Acute respiratory failure in pregnancy. An analysis of 19 cases

Pulmonary Embolism and Amniotic Fluid Embolism

Venous thromboembolism (VTE) as well as other embolic events including amniotic fluid embolism (AFE) remain a leading cause of maternal death in the United States and worldwide. The pregnant patient is at a higher risk of developing VTE including pulmonary embolism. In contrast, AFE is a rare, but catastrophic event that remains incompletely understood. Here the authors review the cause of VTE in pregnancy and look at contemporary and evidence-based practices for the evaluation, diagnosis, and management in pregnancy. Then the cause and diagnostic difficulty of AFE as well as what is known regarding the pathogenesis are reviewed.

Disseminated intravascular coagulation associated organ failure in obstetric patients admitted to intensive care units: a multicenter study in China

We aimed to determine disseminated intravascular coagulation (DIC)-associated organ failure and underlying diseases based on data from three ICU wards in tertiary hospitals in China from 2008 to 2016. The diagnosis of DIC was confirmed by an International Society of Thrombosis and Hemostasis score greater than or equal to 5. The maternal outcomes included the changes in organ function 24 h after ICU admission. The durations of hospital stay and ICU stay were recorded as secondary outcomes. Among 297 ICU admissions (median Sequential Organ Failure Assessment score, 4) for obstetric diseases, there were 87 DIC cases, with an estimated DIC incidence of 87 per 87,580 deliveries. Postpartum hemorrhage was the leading disease associated with DIC (71, 81.6%), followed by hypertensive disorders (27, 31.0%), sepsis (15, 17.2%), acute fatty liver of pregnancy (11, 12.6%) and amniotic fluid embolism (10, 11.5%). Compared with patients without DIC, those with DIC had higher rates of multiple organ dysfunction syndrome/death (27.6% vs 4.8%, p = 0.000), organ failure (36.8% vs 24.3%, p = 0.029), among which organ failure included acute renal failure (32.2% vs 10.0%, p = 0.000), respiratory failure (16.1% vs 8.6%, p = 0.057), disturbance of consciousness (12.6% vs 2.4%, p = 0.000) and DIC group also had higher rates of massive transfusion (52.9% vs 21.9%, p = 0.000), hysterectomy (32.2% vs 15.7%, p = 0.001), longer ICU (4 days vs 2 days, p = 0.000) and hospital stays (14 days vs 11 days, p = 0.005). DIC and amniotic fluid embolism were independent risk factors for organ failure in patients admitted to the ICU. Postpartum hemorrhage was the leading cause of DIC associated organ failure in obstetrics admitted to the ICU. The control of obstetric bleeding in a timely manner may improve obstetric prognoses.

Acute pyelonephritis during pregnancy: a systematic review of the aetiology, timing, and reported adverse perinatal risks during pregnancy

We performed a comprehensive systematic review of acute pyelonephritis in pregnancy using PubMed, SCOPUS, ClinicalTrials.gov, and Ovid from inception to April 2018. About 7796 references were screened for inclusion, and 52 references from 1908 to 2017 were included. One hundred seven cases of acute pyelonephritis in pregnant women were reviewed. Gestational age at diagnosis was reported as 2 (2%), 43 (40%), and 51 (52%) during the first, second, and third trimesters, respectively. Maternal complications included sepsis (49%), acute respiratory distress syndrome (47%), anaemia (33%), acute kidney injury (10%), renal abscess (6%), and death (6%). 25 preterm deliveries (23%), 6 intrauterine foetal demises (6%), 4 spontaneous abortions (4%), and 8 neonatal intensive care unit admissions (7%) were reported. Microorganisms cultured included Escherichia coli (51%), Klebsiella (8%), Proteus (5%), Staphylococcus aureus (5%), Streptococcus (4%), and Enterococcus (3%). Early diagnosis and management led to fewer complications.Impact statementWhat is already known on this subject? Acute pyelonephritis during pregnancy can lead to adverse pregnancy outcomes and in this article, we highlight the most common outcomes previously reported. Previous studies have reported maternal adverse outcomes and only very few stressed on fetal/neonatal outcomes.What do the results of this study add? The results add that not only is maternal morbidity/mortality is increased, but also increases adverse outcomes for the fetus/neonate, such as preterm delivery and fetal/neonatal demise.What are the implications of these findings for clinical practice and/or further research? The implications from this article serve to increase a medical providers knowledge on how to appropriately counsel pregnant women with acute pyelonephritis. In addition, future research can aim to understand why pregnant women are more prone to morbidity and mortality compared to nonpregnant women.

