Maternal Cardiac Arrest

Learning objectives

After completing this chapter, you should be able to perform high-quality CPR with manual uterine displacement; apply standard defibrillation and medication principles; optimize airway and vascular access; organize reversible causes using pregnancy-specific priorities; explain the purpose and timing of resuscitative delivery; manage common arrest mechanisms; and make appropriate scene, transport, and post-ROSC decisions.

Opening transport scenario

A 36-year-old patient at 34 weeks suddenly collapses during transfer for severe preeclampsia. She is pulseless in ventricular fibrillation. Magnesium is infusing. The team immediately begins CPR, performs manual left uterine displacement, defibrillates using standard energy, stops magnesium, prepares calcium, and activates a resuscitative-delivery response. The central challenge is to perform ordinary ACLS exceptionally well while removing pregnancy-specific barriers to circulation and preparing definitive obstetric intervention without delay.

1. Immediate actions

1. Recognize arrest, activate the maternal cardiac-arrest team, and begin high-quality CPR.
2. Place the patient supine on a firm surface while continuously displacing the uterus leftward when the fundus is at or above the umbilicus.
3. Attach defibrillation pads and follow standard rhythm-based ACLS.
4. Provide oxygen, ventilate effectively, and secure the airway early with the most experienced operator available.
5. Obtain IV or IO access preferably above the diaphragm.
6. Stop magnesium if infusing and administer calcium when magnesium toxicity is suspected.
7. Remove or disconnect fetal monitors that interfere with resuscitation.
8. Prepare immediately for resuscitative delivery if there is no rapid ROSC and the uterus is large enough to impair circulation.

2. High-quality CPR and uterine displacement

Use standard adult compression rate and depth, allow full recoil, minimize interruptions, and change compressors approximately every two minutes. The patient remains supine for effective compressions. Manual left uterine displacement is preferred over tilting the entire patient because excessive lateral tilt can reduce compression quality.

• Assign one person solely to continuous uterine displacement.
• Use a mechanical CPR device only when it fits correctly, does not delay compressions, and follows protocol.
• Monitor waveform capnography after airway placement; a sudden sustained rise may indicate ROSC.
• Do not stop compressions for fetal assessment, ultrasound, transport loading, or procedural preparation.

3. Defibrillation and medications

Defibrillation energy and rhythm management are the same as for a nonpregnant adult. Pregnancy is not a reason to delay shock. Use standard ACLS medications and intervals unless a specific toxicologic or obstetric mechanism changes therapy. There is no evidence that standard defibrillation harms the fetus in a way that outweighs the need to restore maternal circulation.

4. Airway and ventilation

Pregnancy increases oxygen consumption, reduces functional residual capacity, and may produce airway edema. Desaturation occurs quickly. Use the most experienced airway clinician, optimize position, preoxygenate when any time exists, prepare suction and backup devices, and consider a smaller endotracheal tube. Confirm with waveform capnography.

• Use standard ventilation rates after advanced-airway placement and avoid hyperventilation.
• Consider aspiration, pulmonary edema, asthma, PE, and AFE as mechanisms.
• If intubation attempts interrupt compressions or oxygenation, use an effective supraglottic airway and continue resuscitation.

5. Reversible causes: pregnancy-focused A–H framework

6. Resuscitative delivery

When the uterine fundus is at or above the umbilicus and ROSC has not occurred rapidly, prepare for resuscitative delivery at the location of the arrest. The 2025 AHA algorithm states a goal of completing delivery by five minutes after arrest. Preparation begins immediately; do not wait until four minutes to assemble equipment or personnel.

Why it helps the mother

• Relieves aortocaval compression.
• Improves venous return and cardiac output during CPR.
• Reduces oxygen demand and allows better diaphragmatic excursion.
• May make resuscitation procedures and abdominal access easier.

Operational principles

• Do not transport to an operating room before beginning the procedure when that movement delays delivery.
• Continue CPR throughout preparation and procedure.
• Prepare a separate neonatal resuscitation team and equipment.
• Continue maternal resuscitation after delivery; delivery is not the end point.

