Impact of patient position on the incidence of ventilator-associated pneumonia: A meta-analysis of randomized controlled trials

doi:10.1016/j.jcrc.2008.09.003

Journal of Critical Care

Volume 24, Issue 4, December 2009, Pages 515-522

https://doi.org/10.1016/j.jcrc.2008.09.003 Get rights and content

Abstract

Objective

The aim of this study is to summarize the effect of position (prone and semirecumbent 45°) of mechanically ventilated patients on the incidence of ventilator-associated pneumonia (VAP) and other outcomes.

Methods

A systematic search for randomized control trials (RCTs) was done. We estimated pooled odds ratios (ORs) and 95% confidence intervals (CIs) using fixed effects model or random effects model, where appropriate. For continuous variables, we calculated the estimation of weighted mean differences.

Results

We analyzed data extracted from 3 RCTs studying the semirecumbent 45° and 4 RCTs studying the prone position with a total of 337 and 1018 patients, respectively. The odds of developing clinically diagnosed VAP were significantly lower among patients in the semirecumbent 45° position compared to patients in the supine position (OR = 0.47; 95% CI, 0.27-0.82; 337 patients). The comparison of prone vs supine position group showed a moderate trend toward better outcomes regarding the incidence of clinically diagnosed VAP among patients in the prone position (OR = 0.80; 95% CI, 0.60-1.08; 1018 patients). The subanalysis regarding the incidence of microbiologically documented VAP, the length of intensive care unit stay, and the duration of mechanical ventilation showed that patients in the semirecumbent 45° position have a moderate trend toward better clinical outcomes.

Conclusion

This meta-analysis provides additional evidence that the usual practice of back-rest elevation of 15° to 30° is not sufficient to prevent VAP in mechanically ventilated patients. Patients positioned semirecumbently 45° have significantly lower incidence of clinically diagnosed VAP compared to patients positioned supinely. On the other hand, the incidence of clinically diagnosed VAP among patients positioned pronely does not differ significantly from the incidence of clinically diagnosed VAP among patients positioned supinely.

Introduction

Ventilator-associated pneumonia (VAP) is the most common infection among mechanically ventilated patients and has been associated with increased mortality, morbidity, length of intensive care unit (ICU) stay and duration of mechanical ventilation. The pathogenesis of VAP starts with bacterial colonization of the oral cavity followed by aspiration of oropharyngeal fluids along the endotracheal tube [1], [2]. Bacterial colonization of the stomach and gastroesophageal aspiration may also contribute to the pathogenesis of VAP [3]. Gastroesophageal aspiration is promoted by the presence of the nasogastric tube and supine body position [4]. Experimental studies with radioactive-labeled enteral feeding suggested that endotracheal aspiration of gastric contents occurred more frequently among patients positioned supinely (lying on the back) rather than semirecumbently (patient's head and back elevated at 45°) [5]. On the basis of these findings, the Centers for Disease Control and Prevention suggested treatment of mechanically ventilated patients in a semirecumbent 45° position as a VAP-preventive measure [6].

Despite the recommendation of several professional associations, the above intervention has not been widely used as standard clinical policy [7], and mechanically ventilated patients treated in the ICU are most frequently positioned in a small back rest elevation of 10° to 30° [8]. This may be at least partly attributed to the insufficient awareness of the benefit of this position, the disagreement about who is responsible for patients' bed positioning, and certain difficulties in enabling and reinforcing such strategies [7]. Prone positioning (lying with the front or face downward) has been supported by several researchers for the management of patients with acute lung injury (ALI) or adults respiratory distress syndrome (ARDS) [9], [10], [11]. Certain randomized control trials (RCTs), studying the effect of prone and semirecumbent position on various outcomes, have supported that nonsupine position (semirecumbent 45° or prone position) of the patient may lead to reduction of VAP incidence and/or shorter duration of mechanical ventilation and ICU stay. However, current evidence is rather controversial, and available RCTs have small sample sizes and reduced statistical power. The mechanism of how prone position may decrease the incidence of VAP is still unclear. On the other hand, the role of pronation in the improvement of oxygenation among patients with ALI or ARDS has been well documented [9], [10], [11]. Furthermore, pronation has a drainage effect of respiratory secretions, which has not been systematically investigated [12]. We sought to perform a meta-analysis of RCTs to determine the effect of prone and semirecumbent 45° positional strategies on the incidence of VAP and various other clinical outcomes among mechanically ventilated patients.

Section snippets

Data sources

This meta-analysis was conducted according to the guidelines issued by the “quality of reporting of meta-analyses” conference [13]. To identify relevant RCTs, we systematically searched PubMed (until December 2007) and Cochrane Central Register of Controlled Trials by using the following keywords: “prone” or “semirecumbent” using as a limit “type of article: Randomized Controlled Trial.” Furthermore, we reviewed the references of the included RCTs. Abstracts of conference proceedings were not

Selected randomized controlled trials

In Fig. 1, we present a flow diagram describing the selection process followed to identify the pool of RCTs included in the meta-analysis. PubMed search yielded 579 potentially relevant articles; search using the Cochrane Central Register of Controlled Trials did not reveal any additional relevant RCTs. Seven RCTs [12], [15], [16], [17], [18], [19], [20] of the 579 initially located articles fulfilled the inclusion criteria for this meta-analysis. It should be noted that 2 studies by Beuret et

Discussion

The most important finding of this meta-analysis is that patients positioned semirecumbently 45° have significantly lower incidence of clinically diagnosed VAP compared to patients positioned supinely. On the other hand, despite the noted moderate trend toward lower incidence of clinically diagnosed VAP among patients positioned pronely compared to patients positioned supinely, the results are not statistically significant. Furthermore, it should be noted that no significant difference was

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Respiration/Ventilation and TracheostomyImpact of patient position on the incidence of ventilator-associated pneumonia: A meta-analysis of randomized controlled trials

Abstract

Objective

Methods

Results

Conclusion

Introduction

Section snippets

Data sources

Selected randomized controlled trials

Discussion

Intensive Crit Care Nurs

Intensive Crit Care Nurs

Lancet

Chest

Lancet

Association of respiratory tract colonization with adherence of gram-negative bacilli to epithelial cells

J Infect Dis

Nosocomial respiratory infections with gram-negative bacilli. The significance of colonization of the respiratory tract

Ann Intern Med

Role of colonization of the upper intestinal tract in the pathogenesis of ventilator-associated pneumonia

Clin Infect Dis

Gastroesophageal reflux in intubated patients receiving enteral nutrition: effect of supine and semirecumbent positions

J Parenter Enteral Nutr

Pulmonary aspiration of gastric contents in patients receiving mechanical ventilation: the effect of body position

Ann Intern Med

Guidelines for prevention of nosocomial pneumonia

MMWR Morb Mortal Wkly Rep

Toward understanding evidence uptake: semirecumbency for pneumonia prevention

Crit Care Med

Backrest elevation for the prevention of ventilator-associated pneumonia: back to the real world?

Crit Care Med

Nursing patients with ARDS in the prone position

Nurs Stand

Respiration/Ventilation and Tracheostomy
Impact of patient position on the incidence of ventilator-associated pneumonia: A meta-analysis of randomized controlled trials