Electrical impedance tomography may optimize ventilation in a postpartum woman with respiratory failure

Amniotic fluid embolism is a rare peripartum complication with the sudden onset of haemodynamic instability, respiratory failure and coagulopathy during labour or soon after delivery. A 31-year-old woman with amniotic fluid embolism was treated with vasopressors, inotropes, intravenous fluid, tranexamic acid and ventilatory support. Assessment of respiratory impairment was made using conventional chest X-ray, computed tomography and electrical impedance tomography. The potential for electrical impedance tomography to improve monitoring and guide respiratory therapy is explored.

Amniotic fluid embolism

The disastrous entry of amniotic fluid into the maternal circulation leads to dramatic sequelae of clinical events, characteristically referred to as Amniotic fluid embolism (AFE). The underlying mechanism for AFE is still poorly understood. Unfortunately, this situation has very grave maternal and fetal consequences. AFE can occur during labor, caesarean section, dilatation and evacuation or in the immediate postpartum period. The pathophysiology is believed to be immune mediated which affects the respiratory, cardiovascular, neurological and hematological systems. Undetected and untreated it culminates into fulminant pulmonary edema, intractable convulsions, disseminated intravascular coagulation (DIC), malignant arrhythmias and cardiac arrest. Definite diagnosis can be confirmed by identification of lanugo, fetal hair and fetal squamous cells (squames) in blood aspirated from the right ventricle. Usually the diagnosis is made clinically and by exclusion of other causes. The cornerstone of management is a multidisciplinary approach with supportive treatment of failing organs systems. Despite improved modalities for diagnosing AFE, and better intensive care support facilities, the mortality is still high.

Amniotic fluid embolism

Amniotic fluid embolism is one of the most catastrophic complications of pregnancy. First described in 1941, the condition is exceedingly rare and the exact pathophysiology is still unknown. The etiology was thought to be embolic in nature, but more recent evidence suggests an immunologic basis. Common presenting symptoms include dyspnea, nonreassuring fetal status, hypotension, seizures, and disseminated intravascular coagulation. Early recognition of amniotic fluid embolism is critical to a successful outcome. However, despite intensive resuscitation, outcomes are frequently poor for both infant and mother. Recently, aggressive and successful management of amniotic fluid embolism with recombinant factor VIIa and a ventricular assist device, inhaled nitric oxide, cardiopulmonary bypass and intraaortic balloon pump with extracorporeal membrane oxygenation have been reported and should be considered in select cases.

Complement C3a expression and tryptase degranulation as promising histopathological tests for diagnosing fatal amniotic fluid embolism

To date, the most recent specific diagnostic investigations for amniotic fluid embolism have been unable to conclusively identify any mechanism of disease other than a physical block to the circulation. We selected eight fatal cases in previously healthy women with uneventful singleton term pregnancies who presented to tertiary care centers in Italy for delivery. Pathologic features were assessed immunohistochemically using anti-fibrinogen, anti-tryptase, anti-C(3a), and anti-cytokeratin antibodies. AE1/AE3 cytokeratin stains proved positive, and tryptase-positive material was documented outside pulmonary mast cells. In all studied cases, expression of complement C(3a) was twofold lower than in the control group, suggesting a possible complement activation in AFE, initiated by fetal antigen leaking into the maternal circulation.

Amniotic fluid embolism managed with success during labour: report of a severe clinical case and review of literature

BACKGROUND

AFE (amniotic fluid embolism) is widely known as a disastrous rapid-progressing clinical entity. The incident ranges from 1:800 to 1:8,000. The mortality rate reaches 61-86%. Neonatal survival is reported at 70%.

METHODS

We describe the case of a healthy 29-year old primigravida developing amniotic fluid embolism during labour. Acute respiratory failure and hypotension combined with seizures were the initial symptoms. The patient under went an urgent caesarean section with extreme blood loss, complicated by disseminated coagulopathy.

RESULTS

A total hysterectomy was performed due to profuse bleeding. Aggressive management was practiced with continuous transfusion of blood products and administration of vasocopressors.

CONCLUSION

Amniotic fluid embolism or anaphylactoid syndrome of pregnancy is a life-threatening condition. Diagnosis is one of the exclusion. Its management is very difficult and requires quick management and cooperation of physicians from different specialties.

