ICU Management & Practice, Volume 16 - Issue 1, 2016
Acute respiratory distress syndrome (ARDS) seems to be
underrecognised, under-treated and associated with a high risk of mortality,
according to the results of the ESICM LUNG-SAFE observational study, published
in JAMA. Speaking to ICU Management & Practice,John G. Laffey, MD, MA, of
the Departments of Anesthesia and Critical Care Medicine, Keenan Research
Centre for Biomedical Science, St Michael’s Hospital, University of Toronto,
Canada, said: “This global study gives us unparalleled insights into the burden
and current management approaches for ARDS in the 21st century. We now need to
understand and overcome barriers to clinician recognition of ARDS, and to
continue to develop the evidence base for interventions that may benefit
patients suffering from this devastating condition.”
Laffey acknowledged that the true extent of ARDS came as
somewhat of a surprise: “We had anticipated finding an incidence of ARDS of approximately
half of what we actually found in the LUNG-SAFE study.We think that the
difference is explained by the fact that we did not rely on clinician
recognition of ARDS, but rather collected data directly on each of the Berlin
diagnostic criteria, enabling us to make the diagnosis directly. This enabled
us to determine that 10% of ICU admissions globally suffer from ARDS.”
The Large Observational Study to UNderstand the GlobalImpact of Severe Acute Respiratory FailurE (LUNG-SAFE) study was initiated by
the European Society of Intensive Care Medicine. The group studied patients
undergoing invasive or noninvasive ventilation, on whom data was collected
during 4 consecutive weeks in winter 2014 in 459 ICUs from 50 countries across
5 continents.
Results
The participating ICUs admitted 29,144 patients:
- 3,022 (10.4%) fulfilled ARDS criteria;
- 2,377 patients developed ARDS in the first 48 hours and received invasive mechanical ventilation;
- ARDS patients represented 23.4% of ventilated patients, ranging from 0.27-0.57 cases per ICU bed per 4 weeks across the different continents.
In-hospital mortality
- mild ARDS 34.9%
- moderate ARDS 40.3%
- severe ARDS 46.1%
Recognition
60.2% of ARDS cases were identified at any point during
their clinical course; recognition ranged from 51.3% in mild to 78.5% in severe
ARDS. Only 34% of cases were identified at the initial time that ARDS criteria were
met. Clinician recognition of ARDS was associated with higher PEEP, greater use
of neuromuscular blockade and prone positioning. Factors that prompted
clinician recognition of ARDS were found to be younger patient age, lower
predicted body weight, the presence of extrapulmonary sepsis or pancreatitis,
and greater disease severity. Lower numbers of nurses and physicians per ICU
patient were both associated with reduced clinician recognition of ARDS.
Treatment
Laffey explained that they found that over one third of
patients did not receive protective lung ventilation strategies; this was defined
as a tidal volume of up to 8ml/kg predicted body weight and a plateau pressure
of 30 cmH2O or less. Less than 2% of patients received the combination of high
tidal volumes and had high plateau pressures. The use of adjunctive measures to
aid gas exchange, such as prone positioning (used in 16.3% of patients with severe
ARDS), the use of neuromuscular blockade, recruitment manoeuvres or
extracorporeal support was also quite low. Laffey added: “This may be due in
part to doubts in regard to the strength of the evidence for these adjunctive
approaches. This can be addressed by performing additional definitive studies
into these interventions.”
Next Steps
In an accompanying editorial, Brendan J. Clark, MD and Marc Moss, MD, Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Aurora, USA, note that the underrecognition of ARDS is concerning, especially when clinicians probably knew their hospital was participating in the LUNG-SAFE study and were subject to the Hawthorne effect. Clark and Moss write, “it is possible that…these low rates of clinician recognition of ARDS are overestimates of what likely happens in daily practice.”
Despite good evidence on effective treatment of ARDS,
bridging the evidence-practice gap remains difficult, acknowledge Clark and
Moss. Multiple approaches may be needed, such as an improvement “champion”, interprofessional
teamwork, and at the macro level financial investment in implementation
science. They conclude: “The medical and critical care community should
prioritise the proper implementation of beneficial therapies, engage the
necessary stakeholders, and take the next steps to dial in the evidence to
improve the treatment and outcomes of patients with ARDS.”
Laffey emphasised the need to find more reliable ways to
diagnose ARDS. “ We need to increase our efforts,” he said. “ARDS remains a syndrome
diagnosis, and therefore requires clinician recognition of a pattern of
clinical findings to make the diagnosis. While the reasons underlying clinician
failure to recognise ARDS in critically ill patients are complex, the fact that
there is no single test for diagnosing ARDS is a likely contributing factor.”
References:
Bellani G, Laffey JG, Pham T, Fan E, Brochard L, Esteban A, Gattinoni L, van haren F, Larsson A, McAuley DJ, Ranieri M, Rubenfeld G, Thompson BT, Wrigge H, Slutsky AS, Pesenti A; for the LUNG SAFE Investigators and the ESICM Trials Group (2016) Epidemiology, patterns of care, and mortality for patients with acute respiratory distress syndrome in intensive care units in 50 countries. JAMA, 315(8): 788-800.
Clark BK, Moss M. The acute respiratory distress syndrome: dialing in the evidence? JAMA, 315(8) 759-61.