Study designs of evaluations included in the review
Randomised controlled trials (RCTs) were eligible for inclusion in the review.
Specific interventions included in the review
Studies comparing an open suction system with a closed suction system were eligible for inclusion. The included studies considered closed suction systems: Trach Care, Steri Cath and Hi-Care. One study did not state the type of closed system used. Where reported, closed systems were changed after 24 hours, with the exception of one study where the suction system was only changed if it became soiled or failed, or if the patient required reintubation.
Participants included in the review
Studies including intensive care patients requiring mechanical ventilation were eligible for inclusion. Studies of premature infants were excluded from the review. The majority of participants included in the review were treated in medical or surgical intensive care units (ICUs); one study included trauma patients and one study included liver transplant patients. Patients with pneumonia on admission were excluded from all included studies, and the average Acute Physiology and Chronic Health Evaluation (APACHE II) scores (where stated) ranged from 12 to 25.6.
Outcomes assessed in the review
Eligible studies had to assess the incidence of VAP. The criteria for the diagnosis of nosocomial VAP varied between studies, but in most studies were similar to the definitions proposed by the Centers for Disease Control and Prevention.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.