7. High-risk arrest mechanisms

Hemorrhage

Use immediate blood products, massive-transfusion protocol, calcium, warming, and surgical source control. Crystalloid alone is inadequate for exsanguinating hemorrhage.

Amniotic fluid embolism

AFE can cause abrupt hypoxemia, shock/arrest, and DIC. Management is high-quality resuscitation, early blood products, coagulation support, and rapid obstetric/critical-care intervention.

Pulmonary embolism

Massive PE may require systemic thrombolysis during arrest, catheter therapy, embolectomy, or ECMO depending on system capability. Pregnancy is not an absolute contraindication to lifesaving thrombolysis.

Magnesium toxicity

Stop magnesium and administer calcium when toxicity is suspected. Support ventilation and circulation; renal failure may require dialysis after ROSC.

Trauma

Address hemorrhage, tension pneumothorax, tamponade, airway injury, and other traumatic causes. Resuscitative thoracotomy and hysterotomy decisions require immediate trauma and obstetric coordination.

8. Scene and transport decisions

High-quality resuscitation should not be degraded by premature movement. In-hospital arrest is treated where it occurs until immediate interventions, including resuscitative delivery when indicated, are underway. Prehospital systems should follow local termination and transport protocols, considering cause, resources, travel time, mechanical CPR capability, and whether definitive rescue such as ECMO or surgery is realistically available.

• Notify the receiving center early and request obstetric, anesthesia, neonatal, blood bank, surgery, and ECMO resources as appropriate.
• If transport occurs, maintain continuous CPR, uterine displacement, airway security, medication access, and device securement.
• Do not delay shock, decompression, blood, antidote, or resuscitative delivery for loading.
• Document exact arrest time, CPR start, shocks, medications, airway, suspected cause, delivery time, and ROSC.

9. Post-ROSC care

After ROSC, optimize oxygenation and ventilation, treat shock, obtain ECG and echocardiography, control hemorrhage, correct electrolytes and temperature, and continue cause-directed care. Avoid both hypoxemia and unnecessary hyperoxia after reliable measurement is available. Post-arrest temperature-control decisions are individualized with critical-care and obstetric teams.

If pregnancy continues, reassess fetal status and determine delivery timing based on maternal stability, gestation, and fetal condition. After resuscitative delivery, prepare for major hemorrhage, coagulopathy, uterine atony, and neonatal resuscitation.

10. Evolving case study

Phase 1: Shockable arrest

CPR and uterine displacement begin immediately. VF is defibrillated with standard energy. Epinephrine follows standard ACLS timing. The airway is secured with minimal interruption.

Phase 2: Reversible cause and delivery

Because magnesium is infusing and renal function was worsening, the infusion is stopped and calcium is administered. No ROSC occurs rapidly; the procedure team begins resuscitative delivery at the bedside while CPR continues.

Phase 3: After delivery

ROSC occurs shortly after delivery. The maternal team treats pulmonary edema and evaluates intracranial, cardiac, embolic, and toxic causes. The neonatal team continues separate resuscitation and transport planning.

11. High-yield chapter summary

1. Use standard high-quality CPR and ACLS without delay.
2. Perform continuous manual left uterine displacement when the uterus is large enough to impair circulation.
3. Use standard defibrillation energy and medications.
4. Secure airway and IV/IO access above the diaphragm when possible.
5. Stop magnesium and give calcium when toxicity is suspected.
6. Search aggressively for pregnancy-specific and standard reversible causes.
7. Prepare immediately for resuscitative delivery; aim to complete delivery by five minutes when indicated.
8. Perform the procedure at the arrest location rather than delaying for transport to an OR.
9. Maternal resuscitation continues after delivery.
10. Avoid degrading CPR through premature movement or nonessential procedures.

References

1. International Board of Specialty Certification. Maternal Fetal Transport Microcredential Candidate Handbook. Updated April 2026.
2. American Heart Association. 2025 Cardiac Arrest in Pregnancy Algorithm.
3. American Heart Association. 2025 Guidelines: Adult and Pediatric Special Circumstances of Resuscitation.
4. American College of Obstetricians and Gynecologists. Maternal cardiac arrest and resuscitative cesarean guidance.
5. Society for Obstetric Anesthesia and Perinatology. Maternal resuscitation resources.