FormalPara Bullet Points

  • Cardiac arrest is uncommon in pregnant patients. Therefore, few intensivists have experience with post-cardiac arrest care in pregnancy.

  • Pregnant post-cardiac arrest patients should receive tailored intensive care considering the state of pregnancy, general principles of post-cardiac arrest care and the disease causing the arrest.

  • Cardiac causes commonly lead to ventricular fibrillation or ventricular tachycardia and may result from a myocardial infarction, cardiomyopathy or myocarditis.

  • Non-cardiac causes such as hypovolemia related to bleeding, hypoxia, thromboembolism, maternal fluid embolism and air embolism as well as intracranial bleeding are possible causes of cardiac arrests with a non-shockable rhythm such as pulseless electrical activity or asystole.

  • Immediately after return of spontaneous circulation, the patient should be assessed according to an ABCD approach.

  • The airway should be secured in all patients after cardiac arrest unless they are conscious and have stable vital signs. Endotracheal intubation may be difficult and should be done with diligence.

  • Hypoxia, extreme hyperoxia as well as hypo- and hypercarbia should be avoided. Mechanical ventilation should be undertaken utilising a lung-protective strategy.

  • Blood pressure may be high immediately after return of spontaneous circulation if the patient has received adrenaline during cardiopulmonary resuscitation but afterwards patients may require intravenous fluid and/or vasopressors. The blood pressure target should be between 65 and 70 mmHg.

  • Manage patient temperature targeting to 33–36 °C. In patients with bleeding or severe shock, targeting to 36° may be preferable.

  • Use short-acting sedative agents such as propofol and remifentanil to facilitate early extubation in the neurologically improving patient.

  • Avoid hyper- and hypoglycaemia using insulin if needed. If the patient is not arousable within 48–72 h, a multimodal approach should be used to determine prognosis and guide future care. Include a thorough neurological examination, electroencephalography, a computed tomography of the brain, somatosensory evoked potentials and biomarkers.

  • Recovery from cardiac arrest takes time and may require rehabilitation and support for both patient and family.

1 Introduction and Epidemiology

Given the rarity of cardiac arrest in pregnancy, most intensivists will have limited practical experience in post-cardiac arrest care of maternal patients. The United Kingdom cardiac arrest in pregnancy study (CAPS) published in 2017 identified 66 maternal deaths occurring in 1 year, equalling an incidence of 2.78 cases per 100,000 maternities [1]. Most of these deaths occurred in the hospital, and many were related to an anaesthetic procedure. The 12-month FINNRESUSCI study conducted in Finland (two large emergency medical systems and all Finnish intensive care units) identified no pregnant women among the 548 cardiac arrest patients who survived to intensive care unit (ICU) admission [2, 3]. In the United States, related at least in part to the opioid crisis, critical cardiovascular events such as cardiac arrests are increasing during pregnancy [4]. This trend may lead to a rise in the number of pregnant women with cardiac arrest who will require ICU care in the future.

All randomised controlled trials on post-resuscitation care have excluded pregnant patients [5,6,7,8]. Thus, the discussion regarding management of pregnant patients after cardiac arrest in this chapter is based on interpretation of the applicability, benefits and possible harms of the available therapeutic interventions given the state of the pregnancy, as well as on generally accepted principles of critical care management of the pregnant patient.

2 Pathophysiology of the Post-Cardiac Arrest Syndrome

Non-pregnant patients who initially survived cardiac arrest to be admitted to an ICU die mostly due to brain injury and less commonly due to cardiac injury [9, 10]. The main cause of brain injury is global hypoxia, which initiates a series of events that result in various degrees of hypoxic-ischaemic brain injury (HIBI) or hypoxic-ischaemic encephalopathy (HIE) [11, 12]. The damage occurring after cardiac arrest is usually described as a ‘two-hit model’. The primary injury occurs during cardiac standstill and is highly dependent on both the no-flow time (the period the patient is in cardiac arrest and does not receive any basic life support) and the low-flow time (the period of chest compression, during which there is some circulation) [13]. The development of HIBI appears to be predominantly related to the length of the no-flow state, accentuating the importance of immediate basic life support. The magnitude of pre-arrest hypoxia and hypotension also seem to be important [14]. Patients with cardiac arrest related to hypoxia (suffocation, hanging) appear to develop a severe form of HIBI and have a worse prognosis [15]. There are limited data about the cause of death in pregnant patients treated in the ICU after cardiac arrest, and there is little likelihood of data on this topic forthcoming soon. At this time, it is therefore reasonable to assume that these findings may be relevant in the pregnant population as well.

