Page 1796 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 127: Critical Illness in Pregnancy 1265

■
tolerance of permissive hypercapnia when it results in a significant RESPIRATORY INFECTIONS
maternal acidemia, as this impairs fetal oxygen extraction. Low tidal The incidence of pneumonia during pregnancy may be increasing, par-
volumes, a low respiratory rate, and a high inspiratory flow minimize alleling the increased burden of comorbidities among women of child-
intrinsic positive end expiratory pressure (PEEPi). bearing age, including cystic fibrosis, the use of immunosuppressive
■ OTHER CHRONIC LUNG DISEASES therapies, and human immunodeficiency virus (HIV) infection. 126,127
An altered cell mediated immunity places pregnant women at increased
Life expectancy for people with cystic fibrosis has increased dramati- risk for a few particular pulmonary infections, as discussed below. 128,129
cally, and pregnancy has become an important consideration in their Otherwise, the microbial causes of pneumonia are similar to those in
long-term management. Maternal and fetal morbidity and mortality are the nonpregnant population. 126,130 Complications of pneumonia during
increased among gravidas with cystic fibrosis. Coexistent pulmonary pregnancy include preterm labor and delivery, respiratory failure, and
hypertension, poor prepregnancy lung function, poor nutritional status, maternal and fetal mortality.
and colonization with Burkholderia cepacia are predictors of especially It is not clear that pregnant patients are more likely to become infected
poor outcomes. Patients with cystic fibrosis who become pregnant with influenza, but ample evidence supports that when infection occurs
122
require close follow-up; therapeutic abortion may be recommended for they are at increased risk for developing severe pneumonia. Severe
those with early and serious declines in pulmonary function. 122 influenza is associated with fetal and maternal harm. Compared to
131
Most other chronic pulmonary conditions that result in respiratory nonpregnant patients with influenza, pregnant patients have higher rates
failure, such as chronic obstructive pulmonary disease, interstitial lung of hospitalization and influenza-related complications. The morbid-
diseases, and neuromuscular diseases, are uncommon in pregnant ity is even higher with pandemic strain infections, where mortality is
women. However, myasthenia gravis, which most commonly affects also increased. During the 2009 influenza H1N1 pandemic, pregnant
132
women of child-bearing age, is an important cause of respiratory insuf- women accounted for 1% of the American population but up to 5% of
ficiency and failure in pregnancy. During pregnancy, myasthenia gravis H1N1 related deaths. Sixty percent of these deaths occurred in the third
improves in about a third of patients and deteriorates in about a third of trimester, when influenza morbidity and mortality are known to be
133
patients; the course for a given individual is often unpredictable. While higher. Pregnant patients presented similarly to, and were diagnosed
123
deterioration is most likely to occur during the first trimester, it can as promptly as nonpregnant patients, but they experienced greater delay
occur anytime, including postpartum. Finally, pregnancy in patients in receiving antiviral treatment, which may be related to concern of fetal
124
who have previously undergone lung transplantation can be complicated effects. While documented bacterial coinfection was rare in H1N1
133
and high risk, in spite of possibly normal baseline pulmonary function infected pregnant patients, coinfection was not uncommon in the gen-
testing. While successful outcomes have been reported, pregnancy in eral population, and empiric coverage in the setting of severe pandemic
134
this population is associated with maternal, fetal, and graft risk. 125 influenza is reasonable. Rapid influenza testing is less sensitive in
adults than in children; even if a rapid influenza test is negative, preg-
Management: For patients with cystic fibrosis, the continuation of nant patients should be treated empirically with antivirals if infection is
maximum nutritional support, airway clearance maneuvers, and anti- suspected, particularly during pandemic seasons. 135
biotics for infectious exacerbations are indicated. Labor and delivery When Mycobacterium tuberculosis infection occurs during pregnancy,
can be high risk. Epidural anesthesia is important for pain control and maternal and fetal outcomes are generally good if appropriate and timely
to facilitate a cesarean section should it become necessary, as general therapy is provided. Congenital tuberculosis is rare and is associated
anesthesia is avoided if possible in patients with cystic fibrosis. An with worse outcomes. Although the QuantiFERON-TB Gold test has
echocardiogram, or less commonly right heart catheter monitoring, not been extensively evaluated in pregnant patients, it was shown to per-
may be useful in assessing hemodynamics when cor pulmonale is form well in one report, and the Centers for Disease Control guidelines
suspected. 122 no longer exclude pregnant patients from testing. Pregnancy does not
136
For patients with myasthenia gravis, a low threshold for hospital affect the response to tuberculin skin testing. 137
admission is advisable for increased symptoms or respiratory difficulty, HIV patients who become pregnant are at particularly increased
as severe exacerbations can develop suddenly. Frequent bedside vital risk for Pneumocystis jirovecii pneumonia (PCP). PCP infection during
capacity monitoring is important and systemic corticosteroids are often pregnancy has a high associated rate of respiratory failure, and with
indicated for a decline in function. If required, plasmapheresis and a mortality rate of 50%, PCP infection is the most common cause of
intravenous immunoglobulin (IVIG) are generally safe in pregnancy, AIDS-related death during pregnancy in the United States. Fetal mor-
138
although volume shifts should be anticipated. During labor, striated tality is also high and appears to be worse if infection occurs in the first
muscles can be prone to fatigue, and assisted delivery may be needed. or second trimester. 138
General anesthesia and IV magnesium may exacerbate weakness in Finally, altered cell-mediated immunity may predispose to vari-
myasthenia gravis, and should be used with extreme caution in patients cella and coccidioidomycosis pneumonia and disseminated disease.
who are not on assisted ventilation. Non-depolarizing paralytics may Although the overall prevalence is low, coccidioidomycosis fungal
also have a prolonged effect in patients with myasthenia gravis. pneumonia has a notably increased risk of dissemination during preg-
123
Pregnant patients with ventilatory insufficiency from chest wall dis- nancy. This is especially the case if contracted in the third trimester or
ease or respiratory muscle weakness often respond well to nocturnal immediately postpartum. 126,139
NIPPV. Overnight pulse oximetry should be used to monitor patients
with marginal ventilatory function for nocturnal hypoxemia. Close Management: The choice of antimicrobials for pneumonia during
patient follow-up, which may include monitoring vital capacity and pregnancy should take potential fetal toxicity into account. Penicillins,
arterial blood gases in addition to symptoms and oxygen saturation, cephalosporins, and macrolides (except for erythromycin formulated
is important. Hospital admission until delivery is often indicated for with estolate) are considered safe. 126,140 Tetracycline and chloram-
those with evolving respiratory insufficiency; if respiratory failure is phenicol are contraindicated, and sulfa-containing regimens should
imminent, delivery should be considered as soon as fetal development is be avoided except in the treatment of PCP. 126,130 For those patients
adequate. For lung transplant patients, close follow-up of lung function with suspected or established influenza, treatment with oseltamivir
and clinical status is indicated. Immunosuppression dosing may need to is considered safe during pregnancy, and when given within the first
be adjusted to compensate for increased circulating volume and renal 4 days of symptom onset has been associated with decreased rates
clearance. Mycophenolate mofetil is teratogenic and should not be used of complications and death. 141,142 Amantadine has been shown to be
during pregnancy. The fetal effects of newer immunosuppressives are teratogenic at very high doses in animals; its use is not well studied in
not well known, and these agents are also best avoided. 125 pregnant women. Active tuberculosis during pregnancy is treated
140

section11.indd 1265 1/19/2015 10:52:23 AM