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Subglottic aspiration of secretions reduces the incidence of ventilator-associated pneumonia.

Dr Joyce Stuart on behalf of the SICS EBM Group.

Consultant, Intensive Care Unit, Western General Hospital, Edinburgh

Correspondence to: Joyce.Stuart@luht.scot.nhs.uk

SICS EBM web site December 2004

Citation: EBM Reviews. Scottish Intensive Care Society EBM Group. Stuart J. Subglottic aspiration of secretions reduces the incidence of ventilator-associated pneumonia. 2004.

Background: One of the main causes of pneumonia developing in ventilated ICU patients after 48 hours or more is thought to be the aspiration of secretions which trickle down from the larynx past the tracheal tube cuff. Tracheal tubes have been devised which have an extra lumen ending just above the cuff to facilitate the drainage of secretions before they are aspirated past the cuff.

Objectives: Review of well-conducted, prospective, randomised controlled trials that compared the incidence of ventilator associated pneumonia (VAP) with and without subglottic drainage of secretions.

Search strategy: Medline search using terms: critical care; ventilation; subglottic drainage; pneumonia; ventilator-associated pneumonia.

Selection criteria: RCTs comparing incidence of VAP with and without subglottic drainage in ventilated ICU patients where everything else was the same.

Data collection and analysis: Study data were collated to calculate the relative and absolute risks of VAP in the two treatment groups. Subglottic drainage was considered the experimental intervention, and standard care minus subglottic drainage was considered the control group. Pooled data.

Main results: 12 ventilated patients need to be treated with subglottic drainage of secretions to prevent one episode of VAP, with 95% CI of 8-24.

Reviewer’s conclusions:

Only 4 studies were found which met the above criteria. One of the studies included data using combinations of subglottic drainage and stress ulcer prophylaxis. This study has been included, looking only at the effect of subglottic drainage on the incidence of VAP.
In one of the studies the patients were in a cardiothoracic ICU rather than a general ICU and were probably quite a different population from those studied in the other 3 ICU’s.
The studies did not seem to be blinded, and there was very little data about how else the patients were managed.
Although all 4 studies demonstrated a clear difference in the incidence of VAP between the 2 groups, and tended to show a delay in the onset of VAP in the experimental group, there was no overall difference in length of ICU stay or mortality. One of the studies did not report any useful data of this type.
It is unknown if subglottic drainage is of benefit in addition to semi-recumbency
Nevertheless, for such a simple and inexpensive intervention the reduction in the incidence of VAP is quite impressive, and I conclude that subglottic drainage of secretions can be recommended as an intervention for this purpose. Grade A recommendation.

Citation List:

Smulders K, et al. A randomized clinical trial of intermittent subglottic secretion drainage in patients receiving mechanical ventilation. Chest 2002; 121: 858-862. CAT.
Kollef M, et al. A randomised clinical trial of continuous aspiration of subglottic secretions in cardiac surgery patients. Chest 1999; 116: 1339-1346. CAT.
Valles J, et al. Continuous aspiration of subglottic secretions in preventing ventilator-associated pneumonia. Ann Intern Med 1995; 122: 179-186. CAT.
Mahul P, et al. Prevention of nosocomial pneumonia in intubated patients: respective role of mechanical subglottic secretions drainage and stress ulcer prophylaxis. Intensive Care Medicine 1992; 18: 20-25. CAT.
Pooled results. J Stuart 2004. CAT.

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