Spontaneous breathing trials are often used in children to evaluate extubation readiness, but the optimal length of such a trial is not known. Researchers undertook a secondary analysis of a clinical trial to determine when and why spontaneous breathing trials fail in children with pediatric acute respiratory distress syndrome (ARDS) and whether clinical parameters at 30 minutes-either alone or in combination with diagnostic risk factors-are helpful in predicting outcomes at 120 minutes.

The analysis included 100 children, and 305 spontaneous breathing trials were performed. Of these trials, 130 (43%) were successful, 76 (25%) failed within 30 to 120 minutes (late failure), and 99 (33%) failed within 30 minutes. The researchers found that more than 40% of children who are passing a spontaneous breathing trial at the 30-minute mark will go on to meet failure criteria if that trial is continued to 120 minutes. Additionally, more than 80% of the children who fail spontaneous breathing trials have high respiratory effort on esophageal manometry, according to the authors. At 30 minutes, there were no clear thresholds for clinical parameters, such as respiratory rate, tidal volume, and rapid shallow breathing index, that could reliably predict spontaneous breathing trial outcomes at 120 minutes.

The authors conclude that a spontaneous breathing trial of 120 minutes that includes a measure of effort of breathing is needed in children recovering from ARDS.

Because their analysis focused on spontaneous breathing trial passage, not extubation, it's unknown whether some patients who had late trial failure may have done well on extubation. Also, most failures were based on high pressure-rate product, which isn't easily measured at the bedside, and clinical data on retractions at 30 minutes weren't included in the analysis.