Pulmonary Problems During Pregnancy
- Asthma
- While there is no evidence that the inflammation underlying asthma is worse
during pregnancy, the increased minute ventilatory requirements often worsen the symptoms
of asthma. The fetus is especially susceptible to maternal hypoxemia so exacerbations of
asthma must be treated early and aggressively. Therapy is no different than in the
non-pregnant patient. Close follow up is essential.
- Pulmonary Embolism
- The risk of pulmonary embolism is substantially increased during the peripartum
period. A high clinical suspicion must be maintained and heparin prophylaxis should be
considered in patients with additional risk factors.
- ARDS
- Perhaps, because of the higher hydrostatic and lower oncotic pressures associated
with pregnancy, pregnant patients are at increased risk of developing hypoxemia and even
ARDS with systemic infections. Again concern for maternal and fetal oxygenation in the
face of an already increased maternal cardiac output and oxygen consumption necessitates
early aggressive supportive care.
- Aspiration
- Mechanical factors associated with the gravid uterus as well as hormonal effects
which tend to lower esophageal sphincter tone increase the risk of aspiration of gastric
contents late in pregnancy.
- Tocolytic Induced Pulmonary Edema
- The systemic use of (2 agonists (terbutaline, salbutamol) to interrupt preterm
labor is associated with a substantial risk of pulmonary edema. The pathogenesis is
unknown. Pulmonary edema generally develops within 72 hours of the initiation of therapy.
It resolves within 24 hours of discontinuation of the drug. The pulmonary edema may be
sever leading to respiratory failure. Given their disputed efficacy, some authors have
recommended against the use of these agents.
- Amniotic Fluid Embolism
- This is a rare but catastrophic complication of pregnancy which presents as the
acute onset of dyspnea, cyanosis and tachypnea during or immediately after labor.
Mechanical obstruction or cytokine mediated constriction of the pulmonary vasculature
leads to acute cardiorespiratory collapse which is often fatal. Risk factors include
advanced maternal age, multiparity, amniotomy, c-section, and IUDs.
- Airway Management
- Endotracheal intubation is more difficult in the pregnant patients for multiple
reasons. First, mild upper airway edema which narrows the caliber of the airway. Second,
the risk of aspiration during endotracheal intubation is increased. Finally the rate of
oxygen consumption is increased, limiting the efficacy of preoxygenation.
- Cardiac Disease
- The cardiopulmonary changes of pregnancy increase the susceptibility of patients
with cardiac disease to pulmonary edema as outlined above. In addition, peripartum
cardiomyopathy, an idiopathic diffuse cardiomyopathy may occur in the third trimester or
in the 3-6 months post partum. It is therefore important to exclude pre-existing or new
cardiac disease as a cause of dyspnea in the peripartum period.