open access

Vol 48, No 5 (2016)
Review articles
Published online: 2016-12-19
Submitted: 2016-03-01
Accepted: 2016-11-23
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Early severe acute respiratory distress syndrome: What’s going on? Part I: pathophysiology

Fabrice Petitjeans, Cyrille Pichot, Marco Ghignone, Luc Quintin
DOI: 10.5603/AIT.2016.0056
·
Anaesthesiol Intensive Ther 2016;48(5):314-338.

open access

Vol 48, No 5 (2016)
Review articles
Published online: 2016-12-19
Submitted: 2016-03-01
Accepted: 2016-11-23

Abstract

Severe acute respiratory distress syndrome (ARDS, PaO2/FiO2 < 100 on PEEP ≥ 5 cm H2O) is treated using controlled mechanical ventilation (CMV), recently combined with muscle relaxation for 48 h and prone positioning. While the amplitude of tidal volume appears set < 6 mL kg-1, the level of positive end-expiratory pressure (PEEP) remains controversial. This overview summarizes several salient points, namely: a) ARDS is an oxygenation defect: consolidation/ difuse alveolar damage is reversed by PEEP and/or prone positioning, at least during the early phase of ARDS b) ARDS is a dynamic disease and partially iatrogenic. This implies that the management of the ventilator may be a life-saver by reducing the duration of mechanical ventilation, or detrimental by extending this duration, leading into critical care-acquired diseases. Indeed, a high PEEP (10−24 cm H2O) appears to be a life-saver in the context of early severe diffuse ARDS; c) tidal volume and plateau pressure cannot be identical for all patients; d) the only remaining rationale for CMV and muscle relaxation is to suppress patient-ventilator asynchrony and to lower VO2, during the acute cardio-ventilatory distress. Therefore, in early severe diffuse ARDS, this review argues for a combination of a high PEEP (preferably titrated on transpulmonary pressure) with spontaneous ventilation + pressure support (or newer modes of ventilation). However, conditionalities are stringent: upfront circulatory optimization, upright positioning, lowered VO2, lowered acidotic and hypercapnic drives, sedation without ventilatory depression and without lowered muscular tone. As these propositions require evidence-based demonstration, the accepted practice remains, in 2016, controlled mechanical ventilation, muscle relaxation, and prone position.

Abstract

Severe acute respiratory distress syndrome (ARDS, PaO2/FiO2 < 100 on PEEP ≥ 5 cm H2O) is treated using controlled mechanical ventilation (CMV), recently combined with muscle relaxation for 48 h and prone positioning. While the amplitude of tidal volume appears set < 6 mL kg-1, the level of positive end-expiratory pressure (PEEP) remains controversial. This overview summarizes several salient points, namely: a) ARDS is an oxygenation defect: consolidation/ difuse alveolar damage is reversed by PEEP and/or prone positioning, at least during the early phase of ARDS b) ARDS is a dynamic disease and partially iatrogenic. This implies that the management of the ventilator may be a life-saver by reducing the duration of mechanical ventilation, or detrimental by extending this duration, leading into critical care-acquired diseases. Indeed, a high PEEP (10−24 cm H2O) appears to be a life-saver in the context of early severe diffuse ARDS; c) tidal volume and plateau pressure cannot be identical for all patients; d) the only remaining rationale for CMV and muscle relaxation is to suppress patient-ventilator asynchrony and to lower VO2, during the acute cardio-ventilatory distress. Therefore, in early severe diffuse ARDS, this review argues for a combination of a high PEEP (preferably titrated on transpulmonary pressure) with spontaneous ventilation + pressure support (or newer modes of ventilation). However, conditionalities are stringent: upfront circulatory optimization, upright positioning, lowered VO2, lowered acidotic and hypercapnic drives, sedation without ventilatory depression and without lowered muscular tone. As these propositions require evidence-based demonstration, the accepted practice remains, in 2016, controlled mechanical ventilation, muscle relaxation, and prone position.

Get Citation

Keywords

acute respiratory distress syndrome, ARDS, severe ARDS; acute hypoxic non-hypercapnic respiratory failure; driving pressure; tidal volume, Vt, low tidal volume, ultra-low tidal volume; positive end-expiratory pressure, PEEP; transpulmonary pressure; contr

About this article
Title

Early severe acute respiratory distress syndrome: What’s going on? Part I: pathophysiology

Journal

Anaesthesiology Intensive Therapy

Issue

Vol 48, No 5 (2016)

Pages

314-338

Published online

2016-12-19

DOI

10.5603/AIT.2016.0056

Bibliographic record

Anaesthesiol Intensive Ther 2016;48(5):314-338.

Keywords

acute respiratory distress syndrome
ARDS
severe ARDS
acute hypoxic non-hypercapnic respiratory failure
driving pressure
tidal volume
Vt
low tidal volume
ultra-low tidal volume
positive end-expiratory pressure
PEEP
transpulmonary pressure
contr

Authors

Fabrice Petitjeans
Cyrille Pichot
Marco Ghignone
Luc Quintin

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