This prospective, randomized crossover trial will enroll adult healthy volunteers. Initially, the subject's peak inspiratory flow will be measured using a mask connected with a respiratory monitor. Subsequently, the volunteers will undergo HFNC treatment at different flow settings while their peak inspiratory flow will be continuously monitored. The primary outcome of this study is the lung aeration with different flow settings. Secondary outcomes include the lung aeration with different devices, subject's comfort at different flow settings, and the correlation between the subject's peak inspiratory flow measured by HFNC and by a mask connected with a respiratory monitor.
Background: High-flow nasal cannula (HFNC) is a device that can reduce the work of breathing (WOB) and improve oxygenation by providing a flow that matches or exceeds patient's peak inspiratory flow during tidal breathing. Despite its widespread use, there remains a lack of consensus regarding the optimal flow settings. Two new HFNC devices that can provide information regarding patient's peak tidal inspiratory flow breath by breath are recently available, which might help guide set and titrate the flow settings. This study aims to investigate the effects of different flow settings on lung impedance in a cohort of healthy volunteers by using the two new HFNC devices. Methods: This prospective, randomized crossover trial will enroll adult healthy volunteers. Initially, the subject's peak inspiratory flow will be measured using a mask connected with a respiratory monitor. Subsequently, the volunteers will undergo HFNC treatment at different flow settings while their peak inspiratory flow will be continuously monitored. The primary outcome of this study is the lung aeration with different flow settings. Secondary outcomes include the lung aeration with different devices, subject's comfort at different flow settings, and the correlation between the subject's peak inspiratory flow measured by HFNC and by a mask connected with a respiratory monitor.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
NONE
Enrollment
26
Eligible participants will use the high-flow nasal cannula device (Airvo3 or HFT 750) with flow set at 40 L/min or higher
Rush University
Forest Park, Illinois, United States
Change in End-expiratory Lung Impedance From Baseline Measured by Electrical Impedance Tomography (EIT)
End-expiratory lung impedance (EELI) was measured continuously using electrical impedance tomography (EIT). For each flow-setting condition, EELI values were averaged over a stable 1-minute period. The outcome represents the change in EELI (in arbitrary impedance units) from each participant's baseline measurement prior to intervention. Positive values indicate an increase in end-expiratory lung volume compared to baseline, while negative values indicate a decrease. EIT impedance units are dimensionless and device-specific and are used to represent relative changes in ventilation and lung volume.
Time frame: Up to 4 hours
Changes in Respiratory Rates Compared to Baseline
Respiratory rate was measured as breaths per minute. Change was calculated as the value during each HFNC flow condition minus the baseline respiratory rate. Positive values indicate an increase in respiratory rate, and negative values indicate a decrease.
Time frame: Up to 4 hours
Subject's Comfort Level
Comfort level reported by participants using a visual numerical scale ranging between 0 (extreme discomfort) and 10 (very comfortable) at the end of each flow setting
Time frame: Up to 4 hours
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