Resuscitation of Pregnant Patients

Introduction to Physiological Changes

• The American Heart Association recommends that critical care teams immediately recognize the need for supine positioning with manual left uterine displacement in pregnant patients, anticipate rapid desaturation, and prepare for perimortem cesarean delivery within 4 minutes if ROSC is not achieved in patients with uterine size ≥20 weeks gestation 1, 2

Cardiovascular Changes

• The American College of Cardiology notes that the gravid uterus compresses the inferior vena cava in the supine position, reducing venous return by up to 30% and potentially causing complete cardiovascular collapse in the unconscious patient 2, 3
• Cardiac output increases by 30-50% during pregnancy, reaching maximum by 32 weeks, but becomes critically dependent on positioning 3, 4
• Animal studies demonstrate coronary perfusion pressures of 20 mm Hg with supine positioning plus manual left uterine displacement versus only 5 mm Hg with left-lateral tilt (P<0.05) 1, 5

Critical Positioning Strategy

• The American Heart Association recommends placing the patient fully supine on a firm surface for optimal chest compression quality, while a dedicated team member provides continuous manual left uterine displacement 1, 2, 6
• Left-lateral tilt positioning is NOT recommended during CPR as it significantly compromises chest compression effectiveness 1, 5

Respiratory Changes

• Oxygen consumption increases by 20-40% while functional residual capacity decreases by 20%, creating a critically reduced oxygen reserve that leads to rapid desaturation within 1-2 minutes of apnea 2, 7
• Minute ventilation increases by 20-40% above baseline, producing mild respiratory alkalosis as the normal physiologic state 3

Airway Management

• Anticipate a difficult airway in all pregnant patients due to airway edema, increased vascularity, and enlarged breasts that may interfere with laryngoscopy 2, 8
• An experienced provider should perform advanced airway placement, with videolaryngoscopy preferred when available 1

Vascular Access and Medication

• Establish intravenous access above the diaphragm immediately, as inferior vena cava compression renders lower extremity access ineffective during resuscitation 9, 8, 7
• Standard ACLS drug doses and protocols should be followed without modification 9, 8

Time-Critical Interventions

• If ROSC is not achieved within 4 minutes of maternal cardiac arrest in a patient with uterine size ≥20 weeks gestation, begin perimortem cesarean delivery immediately at the bedside 1, 2
• Continue all maternal resuscitative efforts during and after cesarean delivery—the procedure is performed to improve maternal resuscitation by relieving aortocaval compression, not to save the fetus 2, 9

Pre-Event Planning

• All units caring for pregnant patients must have immediate access to cesarean delivery equipment and a pre-established maternal cardiac arrest team 2, 7
• Document gestational age immediately upon patient arrival to any critical care area 9, 8

Pregnancy-Specific Causes of Arrest

• Systematically search for reversible causes specific to pregnancy while performing standard resuscitation, including bleeding/DIC, embolism, anesthetic complications, uterine atony, cardiac disease, hypertension/preeclampsia/eclampsia, and sepsis 9

Common Pitfalls to Avoid

• Never delay defibrillation due to pregnancy—use standard energy levels and pad placement 9, 8
• Do not waste time attempting left-lateral tilt positioning, which compromises compression quality 1, 5
• Do not delay perimortem cesarean delivery waiting for operating room availability—perform at bedside 2, 9

Maternal Positioning During Cardiac Arrest and Resuscitation in Pregnancy

Positioning Strategy for Cardiac Arrest (≥ 20 weeks gestation)

Indications for Manual Uterine Displacement

Positioning in Non‑Arrest Situations

Timing of Perimortem Cesarean Delivery

Common Pitfalls to Avoid

Positioning of Pregnant Trauma Patients During Resuscitation

Hemodynamic Rationale for Left‑Side Displacement

• In pregnant trauma patients with a uterus at or above the umbilicus (≈ ≥ 20 weeks gestation), keeping the patient supine while applying continuous manual left uterine displacement preserves optimal hemodynamics, whereas left‑lateral tilt markedly compromises resuscitation effectiveness. (American College of Cardiology) 14
• Supine positioning of a gravid uterus compresses the inferior vena cava and aorta, reducing venous return by up to 30 % and risking complete cardiovascular collapse; displacement must be directed to the left to relieve this compression. (American College of Cardiology) 14, 15, 16
• In animal models, manual left uterine displacement yields coronary perfusion pressures of ≈ 20 mm Hg versus ≈ 5 mm Hg with left‑lateral tilt—a four‑fold improvement, indicating superior perfusion during resuscitation. (American College of Cardiology – experimental study) 14

Positioning Algorithms

Conscious, Hemodynamically Stable Patients (≥ 20 weeks)

• Position the patient in a full left lateral decubitus posture or apply a left‑lateral tilt to prevent aortocaval compression when the patient is awake, stable, and not undergoing active resuscitation. (Thoracic Society) 17, 18
• If supine positioning is required for imaging, examination, or surgery, employ manual left uterine displacement or a minimum 15° left‑lateral tilt; however, simulation data indicate that a 15° tilt may be insufficient beyond 26 weeks gestation. (Thoracic Society; American College of Obstetricians and Gynecologists) 18, 19

Unstable or Cardiac Arrest Patients (≥ 20 weeks)

• Place the patient fully supine on a firm surface and do not use left‑lateral tilt during active resuscitation or CPR; this is the single most critical positioning principle. (American College of Cardiology) 14, 15, 16
• Assign a dedicated team member to perform continuous two‑handed manual left uterine displacement throughout resuscitation. The technique can be executed either:
  
  • From the patient’s left side, cupping and lifting the uterus upward and leftward, or
  • From the patient’s right side, pushing the uterus upward and leftward. (American College of Cardiology) 14, 15, 16
• The rescuer must avoid downward pressure, which would exacerbate inferior vena cava compression rather than relieve it. (American College of Cardiology) 14, 15, 16

Hemodynamic Consequences of Tilt vs. Manual Displacement

• Left‑lateral tilt greater than 30° still permits inferior vena cava compression and causes lateral displacement of the heart, markedly reducing the effectiveness of chest compressions. (American College of Cardiology) 14, 15, 16
• Compared with a 15° left‑lateral tilt, manual left uterine displacement significantly lowers hypotension and reduces vasopressor requirements during cesarean delivery in non‑arrest patients. (American College of Cardiology) 14, 15, 16

Practical Advantages of Manual Displacement

• Provides easier airway management and defibrillation access while maintaining a firm surface for optimal chest compressions. (American College of Cardiology) 14, 15, 16
• Eliminates the risk of the patient sliding off an inclined surface when tilt exceeds 30°. (American College of Cardiology; additional supporting studies) 16, 20, 21

Gestational and Anatomical Considerations

• The uterine fundus reaches the umbilicus at ≈ 20 weeks gestation, at which point aortocaval compression becomes clinically significant; palpable fundus at or above the umbilicus mandates positioning interventions. (American College of Cardiology) 14, 15, 16
• In morbidly obese patients where uterine size is difficult to assess, attempt manual left uterine displacement if technically feasible. (American College of Cardiology) 14, 15, 16

Respiratory Considerations in Trauma

• Pregnant patients desaturate within 1–2 minutes of apnea due to a ≈ 20 % reduction in functional residual capacity and a 20–40 % increase in oxygen consumption; therefore, deliver 100 % oxygen promptly and anticipate rapid desaturation. (American College of Cardiology) 14, 15, 16