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Cardiac arrest in pregnancy: New consensus statement addresses CPR for expectant moms

pregnantbelly2When 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.

To deal with the physiologic challenges, the new consensus statement has two major recommendations. "First, we recommend left uterine displacement: in addition to the person doing chest compressions, resuscitation teams should have a separate person who pushes the uterus to the patient’s left side to relieve the pressure of the uterus on the big veins," Carvalho said. The second step is to deliver the baby, usually by C-section and as quickly as possible, ideally within 5 minutes of the cardiac arrest. This recommendation comes from an emerging recognition that fast delivery benefits both mom and baby. "There have been case reports in which women spontaneously regained their circulation after the baby was taken out, possibly because delivery relieves compression on mom’s circulatory system," Carvalho said. "Delivery improves maternal survival as well as fetal survival."

The expert recommendations also emphasize that caregivers can use the same drugs they typically give to a non-pregnant patient who has a cardiac arrest. "Caregivers are often reluctant to administer medication to pregnant women because of potential harm to the baby," Carvalho said. "But the best thing you can do for baby is to provide mom the best possible care and not withhold any drugs or procedures that would normally be used managing a critically ill person."

The consensus statement also encourages obstetric care provider teams to hone their resuscitation skills with detailed simulations, an approach that has been well studied at the hospital's Center for Advanced Pediatric and Perinatal Education. Drills conducted in the labor and delivery unit, with caregivers responding exactly as they would in a real emergency in the same location, are especially valuable ways to allow all team members to learn their roles without real patients' lives on the line. "With carefully studied simulations and drills, we've learned a lot of life lessons that have prepared us for the rare real scenarios," Carvalho said.

Previously: New approach to resuscitation training saves more kids, New preeclampsia toolkit will help prevent maternal deaths and Don't just stand there: Rap song teaches CPR to teens
Photo by bethanykphotography

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