CLINICAL OBSTETRICS AND GYNECOLOGY Volume 57, Number 4, 871–881 r 2014, Lippincott Williams & Wilkins
Cardiac Arrest During Pregnancy CARLOS MONTUFAR-RUEDA, MD,* and ALFREDO GEI, MDw *Complejo Hospitalario, Caja de Seguro Social, Panama City, Panama; and w Department of Obstetrics, Gynecology and Reproductive Medicine, Division of Maternal-Fetal Medicine, University of Texas Health Science Center, Houston, Texas Abstract: Cardiac arrest is a rare event during pregnancy. The pregnant population represents a unique subset of cardiac arrest victims. Not only are there unique causes of circulatory collapse during the pregnant state, but the physiological modifications to the maternal physiology during pregnancy require specific modifications to the standard management of the arrest. Lastly, the pregnant victim presents herself with the challenges of a second patient who needs to be considered in the decision-making process. Key words: cardiac arrest, CPR, pregnancy, defibrillation, perimortem cesarean delivery
Introduction Cardiac arrest is a pathophysiological phenomenon referring to the inability of the cardiac pump to adequately maintain a minimal level of blood flow in the circulatory system. The cessation (or near cessation) of blood flow to the different systems results in tissue ischemia, hypoxia, acidosis, and cellular death. As such it is the event that typically precedes the Correspondence: Alfredo Gei, MD, Department of Obstetrics, Gynecology and Reproductive Medicine, Division of Maternal-Fetal Medicine, University of Texas Health Science Center, Houston, TX. E-mail: [email protected] The authors declare that they have nothing to disclose. CLINICAL OBSTETRICS AND GYNECOLOGY
/
death of the individual, the universal fate of all humans. Although the term suggests systole, several electrical rhythms can be associated with the pathophysiological condition we know as cardiac arrest. As women of reproductive age are not considered to be necessarily at high risk for cardiac arrest, obstetrical units are in general ill-prepared to handle these events. The pregnant population represents a specific subset of cardiac arrest victims for a variety of reasons. Not only are there unique causes of circulatory collapse during the pregnant state, but the physiological modifications to the maternal physiology during pregnancy require specific modifications to the standard management of cardiac arrest. Lastly, the pregnant victim presents herself with the challenges of a second patient who needs to be considered in the decision-making process.
Epidemiology An estimated 450,000 Americans suffer cardiac arrest each year and another 350,000 to 700,000 people in Europe.1,2 VOLUME 57
/
NUMBER 4
/
DECEMBER 2014
www.clinicalobgyn.com | 871
872
Montufar-Rueda and Gei
Despite increased education and availability of automated external defibrillators, survival rates of out-of-hospital cardiac arrests continue to decrease (2% to 5%), with improved rates reported for in-hospital cardiac arrests (B15%).3 This difference likely reflects a delay in identification and implementation of cardiopulmonary resuscitation and cardio version/defibrillation of potentially lethal arrhythmias. Most out-of-hospital cardiac arrests present with ventricular fibrillation (VF) or pulse less ventricular tachycardia (PVT). Cardiac arrest in the pregnant or postpartum woman is a rare event. Although no exact statistics are available, it is estimated to occur in 1/30,000 pregnancies.4 The most recent United Kingdom confidential enquiry reported an incidence of cardiac arrest in 1/20,000 pregnancies.5 Advances in medicine have allowed women with chronic conditions reach reproductive age.6 It has also increased the number of pregnancies in women older than 35 years.7 This has led to an increase in the number of pregnancies with morbid conditions associated with a possibility of a cardiac arrest.7 Most episodes of cardiac arrest during pregnancy are associated with events surrounding delivery secondary to conditions such as hemorrhage, eclampsia, and sepsis.3 Therefore, the out-of-hospital versus in-hospital causes of cardiac arrest vary from country to country in association with their rate of in-hospital delivery. In-hospital cardiac arrests, including among pregnant patients, have a higher frequency of nonshockable rhythms such as pulseless electrical activity (PEA) and asystole. To improve the likelihood of succeeding in the management of the cardiac arrest, it is imperative to consider the underlying cause. In addition, understanding of the physiology of the pregnant woman will improve the likelihood of success when trying to resuscitate such a patient. www.clinicalobgyn.com
Causes The most common causes of cardiac arrest during pregnancy and the postpartum period can be divided into obstetric, nonobstetric, and iatrogenic etiologies. Obstetric causes include preeclampsia/ eclampsia, anaphylactoid syndrome of pregnancy (amniotic fluid embolism), massive obstetric hemorrhage, and peripartum cardiomyopathy. In general, the most common causes of cardiac arrest are thromboembolism, preeclampsia/eclampsia, sepsis, trauma, obstetric hemorrhage (antepartum and postpartum), stroke, asthma, anesthetic complications, preexisting chronic (mostly cardiac or pulmonary) disease, and amniotic fluid embolism.8 The conditions that may complicate pregnancy causing severe maternal morbidity and possibly mortality differ between developing and developed countries. In the United States, the most frequent cause of cardiac arrest during pregnancy is thromboembolic disease.9 However, in developing countries the main causes of cardiac arrest leading to maternal death are hemorrhage and preeclampsia.3 Among preeclamptic patients there is a stronger association with maternal mortality in the setting of hemolysis, elevated liver enzymes, and low platelet count syndrome (HELLP syndrome).10 The syndrome of amniotic fluid embolism is a rare but important cause of obstetric circulatory collapse and cardiac arrest associated with a high mortality.5 It is responsible for about 10% of maternal deaths in the United States11 and 8.4% in the United Kingdom.12 Another important cause of maternal death is severe obstetric hemorrhage, the most common form of which is uterine atony.13 The resuscitation of these patients involves basic and advanced life support, as well as fluid resuscitation/ blood transfusion to restore intravascular volume, oxygen carrying capacity, and tissue perfusion.
Cardiac Arrest and Pregnancy TABLE 1.
873
Causes of Maternal Mortality
Obstetrical
Medical
Iatrogenic
Postpartum hemorrhage Antepartum hemorrhage Amniotic fluid embolism Obstetrical sepsis Eclampsia Peripartum cardiomyopathy
Heart failure or cardiac decompensation Pulmonary hypertension No-Obstetrical sepsis Aspiration pneumonitis Venous thromboembolism Trauma Pulmonary edema Acute myocardial infarction Status asthmaticus Anaphylaxis Aortic dissection
Anesthesia complication Magnesium toxicity Anaphylaxis
Among nonobstetric causes, the most common are pulmonary embolism, sepsis, preexisting cardiac conditions, and cerebrovascular accidents.5 Cardiac disorders leading to cardiac arrest during pregnancy and the postpartum period include myocardial infarction, aortic dissection, peripartum cardiomyopathy, arrhythmias, and pulmonary hypertension.5 Iatrogenic causes include anesthetic complications and magnesium sulfate toxicity. Complications associated with anesthesia have been reported both in general anesthesia (failed intubation, failure to oxygenate) and regional anesthesia (vagal effect by sympathetic blockade leading to severe bradycardia).5,14 It is estimated that more than half of the episodes of cardiac arrest caused by the administration of regional anesthesia are secondary to the direct effects of anesthetic drugs.15 Most causes of cardiac or near cardiac arrest mediate through potentially reversible causes if they are timely recognized and properly handled. The latter include the 5 Hs and the 5 Ts: hypovolemia, hypoxia, acidosis, hypokalemia and hyperkalemia, hypothermia, hypoglycemia (Hs), and trauma, cardiac tamponade, tension pneumothorax, thrombosis, and drug toxicity (Ts).16 These predisposing conditions need to be considered in the management of cardiac arrest as specific treatments might increase the likelihood
of success of resuscitation. Table 1 summarizes the most common causes of cardiac arrest during pregnancy.
