Theme Issue Editorial
Efficacy of prone ventilation in adult patients with acute respiratory failure: A meta-analysis

https://doi.org/10.1016/j.jcrc.2007.09.003Get rights and content

Abstract

Purpose

The use of prone ventilation in acute respiratory failure has been investigated by several randomized controlled trials in the recent past. To date, there has been no systematic review or meta-analysis of these trials.

Material and Methods

Systematic literature search was performed between 1966 and July 2006 to identify randomized trials evaluating prone ventilation. Outcome measures included mortality, changes in oxygenation, incidence of pneumonia, duration of mechanical ventilation, intensive care unit (ICU) and hospital stay, cost-effectiveness, and adverse effects including pressure sores, endotracheal tube, or intravascular catheter complications.

Results

Prone ventilation was not associated with reduction in mortality, but improvement in oxygenation was statistically significant (mean difference, 21.2 mm Hg; P < .001). There was no significant difference in incidence of pneumonia, ICU stay, and endotracheal tube complications. There was a trend toward an increased incidence of pressure sores in prone ventilated patients (odds ratio = 1.95; 95% confidence interval, 0.09-4.15; P = .08). The data on other outcomes were not suitable for meta-analysis.

Conclusions

The use of prone ventilation is associated with improved oxygenation. It is not associated with a reduction in mortality, pneumonia, or ICU stay and may be associated with an increased incidence of pressure sores.

Introduction

Acute respiratory failure (ARF) caused by the acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) is one of the common causes for admission of patients to the intensive care unit (ICU). In spite of the improvements in the care of patients managed in ICUs, the mortality of patients admitted with ARDS remains high [1]. The advances in intensive care medicine over the last few decades have introduced a number of novel treatment practices such as liquid ventilation, surfactant, prone ventilation, and inhalation of nitric oxide to aid in mechanical ventilation and reduce ventilator-associated lung injury. Prone position ventilation has been extensively investigated over the last 2 decades. Prone ventilation was reported to have beneficial effects not only in terms of improved oxygenation but also in reducing the incidence of ventilator-induced lung injury and oxygen toxicity in patients with severe respiratory failure [2]. In addition, a reduction in mortality was also reported when prone ventilation was used [3], [4]. However, most of these studies were either retrospective evaluations or prospective nonrandomized clinical trials. The first randomized controlled evaluation of prone ventilation was reported by Gattinoni et al [5] in 2001. In this study, the use of prone ventilation was shown to improve oxygenation but did not confirm a reduction in mortality. Subsequently, several other investigators evaluated the effects of prone ventilation using randomized controlled trials (RCTs) with variable results in different groups of patients with acute severe hypoxic respiratory failure [6], [7], [8], [9], [10]. Some of these trials were conducted with physiological parameters as end points and others with mortality/survival as the end point. There is no systematic review after the publication of these RCTs.

The primary objective of this systematic review was to assess the efficacy of prone position ventilation in reducing mortality in adult patients with ALI and ARDS requiring invasive mechanical ventilation. The secondary objectives were to assess the impact of prone position ventilation on oxygenation (Pao2: Fio2), ventilator-associated pneumonia (VAP), duration of mechanical ventilation, duration of ICU and hospital stay, adverse effects (such as loss of intravenous or arterial lines, development of pressure sores, and endotracheal [ET] tube complications including selective intubation, obstruction, or dislodgement) and cost-effectiveness of managing adult patients with severe respiratory failure using prone ventilation.

Section snippets

Identification of studies

The following databases were searched for reports of RCTs using prone ventilation in adult patients with acute severe respiratory failure: the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Registry of Current Controlled Trials, Database of Abstracts of Reviews of Effects, NHS Economic Evaluation Database, and the Health Technology Assessment database. The search was performed using the exploded medical subject headings and text words: ‘adult respiratory distress syndrome’ or

Description of studies

A total of 2927 article titles were screened during the search process. Of these articles, only 5 studies [5], [6], [7], [9], [10] met the inclusion criteria. The reasons for exclusion of the rest of the studies are presented in Fig. 1. General characteristics and quality assessment of the included studies are presented in Table 1. The demographic characteristics of the study population of individual studies are presented in Table 2. Of the 5 RCTs included, the studies by Gattinoni et al [5],

Discussion

This is the first systematic review of the use of prone ventilation in patients with ALI and ARDS. This review allowed performing meta-analysis of the effects of prone ventilation on mortality, oxygenation, duration of ICU stay, VAP, pressure sores, and ET tube complications. The pooled results reveal that prone ventilation significantly improved oxygenation. Among the other variables assessed mortality, ICU stay, VAP, and ET tube complications were not significantly affected by prone

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