If return of spontaneous circulation (ROSC) is achieved, the second hit develops over the following 24–48 h [16]. The pathophysiology behind the second hit neurological injury is complex but includes reperfusion injury, disturbed autoregulation, local brain hypoxia and brain tissue oedema [11, 17]. Fever is a common feature and multiple studies have suggested harm from fever after cardiac arrest. During the first 24 h, cerebral blood flow decreases and oxygen deficit develops [18, 19]. In severe cases, catastrophic cerebral oedema may develop, leading to brain death. Patients may also develop a generalised systemic inflammatory response similar to that observed in sepsis, with elevation of inflammatory marker and cytokine levels [20, 21]. This inflammatory response tends to manifest in patients who also develop extracranial organ failure [22, 23]. Myocardial dysfunction, which typically occurs during the first 24 h following ROSC and then tends to abate, is probably an important cause of this organ failure [24]. Treatment in cases with an evolving inflammatory response remains mainly supportive [22]. High-volume haemofiltration has been tried as a means of reducing inflammatory cytokine levels with inconclusive results [25].

3 Stage of Pregnancy and Change in Physiology Relevant to the ICU Physician

The stage of pregnancy will influence the type of ICU care provided after cardiac arrest [26]. During early pregnancy (up to a gestational age of 20 weeks), post-resuscitation treatment of the pregnant woman should adhere to the principles of post-resuscitation management for the general population [12]. At this time, the most profound physiological changes of pregnancy have yet to occur, and the fetus is not viable. Thus, the strategy should be to maximise the likelihood of benefit for the mother and, by proxy, that of the fetus. After 20 weeks of gestation, the physiological changes of pregnancy become more apparent and therefore merit greater consideration when planning care.

4 Immediate Management after Return of Spontaneous Circulation

Immediately after return of spontaneous circulation (ROSC) the woman should be surveyed according to an ABCD type approach.

Airway: Evidence shows that most women undergoing in-hospital resuscitation are intubated during the cardiac arrest [27]. However, the importance of intubation during CPR has recently been challenged [27]. Therefore, more patients may undergo cariopulmonary resuscitaiton (CPR) with only bag-valve-mask ventilation or airway devices in the future. After ROSC, the airway must be secured, with the sole exception of the completely conscious patient who has experienced a very brief cardiac arrest. Pregnant women also have an increased risk of regurgitation, placing even greater importance on securing of the airway with an endotracheal tube (ETT). Since endotracheal intubation is more difficult in pregnant women than in the general population, this should be performed in a controlled manner. Ideally, an airway checklist should be used (Table 28.1) [28]. Correct placement of the endotracheal tube is best confirmed by combining visual inspection of chest rise, fogging of the tube, continuous capnography and assessment of tube location by auscultation (i.e. absence of auditory sound over the stomach indicating oesophageal intubation followed by auditory signs indicating entry to air into the lungs during inspirium) [29]. Initially the tube should be placed and secured at a depth of 21–23 cm. Placement at the correct depth is then verified by chest radiography or direct fiberoscopy (see also Chap. 21).

Table 28.1 Checklist to be used for safe management of the airway outside the operating room. All parts of the list are addressed by the whole team prior to initiating the procedure (modified from a list used since 2011 in the ED of Helsinki University Hospital and developed by RN M Kemppainen, RN A Rantanen, MD S Urtamo, MD J Puolakka)
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Breathing: Most pregnant/post-partum women after cardiac arrest will likely require ventilator support. While there is no direct evidence to support this assumption, controlled mechanical ventilation may be less damaging than manual ventilation with unknown and probably dynamic parameters. Thus, mechanical ventilation is best initiated early after ROSC. Minute ventilation increases up to 50% during pregnancy [30]. Initial ventilation settings should take this change into consideration. As a rule of thumb, the aim should be for 14–16 breaths per minute, a tidal volume of between 400 and 500 mL (6–8 mL/kg ideal body weight) and a positive end-expiratory pressure (PEEP) of 6 cmH2O.

During CPR, all patients receive 100% oxygen, and there is no accurate way to monitor the adequacy of oxygenation. After ROSC, oxygenation should be monitored using pulse oximetry (peripheral oxygen saturation) and by sampling of arterial blood gases. The fraction of inspired oxygen (FiO2) should be titrated to achieve an oxygen saturation of 94–98% [29]. If the woman is still undergoing bag-valve-mask ventilation, FiO2 may be adjusted by regulating fresh oxygen flow [31]. The FiO2 achieved will depend on minute ventilation; with an oxygen flow of 4 L/min, the FiO2 approximates 50% [31]. Most women will not require prolonged ventilation with 100% oxygen. However, if arrest had occurred secondary to hypoxia (e.g. suffocation, acute asthma, pulmonary embolism or aspiration), ongoing treatment with high FiO2 may be required to maintain appropriate oxygen saturation. If the cause of the arrest was cardiac and CPR was promptly initiated, less oxygen will probably be required. In this situation, prolonged use of 100% oxygen will result in extreme hyperoxia [32].

