When a pregnant woman’s heart stops, two lives are threatened. Yet few caregivers know how to modify their cardiopulmonary resuscitation technique for the expectant mom and her fetus, and few hospitals are optimally prepared for such an event.
To fill the knowledge gap, the Society for Obstetric Anesthesia and Perinatology commissioned a Stanford-led team of experts from several medical disciplines to write a consensus statement of expert recommendations, publishing in the May issue of Anesthesia & Analgesia, that describes best practices for CPR on a pregnant patient. The new statement is one of many examples of Stanford leadership in helping to save the lives of pregnant women around the world; our experts have also helped to develop widely-adopted protocols for dealing with massive hemorrhage during delivery and for treatment of pre-eclampsia, for example.
I asked two Stanford scientists who helped prepare the statement, lead author Steven Lipman, MD, and senior author Brendan Carvalho, MD, for their perspectives on the challenges of resuscitation in pregnancy. Both are obstetric anesthesiologists at Lucile Packard Children’s Hospital Stanford, where Carvalho is chief of obstetric anesthesia.
“The good news is that cardiac arrest in pregnancy is very rare, and also that rates of survival are higher than for the non-pregnant population,” Lipman said. Only about one in every 20,000 women with access to modern obstetric care experiences cardiac arrest while pregnant. Higher survival among pregnant patients may be partly due, he said, to the fact that many maternal cardiac arrests are witnessed: They tend to occur during labor or delivery, when the woman is already in a hospital and being closely monitored by trained medical staff who can begin CPR right away.
But rarity creates challenges. Because maternal cardiac arrests happen infrequently, obstetric caregivers have less experience in performing resuscitation than people who work in other parts of the hospital, such as the emergency room or intensive care unit. And it’s impossible to conduct randomized clinical trials – usually considered the gold standard for evidence-based medicine – on these emergencies to determine what works best.
“Also, in pregnancy, there is an asymmetry between people’s expectations and the reality of the risk,” Lipman said. “People think, ‘Oh, I’m just having my baby, it’s just natural.’ But if you look at third-world countries with no developed medical infrastructure, the rates of maternal mortality are extremely high. Yes, it’s natural and people expect an easy delivery and a healthy baby, but the reality is that it can be a risky process, and people can become critically ill very quickly.”
The physiology of pregnancy also presents challenges for resuscitation. During the second half of pregnancy, when a pregnant woman lies flat on her back, the fetus and the enlarged uterus compress the large vein that returns most of the blood to her heart. This decreases the amount of blood available to the heart and makes it harder to provide effective chest compressions in CPR. And resuscitators also must think about how to balance the needs of the mother with those of the fetus.
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