Respiratory physiologic changes in pregnancy

In summary, the major physiologic changes that occur in pregnancy are the increased minute ventilation, which is caused by increased respiratory center sensitivity and drive; a compensated respiratory alkalosis; and a low expiratory reserve volume. The vital capacity and measures of forced expiration are well preserved. Patients who have many lung diseases tolerate pregnancy well, with the exception of those who have pulmonary hypertension or chronic respiratory insufficiency from parenchymal or neuromuscular disease.

Successful pregnancy after amniotic fluid embolism: a case report

BACKGROUND

Amniotic fluid embolism (AFE) has a mortality rate of 60% to 80% and accounts for approximately 10% of all maternal deaths in the United States. Although AFE is thought to be an anaphylactoid reaction, there are few reports of subsequent pregnancy after AFE.

CASE

A healthy 29-year-old underwent an uncomplicated planned Caesarean section for her third pregnancy. She had a history of placental abruption with the first pregnancy and amniotic fluid embolism with the second pregnancy, for which she was treated with blood products and recovered fully.

CONCLUSION

This case of a 29-year-old woman with successful subsequent pregnancy after amniotic fluid embolism and a limited number of case reports in the literature suggest that AFE is a sporadic event.

Sepsis during pregnancy

OBJECTIVES

To provide a current review of the literature regarding the assessment and management of sepsis during pregnancy.

DESIGN

A comprehensive review of current English-language literature search was performed with Ovid MEDLINE using the Medical Subject Headings pregnancy and sepsis, with Medical Subject Headings or keywords seeking randomized controlled trials and clinical reports, and by reviewing the bibliographies of clinical practice guidelines.

RESULTS

Sepsis-related maternal morbidity and mortality is a significant and persistent problem in the modern critical care obstetric unit. The management of sepsis during pregnancy is challenging. The obstetric intensivist must simultaneously discern the effect of maternal physiologic changes on fetal vulnerability and the effect of the fetus on maternal status throughout the various phases of pregnancy. Little direct evidence exists to validate the extrapolation of some sepsis treatment modalities from other nonpregnant patient populations. Nevertheless, early detection, accurate diagnosis, and aggressive appropriate treatment strategies may significantly improve outcome. Approaches like the Surviving Sepsis Campaign guidelines are unproven but seem reasonable and practical.

CONCLUSIONS

Sepsis during pregnancy is uncommon yet potentially fatal. Diagnostic and therapeutic guidelines should predominantly pattern those currently utilized for nonpregnant patients.

Pulmonary complications of pregnancy

Pregnancy induces significant physiologic stresses on the pulmonary and cardiovascular systems that may precipitate respiratory compromise. In addition, certain disease states that are unique to the pregnant woman, such as amniotic fluid emboli syndrome, may be associated with respiratory failure. The physiologic changes that affect the pregnant woman are reviewed. Pregnancy-related conditions are discussed as well as how common diseases, such as the acute respiratory distress syndrome, asthma, pneumonia, and AIDS,have to be approached when balancing the needs of the fetus with maternal well-being.

Amniotic fluid embolism with involvement of the brain, lungs, adrenal glands, and heart

The case of a healthy 31-year-old woman in the 40th week of second pregnancy is presented. During preparation for an emergency caesarean section, she developed an amniotic fluid embolism (AFE) with unusual and unique features. The acute onset of disease with cardiorespiratory failure with hypotension, tachycardia, cyanosis, respiratory disturbances and loss of consciousness, suggested at first a pulmonary thromboembolism, but the appearance of convulsions led to the diagnosis of AFE. The patient died after 5 days due to an untreatable brain edema. At autopsy, AFE with the usually associated disseminated intravascular coagulation was found in the lungs, brain, left adrenal gland, kidneys, liver and heart. Eosinophilic inflammatory infiltrates were found in the lungs, hepatic portal fields and especially in the heart, suggesting a specific hypersensitivity reaction to fetal antigens. Moreover, intravascular accumulation of macrophages in the lungs also favored a non-specific immune reaction to amniotic fluid constituents.