Ventilation should be adjusted to achieve a PaCO2 of around 32–34 mmHg, which is normal during pregnancy [30]. Hyperventilation (PaCO2 < 32 mmHg) is harmful both during and after cardiac arrest in the non-pregnant patient [33, 34]. In pregnant women, hyperventilation may also cause vasoconstriction with a resultant decrease in uterine blood flow, which may lead to foetal distress [35]. End-tidal CO2 level monitored by capnography may provide some guidance for setting ventilation after the woman has stabilised. However, in the first hours after cardiac arrest, there may be a large arterial-alveolar difference due to faulty tissue perfusion (including the lungs). Thus, setting the correct minute ventilation requires frequent arterial blood gas sampling in the first hours of ventilation [36]. This will also aid in adjusting FiO2.

4.1 Circulation

During the first 20 min after ROSC, the risk of re-arrest is high. Efforts should be invested in ensuring adequate monitoring of patient vital signs. This should include continuous electrocardiography (ECG), blood pressure and capnography. A sudden drop in end-tidal CO2 suggests impending re-arrest; this can be verified by identifying lack of a palpable pulse and loss of an organised cardiac rhythm on the ECG. The treating staff should be prepared to identify and rapidly manage re-arrest should this occur. If the woman had a shockable initial rhythm and sequences of shock-resistant ventricular fibrillation/tachycardia (VF/VT), these arrhythmias may recur. In such cases, a defibrillator must remain available nearby. If the woman was resuscitated from a non-shockable rhythm such as pulseless electrical activity (PEA) or asystole, recurrent PEA or severe hypotension are more likely. These can only be identified if blood pressure is measured continuously parallel to monitoring of electrocardiography. A high-monitoring environment and invasive blood pressure measurement are preferred as these will facilitate the response to possible maternal re-arrest.

Adrenaline received during resuscitation can sometimes greatly elevate systemic blood pressures. The half-life of adrenaline approximates 5 min, therefore the treating clinician should be alert to the option of hypotension occurring shortly (within 5–10 min) after ROSC [12]. The likelihood of such occurrence may even be higher in women whose cause of arrest was hypovolemia (e.g. hemorrhage).

Disability: A brief neurological examination should be undertaken after ROSC. If the woman has received adrenaline or atropine her pupils may be dilated. If the patient is restless or combative, a sedative agent or opiate should be administered. Generally, extubation should not be performed shortly after ROSC; the added work of spontaneous breathing may augment post-arrest intracellular energy deficit, and the patient may not be able to protect her airway, resulting in gastric aspiration. Sedation must be tailored first and foremost to maternal condition, as foetal well-being hinges on maternal well-being. Additional considerations affecting the choice of sedation are the stage of pregnancy and the pregnancy management plan. If immediate delivery is planned, an obstetric anaesthesiologist and a neonatologist should be involved in the decision-making process at this stage. For example, if caesarean delivery is being planned, sedation should be kept to a minimum in order to diminish the likelihood of neonatal respiratory depression. See below the discussion regarding sedation options.

5 Logistics of ICU Care

Comatose post-ROSC patients commonly require intensive care for a minimum of 48–72 h. Observational data from non-pregnant out of hospital cardiac arrest patients suggests that transfer from the scene of the arrest to a specialised cardiac arrest centre may be associated with better outcomes than transfer to the nearest hospital [37,38,39]. Pregnant and peripartum women who have arrested outside the hospital, and achieved ROSC should be transferred to a hospital with both intensive care and obstetric expertise. The details of the arrest and the clinical condition of the patient after ROSC should be ascertained from the emergency medical service (in case of out-of-hospital arrest) or the resuscitation team (in case of in-hospital arrest) and diligently documented. These details are of paramount importance for decisions at a later stage of intensive care (Table 28.1). A protocol should ideally be used in all intensive care units when managing patients after cardiac arrest [40]. This is particularly true for pregnant women, as care is being delivered to two patients rather than one.

6 Determining the Cause of the Arrest

Important information regarding cardiac arrest management will provide clues on arrest cause, and should be collected from the CPR providers, either the emergency medical service providers or members of the in-hospital cardiac arrest team (Table 28.2). Acute myocardial infarction is the most common cause for cardiac arrest in non-pregnant patients, but it is less common in pregnant patients [41]. In pregnant women, heart failure due to exacerbation of pre-existing heart disease, cardiomyopathy or myocarditis are more common [42] and may cause a primary cardiac arrhythmia. However, myocardial infarction has also been reported during pregnancy [43]. Ventricular fibrillation may also be related to certain electrolyte disturbances and intoxications [44].

