Related Experiment Video
Updated: Oct 29, 2025

Monitoring Lung Function with Electrical Impedance Tomography in the Intensive Care Unit
Published on: September 6, 2024
Continuous estimation of airway resistance in non-invasive ventilation
Yuqing Chen1, Yueyang Yuan2, Hai Zhang1
1Department of Respiratory Medicine, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai 200030, China.
Background:
This study aimed to evaluate the accuracy of expiratory time constant (RCexp) to continuously calculate the airway resistance (Raw).
Material And Methods:
A Respironics V60 ventilator was connected to a lung simulator for modeling different profiles of respiratory mechanics.
Results:
During assisted ventilation, the respiratory system compliance (Crs) calculation was always overestimated in most lung models. The Raw estimation using the expiratory resistance (Rexp) method was close to the calculated value with the occlusion method during volume-controlled ventilation (VCV). In expiratory flow limitation (EFL) lung models, similar results were obtained in the estimation of inspiratory resistance (Rinsp), but different variations were observed in the calculation of the Rexp. The results estimated with RCexp and with dynamic signal analysis had significant variation and accuracy (p < 0.001).
Conclusion:
The RCexp method is a robust approach to provide real-time assessments of Rinsp and Rexp in spontaneously breathing patients during noninvasive ventilation. An underestimation of Rexp was observed in EFL lung models.
More Related Videos
Related Concept Videos
Assessment of Ventilation I: Respiratory Rate
A Ventilation assessment is critical for monitoring a patient's health status. Respiration, one of the most accessible vital signs, provides insights into the function of numerous body systems and can indicate serious health issues, such as brainstem injuries from head trauma.
Critical Guidelines for Assessing Ventilation:
Respiratory Volumes
Tidal Volume (TV) Tidal volume (TV) is the air inhaled or exhaled in a...
Mechanical Ventilation II: Invasive Ventilation
Negative-Pressure Ventilators
Negative-pressure ventilators create a vacuum around the chest or body to draw air into the lungs, simulating breathing. This method does not require an...
Mechanical Ventilation III: Noninvasive Ventilation
Noninvasive Positive-Pressure Ventilation...
Respiratory Volumes and Capacities
Assessment of Ventilation II: Respiratory Depth and Rhythm
Respiratory depth measures the volume of air inhaled or exhaled during a breath. It can vary from shallow to deep and typically remains consistent when a person is at rest or asleep. Occasionally, individuals will automatically inhale deeply, known as sighing, which inflates the lungs with more air than normal breathing.
To assess respiratory depth, observe the degree of chest excursion or movement:

