Importance
Acute respiratory distress syndrome (ARDS) is a
life-threatening form of respiratory failure that affects approximately
200 000 patients each year in the United States, resulting in nearly
75 000 deaths annually. Globally, ARDS accounts for 10% of intensive
care unit admissions, representing more than 3 million patients with
ARDS annually.
Objective
To review advances in diagnosis and treatment of ARDS over the last 5 years.
Evidence Review
We searched MEDLINE, EMBASE, and the Cochrane Database of
Systematic Reviews from 2012 to 2017 focusing on randomized clinical
trials, meta-analyses, systematic reviews, and clinical practice
guidelines. Articles were identified for full text review with manual
review of bibliographies generating additional references.
Findings
After screening 1662 citations, 31 articles detailing major
advances in the diagnosis or treatment of ARDS were selected. The Berlin
definition proposed 3 categories of ARDS based on the severity of
hypoxemia: mild (200 mm Hg<Pao2/Fio2≤300 mm Hg), moderate (100 mm Hg<Pao2/Fio2≤200 mm Hg), and severe (Pao2/Fio2
≤100 mm Hg), along with explicit criteria related to timing of the
syndrome’s onset, origin of edema, and the chest radiograph findings.
The Berlin definition has significantly greater predictive validity for
mortality than the prior American-European Consensus Conference
definition. Clinician interpretation of the origin of edema and chest
radiograph criteria may be less reliable in making a diagnosis of ARDS.
The cornerstone of management remains mechanical ventilation, with a
goal to minimize ventilator-induced lung injury (VILI). Aspirin was not
effective in preventing ARDS in patients at high-risk for the syndrome.
Adjunctive interventions to further minimize VILI, such as prone
positioning in patients with a Pao2/Fio2
ratio less than 150 mm Hg, were associated with a significant mortality
benefit whereas others (eg, extracorporeal carbon dioxide removal)
remain experimental. Pharmacologic therapies such as β2
agonists, statins, and keratinocyte growth factor, which targeted
pathophysiologic alterations in ARDS, were not beneficial and
demonstrated possible harm. Recent guidelines on mechanical ventilation
in ARDS provide evidence-based recommendations related to 6
interventions, including low tidal volume and inspiratory pressure
ventilation, prone positioning, high-frequency oscillatory ventilation,
higher vs lower positive end-expiratory pressure, lung recruitment
maneuvers, and extracorporeal membrane oxygenation.
Conclusions and Relevance
The Berlin definition of acute respiratory distress syndrome
addressed limitations of the American-European Consensus Conference
definition, but poor reliability of some criteria may contribute to
underrecognition by clinicians. No pharmacologic treatments aimed at the
underlying pathology have been shown to be effective, and management
remains supportive with lung-protective mechanical ventilation.
Guidelines on mechanical ventilation in patients with acute respiratory
distress syndrome can assist clinicians in delivering evidence-based
interventions that may lead to improved outcomes.
