The quality and composition of surfactant are abnormal in acute lung injury. In adult patients surfactant replacement has had little effect on outcomes, but preliminary studies in paediatric patients have supported further research. The importance of the constitution of the administered surfactant is increasingly being recognised. Calfactant is a modified bovine surfactant that closely resembles endogenous surfactant in composition and function.

This study is a randomised controlled trial in American paediatric intensive care units (ICU) with all patients receiving a protective ventilation strategy. The study was designed to recruit 300 patients in 2 years. The number of ventilator free days in the 28 days following study entry, a marker of the duration of respiratory failure, was the primary outcome. Because of difficulties recruiting adequate numbers of patients, the trial ended after 3 years with 152 patients randomised. Patients were randomised to two doses of intratracheal Calfactant or air placebo.

There was no difference in primary outcome between the groups (mean (SD) ventilator free days 13.2 (10) in the treatment group and 11.5 (10.5) in the placebo group; p = 0.21). However, while the study was not powered to detect a mortality difference, mortality was reduced in the Calfactant group (15/77 patients versus 27/75, OR 2.32, 95% CI 1.15 to 4.85) and oxygenation also improved after treatment. No patient was removed because of treatment complications.

This study failed to show a difference in duration of mechanical ventilation in paediatric ICU patients, but was underpowered and illustrates the difficulties in recruiting adequate patient numbers even to well designed trials in ICU.