Should we be addressing work of breathing earlier in acute critical illness?

In a recent article in Frontiers in Medicine, “Back to the Basics: Should we be focusing on reducing work of breathing earlier?”^[i], a group from the University of Tennessee College of Medicine Department of Emergency Medicine hypothesized that clinicians should be focused on treating work of breathing earlier in the critical illness with high flow oxygen therapy instead of the current standard of care of supplemental oxygen via low flow nasal cannula.

Their hypothesis is based on the following logic:

• High work of breathing can be an early indicator of a poor prognosis.
• Cardiac output dedicated to work of breathing in a critically ill patient can increase from 1-3% to up to 25%, redirecting blood away from other vital organs (i.e. heart, liver, kidneys, gastrointestinal system).
• High work of breathing can be present due to pulmonary or non-pulmonary conditions (i.e. cardiovascular, hematologic and metabolic).
• Work of breathing is difficult to measure. Patient reported dyspnea and increased respiratory rate and accessory muscle are often used as surrogates to determine increased work of breathing.
• Historically, the focus of treatment is to make oxygen delivery supranormal with hyperoxia, fluids, blood transfusions and vasoactive drugs, which have not been shown to improve patient outcomes and may cause harm.   Less attention has been spent on oxygen consumption, specifically work of breathing.
• While supplemental oxygen does benefit hypoxemia, increased work of breathing is not the equivalent of hypoxia and there is no evidence that shows the use of supplemental oxygen improves clinical outcomes in non-hypoxic patients.
• The authors speak to a recent study which suggests the high flow nasal oxygen reduces work of breathing in non-pulmonary patients (sepsis and septic shock) compared to supplemental oxygen therapy.

The authors then review three case studies in which high velocity therapy, an advanced form of high flow therapy, was used with patients of various pathologies.  In all cases, the patients showed improved vital signs and lactate levels prior to other interventions to directly address the underlying pathology.  The authors note that the use of high velocity therapy, known to help reduce work of breathing, may have contributed to the physiological improvements of these patients.

The authors propose further studies are warranted to identify patient populations and treatment strategies as well as to understand the clinical and economic outcomes this change in clinical practice.

Watch Dr. Greenburg give a live recorded presentation on Work of Breathing: Rethinking the ABCs

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