The diagnostic workup of patients resuscitated from a shockable rhythm should start with a 12-lead ECG. In cases of prolonged CPR with use of adrenaline, changes suggesting ischaemia may be seen immediately after ROSC. Therefore decisions should be made based on the findings of an ECG obtained 20 min from ROSC [42].

If ongoing ST-segment elevation is observed, additional investigations should be undertaken without delay regardless of pregnancy [43, 45]. The value of measuring cardiac enzyme levels early after cardiac arrest remains unclear even in the general population [46]. An echocardiogram (ECHO) may reveal regional wall motion abnormalities, valvular abnormalities (e.g. aortic stenosis, mitral regurgitation), cardiomyopathy or severe cardiac failure. Computed tomography may be required to rule out alternative causes (e.g. aortic or coronary dissection). If indicated, iodinated contrast media may be used despite ongoing pregnancy. To date, no teratogenic effects have been clearly attributed to exposure to the newer generation of low-osmolality contrast media during pregnancy [47].

The option of coronary artery disease as the cause of cardiac arrest is commonly overlooked even in non-pregnant women [48]. While pregnant women are younger, aortic dissection, coronary artery dissection and clinically significant atherosclerotic coronary artery disease have all been described during pregnancy [49]. Maternal mortality from myocardial infarction ranges between 5% and 37% even in developed countries [47, 50, 51]. Therefore, regardless of pregnancy, the mother should receive appropriate workup and treatment. In the presence of ongoing ST-elevation (and in some cases with non-ST elevation myocardial infarction), early coronary angiography may be indicated [52]. Coronary rupture has been reported during performance of coronary angiography in pregnant women, and foetal exposure to ionising radiation should be minimised, therefore such catheterisation should only be performed by an experienced invasive cardiologist. In such cases, the risk-benefit ratio must always be weighed together with the family on an individual basis, the understanding being that the benefit of the mother comes before that of the fetus.

Subarachnoid hemorrhage (SAH) may also cause ventricular fibrillation in rare instances. If the ECG and ECHO results are normal, computed tomography imaging of the brain is indicated. The presence of a headache preceding the arrest is often described in SAH-related cardiac arrest. However, the absence of a pre-arrest headache does not rule out SAH [53].

For pregnant women with PEA as their initial non-perfusing rhythm, the mnemonic BEAUCHOPS (bleeding, embolism, anaesthetic complications, uterine atony, cardiac disease, hypertension due to eclampsia, other causes and sepsis) summarises the etiological factors that should be considered (Table 28.3) [54]. Efforts should be made to identify and treat these causes as well as the causes of PEA observed in the general population even during resuscitation [55]. If this has not been completed before ROSC, the likely etiology should be ascertained with further investigations after ROSC and treatment should be targeted accordingly (Table 28.2). Initial workup should include 12-lead ECG, arterial blood gas analysis with lactate, haemoglobin and electrolytes and chest radiography. A computed tomography scan of the brain, thorax, abdomen, and pelvis should be considered. CT angiogram must be undertaken if pulmonary embolism or arterial dissection is suspected and in select cases with suspected coronary heart disease. A drug and toxicology screen is in order when there is reason to suspect drug abuse or foul play and when no other obvious cause of arrest has been identified.

Table 28.2 Pre- and intra-arrest factors that should be ascertained from the emergency medical service (in case of out-of-hospital arrest) or the resuscitation team (in case of in-hospital arrest) and diligently documented. These details are of paramount importance for decisions at a later stage of intensive care
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The circumstances surrounding the arrest will also be important for prognostication purposes (Table 28.2) [56] and must therefore be accurately documented in the hospital charts. If the CA occurs in the hospital during delivery (either vaginal or C-section), hemorrhage, eclampsia and maternal fluid and air embolism need to be kept in mind. Maternal amniotic fluid embolism is a dramatic event which occurs most commonly immediately after delivery of the placenta [57].

7 Mechanical Ventilation

Most patients with cardiac arrest who have been admitted to intensive care remain ventilated for 24–72 h [58]. The goals of positive pressure mechanical ventilation are to provide stable oxygenation and ventilation while protecting the lungs from secondary damage [59].