Effects of Pregnancy on Cardiopulmonary Resuscitation (CPR) In general, the protocols established for the patient in cardiac arrest are the same for nonobstetric and the pregnant/postpartum patient. However, during pregnancy several physiological changes have implications for the management of cardiac arrest. The most important cardiovascular changes to consider include: an increase in cardiac output of 30% to 50%; an increase in myocardial oxygen consumption; a decrease in systemic vascular resistance; and a decrease in plasma oncotic pressure. There is an increase in the proportion of cardiac output supplied to the uterus from B2% in the nonpregnant state to B20% to 30% during pregnancy.17 An important physiological modification to consider during the resuscitation of cardiac arrest in a pregnant woman is the aorto-caval compression caused by the increase in the volume and weight of the uterus.18,19 Because of the differences in the thickness of these blood vessels (inferior vena cava and descending aorta) and the relative pressure between www.clinicalobgyn.com
874
Montufar-Rueda and Gei
venous and arterial systems, the venous return tends to be more compromised than the systemic perfusion. This aorto-caval compression is the most influential phenomenon in CPR in the pregnant woman. During chest compressions it is estimated that only 30% of the cardiac output is preserved. Because of decrease in venous return with the pregnant patient supine it has been estimated that only 10% of the cardiac output is being delivered through effective chest compressions. Consequently, during pregnancy, administration of chest compressions is more efficient with the patient’s abdomen on a side slope toward the left. One study showed that the effort made by a rescuer to perform chest compressions in a pregnant woman is decreased to 67% in the supine position and 37% if the pregnant patient is in full lateral position. With an inclination angle of 27 degrees the force rescuer can reach 80%.20 Respiratory changes include an increase in minute ventilation with a mild respiratory alkalosis and a 20% reduction in the functional residual capacity. This change makes the pregnant woman more susceptible to hypoxemia. The upward displacement of the diaphragm of approximately 4 cm causes a decrease in the thoracic compliance. During the approach to a cardiac arrest in an obstetric patient, it is important to take into account other physiological changes such as congestion and edema of the nasal cavity and upper airway resulting in more difficult endotracheal intubation.1 Failed intubation is 8 times more frequent in pregnant than in nonobstetric patients.21 Pregnant women have also an increased risk for gastroesophageal regurgitation and aspiration.17 Given these considerations, it is important to choose smaller endotracheal tubes (size 6) compared with those in a nonpregnant adult. Only experienced practitioners should attempt endotracheal intubation during cardiac arrest. www.clinicalobgyn.com
To support their physiological functions and the demands of the growing fetus, pregnant women have an increase in their oxygen consumption. They also maintain a ‘‘normal’’ state of respiratory alkalosis secondary to the loss of CO2 by an increase in minute ventilation promoting the fetal unload of CO2.
CPR The chain of survival in a cardiac arrest event includes early recognition, activation of the emergency system, early CPR based on continuous chest compressions, rapid defibrillation, advanced life support care, and postcardiac arrest management. Obstetrical units should be prepared for appropriate resuscitation of the mother and newborn including code cart equipment (adult and newborn) as well as instruments for perimortem cesarean section and education of the personnel in advanced life support techniques. The chances of a successful resuscitation in cardiac arrest secondary to VF or PVT are based on effective chest compressions and early defibrillation. The management of other cardiac arrest rhythms such as PEA and asystole is based on adequate CPR and administration of vasoactive drugs. Identification of any reversible causes (Ts and Hs discussed previously) is of paramount importance. Unlike the previous sequence proposed by the American Heart Association in 2005 (ABC for Airway-Breathing-Circulation), the current recommendations propose beginning resuscitation with chest compressions in a CAB sequence (AHA 2010). The study by Bobrow et al22 (in a nonpregnant population) demonstrated that chest compressiononly CPR was associated with a significant increase in the survival rate of bystander CPR for adults who experienced outof-hospital cardiac arrest. Furthermore, chest compression-only CPR was independently associated with increased
Cardiac Arrest and Pregnancy rate of survival compared with no bystander CPR or conventional CPR. Cardio-cerebral resuscitation makes emphasis on a constant blood flow to the heart and brain by continuous chest compressions. Basic life support begins with an acknowledgment that the victim is either not breathing or not doing so normally. Activation of the emergency system (in or out of hospital) needs to occur at this time. Then, after proper positioning of the victim, chest compressions need to be initiated at a rate of at least 100/min with minimal interruptions (24 wk), are aggressive airway management, left lateralization of the uterus, caution in the use of bicarbonate, and consideration of a perimortem cesarean delivery.
875
During resuscitation, early control of the airway should be obtained and supplemental oxygen should be administered at 100%. This is important because of the difficulty of the pregnant woman and the fetus to manage hypoxemic states and the high risk for aspiration. Endotracheal intubation is the optimal method for maintaining a patent and secure airway. Early intubation is recommended if experienced providers are available. Bag valve mask ventilation with supplemental oxygen (if available) is recommended before intubation attempts because of the faster trend to desaturation in pregnant women.9 It is estimated that endotracheal intubation takes an average duration of 47 seconds.24 One third of these procedures last more than a minute, and a quarter exceed 3 minutes.24 These interruptions are considered lethal to a patient in cardiopulmonary arrest, and intubation should be ideally performed after the return of spontaneous circulation (ROSC) if no trained personnel is immediately available. In the latter situation, the patient will be better served with ventilation with a bag mask device. When an advanced airway (endotracheal tube) is obtained, ventilation should be performed every 6 to 8 seconds, which equals 8 to 10 breaths/min independently of chest compressions. In the resuscitation of a pregnant patient, the pressure applied on the cricoid cartilage (Sellick maneuver) during intubation to decrease the risk for aspiration is accepted. As in episodes of hypoventilation, hyperventilation cause harmful effects. Hyperventilation increases intrathoracic pressure and decreases venous return; in addition, hyperventilation may decrease cerebral blood flow.25 To achieve aorto-caval decompression, the gravid uterus should be deflected to the left; several options are available. It may be leaning toward the left to the patient by placing pillows or sheets on the right hip. Another way is that a www.clinicalobgyn.com
876
Montufar-Rueda and Gei
rescuer performs the function of a ‘‘human wedge’’ kneeling on the floor behind the back of the patient. The use of a tool specifically designed to displace the uterus laterally (Cardiff wedge) may also be considered. The most practical is the simple manual uterine deviation to the left side by a member of the rescuer team.26 Given that CPR is more easily performed in the supine position and that adequate wedges are not commonly available, it is reasonable to begin CPR with manual leftward uterine displacement and proceed to a 27-degree wedge if CPR is ineffective. Heart rates of in-hospital arrests tend to be nonshockable rhythms (PEA and asystole). In these cases, once the defibrillator/monitor identifies a nonshockable rhythm, CPR should be resumed with the cycles of compressions/ventilations at a 30:2 ratio as recommended by the latest AHA guidelines. If during resuscitation the heart rhythm changes to PVF/VF, the patient should be
defibrillated. After the brief interruption associated with defibrillation of a shockable rhythm (VF and PVT), chest compressions and ventilations need to be resumed at rates of at least 100/min and 6 to 8/min, respectively. In either case it is important to consider and correct the factors that lead to cardiac arrest (Hs and Ts). Figures 1–3 depict the initial steps in the management of cardiac arrest during pregnancy.
Vasopressors The purpose of the use of vasopressors in cardiac arrest is to increase the perfusion pressure of the heart and brain. This would help achieve ROSC and improve the chances of an intact neurological survival. The AHA 2010 guidelines recommend administering 1 mg epinephrine intravenously (IV) or intraosseous every 3 to 5 minutes during advanced life support.
FIGURE 1. Flowchart of Intra and Postpartum maternal collapse.
www.clinicalobgyn.com
Cardiac Arrest and Pregnancy
877
FIGURE 2. Flowchart management in cardiac arrest secondary to obstetric hemorrhage.
