Restrictive versus liberal fluid strategy in respiratory failure

Simon Oczkowski, MD, MHSc, MSc, is an associate professor of medicine in the Division of Critical Care at McMaster University.

Is the restrictive fluid strategy better than the liberal one in the case of respiratory failure?

That’s a great question. I think when you’re talking about fluid management strategies in patients with respiratory failure, you have to actually go back and look at the evidence supporting a restrictive fluid strategy.

The rationale behind a restrictive fluid strategy is, if you have a patient whose lungs are not functioning well, we do not want those lungs to have an element of pulmonary edema as well. We want dry lungs, not wet lungs.

The original evidence suggesting that a conservative fluid strategy may be helpful actually goes back to the FACTT (Fluids and Catheters Treatment Trial). This was done in ventilated patients with acute respiratory distress syndrome (ARDS), and that trial suggested a shorter duration of ventilation in that population. It’s not clear to me at all now, almost 20 years on since that study, whether or not the fluid management algorithm they use truly represents current practice.

They used central venous pressure monitoring, which is increasingly falling by the wayside with the advent of things like point-of-care ultrasound (POCUS). On top of that, it was really looking at patients with ARDS, and populations with respiratory failure… we are now often managing them noninvasively, with nasal high-flow [therapy], noninvasive ventilation. It’s not clear whether or not that original trial would apply to those patients. Even in patients with ARDS who are ventilated, the actual algorithm used in the trial is not really reminiscent of modern clinical practice. I’d actually say this is an open question.

The approach I’d suggest for the bedside clinician is you want to avoid creating more problems for yourself, so avoid giving extra fluid and causing pulmonary edema. What we don’t really know is whether or not there’s a specific strategy of conservative fluid management that actually improves patient outcomes now.

Data in patients with sepsis and septic shock… there have been a number of trials looking at conservative fluid approaches. In general, it doesn’t seem to be any better than patients managed with a typical fluid strategy or a liberal fluid strategy. I’d actually say in patients with respiratory failure, this is still an open question.