Nicardipine-induced acute respiratory failure: Case report and literature review.

Hypoxic pulmonary vasoconstriction (HPV) is a major physiological mechanism that prevents the development of hypoxemia secondary to a regional decrease in the ventilation-perfusion ratio (the intrapulmonary shunt effect). Calcium plays a critical role in the cellular response to hypoxia and the regulation of the pulmonary vascular tone. Therefore, calcium channel antagonists such as nicardipine have the potential to interfere with the pulmonary response to hypoxia, increasing intrapulmonary blood shunt and thus worsening underlying hypoxemia.