FIGURE 3. Flowchart of antepartum maternal collapse.
www.clinicalobgyn.com
878
Montufar-Rueda and Gei
However, no clinical studies have shown that the use of epinephrine improves longterm survival. Jacobs et al28 found equal rate of survival (to hospital discharge) with or without epinephrine (5.1% vs. 5.0%). A Swedish study, in which 42% of the 10,966 patients who had suffered a cardiac arrest received epinephrine, found that use of vasopressor drugs did not improve survival.29 A study by Olasveengen et al30 showed an increase in ROSC with epinephrine (24% vs. 8%), and higher (but no significant) differences in survival to hospital discharge (4% vs. 2%). Although there are animal studies that suggest that a dose of epinephrine of 0.045 mg/kg is required for a good myocardial perfusion and to achieve ROSC, the 2010 AHA resuscitation guidelines still recommend the use of 1 mg.31 Vasopressin does not have a direct effect on myocardial contractility but increases blood flow to vital organs. In advanced cardiac life support 40 U vasopressin can be administered as an alternative for either the first or second doses of epinephrine.27 To date no superiority has been demonstrated between vasopressin and epinephrine in terms of survival to hospital discharge, rates of ROSC, or neurological integrity of cardiac arrest survivors.32–35 There are differences in opinion as of what is the optimum time for the administration of vasopressors during CPR. The AHA guidelines recommend epinephrine administration after at least 1 shock and 2 minutes of CPR,27 whereas the European Resuscitation Council guidelines recommend it immediately after the third shock.36 There are no studies with sufficient power, showing that the administration of a vasopressor for the treatment of PVT, VF, pulseless electric activity, or asystole improves survival. The use of epinephrine may even be associated with more postarrest cardiac and neurological dysfunction. www.clinicalobgyn.com
Other Considerations Bicarbonate use is not recommended during cardiac arrest resuscitation. It has not been associated with improved outcomes except in special circumstances such as tricyclic or sodium channel blocker overdoses. The Heimlich maneuver for the expulsion of foreign bodies lodged in the upper airway should be used with caution in advanced pregnancies (>24 wk), as it is less effective and may even cause uterine rupture.37 It may be performed providing pressure in the sternum as opposed to the abdomen. There are no data to support a change in defibrillation patterns recommended in the current advanced cardiac life support for pregnant or postpartum patients.38 Likewise, the indications for defibrillation remain in the rhythms of ventricular tachycardia and VF.23
Antiarrhythmics Lidocaine is a local anesthetic that has an antiarrhythmic action by increasing the threshold for electrical stimulation during ventricular diastole. Lidocaine is less successful in producing ROSC when compared with amiodarone. The study of Dorian et al39 concluded that amiodarone leads to a substantially higher rate of survival to hospital discharge in patients with shockresistant VF compared with lidocaine, but the final outcomes were not different. The AHA recommends the use of amiodarone for VF or PVT that is unresponsive to CPR, shock, and/or a vasopressor. This drug is first given as a dose of 300 mg IV, which can be followed with a second dose of 150 mg IV after 5 minutes. AHA recommends lidocaine as an alternative to amiodarone. Lidocaine must be administered as an initial dose of 1.0 to 1.5 mg/kg IV, followed by 0.5 to 0.75 mg/kg IV push, at 5-minute intervals if VF or PVT persist (maximum dose 3 mg/kg). Similarly to vasopressors, no antiarrhythmic has been
Cardiac Arrest and Pregnancy showed to improve outcomes in patients with cardiac arrest.
Perimortem Cesarean Delivery Caesarean section during CPR of a pregnant patient aims to improve maternal outcomes during resuscitation and increase the chances of neonatal survival with minimal neurological damage.16 The benefits of a perimortem cesarean delivery are mainly aimed at relieving uterine-mediated inferior vena cava compression (mostly among pregnancies beyond 20 wk of gestation).40–42 Katz and colleagues assessed neonatal outcomes in a group of patients undergoing perimortem cesarean sections and found successful outcomes for both mother and neonate in some cases. This finding supported the concept of performing perimortem cesarean section as part of CPR in the pregnant patient.43 Studies have shown that fetal neurological damage starts about 5 minutes after the cessation of blood flow, although infants in good neurological status have been delivered after up to 30 minutes of cardiac arrest.43 A perimortem cesarean section should be considered after 20 weeks of gestation if no return of pulse is noticed after 4 to 5 minutes of CPR.
Postcardiac Arrest Care The postcardiac arrest syndrome comprises brain injury, myocardial dysfunction, and systemic response to ischemia/ reperfusion.44 Postcardiac arrest care includes treatment with induced hypothermia, optimization of ventilation and circulation, coronary reperfusion, glycemic control, and neurological care. There is evidence that the use of mild hypothermia (32 to 341C) induced in comatose patients who survived an out-of-hospital cardiac arrest caused by VF/PVT improves survival and neurological outcomes.45,46
879
The 2010 AHA resuscitation guidelines recommend considering the use of induced hypothermia in patients with ROSC after cardiac arrest regardless of the initial rhythm or location of the arrest despite the fact that most of the evidence is limited to patients with out-of-hospital arrests with initial shockable rhythms. Oxygen should be administered to maintain arterial oxygen saturation close to 94%. High oxygen concentrations should be avoided as they may worsen ischemia reperfusion injuries (100% oxygen is not usually required and may be harmful). There is no evidence to establish specific values of PCO2; however, it is recommended to maintain normocapnia (PaCO2 40 to 45 mm Hg). After cardiac arrest a systemic inflammatory response with profound vasodilation and cardiac stunning is common. The latter frequently requires treatment with fluids, vasopressors, and inotropes to maintain a mean arterial blood pressure of 65 mm Hg.44 In patients with high suspicion of coronary artery disease or diagnosis of a myocardial infarction with ST elevation, coronary angiography should be performed without delay.48 It has been shown that hyperglycemia causes an increase in morbidity and mortality when present in patients with acute critical pathology. On the basis of available data, blood glucose levels should be maintained after ROSC between 140 and 180 mg/dL.49 Severe hypoglycemia should also be avoided.50,51 Seizures may occur in up to 10% to 40% of patients who survive a cardiac arrest. When diagnosed, seizures should be treated aggressively to decrease the risk of ongoing brain injury.52
Summary Cardiac arrest is a rare event during pregnancy. All obstetrical units should be prepared for such a devastating event. Personnel should be trained periodically www.clinicalobgyn.com
880
Montufar-Rueda and Gei
in the management of arrest, and algorithms specific for pregnant victims should be widely available. Obstetrical providers should play a primary role in the management of these patients as certain interventions such as a perimortem cesarean section may be required early in the resuscitation process.
