Circulation. 2005;112:IV-150-IV-153
Published online before print November 28, 2005,
doi: 10.1161/CIRCULATIONAHA.105.166570
(Circulation. 2005;112:IV-150 IV-153.)
© 2005 American Heart Association, Inc.
2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care |
Part 10.8: Cardiac Arrest Associated With Pregnancy
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Introduction
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During attempted resuscitation of a pregnant woman, providers
have two potential patients, the mother and the fetus. The best
hope of fetal survival is maternal survival. For the critically
ill patient who is pregnant, rescuers must provide appropriate
resuscitation, with consideration of the physiologic changes
due to pregnancy.
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Key Interventions to Prevent Arrest
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To treat the critically ill pregnant patient:
- Place the patient in the left lateral position (see below).
- Give 100% oxygen.
- Establish intravenous (IV) access and give a fluid bolus.
- Consider reversible causes of cardiac arrest and identify any preexisting medical conditions that may be complicating the resuscitation.
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Resuscitation of the Pregnant Woman in Cardiac Arrest
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Modifications of Basic Life Support
Several modifications to standard BLS approaches are appropriate
for the pregnant woman in cardiac arrest (
Table). At a gestational
age of 20 weeks and beyond, the pregnant uterus can press against
the inferior vena cava and the aorta, impeding venous return
and cardiac output. Uterine obstruction of venous return can
produce prearrest hypotension or shock and in the critically
ill patient may precipitate arrest.
1,2 In cardiac arrest the
compromise in venous return and cardiac output by the gravid
uterus limits the effectiveness of chest compressions. The gravid
uterus may be shifted away from the inferior vena cava and the
aorta by placing the patient 15° to 30° back from the
left lateral position (Class IIa) or by pulling the gravid uterus
to the side.
3 This may be accomplished manually or by placement
of a rolled blanket or other object under the right hip and
lumbar area. Other modifications are discussed below.
- Airway and breathing
Hormonal changes promote insufficiency of the gastroesophageal sphincter, increasing the risk of regurgitation. Apply continuous cricoid pressure during positive-pressure ventilation for any unconscious pregnant woman.
- Circulation
Perform chest compressions higher on the sternum, slightly above the center of the sternum. This will adjust for the elevation of the diaphragm and abdominal contents caused by the gravid uterus.4
- Defibrillation
Defibrillate using standard ACLS defibrillation doses (Class IIa).5 Review the ACLS Pulseless Arrest Algorithm (see Part 7.2: "Management of Cardiac Arrest"). There is no evidence that shocks from a direct current defibrillator have adverse effects on the heart of the fetus.
If fetal or uterine monitors are in place, remove them before delivering shocks.
Modifications of Advanced Cardiovascular Life Support
The treatments listed in the standard ACLS Pulseless Arrest Algorithm, including recommendations and doses for defibrillation, medications, and intubation, apply to cardiac arrest in the pregnant woman (see the Table). There are important considerations to keep in mind, however, about airway, breathing, circulation, and the differential diagnosis.
- Airway
Secure the airway early in resuscitation. Because of the potential for gastroesophageal sphincter insufficiency with an increased risk of regurgitation, use continuous cricoid pressure before and during attempted endotracheal intubation.
Be prepared to use an endotracheal tube 0.5 to 1 mm smaller in internal diameter than that used for a nonpregnant woman of similar size because the airway may be narrowed from edema.6
- Breathing
Pregnant patients can develop hypoxemia rapidly because they have decreased functional residual capacity and increased oxygen demand, so rescuers should be prepared to support oxygenation and ventilation.
Verify correct endotracheal tube placement using clinical assessment and a device such as an exhaled CO2 detector. In late pregnancy the esophageal detector device is more likely to suggest esophageal placement (the aspirating bulb does not reinflate after compression) when the tube is actually in the trachea. This could lead to the removal of a properly placed endotracheal tube.
Ventilation volumes may need to be reduced because the mothers diaphragm is elevated.
- Circulation
Follow the ACLS guidelines for resuscitation medications.
Vasopressor agents such as epinephrine, vasopressin, and dopamine will decrease blood flow to the uterus. There are no alternatives, however, to using all indicated medications in recommended doses. The mother must be resuscitated or the chances of fetal resuscitation vanish.
- Differential diagnoses. The same reversible causes of cardiac arrest that occur in nonpregnant women can occur during pregnancy. But providers should be familiar with pregnancy-specific diseases and procedural complications. Providers should try to identify these common and reversible causes of cardiac arrest in pregnancy during resuscitation attempts.7 The use of abdominal ultrasound by a skilled operator should be considered in detecting pregnancy and possible causes of the cardiac arrest, but this should not delay other treatments.
Excess magnesium sulfate. Iatrogenic overdose is possible in women with eclampsia who receive magnesium sulfate, particularly if the woman becomes oliguric. Administration of calcium gluconate (1 ampule or 1 g) is the treatment of choice for magnesium toxicity. Empiric calcium administration may be lifesaving.8,9
Acute coronary syndromes. Pregnant women may experience acute coronary syndromes, typically in association with other medical conditions. Because fibrinolytics are relatively contraindicated in pregnancy, percutaneous coronary intervention is the reperfusion strategy of choice for ST-elevation myocardial infarction.10
Pre-eclampsia/eclampsia. Pre-eclampsia/eclampsia develops after the 20th week of gestation and can produce severe hypertension and ultimate diffuse organ system failure. If untreated it may result in maternal and fetal morbidity and mortality.
