Review
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Crit Care Med. May 4, 2016; 5(2): 121-136
Published online May 4, 2016. doi: 10.5492/wjccm.v5.i2.121
Efficacy of prone position in acute respiratory distress syndrome patients: A pathophysiology-based review
Vasilios Koulouras, Georgios Papathanakos, Athanasios Papathanasiou, Georgios Nakos
Vasilios Koulouras, Georgios Papathanakos, Athanasios Papathanasiou, Georgios Nakos, Intensive Care Unit, University Hospital of Ioannina, 45500 Ioannina, Greece
Author contributions: All authors equally contributed to this paper with literature review and analysis, drafting and critical revision and editing, and final approval of the final version.
Conflict-of-interest statement: Authors declare no conflict of interests for this article.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Vasilios Koulouras, Associate Professor in Intensive Care Medicine, Intensive Care Unit, University Hospital of Ioannina, Stavros Niarchos Avenue, 45500 Ioannina, Greece. vpkoulouras@yahoo.gr
Telephone: +30-26-51099353 Fax: +30-26-51099343
Received: November 28, 2015
Peer-review started: November 30, 2015
First decision: December 28, 2015
Revised: January 11, 2016
Accepted: March 7, 2016
Article in press: March 9, 2016
Published online: May 4, 2016
Abstract

Acute respiratory distress syndrome (ARDS) is a syndrome with heterogeneous underlying pathological processes. It represents a common clinical problem in intensive care unit patients and it is characterized by high mortality. The mainstay of treatment for ARDS is lung protective ventilation with low tidal volumes and positive end-expiratory pressure sufficient for alveolar recruitment. Prone positioning is a supplementary strategy available in managing patients with ARDS. It was first described 40 years ago and it proves to be in alignment with two major ARDS pathophysiological lung models; the “sponge lung” - and the “shape matching” -model. Current evidence strongly supports that prone positioning has beneficial effects on gas exchange, respiratory mechanics, lung protection and hemodynamics as it redistributes transpulmonary pressure, stress and strain throughout the lung and unloads the right ventricle. The factors that individually influence the time course of alveolar recruitment and the improvement in oxygenation during prone positioning have not been well characterized. Although patients’ response to prone positioning is quite variable and hard to predict, large randomized trials and recent meta-analyses show that prone position in conjunction with a lung-protective strategy, when performed early and in sufficient duration, may improve survival in patients with ARDS. This pathophysiology-based review and recent clinical evidence strongly support the use of prone positioning in the early management of severe ARDS systematically and not as a rescue maneuver or a last-ditch effort.

Keywords: Prone position, Acute respiratory distress syndrome, Mechanical ventilation, Ventilator-induced lung injury, Pathophysiology

Core tip: Lung protective ventilation has become the standard treatment strategy for patients with acute respiratory distress syndrome (ARDS). The physiological basis of prone positioning seems to act beneficially in most pathophysiological disorders of ARDS improving hemodynamics, gas exchange and respiratory mechanics. Moreover prone positioning seems to exert an additional beneficial effect against ventilator-induced lung injury. In patients with severe ARDS, early use of prolonged prone positioning in conjunction with lung-protective strategies decreases mortality significantly.