References 1. Callans DJ. Out-of-hospital cardiac arrest-the solution is shocking. N Engl J Med. 2004;351:632–634. 2. Sans S, Kesteloot D, Kromhout D. The burden of cardiovascular diseases mortality in Europe. Task Force of the European Society of Cardiology on Cardiovascular Mortality and Morbidity Statistics in Europe. Eur Heart J. 1997;18:1231–1248. 3. Schneider AP II, Nelson DJ, Brow DD. In-hospital cardiopulmonary resuscitation: a 30-year review. J Am Board Fam Pract. 1993;6:91–101. 4. Brace V, Penney G, Hall M. Quantifying severe maternal morbidity: a Scottish population study. BJOG. 2004;111:481–484. 5. Lewis G. Saving mothers’ lives reviewing maternal deaths to make motherhood safer-2003-2005: the seventh report of confidential enquiries into Maternal Deaths in the United Kingdom. CEMACH 2007. Available at: www.cemach.org.uk. 6. Berg CJ, MacKay AP, Qin C, et al. Overview of maternal morbidity during hospitalization for labor and delivery in the United States. Obstet Gynecol. 2009;113:1075–1081. 7. Mathews TJ, Hamilton BE. Delayed childbearing: more women are having their first child later in life. NCHS Data Brief. 2009;21:1–8. 8. Farinelli CK, Hameed AB. Cardiopulmonary resuscitation in pregnancy. Cardiol Clin. 2012;30: 453–461. 9. Atta E, Gardner M. Cardiopulmonary resuscitation in pregnancy. Obstet Gynecol Clin North Am. 2007;34:585–597. 10. Chhabra S, Kakani A. Maternal mortality due to eclamptic and noneclamptic hypertensive disorders: a challenge. J Obstet Gynaecol. 2007;27:25–29. 11. Clark SL, Hanskins GD, Dudle DA, et al. Amniotic fluid embolism: analysis of the national registry. Am J Obstet Gynecol. 1995;172:1158–1167. 12. Tuffnell DJ. United Kingdom amniotic fluid embolism register. BJOG. 2005;112:1625–1629. 13. Montufar-Rueda C, Rodriguez L, Jarquin JD, et al. Severe postpartum hemorrhage from uterine atony: a multicentric study. J Pregnancy. 2013; 2013:525914. 14. Joseph KS, Liu S, Rouleau J, Maternal Health Study Group of the Canadian Perinatal
www.clinicalobgyn.com
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
Surveillance System Severe maternal morbidity in Canada, 2003 to 2007: surveillance using routine hospitalization data and ICD-10CA codes. Available at: www.cemach.org.uk. Arendt KW, Segal S. Present and emerging strategies for reducing anesthesia-related maternal morbidity and mortality. Curr Opin Anaesthesiol. 2009;22:330–335. Maternal Collapse in Pregnancy and Puerperium. RCOG Green-top Guideline No 56. January 2011. Available at: www.cemach.org.uk. Malampalli A, Powner DJ, Gardner M. CPR and somatic support of the pregnant patient. Crit Care Clin. 2004;20:747–763. DoanWiggins L. Resuscitation of the pregnant patient suffering sudden death. In: Paradis NA, Halperin HR, Nowak RM eds. Cardiac Arrest and Practice of Resuscitation Medicine. Baltimore, MD: Williams & Wilkins;1997:812–819. Kerr MG. The mechanical effects of the gravid uterus in late pregnancy. J Obstet Gynaecol Br Commonw. 1965;72:513–529. Rees GA, Willis BA. Bioimpedance measurement of cardiac output. Eur J Obstet Gynecol Reprod Biol. 1990;36:11–17. Barnardo PD, Jenkins JG. Failed tracheal intubation in obstetrics: a 6-year review in a UK region. Anaesthesia. 2002;55:690–694. Bobrow BJ, Spaite DW, Berg RA, et al. Chest compression-only CPR by Lay Rescuers and Survival from out-of-hospital cardiac arrest. JAMA. 2010;304:1447–1454. ECC Committee, Subcommittes and Task Forces of the American Heart Association. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010;122: S640–S861. Wang HE, Simeone SJ, Weaver MD, et al. Interruptions in cardiopulmonary resuscitation from paramedic endotracheal intubation. Ann Emerg Med. 2009;54:645–652. Yannopoulos D, Nadkarni VM, McKnite SH, et al. Intrathoracic pressure regulator during continuous-chest-compression advanced cardiac resuscitation improves vital organ perfusion pressures in a porcine model of cardiac arrest. Circulation. 2005;112:803–811. Goodwin AP, Pearce AJ. The human wedge. A maneuver to relieve aortocaval compression during resuscitation in late pregnancy. Anaesthesia. 1992;47:433–434. Neumar RW, Otto CW, Link MS, et al. Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010;122 (suppl 3):S729–S767.
Cardiac Arrest and Pregnancy 28. Jacobs IG, Finn JC, Felinek GA, et al. Effect of adrenaline on survival in out-of-hospital cardiac arrest: a randomised double´-blind placebocontrolled trial. Resuscitation. 2011;82:1138–1143. 29. Holmberg M, Holmberg S, Herlitz J. Low chance of survival among patients requiring adrenaline (epinephrine) or intubation after out-of-hospital cardiac arrest in Sweden. Resuscitation. 2002;4: 37–45. 30. Olasveengen TM, Sunde K, Brunborg C, et al. Intravenous drug administration during outof-hospital cardiac arrest: a randomized trial. JAMA. 2009;302:2222–2229. 31. Lindner KH, Ahnefeld FW, Bowdler IM. Comparison of different doses of epinephrine on myocardial perfusion and resuscitation success during cardiopulmonary resuscitation in a pig model. Am J Emerg Med. 1991;9:27–31. 32. Wenzel V, Krismer AC, Arntz HR, et al. European Resuscitation Council Vasopressor during cardiopulmonary resuscitation Study Group. A comparison of vasopressin and epinephrine for out-of-hospital cardiopulmonary resuscitation. N Engl J Med. 2004;350:105–113. 33. Stiell IG, Hebert PC, Wells GA, et al. Vasopressin versus epinephrine for inhospital cardiac arrest: a randomised controlled trial. Lancet. 2001;358:105–109. 34. Aung K, Htay T. Vasopressin for cardiac arrest: a systematic review and meta-analysis. Arch Intern Med. 2005;165:17–24. 35. Metzelopoulos SD, Zakynthinos SG, Siempos I, et al. Vasopressin for cardiac arrest; meta-analysis of randomized controlled trials. Resuscitation. 2012;83:32–39. 36. Deakin CD, Nolan JP, Soar J, et al. European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support. Resuscitation. 2010;81:1305–1352. 37. Whitty JE. Maternal cardiac arrest in pregnancy. Clin Obstet Gynecol. 2002;45:377–392. 38. Nanson J, Elcock D, Williams M, et al. Do physiological changes in pregnancy change defibrillation energy requirements? Br J Anaesth. 2001;87:237–239. 39. Dorian P, Cass D, Schwartz B, et al. Amiodarone as compared with Lidocaine for shock-resistant ventricular fibrillation. N Engl J Med. 2001;346:884–890. 40. Katz VL, Cefalo RC. History and evolution of cesarean delivery. In: Phelan JP, Clark SL eds. Cesarean Delivery. New York: Elsevier;1988:1.
881
41. Weber CE. Postmortem cesarean section: review of the literature and case reports. Am J Obstet Gynecol. 1971;110:158–165. 42. Hayden FJ. Maternal mortality in history and today. Med J Aust. 1970;1:100–109. 43. Katz VL, Dotters DJ, Droegmueller W. Perimortem cesarean delivery. Obstet Gynecol. 1986;68: 571–576. 44. Nolan JP, Neumar RW, Adrie C, et al. Post-cardiac arrest syndrome: epidemiology, pathophysiology, treatment, and prognostication. A Scientific Statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke. Resuscitation. 2008;79: 350–379. 45. Gunn AJ, Thoresen M. Hypothermic neuroprotection. NeuroRx. 2006;3:154–169. 46. Froehler MT, Geocadin RG. Hypothermia for neuroprotection after cardiac arrest: mechanisms, clinical trials and patient care. J Neurol Sci. 2007;261:118–126. 47. Hazinski MF, Nolan JP, Billi BW, et al. Part 1: Executive summary: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2010;122 (suppl):S250–S275. 48. Spaulding CM, Joly LM, Rosenberg A, et al. Immediate coronary angiography in survivors of out-of-hospital cardiac arrest. N Engl J Med. 1997;336:1629–1633. 49. Padkin A. Glucose control after cardiac arrest. Resuscitation. 2009;80:611–612. 50. Krinsley JS, Grover A. Severe hypoglycemia in critically ill patients: risk factors and outcomes. Crit Care Med. 2007;35:2262–2267. 51. Cerchiari EL, Safar P, Klein E, et al. Visceral, hematologic and bacteriologic changes and neurologic outcome after cardiac arrest in dogs. The visceral post-resuscitation syndrome. Resuscitation. 1993;25:119–136. 52. Snyder BD, Hauser WA, Loewenson RB, et al. Neurologic prognosis after cardiopulmonary arrest, III: seizure activity. Neurology. 1980;30: 1292–1297.