Respiratory complications of pregnancy

The pregnant woman is susceptible to a variety of respiratory complications. When a pregnant patient presents with an abnormal chest x-ray or a pulmonary complaint, an understanding of the pathophysiology of pregnancy will guide the clinician in establishing a diagnosis. Pregnancy brings about many changes to a woman's body. One of the more intriguing is a decrease in the T helper cells, resulting in a state of relative immunosuppression. Despite this, the prevalence of infectious pneumonia is not increased in pregnancy. Complications from pneumonia, however, are increased in the pregnant host. Most notably are increases in both mortality related to influenza infection and the risk for dissemination of coccidioidomycosis. Other physiologic changes predispose the pregnant woman to certain disease processes. Hypercoagulability associated with pregnancy results in a marked increase in the incidence of thromboembolic disease. Although rare, pregnancy is also associated with other embolic phenomena including amniotic fluid embolism, air embolism, and trophoblastic embolism. Because of the increases in intravascular volume and cardiac output that occur in pregnancy, women with underlying structural heart disease will frequently present for the first time or have an exacerbation of their disease. This is especially true of mitral stenosis. Peripartum cardiomyopathy also can occur, and for the majority of patients, the heart remains damaged for life. Finally, although uncommon, lymphangioleiomyomatosis will often present or become exacerbated during pregnancy. Patients with this disorder need to be counseled concerning the increased risk associated with pregnancy. This paper reviews the various respiratory complications associated with pregnancy.

Amniotic fluid embolus: a review of the research literature

The diagnosis of Amniotic Fluid Embolus (AFE) is often missed clinically leading to the incorrect attribution of a major post-partum haemorrhage, which may accompany AFE, to uterine atony. This paper reviews the research on AFE with particular emphasis on the clinical presentation and diagnosis; both before and after death. It begins by dealing with the difficulty of defining AFE due to confusion about the underlying pathophysiological events. As this paper will demonstrate, the theory that AFE is an embolic event is no longer valid. A description of the clinical manifestations is provided so that these can be explained by the contemporary theory of AFE as an 'anaphylactoid' reaction. Finally, the difficulties of diagnosis, particularly laboratory diagnosis, will be discussed. The research indicates that it is not possible to accurately diagnose AFE, either, pre or post mortem, by any currently available laboratory tests. Because of better diagnosis it is now known that AFE in not uncommon and, if it is diagnosed early, a much higher rate of intact survival can be achieved than was previously thought possible.

Amniotic fluid embolism: a case report and review

A 41-year old primigravida underwent caesarean section because of foetal distress following prostin induction of labour. Intraoperative coagulopathy, haemorrhage and hypotension necessitated a hysterectomy. Subsequently, she developed respiratory and renal failure, requiring mechanical ventilation and haemodialysis. She made a full recovery. The likely diagnosis was amniotic fluid embolism (AFE), a rare complication of pregnancy with a variable presentation, ranging from cardiac arrest and death through to mild degrees of organ system dysfunction with or without coagulopathy. The differential diagnosis includes pre-eclamptic toxaemia/pregnancy-induced hypertension, anaphylaxis and pulmonary embolism. There is no diagnostic test for AFE; the finding of foetal elements in the maternal circulation is non-specific. Historically, AFE was thought to induce cardiovascular collapse by mechanical obstruction of the pulmonary circulation. It is now thought that a combination of left ventricular dysfunction and acute lung injury occur, with activation of several of the clotting factors. An immunological basis for these effects is postulated. There is no specific therapy and treatment is supportive. The mortality of the condition remains high.

The effect of amniotic fluid on the human omental artery in vitro

OBJECTIVE

The aim of the study was to determine the effect of amniotic fluid on the in vitro contractility of the human omental artery.

STUDY DESIGN

Amniotic fluid and a segment of omentum were obtained from each of 5 patients at the time of planned cesarean delivery at normal term gestation for the indication of previous cesarean delivery. The omental artery was cleaned and cut into 3-mm rings, which were placed in 10-mL organ chambers for isometric tension recording. The chambers were filled with Krebs-Henseleit solution bubbled with 5% carbon dioxide in air and maintained at 37 C, pH 7.4. The rings were then equilibrated at 1 g passive tension for 90 minutes. The amniotic fluid was centrifuged for 10 minutes at 3000 rpm to remove all debris. Increasing volumes of supernatant (10-2000 microL) were added to the omental artery rings at baseline tone or after contraction with U46619 (10(-7) mol/L) or potassium chloride (60 mmol/L) to detect contractile and relaxant effects, respectively. Time-solvent control preparations were also run in parallel.

RESULTS

Amniotic fluid had no effect on the basal tone of omental artery rings. Amniotic fluid had no effect on the tension in rings previously contracted with either U46619 or potassium chloride.

CONCLUSIONS

Amniotic fluid has no direct effect on isolated human omental artery. The catastrophic hemodynamic changes associated with the syndrome of amniotic fluid embolism are not due to a direct effect of circulating amniotic fluid on vascular tone but rather may be due to secondary responses