(1)
Division of Pulmonary and Critical Care Medicine, Eastern Virginia Medical School, Norfolk, VA, USA
Keywords
Obstetric hemorrhagePre-eclampsiaEclampsiaAmniotic fluid embolusPuerperal sepsisHELLP syndromePosterior reversible encephalopathy syndrome (PRES)Critical illness is an uncommon but potentially devastating complication of pregnancy. In Western nations about 1 % of obstetric patients will require admission to an ICU. Mortality of critically ill obstetric patients ranges from 12 to 20 % [1]. The most common cause of maternal death in the ICU is ARDS [1].
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 syndrome, amniotic fluid embolus syndrome, acute fatty liver of pregnancy, and peripartum cardiomyopathy [2]. Physiologic changes associated with pregnancy may result in strain on organ systems with limited reserve and result in deterioration of pre-existing medical conditions (see Table 47.1). Hemorrhage, particularly postpartum, and hypertensive disorders of pregnancy remain the most frequent indications for ICU admission [2].
Table 47.1
Cardio-respiratory changes during pregnancy
System | Changes |
|---|---|
Respiratory | Increased alveolar ventilation |
Relative hypocarbia (PaCO2 25–32 mmHg) | |
Reduced functional residual capacity | |
Increased oxygen consumption | |
Cardiovascular | Increased cardiac output (40 %); increased SV 25 % increased HR 25 % |
Reduced total peripheral resistance | |
Increased blood volume | |
Increased plasma volume | |
Physiologic anemia |
Obstetrical Hemorrhage
Major obstetric hemorrhage is the leading cause of maternal mortality worldwide and is the most frequent indication for ICU admission. It may occur antepartum or postpartum [2].
Antepartum Hemorrhage
Antepartum hemorrhage occurs in 1 in 20 pregnant women; in the majority of cases, there is no risk to the mother or fetus. Causes include abruptio placentae, placenta previa, placenta accreta/increta/percreta, and uterine rupture [2]. The patient may present with pain, vaginal bleeding, uterine tenderness, and increased uterine activity. Depending on the location of bleeding, considerable blood loss may occur prior to diagnosis. Significant hemorrhage is associated with coagulopathy.
Postpartum Hemorrhage
Postpartum hemorrhage (PPH) involves blood loss of greater than 500 mL within 24 h regardless of the mode of birth. In 60–70 % of cases, the cause of PPH is failure of uterine contraction following delivery [2]. Uterine atony results in continuous bleeding that is often painless. Placental retention is the second most common cause of PPH (20–30 % of cases).
Management
An aggressive coordinated multidisciplinary approach is required. Initial management depends on the cause of the hemorrhage and whether delivery of the fetus has occurred. Where the hemorrhage occurs postpartum, uterine atony with or without retained products should be suspected. Oxytocin should be administered, the bladder should be emptied, and the uterus massaged. The obstetrician should examine the genital tract for evidence of trauma. If bleeding persists, prostaglandin therapy – either intravenous prostaglandin E2 or 15-methyl prostaglandin F2α—is administered [2]. Patients should be volume resuscitated with crystalloids, blood and blood products. Surgical intervention should be considered with ongoing bleeding: arterial ligation, Cesarean hysterectomy, or uterine artery embolization.
Hypertension
Hypertension is one of the most common medical disorders affecting pregnancy. It complicates 12 % of pregnancies and is responsible for 18 % of maternal deaths in the United States [3]. The presentation of a patient with gestational hypertension may range from a mild to a life threatening disease process. In 2000, the National High Blood Pressure Education Program Working Group on High Blood Pressure in Pregnancy defined four categories of hypertension in pregnancy, namely [4];
chronic hypertension
gestational hypertension
preeclampsia
preeclampsia superimposed on chronic hypertension.
Pre-eclampsia
Pre-eclampsia is a multiorgan disease process of unknown etiology characterized by the development of hypertension and proteinuria after 20 weeks of gestation. It is characterized by abnormal vascular response to placentation that is associated with increased systematic vascular resistance, enhanced platelet aggregation, activation of the coagulation system and endothelial dysfunction [4]. Pre-eclampsia is a heterogeneous syndrome with a spectrum of maternal and fetal manifestations with probable multiple causative factors. Clinically pre-eclampsia can manifest as a maternal syndrome with hypertension and proteinuria with/without other multisystem abnormalities and/or a fetal syndrome characterized by fetal growth retardation, reduced amniotic fluid and abnormal oxygenation. In general, maternal and perinatal outcomes are usually favorable in women with mild pre-eclampsia developing beyond 34 weeks gestation. In contrast, maternal and perinatal morbidities and mortalities are increased in women who develop the disorder before 33 weeks gestation, in those with pre-existing medical disorders and in those from developing countries.
Several factors have been identified which increase the risk of pre-eclampsia, including:
Primagravida
Extremes of age
Pre-eclampsia in previous pregnancy
Family history of pre-eclampsia
Obesity
Preexistent thrombophilia
Chronic hypertension
Renal disease
Men who have previously fathered a pre-eclamptic pregnancy
Generally, pre-eclampsia is regarded as a disease of first pregnancy. Eclampsia, the occurrence of seizures superimposed on the syndrome of pre-eclampsia, complicates 1 in 2,000 pregnancies in Western nations. In developing countries it is more common, being a common cause of maternal death. It is not clear what percentages of patients with eclampsia have the posterior reversible encephalopathy syndrome (PRES; see Chap. 28).
