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1264 PART 11: Special Problems in Critical Care

evacuation, and fetal survival is well-documented if delivery is arranged asthma deterioration is most likely to occur, with improvement often
early in the course of resuscitation. 110,115 Therefore, when available, seen during the last month of pregnancy. Adverse maternal outcomes
obstetric services should be contacted immediately in an arrest. associated with asthma during pregnancy include pregnancy-induced
hypertension, preeclampsia, and cesarean delivery. Adverse fetal out-
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comes include preterm birth and small for gestational age. 119
RESPIRATORY DISORDERS OF PREGNANCY
Management: The management of the pregnant patient with status
Despite the increased ventilatory demands of pregnancy, frank ventila- asthmaticus is similar to that of the nonpregnant patient, with a few
tory failure is uncommon. When it occurs, respiratory insufficiency is 3 is decreased in pregnancy,
the result of severe underlying lung disease that impairs tolerance of notable exceptions. As the baseline Pa CO 2
and usually falls further in the early stages of an acute asthma attack,
the additional load of pregnancy, exacerbations in a preexisting condi- >35 mm Hg during status asthmaticus should alert the clini-
tion, or de novo pulmonary events. For patients with little pulmonary a Pa CO 2
cian to impending ventilatory failure. Maternal oxygenation status
reserve, close monitoring is important as respiratory failure may develop should be assessed even in mild attacks. Even mild hypoxemia should
precipitously, especially in later pregnancy. In patients with chronic be treated aggressively in the gravid patient as it is detrimental to the
lung disease, a baseline vital capacity of at least 1 L has been considered fetus. Inhaled bronchodilators are a mainstay of treatment of any
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essential for a safe pregnancy, although patients with a vital capacity less asthma attack; parenteral β-agonists are not commonly used. Systemic
than this have had successful pregnancies. 116,117 corticosteroids are indicated for significant exacerbations. The
121
Asthma remains the most common pulmonary problem encountered chronic use of oral corticosteroids has been associated with a twofold
in pregnancy, affecting 1% to 4% of all gravidas, although frank ventila- increase in the incidence of preeclampsia, and rarely with fetal adrenal
tory failure from asthma in pregnancy is uncommon. While less com- insufficiency. In addition, corticosteroid use early in pregnancy con-
mon than asthma, other chronic lung diseases often carry a higher risk fers an increased risk of cleft palate, although the absolute incidence
of respiratory failure. De novo pulmonary events that cause respiratory remains low. Generally, and often significantly, the maternal and
insufficiency in pregnancy include pneumonia, aspiration, tocolysis- fetal risks associated with poorly controlled asthma or with asthma-
induced pulmonary edema, amniotic fluid embolism, venous air embo- related respiratory failure outweigh the risks of corticosteroid use
lism, or ARDS. The following sections review these chronic and de in pregnancy. Heliox, a low-density mixture of helium and oxygen,
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novo conditions in turn, and Figure 127-3 summarizes the evaluation often decreases the work of breathing in status asthmaticus and can
of respiratory distress in pregnant patients. be given to pregnant patients (see Chap. 55). Noninvasive positive
■ ASTHMA pressure ventilation (NIPPV) can be considered for hemodynamically
stable patients without impending respiratory failure. However, any
The course of asthma during pregnancy is variable. Patients with more pregnant patient with impending respiratory failure or with refractory
severe baseline asthma are more likely to experience worsening of their hypoxemia should be intubated for mechanical ventilation. Ventilation
disease during pregnancy. The second and third trimesters are when strategies are similar to the nonpregnant patient, but include a lower
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Evaluation of respiratory distress

- Normal ECG? N Evaluate for
- Normal troponin level? myocardial ischemia
Y
CXR: infiltrate present?

Y N
Focal? - History of prior obstructive lung dz?
- Evidence of obstructive lung dz by
exam or bedside spirometry?
Y N
- Hyperinflation on CXR?
Evaluate for: High pressure
- Pneumonia edema Y N
- Aspiration pattern?
- Infarction Obstructive Evaluate for:
- Contusion lung disease - PE
- Other causes
- Resp muscle
weakness
Y N - Severe anemia
- Right heart
Evaluate for: Evaluate for: dysfunction
- Cardiomyopathy - ALI
- Unsuspected - ARDS
valvular lesion - Alveolar hemorrhage
- ILD

FIGURE 127-3. An approach to the evaluation of respiratory distress in pregnancy is presented. Mild dyspnea is common in pregnancy, but frank distress is not a normal finding and should
be evaluated. Cardiac and pulmonary conditions, pregnancy-related or nonspecific to pregnancy, can cause respiratory distress, and a thorough evaluation of both systems should be performed.
ALI, acute lung injury; ARDS, acute respiratory distress syndrome; CXR, chest x-ray; ECG, electrocardiogram; ILD, interstitial lung disease; PE, pulmonary embolism.

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