Cardiopulmonary Resuscitation During Pregnancy
David Caro
Stephen Topp
The incidence of maternal cardiopulmonary arrest during pregnancy is estimated to occur once in every 30,000 deliveries. Events leading to cardiopulmonary arrest in the pregnant patient (Table 5.1) include those found in the general population and those related specifically to pregnancy (1,2,3,4,5,6). Maternal arrest is a dramatic and difficult situation that requires the practitioner to make rapid decisions and take defined actions in order to maximize survivability. The approach to any cardiopulmonary arrest victim, including those who are pregnant, follows a set of defined algorithms designed to maximize the likelihood of recovery in the event of a cardiopulmonary arrest (7,8).
Cardiopulmonary resuscitation (CPR) refers to the application of both basic (BLS) and advanced (ALS) life support algorithms. Both BLS and ALS follow a streamlined format designed to intervene on life-threatening disorders that could potentially be reversed. A simple and easy-to-recall starting point is to approach each unstable or cardiopulmonary arrest victim in an “ABCDE” method, which is supported by multiple life support training courses (7,8). This ABCDE method becomes the basis for resuscitative evaluation, critical decision making, and intervention.
This chapter is designed to arm the practitioner with the tools necessary to manage the critically unstable patient or cardiopulmonary arrest victim. Cardiopulmonary physiology deserves special attention, especially in light of the dramatic alterations in cardiopulmonary physiology that accompany pregnancy and the unique fetal effects associated with maternal cardiac arrest and resuscitation. Discussion will then turn to BLS and ALS techniques, including critical equipment and medications. Finally, new resuscitation modalities will be reviewed to give a glimpse into recent advances in resuscitative technology.
UNIQUE ANATOMIC AND PHYSIOLOGIC CONSIDERATIONS (SEE TABLES 5.2 AND 5.3)
Critical airway changes occur as the gravid patient approaches term. The most important is edema of the upper airway, causing a number of patients to go from a simple, straightforward laryngoscopic approach to a much more difficult one (9). The anesthesia method of analyzing airway difficulty includes the Mallampati assessment, which is a grading scale for a rapid assessment of the ease of laryngoscopy. Most women go from class 1 or 2 airways (easy intubations) to class 4 airways (most difficult intubations) by term (9). The practitioner must anticipate this during intubation attempts and have an alternative airway plan when attempting to control the airway.
The most critical respiratory concern is the contraction of maternal functional residual capacity when she nears term (9,10,11). The gravid uterus displaces abdominal contents superiorly and will encroach on the reserve of air in the lung bases. The result is lower vital capacity and lower physiologic oxygen reserve, even when fully pre-oxygenated with a nonrebreather mask for 5 to 8 minutes (9). This results in hypoxia developing more rapidly than expected and difficulty reoxygenating a pregnant patient, especially when lying flat (9).
TABLE 5.1 Common Etiologies of Cardiac Arrest During Pregnancy | ||||||||||||||||||||||||||||||||||||||||||||||
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TABLE 5.2 Alterations in Pregnancy: Airway and Respiratory Systems | ||||||||||
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TABLE 5.3 Alterations in Pregnancy: Cardiovascular System | ||||||||||||||
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Maternal blood volume increases during pregnancy and serves to protect maternal cardiovascular physiology in the face of hypovolemia (11). However, the uterine circulation is passive and dependent on normal maternal blood volume and flow, as it is in a parallel circuit with the maternal circulation (10). The gravid uterus also impacts maternal circulation by its size and weight. The uterus can compress the inferior vena cava and the distal aorta during later pregnancy. A critical maneuver to recall in the face of maternal shock or cardiac arrest is to either manually displace the uterus to the patient’s left or to roll the patient into the left lateral decubitus position. These maneuvers will serve to decompress the great vessels and augment cardiac return (1,2,3,6,10,11,12,13,14). Poor venous return from infradiaphragmatic vessels makes the femoral and saphenous sites poor choices for administering drugs and fluids during CPR (6,15), and furthermore, therapeutic resuscitation doses of vasopressors, especially α -adrenergic or combined α- and β-adrenergic agents, may produce uteroplacental vasoconstriction, thereby further compromising already diminished uteroplacental blood flow (10).
