The pregnant mother may be at increased risk of developing pulmonary oedema, because her cardiac output and blood volume are increased considerably compared with prepregnancy values. This increase is greater in the mother with multiple pregnancy. Colloid osmotic pressure is also reduced in pregnancy.
Problems and special considerations
Acute pulmonary oedema in the pregnant woman may mimic an acute asthmatic attack. Attempts to treat the latter will tend to exacerbate the former.
There are multiple aetiologies of pulmonary oedema in pregnancy, but a careful history will usually provide a diagnosis of the underlying cause. Pulmonary oedema may occur:
1. As a complication of coexisting cardiac disease
2. Secondary to complications of pregnancy, e.g. pre-eclampsia, major obstetric haemorrhage, intrauterine fetal death, amniotic fluid embolism, peripartum cardiomyopathy
3. Secondary to aspiration of gastric contents
4. Secondary to major sepsis
5. Following therapeutic or recreational drug administration, e.g. β-adrenergic agonists, glucocorticoids, oxytocics, dexamethasone, cocaine
6. Following excessive administration of intravenous fluid
Hypoxaemia caused by oedema is exacerbated by the increased oxygen demand of pregnancy and the reduced functional residual capacity and oxygen reserve.
Management options
Women who are known to be at increased risk of developing cardiac failure should receive antenatal and intrapartum care in an obstetric unit with high-dependency and intensive care facilities on site. Pulse oximetry is particularly useful, since a fall in saturation may be an early sign of pulmonary oedema.
Women receiving β-adrenergic agonists must have fluid balance and electrolytes monitored rigorously, and supplementary oxygen therapy should be considered. Invasive monitoring of central venous pressure should be considered if regional analgesia or anaesthesia is used in a woman who has been receiving β-agonists, because of the risk of fluid overloading.
Appropriate investigations should be performed, including chest radiography, since this carries negligible risk to the fetus.
In the absence of any obvious cause for cardiac failure, it is important to consider the use of illicit drugs.
Invasive cardiovascular monitoring will guide diagnosis and treatment, and the mother should be transferred to a high-dependency or intensive care unit at the earliest possible opportunity.
Oxygen therapy is invariably beneficial. Delivery of the fetus reduces oxygen demand and relieves the physical effect of the gravid uterus on the diaphragm and lungs. Further therapeutic strategies depend on the underlying cause of pulmonary oedema, but it can be helpful to differentiate between pulmonary oedema associated with pre-eclampsia and pulmonary oedema of other causes. The latter is managed in a similar fashion to pulmonary oedema in the non-pregnant adult, with diuresis and ventilatory support as required. In addition to this, pulmonary oedema associated with pre-eclampsia requires acute control of blood pressure. Intravenous glyceryl trinitrate is usually the drug of choice. Nifedipine and hydralazine may also be considered. The most appropriate place for monitoring and management is often the high-dependency or intensive care unit.
Key points
• Pulmonary oedema is uncommon in pregnancy but may be fatal.
• Chest radiography should not be withheld.
• Delivery of the fetus may be indicated.
• The mother should be managed in a high-dependency or intensive care unit.
Further reading
Dennis AT, Solnordal CB. Acute pulmonary oedema in pregnant women. Anaesthesia 2012; 67: 646-59.
Sciscione AC, Ivester T, Largoza M, et al. Acute pulmonary edema in pregnancy. Obstet Gynecol 2003; 101: 511-15.