Pulmonary Edema Due to Beta Agonist Used as Tocolytic

Pulmonary edema due to beta agonist used as tocolytic

Beta agonist given as a tocolytic to prevent premature labour can rarely cause pulmonary edema. Pulmonary edema with use of beta agonist as tocolytic can occur with both oral and intravenous therapy and may occur within 24 hours of discontinuation of therapy.

Mechanism of pulmonary edema with beta agonist used as tocolytic seems to be unique to the pregnant state as even large doses of beta agonists in non pregnant females with asthma seldom produce pulmonary edema. Hypervolemia of pregnancy and excess fluid given during infusion of tocolytic have been implicated in the pathogenesis, but not proved unequivocally.

Beta agonist induced increase in secretion of antidiuretic hormone can enhance the hypervolemia of pregnancy due to additional water retention and contribute to the genesis of pulmonary edema [1]. Beta agonists activate the renin-angiotensin system which in turn could lead to salt and water retention [2].

Multiple pregnancies also have an etiological role in view of the higher blood volume. 20% of the beta agonist tocolytic induced pulmonary edema have occurred in twin pregnancies. Infections, silent cardiac disease, multiparity, treatment with corticosteroids and magnesium sulphate have been implicated in some cases.

References

1. Bhattacharya AK. A 24 year-old woman with pulmonary edema after labor and delivery. Lung India 2006;23:133-4.
2. Lamont RF. The pathophysiology of pulmonary oedema with the use of beta-agonists. BJOG. 2000;107:439-44.