Oxygenation targets: Maternal hypoxemia (PaO2 < 75 mmHg) should be avoided by means of moderate PEEP and, if required, increased FiO2 [32]. Maternal arterial oxygen in the range of 75–100 mmHg appears to suffice for fetal oxygenation [60, 61]. Retrospective studies have associated extreme hyperoxia (PaO2 > 300 mmHg) in the first days after ROSC with higher death rates and poorer neurological outcomes [62, 63]. Hyperoxia is most commonly observed with inadvertent prolonged use of 100% oxygen [32]. Whether targeting moderate hyperoxia is protective or harmful in cardiac arrest patients is currently unclear [58]. Therefore, until more data is forthcoming. Hyperoxia should be avoided after cardiac arrest.

Ventilation targets: In late pregnancy (>28 weeks), the normal PaCO2 is in the range of 30–32 mmHg, which is lower than in the non-pregnant patient [26]. This is multifactorial, but is in part related to hyperventilation induced by progesterone and beginning after the first trimester. In cardiac arrest patients, the evidence is conflicting regarding optimal PaCO2 targets. It is generally accepted that hyperventilation should be avoided as it can induce arterial vasoconstriction in the brain [58, 64, 65]. As noted above, in pregnant women, hyperventilation may also cause uterine artery vasoconstriction, thereby decreasing blood flow to the fetus [26]. Mild hypercapnia has been shown to increase brain oxygenation [66, 67]. Current investigations in non-pregnant patients after ROSC are therefore focusing on the option of targeting mild hypercapnia. However, in the pregnant patient, even mild hypercapnia may cause acidosis which may be harmful for the fetus and cannot be recommended for pregnant patients at the present time [54, 60]. As there is no conclusive evidence regarding carbon dioxide targets, targeting normoventilation is likely most safe.

Lung protection: Lung-protective ventilation with avoidance of excessive tidal volumes is recommended in patients with ARDS. One study showed an increase in mortality with tidal volumes (TV) exceeding 8 mL/kg (predicted ideal body weight) [68]. Thus, in general, TVs of 5–6 mL/kg should be used and the frequency titrated to achieve the desired PaCO2. This might be slightly more challenging in the pregnant patient than in the general population given the metabolic increase. The indications for and method of lung-protective ventilation are discussed in greater detail in Chap. 23.

8 Targeted Temperature Management

Targeting of systemic temperatures to 33–36 °C for at least 24 h is recommended in non-pregnant cardiac arrest patients [12]. Recent evidence support the use of TTM also in patients resuscitated from non-shockable and in-hospital CA [69]. However, all clinical trials thus far have focused mainly on patients with an assumed cardiac cause for the arrest and have excluded pregnant women. There is little or no data on whether targeted temperature management (TTM) is efficacious in arrests occurring due to non-cardiac causes (e.g. pulmonary embolism, hypoxia, hemorrhage), although the ultimate mechanism of brain injury is likely to be similar (hypoperfusion mixed with increasing hypoxemia over time). In addition, the evidence suggests TTM may be beneficial mainly for patients resuscitated from a shockable initial rhythm [70].

TTM in pregnant and peripartum women: The two main concerns regarding the use of TTM in pregnant and peripartum women after ROSC are the risk of maternal hemorrhage and the potential for fetal damage especially if targeting 33 °C. Nonetheless, case reports have come out in recent years describing successful treatment of pregnant women with TTM which have suggested feasibility and lack of side effects [71]. Cardiac conduction may be modified during hypothermia with prolongation of the QT interval, QRS and PR segments all being observed. This reduction in heart rates usually only occurs within the lower range of temperatures used for TTM [72]. One case reported appearance of maternal bradycardia at 33 °C accompanied by signs of fetal distress [73]. Therefore, TTM of pregnant women must be accompanied by close monitoring and controlling of maternal heart rate and continuous monitoring of fetal heart rate. The decision as to which temperature (33 or 36 degrees) to target should be made on a case-by-case basis while taking into account the possible benefits and risks.

Systemic temperatures below 32 °C may also affect the coagulation cascade and platelet function [74]. This issue is of concern particularly in the peripartum period when there is an increased risk of maternal bleeding regardless of the mode of delivery. Theoretically, the risk of bleeding increases as systemic temperatures decrease. In non-pregnant patients after ROSC, there do not appear to be major differences in outcome when treated with 33 °C versus 36 °C. Therefore, in women after ROSC who are at risk of hemorrhage, a temperature of 36 °C should be targeted. At this time the literature describes only two women who arrested post-partum and were treated with TTM after achieving ROSC; of these, one exhibited coagulopathy [75]. However, the characteristics of the case were suggestive of amniotic fluid embolism which may itself be accompanied by coagulopathy. TTM after cardiac arrest is generally not associated with an increased risk of bleeding [5, 6]. Therefore, this treatment should be provided if it may improve maternal outcome. However, more attention should be directed towards selection of the individuals for treatment and to monitoring to prevent bleeding complications.

