The goal of this study randomized single-center crossover study is to evaluate the impact of asymmetrical versus symmetrical nasal high flow (NHF) therapy on work of breathing (WOB). The main question it aims to answer are: 1\. Does the asymmetrical NHF interface improve the work of breathing compared to the symmetrical NHF interface? Researchers will compare the symmetrical NHF interface to the symmetrical NHF interface to see if the the asymmetrical interface has a greater impact on the work of breathing. Participants will : 1. receive NHF via both interfaces (FiO₂ 0.21, 50 L/min) for 15 minutes, in random order, with esophageal pressure monitoring and bioelectrical impedance analysis performed. 2. baseline characteristics will me monitored throughout the interventions 3. Esophageal pressure and minute ventilation will be monitored.
Each participant will undergo all phases of the study while seated comfortably, breathing room air. Vital signs, including blood pressure, heart rate, and peripheral oxygen saturation (%SpO₂), will be continuously monitored and recorded throughout. Respiratory mechanics will be assessed using esophageal pressure (Pes) monitoring. A thin latex balloon catheter (10 cm long, 3-5 cm circumference; Cooper surgical, USA), filled with 0.5 mL of air, will be placed in the mid-esophagus (\~45 cm from the nares) and will be connected to a pressure transducer (RSS-100HR, Hans Rudolph Inc., USA). Correct positioning will be confirmed by observing equal fluctuations in Pes and airway pressure (Paw) during occluded breaths. Balloon integrity will be verified before, after, and as needed during the procedure. Participants will be instructed to breathe quietly on room air (FiO₂ 0.21) to allow for baseline assessment. Volume will be recorded using a heated pneumotachometer (Series 3813; Hans Rudolph Inc., USA) and the Research Pneumotach System (RSS100-HR), sampling at 50 Hz, a sampling rate exceeding the Nyquist criterion for respiratory signals. A bioelectrical impedance technology device (ExSpiron, Respiratory Motion Inc., Waltham, MA) will then be attached around the chest to assess lung volume changes. Participants will then be randomized in a 1:1 ratio to one of two intervention sequences using a computer-generated randomization schedule. * Sequence 1: Symmetrical NHF Interface - 3-minute washout period - Asymmetrical NHF Interface * Sequence 2: Asymmetrical NHF Interface - 3-minute washout period - Symmetrical NHF Interface In the seated position, participants will both 15-minute phases, separated by a 3-minute washout period to prevent residual effects. During the "Symmetrical Interface" phase, participants will breathe using the conventional symmetrical NHF cannula, and during the asymmetrical phase, the asymmetrical interface (DUET, Fisher and Paykel Healthcare, Auckland, New Zealand) will be used. High-flow oxygen will be delivered using a commercial system (AIRVO 3; Fisher and Paykel Healthcare, Auckland, New Zealand) set at a flow of 50 L/min, temperature of 37°C, and FiO₂ of 0.21.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
30
DUET asymmetric nasal high flow interface that fits best to patients' nostrils (size: one nostril of the patient should be fully occluded) Patients will be crossed - over between the 2 interventions
Well - established conventional nasal high flow cannula (size: medium) Patients will be cross - over between the 2 interventions
University Hospital of Larissa, Department of Pulmonary Medicine
Larissa, Greece
RECRUITINGChange in the pressure time product after the use of symmetrical high flow nasal interface for 15 minutes.
This outcome measures the change in the Pressure-Time Product (PTP) before and after the application of a symmetrical high-flow nasal interface (HFNI) in patients requiring noninvasive respiratory support. The PTP is a physiological index that reflects the work of breathing and respiratory muscle effort. It is calculated using airway pressure and inspiratory time data over a defined period. The primary goal is to assess whether the symmetrical HFNI leads to a measurable reduction in the PTP, indicating improved respiratory mechanics and decreased patient effort.
Time frame: Baseline and 15 minutes
Change in the pressure time product after the use of asymmetrical nasal high flow interface for 15 minutes.
This outcome measures the change in the Pressure-Time Product (PTP) before and after the application of a symmetrical high-flow nasal interface (HFNI) in patients requiring noninvasive respiratory support. The PTP is a physiological index that reflects the work of breathing and respiratory muscle effort. It is calculated using airway pressure and inspiratory time data over a defined period. The primary goal is to assess whether the asymmetrical HFNI leads to a measurable reduction in the PTP, indicating improved respiratory mechanics and decreased patient effort.
Time frame: Baseline and 15 minutes
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