Amniotic fluid embolism

Obstetric Disorders and Critical Illness

In this article, we discuss some of the more common obstetric-related conditions that can lead to critical illness and require management in an ICU. These include the hypertensive disorders of pregnancy, postpartum hemorrhage, hemolysis, elevated liver enzymes, and low platelet syndrome, acute fatty liver of pregnancy, amniotic fluid embolism, and peripartum cardiomyopathy. We also discuss pulmonary embolism and Covid-19. Despite not being specific to obstetric patients, pulmonary embolism is a common, life-threatening diagnosis in pregnancy with particular risks and management aspects. Covid-19 does not seem to occur with higher frequency in pregnant women, but it leads to higher rates of ICU admissions and mechanical ventilation in pregnant women than in their nonpregnant peers. Its prevalence during our current global pandemic makes it important to discuss in this article. We provide a basis for critical care physicians to be engaged in informed conversations and management in a multidisciplinary manner with other relevant providers in the care of critically ill pregnant and postpartum women.

Inhaled nitric oxide might be a contributing tool for successful resuscitation of cardiac arrest related to pulmonary hypertension

We describe a case where inhaled nitric oxide (iNO) was successfully initiated during cardiopulmonary resuscitation (CPR) in a younger patient with cardiac arrest related to pulmonary hypertension after disseminated intravascular coagulation (DIC) postpartum bleeding and hysterectomy. This case illustrates that iNO might be a potential lifesaving tool for resuscitation of patients with cardiac arrest related to pulmonary hypertension, for whom most other resuscitation strategies often are futile.

Critical care in obstetrics

Pregnancy is a normal physiologic process with the potential for pathologic states. Pregnancy has several unique characteristics including an utero-placental interface, a physiologic stress that can cause pathologic states to develop, and a maternal–foetal interface that can affect two lives simultaneously or in isolation. Critical illness in pregnant women may result from deteriorating preexisting conditions, diseases that are co-incidental to pregnancy, or pregnancy-specific conditions. Successful maternal and neonatal outcomes for parturients admitted to a maternal critical care facility are largely dependent on a multidisciplinary input to medical or surgical condition from critical care physicians, obstetric anaesthesiologists, obstetricians, obstetric physicians, foetal medicine specialists, neonatologists, and concerned specialists. Pregnant women requiring maternal critical care unit admission are relatively low in developed nations and range from 0.9% to 1%; but in our country, the admission rates of critically ill parturients range from 3% to 8%. Two-thirds of pregnant women requiring critical care are often unanticipated at the time of conception. In this review, we will look at critical illnesses in pregnant women with a specific focus on pregnancy-induced illnesses.

Amniotic Fluid Embolism: Anaphylactic Reactions With Idiosyncratic Adverse Response

PROBLEM

Amniotic fluid embolism (AFE) is a rare but severe emergency in obstetrics. The aim of the present study was to investigate the pathophysiology of AFE.

METHODS

A search was conducted between 1966 and 2014 through the English-language literature (online MEDLINE PubMed database) using the keyword amniotic fluid embolism combined with anaphylaxis, anaphylactoid, complement activation, mast cells, fetal antigens, and idiosyncratic.

RESULTS

Amniotic fluid embolism is a rare clinical entity but a severe obstetric emergency that can be lethal even in previously healthy women in labor or in the early postpartum period. There appears to be at least 2 mechanisms. First, adverse reactions in AFE are usually unexpected and fetal antigen dose dependent. Given the disastrous entry of amniotic fluid into the maternal circulation, they experience a sudden cardiopulmonary collapse (mechanical obstruction subtype). Second, anaphylactic and anaphylactoid reactions of the remaining AFE are also relatively unexpected and fetal antigen dose independent and can occur at the first exposure to amniotic fluid components. They are associated with complement activation and subsequent postpartum hemorrhage. Cardiac mast cells constitute a central pathogenesis of anaphylactic (immunoglobulin E-dependent) and anaphylactoid (immunoglobulin E-independent) reactions.

CONCLUSIONS

Recent immunologic studies provide a new approach to the study of the pathophysiology of AFE.