Pre-hospital induction of hypothermia with cold fluids during the arrest [76] or after ROSC is not beneficial [77, 78]. Targeted temperature management should therefore be started in the ICU and should continue for at least 24 h (Table 28.3). Outcomes are not better with treatment for 48 h compared to 24 h [5]. At the end of the TTM treatment period, the woman should be rewarmed slowly to 36.5–37 °C. Fever occurs commonly and may be treated with paracetamol. Any rebound hyperthermia may be treated invasively or non-invasively [5]. Temperatures exceeding 38.5 °C should be prevented especially in the comatose patients with signs of hypoxic-ischaemic brain injury.

Table 28.3 Identifying the cause of the arrest and tailoring investigations and management in the ICU according to the mnemonic ‘BEAUCHOPS’
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9 Sedation

In the first 24 h after ROSC, sedation should be kept deep in most cases; waking the patient up in order to perform neurological assessment is best avoided [79]. Most patients are encephalopathic, and the lack of a positive neurological response does not influence treatment decisions. A wake-up test may cause hypertension and arrhythmias and increase intracerebral pressure. Exceptions to this rule include patients with a very brief cardiac arrest, cases with alcohol intoxication or drug overdose, or those needing frequent clinical neurological assessments when findings may change immediate clinical management (e.g. when there are focal findings on the brain CT scan). After 24 h, sedation should be titrated using a sedation scale [80, 81].

Traditionally patients treated with TTM after ROSC were sedated using continuous infusions of midazolam and fentanyl [8]. At this time, short-acting agents such as propofol and remifentanil are preferred as they have been shown to shorten the time to extubation in this population [82]. Propofol is more likely to cause hypotension than midazolam [83, 84]. Thus, despite literature associating this drug with delirium and poorer outcomes, midazolam remains favoured by some for haemodynamically unstable patients [79]. Dexmedetomidine is another option for pregnant post-cardiac arrest women. Dexmedetomidine causes less hypertension and tachycardia than midazolam and has therefore been used in women with eclampsia for control of hypertension [85, 86]. However, in non-pregnant patients undergoing TTM (33 °C), the use of dexmedetomidine has been associated with bradycardia [87]. Dexmedetomidine has also been proposed for sedation during rewarming as shivering may occur at this stage of treatment, although conclusive evidence to support such practice is still lacking [88]. The metabolism of many sedative drugs (e.g. propofol, midazolam, morphine) is prolonged at systemic temperatures below the norm, therefore dosing may require adjustment dependent on the temperatures targeted and the phase of treatment [83].

10 Blood Pressure Management

The optimal blood pressure after cardiac arrest is not well defined. Studies have shown that disturbed cerebral autoregulation and decreases in cerebral blood flow contributes to poor outcome in patients post cardiac arrest [84]. Especially in patients with chronic hypertension, the autoregulation curve is shifted to the right, and patients could benefit from higher blood pressure [89]. Patients with eclampsia also appear to have disturbed autoregulation [90]. Nonetheless recent evidence does not support targeting mean arterial blood pressures higher than 65–70 mmHg after return of spontaneous circulation [91,92,93]. Marked hypotension with blood pressure less than 60 mmHg appears harmful [94] and should be avoided during the first 48 h. Signs of adequate blood pressure include adequate urinary output and decreasing lactate [12]. The one exception to this rule may be the woman with active bleeding where there is some evidence to support carefully monitored hypotensive resuscitation until bleeding has been controlled [94, 95].

Hypotension should generally be treated with either intravenous fluids or vasopressors, depending on the possible cause of the arrest. Hypovolemic shock (i.e. if the cause of arrest was hemorrhage or loss of intravascular volume for any other reason) should continue to be treated with fluids or blood products. Cardiogenic shock (i.e. infarction, arrhythmia, myocarditis) should be treated with vasopressors. Distributive shock (sepsis, anaphylaxis) may require treatment with both. In obstructive shock (e.g. pulmonary embolism, pneumothorax, tamponade), the woman will be less responsive to treatment with either fluids or vasopressors. In this situation the cause of the arrest must be reversed rapidly to maintain circulation, this may include thrombolysis or insertion of a chest drain.