Some fetal physiologic changes are protected during maternal arrest. The oxyhemoglobin dissociation curve of fetal hemoglobin is shifted to the left when compared to maternal hemoglobin, yielding a greater oxygen saturation of fetal hemoglobin at any given partial pressure of oxygen (10,16). This enables the fetus to extract and carry a larger amount of oxygen at lower oxygen tension than the mother. The integrity of vital organs can be preserved for a limited period of time with this central redistribution of blood flow, but if asphyxia persists, such physiologic adjustments become inadequate, and neurologic damage or death of the fetus will occur (16,17).
It is also critical to remember that the best chance for fetal survival is with a resuscitated mother; however, experience with perimortem cesarean section indicates that fetal survival and neurologic outcome are best if delivery is performed within 5 minutes of maternal arrest (6,11,12,18,19). If CPR is unsuccessful,
then rapid cesarean section is the only hope for fetal viability above 24 weeks’ gestation (see Chapter 6).
then rapid cesarean section is the only hope for fetal viability above 24 weeks’ gestation (see Chapter 6).
RESUSCITATION OVERVIEW
The approach to any unstable or unresponsive patient follows the ABCDE paradigm. Each letter in the mnemonic stands for a vital system that must be evaluated in the order that is designated. Any abnormality demands immediate intervention. The ABCDEs of resuscitation help identify reversible life threats that must be dealt with before moving on to the next system or a complete history and physical examination (Table 5.4).
BASIC LIFE SUPPORT
Airway assessment in a crisis includes a quick check to hear if the patient can phonate. A phonating patient has a patent airway. Stridor, snoring, and/or gurgling respiratory sounds should raise concern that the airway is compromised. A cardiac arrest victim may have no spontaneous respirations and will then need BLS maneuvers and bag-mask ventilation to ensure airway patency. BLS airway maneuvers include the chin-lift and jaw-thrust techniques as well as the Heimlich maneuver in out-of-hospital arrest (8,20,21,22).
The chin lift consists of the use of index and long fingers to pull a supine patient’s chin toward the ceiling, thereby pulling the base of the tongue off of the hypopharynx. The jaw thrust consists of using the index and long fingers of both hands to apply anterior pressure behind both angles of the mandible to cause the same effect (9,12). Use the jaw-thrust technique if there is a concern for cervical spine trauma. Either of these maneuvers helps to alleviate airway obstruction caused by loose pharyngeal musculature. The practitioner or an assistant then applies a bag-mask device attached to a high-flow oxygen source to the patient’s face and delivers two breaths to determine if the patient has chest rise. Chest rise reassures that the airway is patent. No chest rise means that an airway obstruction is present and must be relieved; the initial maneuver would then be repositioning the airway, along with better bag-mask seal. If this is unsuccessful, then another airway-clearing maneuver should be considered.
The Heimlich maneuver consists of quick, forceful thrusts to the upper abdomen directed in a posterior/superior vector in an attempt to force air in the
lungs upward through the trachea to dislodge a foreign body. This maneuver is carried out with the rescuer standing behind a standing victim, with arms wrapped around the victim’s abdomen and hands grasped in an overlapping fist. The fists are traditionally placed at a level superior to the umbilicus but below the xiphoid process. Quick, posterior/superior pulls then are applied in an attempt to clear the airway. Alternatively, a supine patient can be straddled, hands can be clasped with fingers interlocked, and the palm heels used to create quick pushes along the same vector. A practitioner with advanced airway equipment can also perform laryngoscopy accompanied by MaGill forceps when faced with an airway obstruction, with the MaGill used to extract any foreign body encountered (9,12,22,23).
lungs upward through the trachea to dislodge a foreign body. This maneuver is carried out with the rescuer standing behind a standing victim, with arms wrapped around the victim’s abdomen and hands grasped in an overlapping fist. The fists are traditionally placed at a level superior to the umbilicus but below the xiphoid process. Quick, posterior/superior pulls then are applied in an attempt to clear the airway. Alternatively, a supine patient can be straddled, hands can be clasped with fingers interlocked, and the palm heels used to create quick pushes along the same vector. A practitioner with advanced airway equipment can also perform laryngoscopy accompanied by MaGill forceps when faced with an airway obstruction, with the MaGill used to extract any foreign body encountered (9,12,22,23).
TABLE 5.4 Immediately Reversible Life Threats | ||||||||
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