Aortic dissection. Pregnant women are at increased risk for spontaneous aortic dissection.
Life-threatening pulmonary embolism and stroke. Successful use of fibrinolytics for a massive, life-threatening pulmonary embolism1113 and ischemic stroke14 have been reported in pregnant women.
Amniotic fluid embolism. Clinicians have reported successful use of cardiopulmonary bypass for women with life-threatening amniotic fluid embolism during labor and delivery.15
Trauma and drug overdose. Pregnant women are not exempt from the accidents and mental illnesses that afflict much of society. Domestic violence also increases during pregnancy; in fact, homicide and suicide are leading causes of mortality during pregnancy.6,7
Emergency Hysterotomy (Cesarean Delivery) for the Pregnant Woman in Cardiac Arrest
Maternal Cardiac Arrest Not Immediately Reversed by BLS and ACLS
The resuscitation team leader should consider the need for an emergency hysterotomy (cesarean delivery) protocol as soon as a pregnant woman develops cardiac arrest.4,1618 The best survival rate for infants >24 to 25 weeks in gestation occurs when the delivery of the infant occurs no more than 5 minutes after the mothers heart stops beating.16,1921 This typically requires that the provider begin the hysterotomy about 4 minutes after cardiac arrest.
Emergency hysterotomy is an aggressive procedure. It may seem counterintuitive given that the key to salvage of a potentially viable infant is resuscitation of the mother.6,10,2224 But the mother cannot be resuscitated until venous return and aortic output are restored. Delivery of the baby empties the uterus, relieving both the venous obstruction and the aortic compression. The hysterotomy also allows access to the infant so that newborn resuscitation can begin.
The critical point to remember is that you will lose both mother and infant if you cannot restore blood flow to the mothers heart.4,18,25,26 Note that 4 to 5 minutes is the maximum time rescuers will have to determine if the arrest can be reversed by BLS and ACLS interventions. The rescue team is not required to wait for this time to elapse before initiating emergency hysterotomy.27 Recent reports document long intervals between an urgent decision for hysterotomy and actual delivery of the infant, far exceeding the obstetrical guideline of 30 minutes.28,29
Establishment of IV access and an advanced airway typically requires several minutes. In most cases the actual cesarean delivery cannot proceed until after administration of IV medications and endotracheal intubation. Resuscitation team leaders should activate the protocol for an emergency cesarean delivery as soon as cardiac arrest is identified in the pregnant woman. By the time the team leader is poised to deliver the baby, IV access has been established, initial medications have been administered, an advanced airway is in place, and the immediate reversibility of the cardiac arrest has been determined.
Decision Making for Emergency Hysterotomy
The resuscitation team should consider several maternal and fetal factors in determining the need for an emergency hysterotomy.
- Consider gestational age. Although the gravid uterus reaches a size that will begin to compromise aortocaval blood flow at approximately 20 weeks of gestation, fetal viability begins at approximately 24 to 25 weeks. Portable ultrasonography, available in some emergency departments, may aid in determination of gestational age (in experienced hands) and positioning. However, the use of ultrasound should not delay the decision to perform emergency hysterotomy.30
Gestational age <20 weeks. Urgent cesarean delivery need not be considered because a gravid uterus of this size is unlikely to significantly compromise maternal cardiac output.
Gestational age approximately 20 to 23 weeks. Perform an emergency hysterotomy to enable successful resuscitation of the mother, not the survival of the delivered infant, which is unlikely at this gestational age.
Gestational age approximately
24 to 25 weeks. Perform an emergency hysterotomy to save the life of both the mother and the infant.
- Consider features of the cardiac arrest. The following features of the cardiac arrest can increase the infants chance for survival:
Short interval between the mothers arrest and the infants delivery19
No sustained prearrest hypoxia in the mother
Minimal or no signs of fetal distress before the mothers cardiac arrest31
Aggressive and effective resuscitative efforts for the mother
The hysterotomy is performed in a medical center with a neonatal intensive care unit
- Consider the professional setting.
Are appropriate equipment and supplies available?
Is emergency hysterotomy within the rescuers procedural range of experience and skills?
Are skilled neonatal/pediatric support personnel available to care for the infant, especially if the infant is not full term?
Are obstetric personnel immediately available to support the mother after delivery?
Advance Preparation
Experts and organizations have emphasized the importance of advance preparation.4,18,26 Medical centers must review whether performance of an emergency hysterotomy is feasible at their center, and if so, they must identify the best means of rapidly accomplishing this procedure. The plans should be made in collaboration with the obstetric and pediatric services.
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Summary
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Successful resuscitation of a pregnant woman and survival of
the fetus require prompt and excellent CPR with some modifications
in basic and advanced cardiovascular life support techniques.
By the 20th week of gestation, the gravid uterus can compress
the inferior vena cava and the aorta, obstructing venous return
and arterial blood flow. Rescuers can relieve this compression
by positioning the woman on her side or by pulling the gravid
uterus to the side. Defibrillation and medication doses used
for resuscitation of the pregnant woman are the same as those
used for other adults in pulseless arrest. Rescuers should consider
the need for emergency hysterotomy as soon as the pregnant woman
develops cardiac arrest because rescuers should be prepared
to proceed with the hysterotomy if the resuscitation is not
successful within minutes.
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Footnotes
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This special supplement to
Circulation is freely available at
http://www.circulationaha.org
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References
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