There is limited evidence to direct the choice of vasopressors after cardiac arrest. However, vasoplegia is often seen after ROSC, particularly in patients who have entered the metabolic stage of cardiac arrest (i.e. in prolonged resuscitation). Norepinephrine is a good treatment option, but large amounts of fluid may also need to be infused. Norepinephrine increases mean arterial blood pressure without resulting in tachycardia [91, 92]. Based on data from patients with cardiogenic shock, treatment with norepinephrine is preferred over treatment with epinephrine which may cause severe tachycardia and recurrent shock [96]. Also see Chap. 38 regarding drug treatment during pregnancy. The response to treatment is best judged by lactate clearance and urinary output (0.5–1 mL/kg) [93, 97, 98]. The possibility of recurring cardiac ischemia should be kept in mind and serial echocardiography imaging to assess cardiac and valve function and left ventricular filling pressures may be indicated. Anecdotal evidence supports the short-term use of inhaled nitric oxide and milrinone in the patient treated after cardiac arrest related to maternal fluid embolism [56].

11 Fluid and Glucose Management

Extrapolation from non-pregnant patients suggests that hypotonic fluids should be avoided during the first 24–48 h unless the patient has documented hypernatremia, and fluids containing glucose should be avoided unless the patient has a documented hypoglycaemia [99,100,101,102]. Apart from these two specific situations, there is limited evidence regarding the choice of fluid after cardiac arrest (see also Chap. 7 regarding fluid therapy). If there is clear evidence of cerebral edema, targeting a blood sodium level of 140–145 mmol/L appears well justified [17]. Hypertonic saline or mannitol may also be used in severe brain edema cases, although conclusive evidence of their benefit is lacking [17].

Hyperglycemia is commonly found in patients admitted after cardiac arrest and is associated with worse outcomes [103]. Lenient normoglycemia (i.e. blood glucose <10 mmol/L) is best targeted [104, 105]. Strict normoglycemia increases the likelihood of iatrogenically induced hypoglycemia without increasing benefit [7, 105].

12 Management of Seizures

Ideally, patients after cardiac arrest should be monitored with continuous electroencephalography (EEG) to allow early identification of epileptic activity. When such monitoring is unavailable, intermittent EEG is also an option. Seizures (and more often myoclonus) often occur in non-pregnant patients after ROSC and are usually related to HIBI [106]. In pregnant or peripartum women, the possibility of pre-eclampsia and eclampsia should also be kept in mind [26]. Differentiating between these two conditions may be difficult. However, HIBI usually occurs after prolonged CPR and tends to appear more than 24 h after ROSC. Epileptic activity and seizures related to HIBI are strongly associated with no- and low-flow times [106].

There is no evidence to support prophylactic seizure prevention after ROSC [12, 107, 108]. The presence of epileptic activity is associated with a poor prognosis, but some patients are amenable to treatment once such activity has appeared. Phenytoin is not particularly effective in treatment of myoclonus or more severe epileptic activity related to HIBI [109]. Sodium valproate is contraindicated in pregnancy given the risk of birth defects. Therefore, in pregnant women with seizure activity after ROSC, levetiracetam is probably the drug of choice [110, 111]. Levetiracetam is eliminated by the kidneys and has linear pharmacokinetics and low protein binding, all of which increase its safety profile for both mother and fetus. Seizures related to eclampsia should also be treated with magnesium and strict control of blood pressure (See also Chap. 16).

13 General Intensive Care Management

If the gestational age is greater than 20 weeks, and the fetus is still in situ, placing the woman in the supine position is accompanied by the risk of aortocaval compression. Aortocaval compression may decrease venous return, causing hypotension and even shock or re-arrest. Therefore, after ROSC, the pregnant woman should be placed in a left lateral tilt position. Because of the option of inferior cava compression, central venous lines should be placed above the diaphragm [26, 54]. The risk of thrombosis is increased in pregnancy. However, coagulation disturbances have been described after cardiac arrest and have been associated with worse outcome [112]. Whether these coagulation disturbances require correction and to what degree such correction is possible and/or may change outcome remains unclear [113]. It is therefore wise to test coagulation periodically in order to balance the risk of administering prophylaxis for deep vein thrombosis with the need to correct coagulation abnormalities on an individual basis.

Aspiration may occur both during and after cardiac arrest, especially with prolonged periods of bag-valve-mask ventilation. Although gastric content may be sterile in non-hospitalised patients, treatment with an antibiotic is justified. In general in patients undergoing TTM after cardiac arrest, prophylactic uses of antibiotics has been shown to decrease the incidence of ventilator associated pneumonia [114]. The antibiotic chosen should depend on the cause of the arrest (e.g. hemorrhage vs. pneumonia) as well as local practices and bacterial resistance patterns. If the cause of arrest was not infectious, a second generation cephalosporin (e.g. cefuroxime) has been shown to suffice in unconscious traumatic brain injury patients [115]. Although there is limited evidence to support such practice, if the woman remains hypoxemic and aspiration is suspected, fiberoptic bronchoscopy and pulmonary lavage may be considered in order to remove residual gastric content and/or sputum[116].