www.clinicalobgyn.com
Cardiac Arrest During Pregnancy CARLOS MONTUFAR-RUEDA, MD,* and ALFREDO GEI, MDw *Complejo Hospitalario, Caja de Seguro Social, Panama City, Panama; and w Department of Obstetrics, Gynecology and Reproductive Medicine, Division of Maternal-Fetal Medicine, University of Texas Health Science Center, Houston, Texas Abstract: Cardiac arrest is a rare event during pregnancy. The pregnant population represents a unique subset of cardiac arrest victims. Not only are there unique causes of circulatory collapse during the pregnant state, but the physiological modifications to the maternal physiology during pregnancy require specific modifications to the standard management of the arrest. Lastly, the pregnant victim presents herself with the challenges of a second patient who needs to be considered in the decision-making process. Key words: cardiac arrest, CPR, pregnancy, defibrillation, perimortem cesarean delivery
Introduction Cardiac arrest is a pathophysiological phenomenon referring to the inability of the cardiac pump to adequately maintain a minimal level of blood flow in the circulatory system. The cessation (or near cessation) of blood flow to the different systems results in tissue ischemia, hypoxia, acidosis, and cellular death. As such it is the event that typically precedes the Correspondence: Alfredo Gei, MD, Department of Obstetrics, Gynecology and Reproductive Medicine, Division of Maternal-Fetal Medicine, University of Texas Health Science Center, Houston, TX. E-mail: [email protected] The authors declare that they have nothing to disclose. CLINICAL OBSTETRICS AND GYNECOLOGY
/
death of the individual, the universal fate of all humans. Although the term suggests systole, several electrical rhythms can be associated with the pathophysiological condition we know as cardiac arrest. As women of reproductive age are not considered to be necessarily at high risk for cardiac arrest, obstetrical units are in general ill-prepared to handle these events. The pregnant population represents a specific subset of cardiac arrest victims for a variety of reasons. Not only are there unique causes of circulatory collapse during the pregnant state, but the physiological modifications to the maternal physiology during pregnancy require specific modifications to the standard management of cardiac arrest. Lastly, the pregnant victim presents herself with the challenges of a second patient who needs to be considered in the decision-making process.
Epidemiology An estimated 450,000 Americans suffer cardiac arrest each year and another 350,000 to 700,000 people in Europe.1,2 VOLUME 57
/
NUMBER 4
/
DECEMBER 2014
www.clinicalobgyn.com | 871
872
Montufar-Rueda and Gei
Despite increased education and availability of automated external defibrillators, survival rates of out-of-hospital cardiac arrests continue to decrease (2% to 5%), with improved rates reported for in-hospital cardiac arrests (B15%).3 This difference likely reflects a delay in identification and implementation of cardiopulmonary resuscitation and cardio version/defibrillation of potentially lethal arrhythmias. Most out-of-hospital cardiac arrests present with ventricular fibrillation (VF) or pulse less ventricular tachycardia (PVT). Cardiac arrest in the pregnant or postpartum woman is a rare event. Although no exact statistics are available, it is estimated to occur in 1/30,000 pregnancies.4 The most recent United Kingdom confidential enquiry reported an incidence of cardiac arrest in 1/20,000 pregnancies.5 Advances in medicine have allowed women with chronic conditions reach reproductive age.6 It has also increased the number of pregnancies in women older than 35 years.7 This has led to an increase in the number of pregnancies with morbid conditions associated with a possibility of a cardiac arrest.7 Most episodes of cardiac arrest during pregnancy are associated with events surrounding delivery secondary to conditions such as hemorrhage, eclampsia, and sepsis.3 Therefore, the out-of-hospital versus in-hospital causes of cardiac arrest vary from country to country in association with their rate of in-hospital delivery. In-hospital cardiac arrests, including among pregnant patients, have a higher frequency of nonshockable rhythms such as pulseless electrical activity (PEA) and asystole. To improve the likelihood of succeeding in the management of the cardiac arrest, it is imperative to consider the underlying cause. In addition, understanding of the physiology of the pregnant woman will improve the likelihood of success when trying to resuscitate such a patient. www.clinicalobgyn.com
Causes The most common causes of cardiac arrest during pregnancy and the postpartum period can be divided into obstetric, nonobstetric, and iatrogenic etiologies. Obstetric causes include preeclampsia/ eclampsia, anaphylactoid syndrome of pregnancy (amniotic fluid embolism), massive obstetric hemorrhage, and peripartum cardiomyopathy. In general, the most common causes of cardiac arrest are thromboembolism, preeclampsia/eclampsia, sepsis, trauma, obstetric hemorrhage (antepartum and postpartum), stroke, asthma, anesthetic complications, preexisting chronic (mostly cardiac or pulmonary) disease, and amniotic fluid embolism.8 The conditions that may complicate pregnancy causing severe maternal morbidity and possibly mortality differ between developing and developed countries. In the United States, the most frequent cause of cardiac arrest during pregnancy is thromboembolic disease.9 However, in developing countries the main causes of cardiac arrest leading to maternal death are hemorrhage and preeclampsia.3 Among preeclamptic patients there is a stronger association with maternal mortality in the setting of hemolysis, elevated liver enzymes, and low platelet count syndrome (HELLP syndrome).10 The syndrome of amniotic fluid embolism is a rare but important cause of obstetric circulatory collapse and cardiac arrest associated with a high mortality.5 It is responsible for about 10% of maternal deaths in the United States11 and 8.4% in the United Kingdom.12 Another important cause of maternal death is severe obstetric hemorrhage, the most common form of which is uterine atony.13 The resuscitation of these patients involves basic and advanced life support, as well as fluid resuscitation/ blood transfusion to restore intravascular volume, oxygen carrying capacity, and tissue perfusion.
Cardiac Arrest and Pregnancy TABLE 1.
873
Causes of Maternal Mortality
Obstetrical
Medical
Iatrogenic
Postpartum hemorrhage Antepartum hemorrhage Amniotic fluid embolism Obstetrical sepsis Eclampsia Peripartum cardiomyopathy
Heart failure or cardiac decompensation Pulmonary hypertension No-Obstetrical sepsis Aspiration pneumonitis Venous thromboembolism Trauma Pulmonary edema Acute myocardial infarction Status asthmaticus Anaphylaxis Aortic dissection
Anesthesia complication Magnesium toxicity Anaphylaxis
Among nonobstetric causes, the most common are pulmonary embolism, sepsis, preexisting cardiac conditions, and cerebrovascular accidents.5 Cardiac disorders leading to cardiac arrest during pregnancy and the postpartum period include myocardial infarction, aortic dissection, peripartum cardiomyopathy, arrhythmias, and pulmonary hypertension.5 Iatrogenic causes include anesthetic complications and magnesium sulfate toxicity. Complications associated with anesthesia have been reported both in general anesthesia (failed intubation, failure to oxygenate) and regional anesthesia (vagal effect by sympathetic blockade leading to severe bradycardia).5,14 It is estimated that more than half of the episodes of cardiac arrest caused by the administration of regional anesthesia are secondary to the direct effects of anesthetic drugs.15 Most causes of cardiac or near cardiac arrest mediate through potentially reversible causes if they are timely recognized and properly handled. The latter include the 5 Hs and the 5 Ts: hypovolemia, hypoxia, acidosis, hypokalemia and hyperkalemia, hypothermia, hypoglycemia (Hs), and trauma, cardiac tamponade, tension pneumothorax, thrombosis, and drug toxicity (Ts).16 These predisposing conditions need to be considered in the management of cardiac arrest as specific treatments might increase the likelihood
of success of resuscitation. Table 1 summarizes the most common causes of cardiac arrest during pregnancy.
