Noninvasive Respiratory Strategies and Intubation or Mortality Among Patients With Acute Hypoxemic Respiratory Failure Due to COVID-19

Do Thresholds for Invasive Ventilation in Hypoxemic Respiratory Failure Exist? A Cohort Study

Rationale: Invasive ventilation is a significant event for patients with respiratory failure. Physiologic thresholds standardize the use of invasive ventilation in clinical trials, but it is unknown whether thresholds prompt invasive ventilation in clinical practice. Objectives: To measure, in patients with hypoxemic respiratory failure, the probability of invasive ventilation within 3 hours after meeting physiologic thresholds. Methods: We studied patients admitted to intensive care receiving Fi_O2 of 0.4 or more via nonrebreather mask, noninvasive positive pressure ventilation, or high-flow nasal cannula, using data from the Medical Information Mart for Intensive Care (MIMIC)-IV database (2008-2019) and the Amsterdam University Medical Centers Database (AmsterdamUMCdb) (2003-2016). We evaluated 17 thresholds, including the ratio of arterial to inspired oxygen, the ratio of saturation to inspired oxygen ratio, composite scores, and criteria from randomized trials. We report the probability of invasive ventilation within 3 hours of meeting each threshold and its association with covariates using odds ratios (ORs) and 95% credible intervals (CrIs). Measurements and Main Results: We studied 4,726 patients (3,365 from MIMIC, 1,361 from AmsterdamUMCdb). Invasive ventilation occurred in 28% (1,320). In MIMIC, the highest probability of invasive ventilation within 3 hours of meeting a threshold was 20%, after meeting prespecified neurologic or respiratory criteria while on vasopressors, and 19%, after a ratio of arterial to inspired oxygen of <80 mm Hg. In AmsterdamUMCdb, the highest probability was 34%, after vasopressor initiation, and 25%, after a ratio of saturation to inspired oxygen of <90. The probability after meeting the threshold from randomized trials was 9% (MIMIC) and 13% (AmsterdamUMCdb). In MIMIC, a race/ethnicity of Black (OR, 0.75; 95% CrI, 0.57-0.96) or Asian (OR, 0.6; 95% CrI, 0.35-0.95) compared with White was associated with decreased probability of invasive ventilation after meeting a threshold. Conclusions: The probability of invasive ventilation within 3 hours of meeting physiologic thresholds was low and associated with patient race/ethnicity.

Providing respiratory and ventilation care in the face of shifting evidence: current opinion in critical care

PURPOSE OF REVIEW

To review the clinical problem and noninvasive treatments of hypoxemia in critically-ill patients with coronavirus disease 2019 pneumonia and describe recent advances in evidence supporting bedside decision making.

RECENT FINDINGS

High-flow nasal oxygen and noninvasive ventilation, along with awake prone positioning are potentially helpful therapies for acute hypoxemic respiratory failure. High-flow nasal oxygen therapy has been widely implemented as a form of oxygen support supported by prepandemic randomized controlled trials showing possible benefit over noninvasive ventilation. Given the sheer volume of patients, noninvasive ventilation was often required, and based on a well conducted randomized controlled trial there was a developing role for helmet-interface noninvasive. Coupled with noninvasive supports, the use of awake prone positioning demonstrated physiological benefits, but randomized controlled trial data did not demonstrate clear outcome superiority.

SUMMARY

The use of noninvasive oxygen strategies and our understanding of the proposed mechanisms are evolving. Variability in patient severity and physiology may dictate a personalized approach to care. High-flow nasal oxygen may be paired with awake and spontaneously breathing prone-positioning to optimize oxygen and lung mechanics but requires further insight before widely applying to clinical practice.