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, ClinicalTrials.gov 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