Muscedere J. Subglottic secretion drainage for the prevention of ventilator-associated pneumonia: A systematic review and meta-analysis. Crit Care Med 2011;39:1985-1991.

In short, it probably works to prevent ventilator-associated pneumonia (13 randomized trials, n=2,442. 12 were positive, pooled risk ratio 0.55, associated with 1-1.5 shorter days in the ICU and on the ventilator). So why not use these tubes on everyone? They require a more expensive endotracheal tube, which may require the nurse or respiratory therapist to do the regular suctioning (passive devices are available that connect to wall suction). Silver-coated tubes and tubes with new-and-improved cuffs have been shown to reduce VAP, but none of these interventions has been shown to reduce mortality. Oral/gastric decontamination with antibiotics also reduces VAP - but at the cost of increasing resistance of bacteria to antimicrobials.