To be eligible for the review, studies had to be randomised controlled trials (RCTs) that examined the role of closed tracheal suction systems compared with open systems for the management of ventilator-associated pneumonia in critically-ill adults. The incidence of ventilator-assisted pneumonia (primary outcome) had to be reported and measured until the patient's death or discharge from the intensive care unit. To be considered as ventilator-associated, findings of pneumonia needed to be present in patients receiving mechanical ventilation for at least 48 hours. All-cause mortality, length of ICU stay, duration of mechanical ventilation, colonisation of the respiratory tract and costs were secondary outcomes. Trials focusing on special issues of endotracheal suctioning were excluded, as were trials that compared different types of closed tracheal suction systems and trials with outcomes relating only to gas exchange and haemodynamics.
In most included trials, diagnosis of ventilator-assisted pneumonia was by clinical, laboratory and imaging findings. Most trials replaced the catheter of the closed tracheal suction systems every 24 hours, with a minority of included trials reporting changing the catheter when it was grossly contaminated with secretions or its integrity was disrupted. Brands of closed tracheal systems included Hi-Care, Steri-Cath and TrachCare.
It appeared that two reviewers were involved in the selection of studies for the review.