Cardiopulmonary arrest in pregnancy is uncommon, occurring only once in every 12,000 obstetrical admissions. Even at the busiest medical centers, this will only total a few obstetrical arrests per year; therefore, few clinicians have had the experience of running many obstetrical codes. There are no published randomized controlled clinical trials of cardiopulmonary resuscitation (CPR) during pregnancy. Most recommendations are supported only by physiological principles and observational studies. The maternal mortality of obstetrical arrest is over 50%.
Advanced cardiac life support (ACLS) guidelines have been developed with a focus on sudden death from ischemic heart disease. Although acute myocardial infarction is increasingly recognized as a cause of maternal arrest during pregnancy, many of the causes of maternal arrest are unique to pregnancy. This and the distinctive physiology of pregnancy necessitate a specific approach to management. The life of the fetus must be highly regarded with the consideration that best outcomes for the baby are likely to be achieved by focusing on resuscitation of the mother. The single most important factor for improving survival is a well-prepared, time-conscious, team approach.
The focus of this chapter will be to help you plan such an approach. We will review (1) pertinent pathophysiology, (2) preparation for ACLS response, (3) how to run an obstetrical code from the perspective of the code leader, (4) the causes of obstetric arrest, and (5) postresuscitative care. It should be noted that the ACLS guidelines published by American College of Cardiologists are the standard in the United States. These are available online at http://circ.ahajournals.org/. Nothing in this chapter should be interpreted as conflicting with these guidelines, but I have taken the liberty of offering simplification in a few areas, while expounding on others.
Current ACLS guidelines have a strong emphasis on minimally interrupted, high-quality CPR.
There are three major specific modifications for the pregnant patient: (1) leftward displacement of the uterus during chest compressions, (2) anticipation of a difficult airway/benefit of early intubation, and (3) consideration of perimortem cesarean delivery within 4 minutes of onset of arrest. These three items are easy to remember and are the most important contents of this chapter.
CLINICAL PATHOPHYSIOLOGY OF CARDIAC ARREST IN PREGNANCY
Fetal and maternal circulation interface at the placenta, driving gas exchange between mother and baby. The maternal cardiopulmonary adaptation to pregnancy provides a balanced delivery of oxygen to maternal and fetal tissues with robust protective mechanisms. Maternal plasma volume and red blood cell mass increase augmenting blood volume by 40% (>1000 mL). The left ventricle dilates and becomes more compliant, increasing stroke volume and cardiac output by 40%. The high oxygen affinity of fetal hemoglobin facilitates oxygen exchange across the placenta and maternal respiratory alkalosis provides a gradient for CO2 exchange. Uterine contractions during labor result in maternal auto-transfusion, enhancing oxygen delivery when it is needed most. Clinical experience ...