Subglottic secretion drainage for preventing ventilator associated pneumonia: A meta-analysis
Introduction
Ventilator associated pneumonia (VAP) in the intensive care unit (ICU) has been shown to be associated with significant morbidity and mortality.1, 2, 3 It has been reported to affect between 9 and 27% of intubated patients receiving mechanical ventilation, and to be associated with increased risk of both ICU and hospital mortality.4, 5, 6 Added to this is an increased duration of mechanical ventilation (MV) and ultimately increased health care costs related to the care of the patient who develops VAP while in the ICU. For all these important reasons, the prevention of VAP has been high on the research agenda of ICU clinicians for the last 25 years.7
Colonization of the upper respiratory tract (oropharaynx and trachea) secretions with potentially pathogeneic organisms, has been recognized as a key factor in the pathogenesis of VAP.1, 3, 7 These secretions radiographically have been shown to pool above the cuff of endotracheal tubes (in the subglottic region), prior to entering the lower respiratory tract as micro-aspirations.8 Therefore, the drainage of subglottic secretions has been proposed and trialed using specially designed endotracheal tubes, in an attempt to reduce the incidence of VAP in ICU patients.9
The results of various randomized controlled trials investigating the benefits of subglottic secretion drainage have been inconclusive and summarized in a previous meta-analysis.9, 10, 11, 12, 13, 14 More recently, results of randomized trials have been published following the previous meta-analysis by Dezfulian and colleagues.9, 15, 16, 17 For this reason, a meta-analysis has been undertaken to summarize the results of published trials of subglottic secretion drainage and the effect on the incidence of VAP; ICU and hospital mortality; and duration of mechanical ventilation.
Section snippets
Data sources and search strategy
Studies were identified by searching MEDLINE (1966 to January 2011), EMBASE (1980–2011), and CINAHL (1982 to January 2011). Search strategies were adapted for all three databases and the following search terms were used:
- 1.
glottis; and
- 2.
suction or drainage; and
- 3.
respiration, artificial or ventilation or intubation, mechanical; and
- 4.
pneumonia
Selection of studies
Studies were selected if mechanically ventilated patients were prospectively randomized to some form of subglottic secretion drainage versus no drainage (control
Results
The search strategy identified a total of 131 potential studies to be included in the meta-analysis. After excluding non-randomized trials and review articles, nine published randomized trials were included in the final analysis (Table 1). The trials by Bo10 and the trail by Yang17 were published in Mandarin, the results from Bo being published in English previously.9 However, the paper by Yang had to be translated by one of the authors (VT).17 Nine trials published between 1992 and 2010,
Discussion
Ventilator associated pneumonia is associated with adverse outcomes in the ICU setting.1, 2, 3 For this reason, any attempt to reduce the incidence of VAP poses significant potential benefit for ICU patients throughout the world. In this meta-analysis of published randomized controls trials of subglottic drainage of secretions for prevention of VAP, it has been estimated that this intervention may reduce the risk of VAP by about 50% (RR = 0.52, 95% CI 0.42–0.65). This estimate of benefit of
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