Clinical review: Special populations--critical illness and pregnancy

Critical illness is an uncommon but potentially devastating complication of pregnancy. The majority of pregnancy-related critical care admissions occur postpartum. Antenatally, the pregnant patient is more likely to be admitted with diseases non-specific to pregnancy, such as pneumonia. Pregnancy-specific diseases resulting in ICU admission include obstetric hemorrhage, pre-eclampsia/eclampsia, HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome, amniotic fluid embolus syndrome, acute fatty liver of pregnancy, and peripartum cardiomyopathy. Alternatively, critical illness may result from pregnancy-induced worsening of pre-existing diseases (for example, valvular heart disease, myasthenia gravis, and kidney disease). Pregnancy can also predispose women to diseases seen in the non-pregnant population, such as acute respiratory distress syndrome (for example, pneumonia and aspiration), sepsis (for example, chorioamnionitis and pyelonephritis) or pulmonary embolism. The pregnant patient may also develop conditions co-incidental to pregnancy such as trauma or appendicitis. Hemorrhage, particularly postpartum, and hypertensive disorders of pregnancy remain the most frequent indications for ICU admission. This review focuses on pregnancy-specific causes of critical illness. Management of the critically ill mother poses special challenges. The physiologic changes in pregnancy and the presence of a second, dependent, patient may necessitate adjustments to therapeutic and supportive strategies. The fetus is generally robust despite maternal illness, and therapeutically what is good for the mother is generally good for the fetus. For pregnancy-induced critical illnesses, delivery of the fetus helps resolve the disease process. Prognosis following pregnancy-related critical illness is generally better than for age-matched non-pregnant critically ill patients.

Surgical treatment of an amniotic fluid embolism with cardiopulmonary collapse

Amniotic fluid embolism is a rare but devastating condition associated with a very high rate of morbidity and mortality. The treatment has traditionally been aggressive supportive care. We report a case of a term pregnant woman with complete cardiovascular collapse secondary to a paradoxical amniotic fluid embolism. The embolism was seen on transesophageal echocardiogram during an emergency Cesarean section as a free-floating interatrial clot through a patent foramen ovale. She was subsequently and successfully treated with immediate cardiopulmonary bypass, thromboembolectomy, and closure of the patent foramen ovale.

Obstetric disorders in the ICU

Obstetric disorders account for 55% to 80% of admissions to the intensive care unit in the obstetric population. Medical conditions are emerging as the leading cause of maternal mortality, partly because of marked improvement in surgical and obstetric care in the developed world. The rise in maternal mortality related to medical conditions can be explained by multiple factors: improved medical care, women with chronic illnesses reaching childbearing years, older age at time of first pregnancy, improved reproductive technologies, and severe medical conditions exacerbated by the physiologic changes of pregnancy. This article reviews obstetric disorders leading to intensive care unit admissions.

Management of the unconscious pregnant patient

The management of the unconscious pregnant patient encompasses many aspects of obstetrics and critical care. It is not uncommon to have to manage such a patient, therefore one needs to be well prepared. There is a spectrum of altered consciousness, brain death being the most extreme. The causes of unconsciousness can be general or pregnancy specific. It is important to consider the physiological changes in pregnancy when managing these patients. The immediate resuscitative measures are mostly the same as for the nonpregnant with a few modifications. It is important to remember that there are two patients involved and this can complicate management issues. A multidisciplinary approach would be prudent. The intermediate and long-term management should also involve the family. The issues of perimortem and somatic support for foetal maturity are also discussed.

Emergencies associated with pregnancy and delivery: peripartum hemorrhage

INTRODUCTION

Peripartum hemorrhage is one of the leading causes of maternal death worldwide (25%).

METHODS

Selective literature review, including international guidelines, for assessment of the causes and optimal management of this condition.

RESULTS

The major causes of hemorrhage are uterine atony, placenta previa, and abruptio placentae. The diagnosis of hemorrhage is suspected from its clinical manifestations and confirmed by ultrasonography. In placenta previa, the placenta is implanted in the lower uterine segment and may cover the internal cervical os. Placenta previa is more common in older and multiparous mothers, as well as in mothers who have previously undergone a cesarean section. Placental abruption is defined as separation of the placenta from the uterine wall before delivery of the infant. The risk factors for this condition include preeclampsia, advanced maternal age, and trauma. When it presents with manifestations of acute blood loss, premature abruption placentae must be diagnosed rapidly and treated without delay to save the life of the mother and child. A rare, but highly lethal, cause of bleeding is amniotic fluid embolism, which manifests itself with sudden and unexplained peripartum respiratory distress and cardiovascular collapse. Amniotic fluid embolism is associated with high fetal and maternal mortality (20% and 60% to 80%, respectively) even when it is optimally treated.

