Noninvasive Tidal Volume Measurements, Using a Time-of-Flight Camera, Under High-Flow Nasal Cannula—A Physiological Evaluation, in Healthy Volunteers*

OBJECTIVES: The mechanisms of high-flow nasal cannula are still debated but may be mediated by the generation of low positive end-expiratory pressure and a washout of the airway dead space. The aims of this study were to assess the effects of high-flow nasal cannula on tidal volume using a noninvasive method using a time-of-flight camera, under various conditions. DESIGN: A physiologic evaluation in healthy volunteers. SETTING: An university hospital ICU. SUBJECTS: Ten healthy volunteers were included in a physiologic study (CamOpt study, identifier: NCT04096183). INTERVENTIONS: All volunteers were submitted to 12 different conditions (i.e., gas flow [baseline = 0; 30–60 L/min]; mouth [open/closed]; respiratory rate [baseline; baseline + 10 breaths/min]). Tidal volume measurements were performed every minute, during a 6-minute recording period. In all combinations, reference respiratory rate was measured by using chronometric evaluation, over a 30-second period (RRREF), and by using the time-of-flight camera (RRTOF). MEASUREMENTS AND MAIN RESULTS: Tidal volume increased while increasing gas flow whatever the respiratory rate and mouth condition (p
Source: Critical Care Medicine - Category: Emergency Medicine Tags: Online Laboratory Investigations Source Type: research