The FLARE Four
- Conservative fluid management is a key evidence-based intervention for acute respiratory distress syndrome (ARDS)
- This strategy is for patients who have been adequately resuscitated and are free of ongoing shock; it involves avoiding positive fluid balance and normalizing intravascular volume
- The best evidence for this approach comes from the Fluid and Catheter Treatment Trial, published in 2006 by the ARDS Clinical Trials Network
- Fluid resuscitation should be guided by dynamic measures of volume responsiveness (those with two data points, such as pulse pressure variation or passive leg raise) rather than single data points such as central venous pressure
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In line with guidance from the Society of Critical Care Medicine, Massachusetts General Hospital recommends conservative fluid management for patients with acute respiratory distress syndrome (ARDS) related to COVID-19. Rene Bermea, MD, a fellow in the Division of Pulmonary and Critical Care at Mass General, explains why in a fast literature update posted on April 14, 2020.
In ARDS, pulmonary edema results from an increase in pulmonary capillary permeability, which can be exacerbated by an increase in hydrostatic forces. The aim of conservative fluid management is to reduce intravascular volume and thereby reduce edema and improve lung function.
Conservative fluid management is for patients who are adequately resuscitated and shock-free. It entails:
- No maintenance fluids
- Diuretics, as tolerated, to normalize volume status until off the ventilator
- Holding diuretics for rising creatinine and/or active urine sediment
- Considering hypovolemia if a patient becomes hypotensive with small increases in positive end-expiratory pressure
The recommendation for this strategy is based on the results of the Fluid and Catheter Treatment Trial (FACTT), published in 2006 by the ARDS Clinical Trials Network. 1,000 intubated patients were randomly assigned to a liberal or conservative fluid strategy and were followed for seven days.
The conservative strategy was clearly superior with regard to cumulative fluid balance, oxygenation index, lung injury score, need for renal replacement therapy and—of special interest during the COVID-19 pandemic when ventilators are scarce—the number of ventilator-free days.
In FACTT, enteral fluid intake was counted toward total body fluid balance and did not seem to affect intravascular volume.
Gauging Fluid Responsiveness
Measures of volume responsiveness can be used to guide fluid resuscitation. Dynamic measures (those with two data points, such as pulse pressure variation or passive leg raise) are preferred over single data points, such as central venous pressure.
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