DISCUSSION

Peripartum hemorrhage is an important source of maternal and fetal morbidity and mortality. The prognosis for both mother and child can be markedly improved if the risk factors for hemorrhage are recognized and the problem is treated rapidly and appropriately when it arises.

Forensic Lung Pathology

Sudden and unexpected natural deaths and nonnatural deaths may result from various pulmonary conditions. Additionally, several nonpulmonary conditions of forensic significance may be complicated by the development of respiratory lesions. Certain situations with pulmonary pathology are particularly likely to be critically scrutinized and may form the basis of allegations of medical negligence, other personal injury liability, or wrongful death.1

Rapid reversal of critical haemodynamic compromise with nitric oxide in a parturient with amniotic fluid embolism

We describe a case of amniotic fluid embolism presenting as cardiovascular collapse during labour. After initial resuscitation and emergency caesarean section, the patient was transferred to the intensive care unit with profound hypoxaemia, a high inotropic drug requirement and severe coagulopathy. A transoesophageal echocardiogram demonstrated acute right ventricular overload, severe pulmonary artery hypertension and marked diastolic dysfunction of the left ventricle secondary to a dilated right ventricle. The introduction of nitric oxide at 40 ppm produced a dramatic improvement in her cardiorespiratory status. Mother and baby both survived with no apparent long term sequelae.

Critical care of the obstetric patient

The obstetric patient poses exceptional challenges in the intensive care unit. Knowledge of the physiologic changes of pregnancy and specific pregnancy-related disorders is necessary for optimal management. Intensive care unit diagnoses may include preeclampsia, including the HELLP syndrome, pulmonary embolic disease, amniotic fluid embolism, status asthmaticus, respiratory infection, the acute respiratory distress syndrome, and sepsis. The management of mechanical ventilation is based on principles of avoiding lung injury, and hypercapnia may be tolerated even during the pregnancy. When the clinician is faced with the extraordinary instance of cardiopulmonary arrest, perimortem cesarean delivery must be considered to improve the potential for maternal and fetal survival.

Delayed presentation of amniotic fluid embolism: Lessons from a case diagnosed at autopsy

Amniotic fluid embolism (AFE) syndrome, a catastrophic cause of respiratory failure typically occurs during labour, or soon after delivery. Systemic hypotension is the most prominent haemodynamic alteration documented in patients with AFE, a consequence principally of severe left-sided heart failure. A 22-year-old female was admitted to the respiratory intensive care unit with severe eclampsia and acute respiratory failure 4 h following delivery. Her blood pressure was elevated (systolic 150-180 mm Hg, diastolic 90-110 mm Hg) throughout the admission. She succumbed in spite of therapy for eclampsia and mechanical ventilation. Autopsy revealed large numbers of polygonal, anucleate foetal squames and mucin in the pulmonary vasculature typical of AFE while changes of eclampsia were found in the liver and kidneys. It appears that AFE syndrome can have a delayed presentation, as late as 4 h after delivery and haemodynamic collapse may not be mandatory if the patient has coexisting systemic hypertension secondary to severe eclampsia.

Aprotinin in the management of coagulopathy associated with amniotic fluid embolus

Amniotic fluid embolus, also known as anaphylactoid syndrome of pregnancy is a rare complication of pregnancy. When it occurs, the maternal mortality rate may be as high as 86%, and in survivors, the morbidity rate may be just as high. Hallmark clinical features include maternal cardiovascular collapse with disseminated intravascular coagulation, and fetal distress. Management centers on strategies to improve oxygenation, support circulation, and correct the coagulopathy. We report the case of a patient who developed amniotic fluid embolus and was effectively managed with aprotinin to control the coagulopathy associated with this devastating complication of pregnancy.

Cardiopulmonary distress during obstetrical anaesthesia: attempts to diagnose amniotic fluid embolism in a case series of suspected allergic anaphylaxis

BACKGROUND

Cardiopulmonary distress during obstetrical anaesthesia may result from a drug-induced allergic reaction, but, in the obstetrical setting, allergic anaphylaxis may be inseparable from amniotic fluid embolism in terms of the clinical presentation. Further investigations, using allergy tests and other laboratory analyses, are then needed to pursue a diagnostic clarification.

METHODS

Twelve women suspected of having developed anaphylaxis during obstetrical anaesthesia underwent allergy follow-up investigations and further serological tests with the amniotic fluid embolism marker sialyl Tn and complement factors (C3 and C4) in an attempt to differentiate amniotic fluid embolism from drug-induced allergic anaphylaxis.

