Noninvasive Ventilation in Ordinary Wards for Acute Hypercapneic Respiratory Failure, Acute Hypoxemic Respiratory Failure, or Both?
I found the article published in a recent issue of Critical Care Medicine by Cabrini et al (1) describing their noninvasive ventilation (NIV) findings in patients with acute respiratory failure in “ordinary wards” intriguing. Certainly, it is encouraging to learn that patients with acute respiratory failure being treated with NIV may fare similarly, regardless of their admission disposition (ICU vs ward) (1). However, despite a well researched and clearly presented study, there is a major question that loomed after reading this article that I wish to underscore. It is unclear whether the acute respiratory failure that was treated was acute hypercapneic respiratory failure, acute hypoxemic respiratory failure, or both. The authors appropriately vetted comorbidities and etiologies for respiratory failure (i.e., pneumonia, congestive heart failure, chronic obstructive pulmonary disease, etc) but neglected to characterize the type of respiratory failure (i.e., failure of ventilation vs failure of oxygenation) (1). This distinction is critical since the treatments and mortality rates (the investigators’ primary outcome) for these two different classes of respiratory failure can be markedly different (2–4). As you are undoubtedly aware, it was recently shown that patients with nonhypercapneic acute hypoxemic failure treated with high-flow oxygen are more likely to survive after 90 days than matched patients treated with NIV (2). The contrasting mortality rates are multifactorial and may be due to NIV administered to patients with severe lung injury, which can increase ventilator-induced lung injury from higher tidal volumes. Furthermore, high-flow oxygen may prevent thick secretions and subsequent atelectasis and be associated with an increased degree of comfort, a reduction in the severity of dyspnea, and a decreased respiratory rate when compared with NIV (2). Thus, I ask that Cabrini et al (1) consider these two types of acute respiratory failure, and the implications that this scrutiny may have on their reported mortality rates in ward-patients treated with NIV.