BACKGROUND:Saline instillation is still used to assist in removal of secretions from endotracheal tubes in some pediatric intensive care units. OBJECTIVE:To compare the effect of using either no saline, quarter-normal (0.225%) saline, or normal (0.9%) saline during endotracheal suctioning of children receiving ventilatory support in a pediatric intensive care unit. METHOD:An unblinded, randomized trial with 3 treatment groups was conducted with 427 children who received ventilatory support for at least 12 hours. Children were randomly assigned to receive no saline, 0.225% saline, or 0.9% saline during routine endotracheal suctioning. RESULTS:The primary outcome was the number of hours of invasive mechanical ventilation; oxygen therapy and length of stay in the unit were secondary outcomes. There were 138 children randomly assigned to the no-saline group, 141 to the 0.225% saline group, and 148 to the 0.9% saline group. In Kaplan-Meier intention-to-treat analysis, the median (interquartile range) number of hours of invasive mechanical ventilation was 32 (20-68), 43 (21-86), and 40 (20-87) in the no-saline, 0.225% saline, and 0.9% saline groups, respectively. Although the no-saline group received fewer hours of invasive ventilation, oxygen therapy, and intensive care than the other groups combined, the differences were not statistically significant. CONCLUSION:Using no saline was at least as effective as using either 0.225% or 0.9% saline in endotracheal suctioning. The optimal policy may be to routinely use no saline with endotracheal suctioning in children but allow the occasional use of 0.9% saline when secretions are thick.