupture, or postpartum bleeding, accounting for about 17% of cases.

• Pregnancy-induced hypertension : Including preeclampsia or eclampsia, which can lead to stroke or heart strain (around 16%).

• Amniotic fluid embolism : A sudden allergic-like reaction where amniotic fluid enters the bloodstream, causing rapid collapse.

• Peripartum cardiomyopathy : Heart muscle weakening late in pregnancy or postpartum (8% of cases).

Non-obstetric causes overlap with general cardiac arrest but are amplified by pregnancy:

• Pulmonary embolism : Most frequent at 19-29%, due to venous thromboembolism risk from hypercoagulability.

• Sepsis : From infections like chorioamnionitis (13%).

• Myocardial infarction or stroke : Less common but rising with age and comorbidities.

Key Risk Factors

Pregnancy alters hemodynamics—heart rate rises 20-30%, stroke volume increases, and the uterus compresses the inferior vena cava after 20 weeks, reducing cardiac output by up to 25% when supine. High-risk groups include:

• Women over 35 or with obesity.
• Those with prior heart disease, multiple gestations, or anemia.
• Recent trends show rising incidence tied to older maternal age and conditions like COVID-19 exacerbating emboli.

Mnemonic: "BEFAST" (Bleeding, Embolism, Fever/Sepsis, Anesthesia, Stroke/Trauma, Tension/pre-eclampsia) helps clinicians recall etiologies quickly.

Management Insights

Left uterine displacement during CPR improves venous return, and perimortem cesarean delivery within 5 minutes boosts survival if arrest persists beyond 4 minutes. Recent 2024 guidelines emphasize early defibrillation and addressing reversible causes aggressively.

TL;DR : Leading causes are pulmonary embolism, hemorrhage, and hypertension-related issues; rapid, pregnancy-adapted resuscitation is essential. Information gathered from public forums or data available on the internet and portrayed here.