Gastric ulcer prophylaxis is commonly used in intensive care, although conclusive evidence to support such practice is lacking [117]. Pregnant and peripartum women also have an increased risk of regurgitation, the symptoms of which may be alleviated with proton-pump inhibitors. Comatose hemodynamically unstable patients have a higher risk of developing gastrointestinal hemorrhage. Patients after myocardial infarction and/or percutaneous coronary intervention commonly receive antiplatelet agents and anticoagulants, further increasing the risk gastrointestinal hemorrhage.

14 Extracorporeal Membrane Oxygenation (ECMO) and Mechanical Assist Devices

The role of ECMO in management of cardiac arrest is unclear, especially in pregnant patients [118]. One centre has reported good results with the use ECMO in pregnant patients but only half of the women described were placed on ECMO during or immediately after CPR (see also Chap. 14). In the patient with extreme shock or hypoxia after return of spontaneous circulation, consideration should be given to treatment in an ECMO center (so-called ECMO watch) [56]. In non-pregnant patients, there is some evidence supporting the use of an intra-aortic balloon pump (IABP) [119,120,121], but there is no data on its applicability in pregnant patients. Furthermore, in late pregnancy, placing the patient in a lateral decubitus position may be difficult with an IABP. Caesarean section may also be considered if there is a chance that surgery will facilitate rather than complicate further care of the mother.

15 Prognostication

Patients after ROSC are usually kept sedated for 24–36 h, after which sedation is stopped, provided patient condition so allows. Continued sedation may be required in severe hypoxia, severe disseminated intravascular coagulopathy with ongoing hemorrhage or when brain edema or other pathological intracranial processes have been diagnosed [12, 79]. Ongoing coma or partial consciousness after termination of sedation suggests hypoxic-ischaemic encephalopathy (HIE). Factors increasing the risk of HIE are the absence of bystander-initiated life support and prolonged delays to return of spontaneous circulation [29]. HIE in general does not occur with ROSC delays briefer than 5 min.

If the patient fails to awaken, consultation with a neurologist is warranted and a multimodal prognostication approach should be applied [122]. Based on test results, the family can be approached with recommendations for further treatment, or in some cases, treatment withdrawal. All unconscious patients should undergo a thorough clinical examination. Important features include the presence/absence of brainstem reflexes (e.g. pupil size and reactivity, gag reflex) and cortical responses. An electroencephalography should again be obtained, as at this time it may identify more severe forms of HIE. Computed tomography of the brain is warranted to rule out intracranial pathology (e.g. severe brain oedema in HIE, hemorrhage). In some cases, magnetic resonance imaging of the brain may provide additional information on the severity of HIE and on the presence of lesions in areas of the brainstem which are seen less clearly in computed tomography. Blood levels of specific brain biomarkers may also be used for prognostication after cardiac arrest. In non-pregnant patients, neuron-specific enolase (NSE) is most widely used and has been validated [123,124,125]; an increase in NSE between 24 and 48 h and elevated NSE 48 h after ROSC suggest severe HIE [125]. At a gestational age of 37 weeks, healthy pregnant women have normal NSE levels. However, NSE levels are physiologically elevated in the early weeks of pregnancy (up to 10 weeks) due to extracerebral sources (e.g. the corpus luteum). Women developing pre-eclampsia have ongoing elevated levels of NSE throughout pregnancy and up to a year later, whereas in healthy women, the levels tend to decline to normal during pregnancy [126, 127]. Furthermore, hemolysis causes elevation of NSE levels [128, 129]. Therefore, NSE should not be used for prognostication in early pregnancy, in women with pre-eclampsia, or in pregnant or post-partum women with disseminated intravascular coagulation, amniotic fluid embolism or those who have undergone massive transfusion due to bleeding.

16 Further Care and Rehabilitation

Recovery after cardiac arrest can take time [130, 131]. Data on long-term survival varies greatly, but survival to hospital discharge is generally higher in pregnant patients than in non-pregnant patients [132, 133]. Beyond somatic recovery, psychological symptoms and even post-traumatic stress disorder are not uncommon after cardiac arrest [134,135,136,137]. Patients may feel guilt, bewilderment and depression. The possible addition of having lost a child or having to care for a child after severe illness is likely to make things even more difficult. Follow-up and counselling is therefore much needed.

17 Conclusions

Care of the pregnant patient after cardiac arrest is challenging. Maternal cardiac arrest during pregnancy, and the peripartum period is fortunately rare. However, this rarity makes it difficult for clinicians and staff to attain clinical experience with this condition. Adequate preparation, education, simulation-based training and adherence to a high standard of intensive care are likely to facilitate efficient performance when needed.