Non-Contact Monitoring of Inhalation-Exhalation (I:E) Ratio in Non-Ventilated Subjects.

Area of Science:

• Biomedical Engineering
• Respiratory Physiology
• Medical Imaging

Background:

• The inhalation-exhalation (I:E) ratio is a critical parameter for assessing respiratory function and disease severity.
• Current methods for I:E ratio determination often require physical contact with the patient, limiting continuous monitoring.
• Non-contact methods are needed to provide a more accessible and less intrusive approach to respiratory monitoring.

Purpose of the Study:

• To develop and validate a non-contact method for determining the I:E ratio using a depth-sensing camera.
• To assess the accuracy of this novel method by comparing it against traditional spirometry.
• To evaluate the potential clinical utility of non-contact I:E ratio monitoring.

Main Methods:

• A depth-sensing camera (Intel D415 RealSense) was used to capture torso movements from healthy volunteers at a distance of 1.1 meters.
• Real-time processing of depth data extracted respiratory signals to calculate the I:E ratio (I:Edepth).
• Statistical analyses, including Bland-Altman and linear regression, were performed to compare I:Edepth with spirometer-derived I:E ratios (I:Espiro).

Main Results:

• The non-contact system successfully generated I:E ratios across a range of physiological values (0.3 to 1.0) at various respiratory rates (4 to 40 breaths/min).
• Bland-Altman analysis showed minimal bias (-0.004) and acceptable limits of agreement [-0.234, 0.227] between I:Edepth and I:Espiro.
• Linear regression demonstrated a strong correlation (I:E[Formula: see text] = I:Espiro - 0.006) with high confidence intervals for slope and intercept, confirming accuracy.

Conclusions:

• The study validates a non-contact depth-sensing camera system for accurate I:E ratio determination in healthy individuals.
• This technology shows significant potential for continuous, non-intrusive respiratory monitoring in clinical settings.
• Non-contact I:E ratio monitoring could become a valuable tool for tracking respiratory status and treatment response in patients with conditions like COPD and asthma.