Wednesday, November 20, 2013

Can we prevent ARDS?

According to a recent review prevention is based on early recognition and management of risk factors. Consideration of certain risk factors suggests various preventive strategies, most of which are not based on high level evidence:

Low tidal volume mechanical ventilation
This is of proven benefit for patients with established ARDS who require invasive mechanical ventilation. What about mechanically ventilated patients who do not have ARDS? The review cites evidence that in such patients it is an effective strategy. This evidence has been accumulating for awhile and I summarized it back in 2010.

Prophylactic PEEP
Although “5 of PEEP” is almost a default setting for mechanically ventilated patients these days the evidence on whether it prevents lung injury is mixed.

Fluid management
Direct evidence is not available concerning fluid management as a preventive strategy. If the cutoff for defining ARDS is arbitrary and lung injury exists along a continuum, one might infer benefit based on findings in patients with established ARDS. It is well known that a conservative fluid strategy is beneficial in such patients.

Appropriate sepsis care
Sepsis is a well known precursor to ARDS. Although the particular outcome of ARDS has not been specifically examined, early application of the sepsis bundle is known to improve general outcomes. ARDS is sometimes a late consequence of sepsis. Halting the sepsis progression early might be a preventive measure.

Transfusion strategies
No such strategies have been studied in controlled trials for prevention of ARDS. However, given the increased recognition of transfusion associated lung injury (TRALI), a restrictive transfusion strategy, as is now generally recommended for hospitalized patients, is appealing.

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