Study designs of evaluations included in the review
Randomised controlled trials (RCTs), quasi-randomised trials, and systematic reviews or meta-analyses of RCTs or quasi-randomised trials were eligible for inclusion in the review. The review only included parallel-group RCTs.
Specific interventions included in the review
Studies that compared closed and open tracheal suctioning were eligible for inclusion. In closed suction interventions, suctioning of secretions involved closed multiple-use catheters routinely changed every 24 hours or not routinely changed. In most open suctioning interventions, patients were disconnected from the respiratory circuit. The review also compared no routine catheter change or routine changes every 48 hours versus routine catheter changes every 24 hours.
Participants included in the review
Studies of patients undergoing mechanical ventilation in ICUs were eligible for inclusion. The primary studies included medical, surgical (including neurosurgical, trauma and burns) and neonatal patients with a variety of underlying conditions and a predicted duration of ventilation of more than 24 to 48 hours.
Outcomes assessed in the review
Studies that assessed VAP as the primary outcome, provided sufficient data to calculate the risk of VAP, and defined pneumonia were eligible for inclusion. In most of the included studies, the diagnosis of pneumonia was based on radiological and clinical criteria; a minority of studies confirmed the diagnosis microbiologically.
How were decisions on the relevance of primary studies made?
Two reviewers independently selected the studies. Any disagreements were resolved by discussion or with the aid of a third reviewer.