Effect of prone positioning on clinical outcomes in children with acute lung injury: a randomized controlled trial

Abstract

Context: In uncontrolled clinical studies, prone positioning appeared to be safe and to improve oxygenation in pediatric patients with acute lung injury. However, the effect of prone positioning on clinical outcomes in children is not known.

Objective: To test the hypothesis that at the end of 28 days infants and children with acute lung injury treated with prone positioning would have more ventilator-free days than those treated with supine positioning.

Design, setting, and patients: Multicenter, randomized, controlled clinical trial conducted from August 28, 2001, to April 23, 2004, of 102 pediatric patients from 7 US pediatric intensive care units aged 2 weeks to 18 years who were treated with supine vs prone positioning. Randomization was concealed and group assignment was not blinded.

Intervention: Patients were randomized to either supine or prone positioning within 48 hours of meeting acute lung injury criteria, with those patients in the prone group being positioned within 4 hours of randomization and remaining prone for 20 hours each day during the acute phase of their illness for a maximum of 7 days, after which they were positioned supine. Both groups were treated using lung protective ventilator and sedation protocols, extubation readiness testing, and hemodynamic, nutrition, and skin care guidelines.

Main outcome measure: Ventilator-free days to day 28.

Results: The trial was stopped at the planned interim analysis on the basis of the prespecified futility stopping rule. There were no differences in the number of ventilator-free days between the 2 groups (mean [SD], 15.8 [8.5] supine vs 15.6 [8.6] prone; mean difference, -0.2 days; 95% CI, -3.6 to 3.2; P = .91). After controlling for age, Pediatric Risk of Mortality III score, direct vs indirect acute lung injury, and mode of mechanical ventilation at enrollment, the adjusted difference in ventilator-free days was 0.3 days (95% CI, -3.0 to 3.5; P = .87). There were no differences in the secondary end points, including proportion alive and ventilator-free on day 28 (P = .45), mortality from all causes (P>.99), the time to recovery of lung injury (P = .78), organ-failure-free days (P = .88), and cognitive impairment (P = .16) or overall functional health (P = .12) at hospital discharge or on day 28.

Conclusion: Prone positioning does not significantly reduce ventilator-free days or improve other clinical outcomes in pediatric patients with acute lung injury.

Figure 1

Patient Flow through Clinical Trial

Figure 2

Number of Ventilator-free Days in the Control Group and the Prone Positioned Group. There were no significant differences between the two groups (two-sample t-test P=0.91).

Figure 3a & 3b

Mean (± SE) PaO₂:FiO₂ ratio (3a) and Oxygenation Index (3b) during the Acute Phase. The prone group is denoted by solid symbols: immediately before prone positioning (circles), after one hour prone (squares), after 20-hour prone (triangles), and at 10am supine on each study day (diamonds). The supine group was denoted by open symbols also at 10am on each study day (circles). Time zero reflects supine values in both groups prior to the implementation of ventilator protocols. Each calculation includes data from all patients, regardless of how many measurements were available from each patient on that day. Also shown are the number of patients who contributed at least one measurement to the calculation. The morning supine PaO₂:FiO₂ ratio and oxygenation index was not significantly different between the two groups for any of the acute phase days (two-sample t-test P≥0.15).

Figure 3a & 3b

Mean (± SE) PaO₂:FiO₂ ratio (3a) and Oxygenation Index (3b) during the Acute Phase. The prone group is denoted by solid symbols: immediately before prone positioning (circles), after one hour prone (squares), after 20-hour prone (triangles), and at 10am supine on each study day (diamonds). The supine group was denoted by open symbols also at 10am on each study day (circles). Time zero reflects supine values in both groups prior to the implementation of ventilator protocols. Each calculation includes data from all patients, regardless of how many measurements were available from each patient on that day. Also shown are the number of patients who contributed at least one measurement to the calculation. The morning supine PaO₂:FiO₂ ratio and oxygenation index was not significantly different between the two groups for any of the acute phase days (two-sample t-test P≥0.15).