Effects of Pregnancy on Cardiopulmonary Resuscitation (CPR) In general, the protocols established for the patient in cardiac arrest are the same for nonobstetric and the pregnant/postpartum patient. However, during pregnancy several physiological changes have implications for the management of cardiac arrest. The most important cardiovascular changes to consider include: an increase in cardiac output of 30% to 50%; an increase in myocardial oxygen consumption; a decrease in systemic vascular resistance; and a decrease in plasma oncotic pressure. There is an increase in the proportion of cardiac output supplied to the uterus from B2% in the nonpregnant state to B20% to 30% during pregnancy.17 An important physiological modification to consider during the resuscitation of cardiac arrest in a pregnant woman is the aorto-caval compression caused by the increase in the volume and weight of the uterus.18,19 Because of the differences in the thickness of these blood vessels (inferior vena cava and descending aorta) and the relative pressure between www.clinicalobgyn.com
874
Montufar-Rueda and Gei
venous and arterial systems, the venous return tends to be more compromised than the systemic perfusion. This aorto-caval compression is the most influential phenomenon in CPR in the pregnant woman. During chest compressions it is estimated that only 30% of the cardiac output is preserved. Because of decrease in venous return with the pregnant patient supine it has been estimated that only 10% of the cardiac output is being delivered through effective chest compressions. Consequently, during pregnancy, administration of chest compressions is more efficient with the patient’s abdomen on a side slope toward the left. One study showed that the effort made by a rescuer to perform chest compressions in a pregnant woman is decreased to 67% in the supine position and 37% if the pregnant patient is in full lateral position. With an inclination angle of 27 degrees the force rescuer can reach 80%.20 Respiratory changes include an increase in minute ventilation with a mild respiratory alkalosis and a 20% reduction in the functional residual capacity. This change makes the pregnant woman more susceptible to hypoxemia. The upward displacement of the diaphragm of approximately 4 cm causes a decrease in the thoracic compliance. During the approach to a cardiac arrest in an obstetric patient, it is important to take into account other physiological changes such as congestion and edema of the nasal cavity and upper airway resulting in more difficult endotracheal intubation.1 Failed intubation is 8 times more frequent in pregnant than in nonobstetric patients.21 Pregnant women have also an increased risk for gastroesophageal regurgitation and aspiration.17 Given these considerations, it is important to choose smaller endotracheal tubes (size 6) compared with those in a nonpregnant adult. Only experienced practitioners should attempt endotracheal intubation during cardiac arrest. www.clinicalobgyn.com
To support their physiological functions and the demands of the growing fetus, pregnant women have an increase in their oxygen consumption. They also maintain a ‘‘normal’’ state of respiratory alkalosis secondary to the loss of CO2 by an increase in minute ventilation promoting the fetal unload of CO2.
CPR The chain of survival in a cardiac arrest event includes early recognition, activation of the emergency system, early CPR based on continuous chest compressions, rapid defibrillation, advanced life support care, and postcardiac arrest management. Obstetrical units should be prepared for appropriate resuscitation of the mother and newborn including code cart equipment (adult and newborn) as well as instruments for perimortem cesarean section and education of the personnel in advanced life support techniques. The chances of a successful resuscitation in cardiac arrest secondary to VF or PVT are based on effective chest compressions and early defibrillation. The management of other cardiac arrest rhythms such as PEA and asystole is based on adequate CPR and administration of vasoactive drugs. Identification of any reversible causes (Ts and Hs discussed previously) is of paramount importance. Unlike the previous sequence proposed by the American Heart Association in 2005 (ABC for Airway-Breathing-Circulation), the current recommendations propose beginning resuscitation with chest compressions in a CAB sequence (AHA 2010). The study by Bobrow et al22 (in a nonpregnant population) demonstrated that chest compressiononly CPR was associated with a significant increase in the survival rate of bystander CPR for adults who experienced outof-hospital cardiac arrest. Furthermore, chest compression-only CPR was independently associated with increased
Cardiac Arrest and Pregnancy rate of survival compared with no bystander CPR or conventional CPR. Cardio-cerebral resuscitation makes emphasis on a constant blood flow to the heart and brain by continuous chest compressions. Basic life support begins with an acknowledgment that the victim is either not breathing or not doing so normally. Activation of the emergency system (in or out of hospital) needs to occur at this time. Then, after proper positioning of the victim, chest compressions need to be initiated at a rate of at least 100/min with minimal interruptions (24 wk), are aggressive airway management, left lateralization of the uterus, caution in the use of bicarbonate, and consideration of a perimortem cesarean delivery.
875
During resuscitation, early control of the airway should be obtained and supplemental oxygen should be administered at 100%. This is important because of the difficulty of the pregnant woman and the fetus to manage hypoxemic states and the high risk for aspiration. Endotracheal intubation is the optimal method for maintaining a patent and secure airway. Early intubation is recommended if experienced providers are available. Bag valve mask ventilation with supplemental oxygen (if available) is recommended before intubation attempts because of the faster trend to desaturation in pregnant women.9 It is estimated that endotracheal intubation takes an average duration of 47 seconds.24 One third of these procedures last more than a minute, and a quarter exceed 3 minutes.24 These interruptions are considered lethal to a patient in cardiopulmonary arrest, and intubation should be ideally performed after the return of spontaneous circulation (ROSC) if no trained personnel is immediately available. In the latter situation, the patient will be better served with ventilation with a bag mask device. When an advanced airway (endotracheal tube) is obtained, ventilation should be performed every 6 to 8 seconds, which equals 8 to 10 breaths/min independently of chest compressions. In the resuscitation of a pregnant patient, the pressure applied on the cricoid cartilage (Sellick maneuver) during intubation to decrease the risk for aspiration is accepted. As in episodes of hypoventilation, hyperventilation cause harmful effects. Hyperventilation increases intrathoracic pressure and decreases venous return; in addition, hyperventilation may decrease cerebral blood flow.25 To achieve aorto-caval decompression, the gravid uterus should be deflected to the left; several options are available. It may be leaning toward the left to the patient by placing pillows or sheets on the right hip. Another way is that a www.clinicalobgyn.com
876
Montufar-Rueda and Gei
rescuer performs the function of a ‘‘human wedge’’ kneeling on the floor behind the back of the patient. The use of a tool specifically designed to displace the uterus laterally (Cardiff wedge) may also be considered. The most practical is the simple manual uterine deviation to the left side by a member of the rescuer team.26 Given that CPR is more easily performed in the supine position and that adequate wedges are not commonly available, it is reasonable to begin CPR with manual leftward uterine displacement and proceed to a 27-degree wedge if CPR is ineffective. Heart rates of in-hospital arrests tend to be nonshockable rhythms (PEA and asystole). In these cases, once the defibrillator/monitor identifies a nonshockable rhythm, CPR should be resumed with the cycles of compressions/ventilations at a 30:2 ratio as recommended by the latest AHA guidelines. If during resuscitation the heart rhythm changes to PVF/VF, the patient should be
defibrillated. After the brief interruption associated with defibrillation of a shockable rhythm (VF and PVT), chest compressions and ventilations need to be resumed at rates of at least 100/min and 6 to 8/min, respectively. In either case it is important to consider and correct the factors that lead to cardiac arrest (Hs and Ts). Figures 1–3 depict the initial steps in the management of cardiac arrest during pregnancy.
Vasopressors The purpose of the use of vasopressors in cardiac arrest is to increase the perfusion pressure of the heart and brain. This would help achieve ROSC and improve the chances of an intact neurological survival. The AHA 2010 guidelines recommend administering 1 mg epinephrine intravenously (IV) or intraosseous every 3 to 5 minutes during advanced life support.
FIGURE 1. Flowchart of Intra and Postpartum maternal collapse.
www.clinicalobgyn.com
Cardiac Arrest and Pregnancy
877
FIGURE 2. Flowchart management in cardiac arrest secondary to obstetric hemorrhage.