RESULTS

The diagnostic programme revealed one case of probable amniotic fluid embolism and four cases of probable drug-induced allergic anaphylaxis. Of the remaining seven cases, there were two cases that, by diagnostic exclusion, could be classified as possible cases of amniotic fluid embolism. The cause of the reactions remained unresolved in five cases.

CONCLUSIONS

It can be difficult to differentiate between anaphylaxis and amniotic fluid embolism, especially amongst survivors. Diagnostic markers that can be applied on peripheral blood samples are promising, but larger studies are needed to validate their use in the diagnosis of causes of cardiopulmonary distress during obstetrical anaesthesia.

[Amniotic fluid embolism: two case reports]

We report two cases of amniotic fluid embolism, confirmed by histological examination. Both patients had an immediate post-partum haemorrhage that required an haemostatic hysterectomy. A typical symptomatology of amniotic fluid embolism revelated the first case. The patient survived without any sequelae. In the second case, amniotic fluid embolism occurred immediately after the delivery. The patient developed an acute respiratory distress with a shock syndrome. Despite haemostatic hysterectomy and resuscitative efforts, she died 6 days later.

Critical illness in pregnancy: an overview

OBJECTIVES

To provide an overview of the critical illnesses that afflict the pregnant patient.

DESIGN

A comprehensive review of the literature was performed with Pubmed Medline using medical subject headings of pregnancy, critical care, epidemiology, prognostic score, dyspnea, fever, and jaundice.

RESULTS

Although pregnant women constitute a small number of admissions to an intensive care unit, they pose a challenge to the health care team. The physiological changes that occur in pregnancy stress and limit the compensatory response required to adapt to a superimposed acute illness. Although a number of conditions are uniquely associated with pregnancy, other medical conditions may complicate the course of pregnancy. The pregnant state also increases susceptibility to a number of illnesses. In this overview, we reviewed the epidemiology and different clinical presentations of critical illness in a pregnant patient.

CONCLUSIONS

The critically ill pregnant patient presents a challenge to the critical care physician due to unique physiology and specific medical disorders in this population.

Amniotic fluid embolism

INCIDENCE

Amniotic fluid embolism is a catastrophic syndrome that occurs during pregnancy or in the immediate postpartum period. Multiple case reports have described the clinical findings and have reported variable success with supportive care. There has been discrepancy with respect to the incidence and mortality of amniotic fluid embolism. One likely explanation for this inconsistency is the lack of sensitive and specific diagnostic studies to definitively identify cases of amniotic fluid embolism, leading to both over- and underreporting. Despite the variation in reported incidence and mortality, amniotic fluid embolism remains a life-threatening condition with significant morbidity and mortality for the pregnant woman. It is the fifth most common cause of maternal mortality in the world.

DIAGNOSIS

The diagnosis of amniotic fluid embolism continues to be a clinical diagnosis and a diagnosis of exclusion based on the rapid development of a complex constellation of findings with sudden cardiovascular collapse, acute left ventricular failure with pulmonary edema, disseminated intravascular coagulation, and neurologic impairment. Given the significant morbidity and mortality associated with this condition, a high index of suspicion is warranted. Suspected risk factors have included tumultuous labor, trauma, multiparity, increased gestational age, and increased maternal age. However, many patients who develop amniotic fluid embolism have no obvious risk factors.

MANAGEMENT

Patients with amniotic fluid embolus are best managed using a multidisciplinary approach. There are no pharmacologic or other therapies that prevent or treat the amniotic fluid embolism syndrome, and supportive care typically involves aggressive treatment of multiple types of shock simultaneously. In this article we discuss the clinical presentation of amniotic fluid embolism syndrome as well as current opinions regarding pathophysiology, diagnosis, and management.

Cardiopulmonary complications of pregnancy

OBJECTIVES

To provide an up-to-date review of the literature on the assessment and management of pulmonary and cardiac conditions that may affect women during pregnancy and the postpartum period.

DESIGN

A review of the current literature was performed.

RESULTS

Pregnancy may be complicated by a variety of pregnancy-specific and other cardiopulmonary complications. Management requires knowledge of the cardiopulmonary physiologic changes occurring in pregnancy, the pregnancy-specific conditions that may occur, and the effect of a fetus on maternal care.

CONCLUSIONS

Admission of the pregnant or postpartum woman to the intensive care unit is uncommon but may require specialized knowledge for successful management.