Page 1791 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

1260 PART 11: Special Problems in Critical Care

so that increased blood flow results in pulmonary pressures that can use of low dose aspirin has been safe in pregnancy. However, doses over
be even higher than baseline. Combined with increased myocardial 150 mg/d are cautionable, and clear recommendations for aspirin dosing
demand from augmented cardiac output, and increased preload from in acute ischemia are lacking. Limited data on clopidogrel and glycopro-
an expanded circulating volume, higher pulmonary pressures can result tein IIb/IIIa inhibitors in pregnancy often preclude their use in pregnant
in florid right heart failure. Labor and delivery are marked by a further patients. While nitrates and most β-blockers are considered reasonably
increase in myocardial oxygen consumption, in addition to large fluid safe in pregnancy, statin medications are contraindicated. 67,68
shifts from blood loss and the “auto-transfusions” of uterine contrac- Labor and delivery are high risk for women with cardiovascular
tions. Accordingly, the immediate postpartum period is a particularly disease. The optimal delivery method in most cases is assisted vaginal
high-risk time for decompensation. 58 delivery in the left lateral decubitus position. Epidural anesthesia miti-
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De novo cardiac conditions of pregnancy include peripartum car- gates the tachycardic response to pain. Indications for cesarean section
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diomyopathy, myocardial ischemia, coronary or aortic dissection, and include obstetric complications, fetal distress, or inability to tolerate
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endocarditis. Peripartum cardiomyopathy develops in up to 1 in 1300 labor and delivery. In addition, general anesthesia and surgical deliv-
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deliveries. Postulated risk factors include African American ancestry, ery may be preferred for patients with hypertrophic cardiomyopathy,
advanced maternal age, multiple gestations, preeclampsia, and gesta- aortic stenosis, or pulmonary hypertension, conditions which place
tional hypertension. While peripartum cardiomyopathy can occur in the patient at particular risk of decompensation during the increased
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the last month of pregnancy and up to 5 months after deliver, the imme- cardiac demand and large fluid shifts of labor and delivery. If possible,
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diate postpartum period is the most common time for presentation. 60,61 labor and delivery should be avoided for at least two weeks following
The presentation can be fulminant, with some patients requiring cardiac an acute myocardial infarction; aggressive antiplatelet therapy can be a
transplantation, although most often the clinical course is marked by the contraindication for vaginal delivery.
gradual recovery of ventricular function. An implantable defibrillator ■
may be indicated during the recovery period. Myocardial infarction is SEPTIC SHOCK
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uncommon during pregnancy, although the incidence may be increas- Sepsis remains an important cause of hypoperfusion and critical illness
ing coincident with a higher burden of cardiovascular comorbidities in in pregnancy, and the associated maternal mortality rate of up to 13%
the general population. Maternal mortality is high in patients delivering is high for an otherwise healthy population. 23,69 Sepsis during pregnancy
within two weeks of a myocardial infarction. Aortic or coronary artery can be complicated by shock, acute respiratory distress syndrome
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dissection can occur during pregnancy, and may be related to hormonal (ARDS), multi-organ system failure, cardiac dysfunction, premature
factors and increased shear stress from augmented cardiac output. 63,64 delivery, fetal demise, and neurological abnormalities in the infant. 69,70
Risk factors for dissection include older age, multiparity, trauma, The hemodynamics of sepsis are similar in pregnant and nonpregnant
hypertension, connective tissue disease, hypothyroidism, coarctation patients. However, as normal pregnancy is associated with a decrease in
of the aorta, or a bicuspid aortic valve. Aortic dissection presents most vascular resistance and an increase in heart rate, determining if hypoten-
commonly during the third trimester, often as a tearing interscapular sion or pathologic tachycardia is present can be difficult. Rapid or major
pain. Pulse asymmetry or signs of aortic insufficiency may be noted on changes in hemodynamics are significant findings that can be concern-
examination. Coronary artery dissection typically presents with chest ing for sepsis. While a mild elevation in the white blood cell count is a
pain and ischemic electrocardiogram (ECG) changes. In pregnant normal finding in late pregnancy, a significant elevation or a left shift on
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patients with no atherosclerosis risk factors who present with acute chest the differential should raise concern for infection. Infections that cause
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pain and signs of ischemia, coronary dissection should be strongly con- sepsis may be obstetric or nonobstetric in nature, as reviewed below and
sidered and thrombolytics should be avoided until angiography has been in Table 127-6.
performed. Finally, bacterial endocarditis is rare in pregnancy. It occurs Obstetric infections include endometritis, septic abortion, chorioam-
most often, although not exclusively, in patients with preexisting cardiac nionitis, intra-abdominal or pelvic abscesses, or surgical site soft tissue
abnormalities. Intravenous drug use is a strong risk factor. Surgical infections, including necrotizing fasciitis. Many of these infections are
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repair should be considered without delay for fastidious organisms or caused by organisms that normally colonize the skin or lower genital
severe valvular regurgitation. 61 tract. Induced abortion, instrumentation, prolonged labor, and the pre-
Management: For patients presenting with signs of cardiac disease, a mature rupture of membranes increase the risk of bacterial ascension
chest radiograph and ECG are imperative. Echocardiography can detect through the cervical canal and the subsequent development of focal or
valvular abnormalities or myocardial dysfunction. Transesophageal invasive infection. Obstetric infections are often polymicrobial; gram-
echocardiography and magnetic resonance imaging are the most positive, gram-negative, and anaerobic organisms are all important
sensitive and specific tests for aortic dissection, although computed considerations.
tomography is often more readily available. For suspected pulmonary Endometritis is a common cause of postpartum fever, although
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hypertension, an echocardiogram is often the initial test of choice, associated sepsis is rare. Cesarean section and untreated group B
although it can both under and overestimate pulmonary pressures. Streptococcus colonization before birth are risk factors. Patients can
Right heart catheterization is indicated for further evaluation if clinical present with abdominal or focal uterine tenderness, and/or purulent
suspicion is high, or to confirm elevated pressures noted on echocardio- lochia. Cervical cultures are often contaminated and generally are not
gram. In patients presenting with ischemia, a troponin level should be helpful. While uncommon, endometritis with toxin-producing strains
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checked, and cardiology consultation considered early. A high B-type of clostridium, streptococcus, and staphylococcus are well described
natriuretic peptide (BNP) level suggests cardiac strain or dysfunction. and can be quickly fatal. Toxic shock syndrome should be considered
Volume status should be optimized. For cardiogenic pulmonary
edema or right heart failure, diuretics can be given as clinically indi-
cated; the starting dose is often low in consideration of the increased TABLE 127-6 Causes of Sepsis in Obstetric Patients
glomerular filtration rate and to avoid abrupt changes in the circulat- Obstetric Nonobstetric Procedure Related
ing volume. Refractory cardiogenic shock is often an indication for
dobutamine. For cases of severe pulmonary hypertension, intrave- Postpartum endometritis Appendicitis Amniocentesis
nous prostacyclin has been given without fetal harm. For suspected Chorioamnionitis Cholecystitis Chorionic villus sampling
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acute myocardial infarction, diagnostic and therapeutic angiography is Septic abortion Pneumonia Surgical wound
strongly preferred to thrombolytic therapy, which is a risk for hemor- Septic pelvic thrombophlebitis
rhage and is contraindicated in ischemia due to dissection; abdominal Antepartum pyelonephritis
shields during angiography reduce the risk of fetal radiation. Extended Abscess
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