A study of infants being withdrawn from inhaled nitric oxide therapy revealed that a single dose of sildenafil (Viagra) prevented rebound pulmonary hypertension and reduced the length of time on mechanical ventilation in the intensive care unit (ICU). Researchers at the Pediatric ICU at the Royal Children's Hospital in Melbourne, Australia, administered 1 dose of sildenafil to 15 infants who had been withdrawn from inhaled nitric oxide therapy. There was no incidence of rebound pulmonary hypertension, a common complication. Fourteen other children received a placebo, and 10 of the 14 had an acute elevation of pulmonary artery pressure of 20% or more during withdrawal. The infants who failed to wean from the nitric oxide treatment were later given sildenafil and then withdrew successfully. Nitric oxide therapy is considered the most effective selective pulmonary vasodilator. After the study was completed, total ICU stay for infants given sildenafil was 47.8 hours, compared with 189 hours for the placebo group. The study was published in the November 15, 2006, edition of the American Journal of Respiratory and Critical Care Medicine.