FIGURE 3. Flowchart of antepartum maternal collapse.
www.clinicalobgyn.com
878
Montufar-Rueda and Gei
However, no clinical studies have shown that the use of epinephrine improves longterm survival. Jacobs et al28 found equal rate of survival (to hospital discharge) with or without epinephrine (5.1% vs. 5.0%). A Swedish study, in which 42% of the 10,966 patients who had suffered a cardiac arrest received epinephrine, found that use of vasopressor drugs did not improve survival.29 A study by Olasveengen et al30 showed an increase in ROSC with epinephrine (24% vs. 8%), and higher (but no significant) differences in survival to hospital discharge (4% vs. 2%). Although there are animal studies that suggest that a dose of epinephrine of 0.045 mg/kg is required for a good myocardial perfusion and to achieve ROSC, the 2010 AHA resuscitation guidelines still recommend the use of 1 mg.31 Vasopressin does not have a direct effect on myocardial contractility but increases blood flow to vital organs. In advanced cardiac life support 40 U vasopressin can be administered as an alternative for either the first or second doses of epinephrine.27 To date no superiority has been demonstrated between vasopressin and epinephrine in terms of survival to hospital discharge, rates of ROSC, or neurological integrity of cardiac arrest survivors.32–35 There are differences in opinion as of what is the optimum time for the administration of vasopressors during CPR. The AHA guidelines recommend epinephrine administration after at least 1 shock and 2 minutes of CPR,27 whereas the European Resuscitation Council guidelines recommend it immediately after the third shock.36 There are no studies with sufficient power, showing that the administration of a vasopressor for the treatment of PVT, VF, pulseless electric activity, or asystole improves survival. The use of epinephrine may even be associated with more postarrest cardiac and neurological dysfunction. www.clinicalobgyn.com
Other Considerations Bicarbonate use is not recommended during cardiac arrest resuscitation. It has not been associated with improved outcomes except in special circumstances such as tricyclic or sodium channel blocker overdoses. The Heimlich maneuver for the expulsion of foreign bodies lodged in the upper airway should be used with caution in advanced pregnancies (>24 wk), as it is less effective and may even cause uterine rupture.37 It may be performed providing pressure in the sternum as opposed to the abdomen. There are no data to support a change in defibrillation patterns recommended in the current advanced cardiac life support for pregnant or postpartum patients.38 Likewise, the indications for defibrillation remain in the rhythms of ventricular tachycardia and VF.23
Antiarrhythmics Lidocaine is a local anesthetic that has an antiarrhythmic action by increasing the threshold for electrical stimulation during ventricular diastole. Lidocaine is less successful in producing ROSC when compared with amiodarone. The study of Dorian et al39 concluded that amiodarone leads to a substantially higher rate of survival to hospital discharge in patients with shockresistant VF compared with lidocaine, but the final outcomes were not different. The AHA recommends the use of amiodarone for VF or PVT that is unresponsive to CPR, shock, and/or a vasopressor. This drug is first given as a dose of 300 mg IV, which can be followed with a second dose of 150 mg IV after 5 minutes. AHA recommends lidocaine as an alternative to amiodarone. Lidocaine must be administered as an initial dose of 1.0 to 1.5 mg/kg IV, followed by 0.5 to 0.75 mg/kg IV push, at 5-minute intervals if VF or PVT persist (maximum dose 3 mg/kg). Similarly to vasopressors, no antiarrhythmic has been
Cardiac Arrest and Pregnancy showed to improve outcomes in patients with cardiac arrest.
Perimortem Cesarean Delivery Caesarean section during CPR of a pregnant patient aims to improve maternal outcomes during resuscitation and increase the chances of neonatal survival with minimal neurological damage.16 The benefits of a perimortem cesarean delivery are mainly aimed at relieving uterine-mediated inferior vena cava compression (mostly among pregnancies beyond 20 wk of gestation).40–42 Katz and colleagues assessed neonatal outcomes in a group of patients undergoing perimortem cesarean sections and found successful outcomes for both mother and neonate in some cases. This finding supported the concept of performing perimortem cesarean section as part of CPR in the pregnant patient.43 Studies have shown that fetal neurological damage starts about 5 minutes after the cessation of blood flow, although infants in good neurological status have been delivered after up to 30 minutes of cardiac arrest.43 A perimortem cesarean section should be considered after 20 weeks of gestation if no return of pulse is noticed after 4 to 5 minutes of CPR.
Postcardiac Arrest Care The postcardiac arrest syndrome comprises brain injury, myocardial dysfunction, and systemic response to ischemia/ reperfusion.44 Postcardiac arrest care includes treatment with induced hypothermia, optimization of ventilation and circulation, coronary reperfusion, glycemic control, and neurological care. There is evidence that the use of mild hypothermia (32 to 341C) induced in comatose patients who survived an out-of-hospital cardiac arrest caused by VF/PVT improves survival and neurological outcomes.45,46
879
The 2010 AHA resuscitation guidelines recommend considering the use of induced hypothermia in patients with ROSC after cardiac arrest regardless of the initial rhythm or location of the arrest despite the fact that most of the evidence is limited to patients with out-of-hospital arrests with initial shockable rhythms. Oxygen should be administered to maintain arterial oxygen saturation close to 94%. High oxygen concentrations should be avoided as they may worsen ischemia reperfusion injuries (100% oxygen is not usually required and may be harmful). There is no evidence to establish specific values of PCO2; however, it is recommended to maintain normocapnia (PaCO2 40 to 45 mm Hg). After cardiac arrest a systemic inflammatory response with profound vasodilation and cardiac stunning is common. The latter frequently requires treatment with fluids, vasopressors, and inotropes to maintain a mean arterial blood pressure of 65 mm Hg.44 In patients with high suspicion of coronary artery disease or diagnosis of a myocardial infarction with ST elevation, coronary angiography should be performed without delay.48 It has been shown that hyperglycemia causes an increase in morbidity and mortality when present in patients with acute critical pathology. On the basis of available data, blood glucose levels should be maintained after ROSC between 140 and 180 mg/dL.49 Severe hypoglycemia should also be avoided.50,51 Seizures may occur in up to 10% to 40% of patients who survive a cardiac arrest. When diagnosed, seizures should be treated aggressively to decrease the risk of ongoing brain injury.52
Summary Cardiac arrest is a rare event during pregnancy. All obstetrical units should be prepared for such a devastating event. Personnel should be trained periodically www.clinicalobgyn.com
880
Montufar-Rueda and Gei
in the management of arrest, and algorithms specific for pregnant victims should be widely available. Obstetrical providers should play a primary role in the management of these patients as certain interventions such as a perimortem cesarean section may be required early in the resuscitation process.