Diagnosis of Pre-eclampsia
Pre-eclampsia is defined as the presence of hypertension with a blood pressure of at least 140/90 mmHg on at least two occasion 4–6 h apart and proteinuria of 300 mg or more in 24 h. If a 24-h urine sample is not available, proteinuria is defined as a protein concentration of 300 mg/L or more in at least two random samples taken at least 4–6 h apart. However a quantitative 24 h urine protein should be measured in all patients with suspected pre-eclampsia. The signs and symptoms of pre-eclampsia include:
Symptoms
Severe headache
Fatigue
Epigastric/RUQ pain
Vomiting
Visual disturbances
Swelling of hands, face and feet
Signs
Hypertension (>140/90 mmHg)
Proteinuria (>300 mg/day)
Hyperreflexia
Oliguria
Seizures
Focal neurological signs
Increased serum creatinine (>0.7 mg/dL)
Increased serum uric acid (>5.8 mg/dL)
Intrauterine growth retardation
Oligohydramnios
HELLP
Reduced platelet count (<100,000/μl)
Elevated liver enzymes (AST > 70 IU/L)
Evidence of microangiopathic hemolytic anemia
LDH > 600 IU/L
Bilirubin > 1.2 mg/dL
Decreased haptoglobin
Schizocytes on peripheral smear
Patients are considered to have severe pre-eclampsia when the systolic blood pressure is at least 160 mmHg, the diastolic ≥110 mmHg or in patients with severe proteinuria (≥5 g/day). Furthermore, patients with pulmonary edema, oliguria, severe central nervous system symptoms or the HELLP (hemolysis, elevated liver enzymes and thrombocytopenia) or posterior reversible encephalopathy (PRES) syndromes are considered to have severe pre-eclampsia. It should be recognized that hypertension or proteinuria may be absent in 10–15 % of women who develop the HELLP syndrome and in up to 35 % of those who develop eclampsia. Women with systemic lupus erythematosus (SLE) may develop lupus nephritis during pregnancy which may be confused with pre-eclampsia, which is itself more common in women with SLE. An auto-immune workup should be considered in women with severe proteinuria, oliguria and/or progressive renal dysfunction. As the treatment of these two disorders is quite different, a renal biopsy may be required to confirm the diagnosis. The complications of pre-eclampsia include:
Central Nervous System
Eclampsia (seizures)
Cerebral hemorrhage
Central venous thrombosis
Hypertensive encephalopathy
Posterior Reversible Encephalopathy Syndrome (PRES); see Chap. 63
Seizures/status epilepticus
Altered mental status
Cortical blindness
Hepatic
Jaundice
Subcapsular/intrahepatic hematoma
Hepatic rupture
HELLP Syndrome
Thrombocytopenia
Hepatic dysfunction
Microangiopathic hemolytic anemia
Coagulation System
Disseminated intravascular coagulation
Microangiopathic hemolysis
Hematoma
Hematuria
Pulmonary embolism
Other
Acute renal failure
Cardiogenic/noncardiogenic pulmonary edema
Infection/sepsis
Placenta infarction
Placenta abruption
Fetal
Death
Preterm birth
Intrauterine growth retardation
HELLP Syndrome
The acronym HELLP describes a variant of severe pre-eclampsia characterized by hemolysis, elevated liver enzymes, right upper quadrant pain and thrombocytopenia. The development of HELLP syndrome places the pregnant patient at increased risk for morbidity and death. The HELLP syndrome usually develops suddenly during pregnancy (27–37 weeks gestation) or in the immediate puerperium. The HELLP syndrome occurs in up to 20 % of pregnancies complicated by severe preeclampsia. The clinical presentation of the HELLP syndrome is variable; 12–18 % of affected women are normotensive and 13 % do not have proteinuria [5, 6]. Hepatic injury appears to play a central role in the HELLP syndrome and it has been proposed that placenta-derived proteins damage hepatocytes. Indeed, Strand et al. demonstrated apoptosis in the liver of HELLP patients and cytotoxicity of human hepatocytes exposed to the serum of patients with HELLP [7]. In many respects the HELLP syndrome mimics many of the features of the systemic inflammatory response syndrome (SIRS) which are superimposed on pre-eclampsia.
Posterior Reversible Encephalopathy Syndrome (PRES)
PRES is a clinico-neuro-radiological entity characterized by headache, vomiting, altered mental status, blurred vision and seizures with neuroimaging studies demonstrating white-gray matter edema involving predominantly the posterior region of the brain (see Chap. 28) [8]. Pre-eclampsia is the commonest cause of PRES. Patients may present with PRES post-partum without the classic pre-eclamptic signs. Furthermore, status epilepticus has been reported to occur in these patients. It is unclear what percentage of patients previously diagnosed with eclampsia or patients with severe-eclampsia and neurological signs/symptoms in actuality met the diagnostic criteria for PRES. This distinction is important as patients with PRES may require aggressive management of raised intracranial pressure.
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