When a pregnant woman experiences cardiac arrest, Cardiopulmonary Resuscitation (CPR) is necessary and must be started right away. The fundamental act of chest compressions and rescue breathing provides a lifeline to both the mother and the fetus. While the urgent need for action is the same as with any other adult collapse, the technique requires immediate and significant modifications compared to standard adult CPR. These adjustments are necessary to overcome the unique physiological changes of pregnancy and maximize the chances of survival for two patients instead of one.
Anatomical Impact of Pregnancy on Circulation
Pregnancy brings about substantial anatomical changes that complicate standard resuscitation efforts, particularly after 20 weeks of gestation when the uterus grows significantly larger. When a woman in the second half of pregnancy lies flat on her back, the weight of the enlarged uterus and its contents presses directly on major blood vessels in the abdomen. This mechanical obstruction affects the inferior vena cava and, to a lesser extent, the aorta, a phenomenon termed aortocaval compression.
Pressure on the inferior vena cava restricts the return of blood to the heart, potentially reducing the blood volume available for circulation by up to 30 to 40%. Chest compressions performed in this position push blood out of the heart, but the heart cannot refill effectively because the veins are compressed. This drastically reduces the effectiveness of CPR, meaning blood flow to the mother’s brain and the fetus is severely limited despite the rescuer’s best efforts.
Critical Adjustment: Left Uterine Displacement
To counteract the life-threatening impact of aortocaval compression, the single most significant modification to CPR in pregnancy is performing Left Uterine Displacement (LUD). LUD is the action of manually moving the enlarged uterus away from the major blood vessels to restore blood flow to the heart. This maneuver must be initiated immediately upon recognizing the need for resuscitation in a visibly pregnant woman and maintained continuously throughout the entire CPR process.
One common method for LUD involves a second rescuer standing on the woman’s right side and using both hands to cup and pull the abdomen toward the patient’s left hip. If a second rescuer is not available, LUD can be achieved by placing a firm wedge, rolled-up towel, or blanket under the woman’s right hip and side. This object should create a slight tilt of 15 to 30 degrees, effectively shifting the uterus off the vena cava and aorta.
The goal is to ensure the uterus is displaced to the left, which relieves the obstruction and allows blood to return to the heart. Restoring this venous return is paramount, as it makes the chest compressions effective again for circulating oxygenated blood to the mother and the fetus. Whether performed manually or with a wedge, this displacement must remain constant and uninterrupted to sustain optimal blood flow during the entire resuscitation attempt.
Standard CPR Adaptations
Once Left Uterine Displacement is established, the rescuer can focus on the other procedural elements of high-quality CPR, which follow standard adult guidelines with minor adaptations. The rate for compressions remains 100 to 120 beats per minute, and the depth should be at least two inches, or approximately five to six centimeters. Hand placement is generally the same as in non-pregnant adults, centered over the lower half of the sternum.
While the heart and other organs are displaced slightly upward due to the elevated diaphragm, current recommendations suggest using the standard sternal compression point for maximum effectiveness. Maintaining the correct depth and rate is crucial, and compressions should be performed on a firm surface, ensuring minimal interruptions, which should not exceed ten seconds.
Airway and Breathing Management
Airway and breathing management also require specific considerations for the pregnant patient. Hormonal changes and increased intra-abdominal pressure significantly increase the risk of regurgitation and aspiration of stomach contents into the lungs during resuscitation. When providing rescue breaths, rescuers should use the head-tilt/chin-lift maneuver to open the airway and be prepared for potential vomiting.
Pregnant women also have a lower lung capacity and higher oxygen demand, meaning they can become critically low on oxygen much faster than non-pregnant adults. Administering rescue breaths with a compression-to-ventilation ratio of 30 compressions followed by two breaths is the standard approach for a single rescuer. Ultimately, these modifications are all aimed at maximizing the delivery of oxygenated blood to the mother’s organs, which provides the best possible chance of survival for both lives.