References 1. Callans DJ. Out-of-hospital cardiac arrest-the solution is shocking. N Engl J Med. 2004;351:632–634. 2. Sans S, Kesteloot D, Kromhout D. The burden of cardiovascular diseases mortality in Europe. Task Force of the European Society of Cardiology on Cardiovascular Mortality and Morbidity Statistics in Europe. Eur Heart J. 1997;18:1231–1248. 3. Schneider AP II, Nelson DJ, Brow DD. In-hospital cardiopulmonary resuscitation: a 30-year review. J Am Board Fam Pract. 1993;6:91–101. 4. Brace V, Penney G, Hall M. Quantifying severe maternal morbidity: a Scottish population study. BJOG. 2004;111:481–484. 5. Lewis G. Saving mothers’ lives reviewing maternal deaths to make motherhood safer-2003-2005: the seventh report of confidential enquiries into Maternal Deaths in the United Kingdom. CEMACH 2007. Available at: www.cemach.org.uk. 6. Berg CJ, MacKay AP, Qin C, et al. Overview of maternal morbidity during hospitalization for labor and delivery in the United States. Obstet Gynecol. 2009;113:1075–1081. 7. Mathews TJ, Hamilton BE. Delayed childbearing: more women are having their first child later in life. NCHS Data Brief. 2009;21:1–8. 8. Farinelli CK, Hameed AB. Cardiopulmonary resuscitation in pregnancy. Cardiol Clin. 2012;30: 453–461. 9. Atta E, Gardner M. Cardiopulmonary resuscitation in pregnancy. Obstet Gynecol Clin North Am. 2007;34:585–597. 10. Chhabra S, Kakani A. Maternal mortality due to eclamptic and noneclamptic hypertensive disorders: a challenge. J Obstet Gynaecol. 2007;27:25–29. 11. Clark SL, Hanskins GD, Dudle DA, et al. Amniotic fluid embolism: analysis of the national registry. Am J Obstet Gynecol. 1995;172:1158–1167. 12. Tuffnell DJ. United Kingdom amniotic fluid embolism register. BJOG. 2005;112:1625–1629. 13. Montufar-Rueda C, Rodriguez L, Jarquin JD, et al. Severe postpartum hemorrhage from uterine atony: a multicentric study. J Pregnancy. 2013; 2013:525914. 14. Joseph KS, Liu S, Rouleau J, Maternal Health Study Group of the Canadian Perinatal
www.clinicalobgyn.com
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
Surveillance System Severe maternal morbidity in Canada, 2003 to 2007: surveillance using routine hospitalization data and ICD-10CA codes. Available at: www.cemach.org.uk. Arendt KW, Segal S. Present and emerging strategies for reducing anesthesia-related maternal morbidity and mortality. Curr Opin Anaesthesiol. 2009;22:330–335. Maternal Collapse in Pregnancy and Puerperium. RCOG Green-top Guideline No 56. January 2011. Available at: www.cemach.org.uk. Malampalli A, Powner DJ, Gardner M. CPR and somatic support of the pregnant patient. Crit Care Clin. 2004;20:747–763. DoanWiggins L. Resuscitation of the pregnant patient suffering sudden death. In: Paradis NA, Halperin HR, Nowak RM eds. Cardiac Arrest and Practice of Resuscitation Medicine. Baltimore, MD: Williams & Wilkins;1997:812–819. Kerr MG. The mechanical effects of the gravid uterus in late pregnancy. J Obstet Gynaecol Br Commonw. 1965;72:513–529. Rees GA, Willis BA. Bioimpedance measurement of cardiac output. Eur J Obstet Gynecol Reprod Biol. 1990;36:11–17. Barnardo PD, Jenkins JG. Failed tracheal intubation in obstetrics: a 6-year review in a UK region. Anaesthesia. 2002;55:690–694. Bobrow BJ, Spaite DW, Berg RA, et al. Chest compression-only CPR by Lay Rescuers and Survival from out-of-hospital cardiac arrest. JAMA. 2010;304:1447–1454. ECC Committee, Subcommittes and Task Forces of the American Heart Association. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010;122: S640–S861. Wang HE, Simeone SJ, Weaver MD, et al. Interruptions in cardiopulmonary resuscitation from paramedic endotracheal intubation. Ann Emerg Med. 2009;54:645–652. Yannopoulos D, Nadkarni VM, McKnite SH, et al. Intrathoracic pressure regulator during continuous-chest-compression advanced cardiac resuscitation improves vital organ perfusion pressures in a porcine model of cardiac arrest. Circulation. 2005;112:803–811. Goodwin AP, Pearce AJ. The human wedge. A maneuver to relieve aortocaval compression during resuscitation in late pregnancy. Anaesthesia. 1992;47:433–434. Neumar RW, Otto CW, Link MS, et al. Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010;122 (suppl 3):S729–S767.
Cardiac Arrest and Pregnancy 28. Jacobs IG, Finn JC, Felinek GA, et al. Effect of adrenaline on survival in out-of-hospital cardiac arrest: a randomised double´-blind placebocontrolled trial. Resuscitation. 2011;82:1138–1143. 29. Holmberg M, Holmberg S, Herlitz J. Low chance of survival among patients requiring adrenaline (epinephrine) or intubation after out-of-hospital cardiac arrest in Sweden. Resuscitation. 2002;4: 37–45. 30. Olasveengen TM, Sunde K, Brunborg C, et al. Intravenous drug administration during outof-hospital cardiac arrest: a randomized trial. JAMA. 2009;302:2222–2229. 31. Lindner KH, Ahnefeld FW, Bowdler IM. Comparison of different doses of epinephrine on myocardial perfusion and resuscitation success during cardiopulmonary resuscitation in a pig model. Am J Emerg Med. 1991;9:27–31. 32. Wenzel V, Krismer AC, Arntz HR, et al. European Resuscitation Council Vasopressor during cardiopulmonary resuscitation Study Group. A comparison of vasopressin and epinephrine for out-of-hospital cardiopulmonary resuscitation. N Engl J Med. 2004;350:105–113. 33. Stiell IG, Hebert PC, Wells GA, et al. Vasopressin versus epinephrine for inhospital cardiac arrest: a randomised controlled trial. Lancet. 2001;358:105–109. 34. Aung K, Htay T. Vasopressin for cardiac arrest: a systematic review and meta-analysis. Arch Intern Med. 2005;165:17–24. 35. Metzelopoulos SD, Zakynthinos SG, Siempos I, et al. Vasopressin for cardiac arrest; meta-analysis of randomized controlled trials. Resuscitation. 2012;83:32–39. 36. Deakin CD, Nolan JP, Soar J, et al. European Resuscitation Council Guidelines for Resuscitation 2010 Section 4. Adult advanced life support. Resuscitation. 2010;81:1305–1352. 37. Whitty JE. Maternal cardiac arrest in pregnancy. Clin Obstet Gynecol. 2002;45:377–392. 38. Nanson J, Elcock D, Williams M, et al. Do physiological changes in pregnancy change defibrillation energy requirements? Br J Anaesth. 2001;87:237–239. 39. Dorian P, Cass D, Schwartz B, et al. Amiodarone as compared with Lidocaine for shock-resistant ventricular fibrillation. N Engl J Med. 2001;346:884–890. 40. Katz VL, Cefalo RC. History and evolution of cesarean delivery. In: Phelan JP, Clark SL eds. Cesarean Delivery. New York: Elsevier;1988:1.
881
41. Weber CE. Postmortem cesarean section: review of the literature and case reports. Am J Obstet Gynecol. 1971;110:158–165. 42. Hayden FJ. Maternal mortality in history and today. Med J Aust. 1970;1:100–109. 43. Katz VL, Dotters DJ, Droegmueller W. Perimortem cesarean delivery. Obstet Gynecol. 1986;68: 571–576. 44. Nolan JP, Neumar RW, Adrie C, et al. Post-cardiac arrest syndrome: epidemiology, pathophysiology, treatment, and prognostication. A Scientific Statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke. Resuscitation. 2008;79: 350–379. 45. Gunn AJ, Thoresen M. Hypothermic neuroprotection. NeuroRx. 2006;3:154–169. 46. Froehler MT, Geocadin RG. Hypothermia for neuroprotection after cardiac arrest: mechanisms, clinical trials and patient care. J Neurol Sci. 2007;261:118–126. 47. Hazinski MF, Nolan JP, Billi BW, et al. Part 1: Executive summary: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2010;122 (suppl):S250–S275. 48. Spaulding CM, Joly LM, Rosenberg A, et al. Immediate coronary angiography in survivors of out-of-hospital cardiac arrest. N Engl J Med. 1997;336:1629–1633. 49. Padkin A. Glucose control after cardiac arrest. Resuscitation. 2009;80:611–612. 50. Krinsley JS, Grover A. Severe hypoglycemia in critically ill patients: risk factors and outcomes. Crit Care Med. 2007;35:2262–2267. 51. Cerchiari EL, Safar P, Klein E, et al. Visceral, hematologic and bacteriologic changes and neurologic outcome after cardiac arrest in dogs. The visceral post-resuscitation syndrome. Resuscitation. 1993;25:119–136. 52. Snyder BD, Hauser WA, Loewenson RB, et al. Neurologic prognosis after cardiopulmonary arrest, III: seizure activity. Neurology. 1980;30: 1292–1297.
www.clinicalobgyn.com
