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Cardiopulmonary arrest in pregnancy is uncommon, occurring once in every 20,000 to 50,000 pregnancies. Even at the busiest medical centers, this will only total a few cases per year. Most of what we know regarding cardiopulmonary resuscitation (CPR) in pregnancy is based on animal experiments or observational studies in humans. There are no published randomized controlled clinical trials of CPR during pregnancy and few clinicians have had the experience of running many obstetrical codes. The mortality of obstetrical arrest is over 90% in some studies.
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Advanced cardiac life support (ACLS) guidelines have been developed with a focus on sudden death from ischemic heart disease. Although acute myocardial infarction can occur during pregnancy, arrest in a previously healthy woman is more likely related to acute events such as pulmonary embolism or hemorrhage. The unpredictability and rarity of sudden death during pregnancy makes preparation difficult. The single most important factor for improving the survival of mother and baby is a well-prepared, time-conscious, team approach.
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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 a code from the aspect of the bedside clinician, (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/content/122/18_suppl_3.toc. 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 expanding in a few others.
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Review of the ACLS guidelines reveals 3 major modifications for the pregnant patient that we will explain in detail: (1) focus on early endotracheal intubation, (2) leftward displacement of the uterus during chest compressions, and (3) consideration of perimortem cesarean delivery within 4 minutes of onset of arrest. These few items are easy to remember and are the most important contents of this chapter. ACLS guidelines have changed since our last edition, with stronger emphasis on minimally interrupted, high-quality CPR, and on postresuscitative care.
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CLINICAL PATHOPHYSIOLOGY OF CARDIAC ARREST IN PREGNANCY
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Fetal and maternal circulation interface at the placenta, driving gas exchange between mother and fetus. Maternal cardiopulmonary adaptation to pregnancy allows balanced delivery of oxygen to the mother’s tissues and the fetus. Synergistic physiologic changes protect oxygen delivery in normal pregnancy. 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. Uterine contractions during labor result in maternal autotransfusion, enhancing oxygen delivery when it is needed most. Clinical experience and animal experimentation indicate that during normal pregnancy, maternal systemic and uterine ...