## 2 Material and Methods
### Measurement Protocol  
A protocol has been designed to facilitate integration of incoming data recorded at various sample time intervals and non-equally distributed in time and frequency domains. The protocol enables the synchronization of both respiratory lung function test data and the EQV data. The measurement protocol begins with a 2 min measurement using FOT, followed by a 5 min rest. Next, we measure for 1 min with RESMON and then the rest for another 5 min. This cycle continues with another 2 min the FOT measurement. Figure 5 illustrates the measurement protocol timeline over a two-hour duration, structured into ten measurements (Meas). Each measurement combines FOT and Resmon measurements interposed with rest periods to ensure tidal breathing conditions (diaphrag muscle relaxation between measurements).  
Figure 6 illustrates the real-time clinical setup used for the measurement protocol, showcasing the two FOT devices and their associated components, alongside the EQV real-time physiological monitoring sensor. The setup includes the standalone Resmon PRO FULL device (highlighted with parts such as the device itself, an arm holder, and a touchscreen display for user interaction). Additionally, the lower-frequency 4P-FOT device is mounted on an adjustable table and connected to a laptop equipped with built-in programs for recording data and interacting with the system.  
Figure 4: Time plot and spectrograms of biomedical signals. (**Top Row**): Time-domain plots of breathing rate (BR), electrocardiogram (ECG), and heart rate (HR) signals over a period of 7000 s. (**Bottom Left**): Three-dimensional spectrograms of BR, ECG, and HR signals. (**Bottom Right**): Two-dimensional spectrograms of BR, ECG, and HR signals.  
This figure also highlights the EQV sensor used for continuous physiological monitoring, displaying the real-time heart rate, respiratory rate, and other vital signals. The combination of these systems is fundamental for the comprehensive assessment of ambulatory respiratory mechanics performed in this study.  
From the initialization of the patient's measurement, we extract data over 2 min intervals and then discard them 11 min before extracting another 2 min interval, repeating this pattern until the end of the measurement. This way, we ensure that the EQV data are accurately synchronized with FOT measurements for a thorough analysis. The protocol timeline begins at 0 min and extends to 125 min (2 h and 5 min), with each measurement window being 13 min. For Meas 10, the measurement will not end with the final rest period as it reaches the end of the measurement protocol. Therefore, Meas 10 takes 8 min instead of the typical 13 min. The measurement protocol is defined as follows:  
* Two min FOT Measurement: Represented in blue, this phase marks the beginning of each measurement session. Participants were instructed to breathe normally while seated for 120 s.
* Five min Rest: Indicated in gray, this phase is a rest period.
* One min Resmon Measurement: Depicted in pink, this phase involves using the Resmon device. Participants were asked to breathe normally while seated for 60 s.
* Five min Rest: Another rest period, shown in gray.  
Figure 5: Illustration of the two-hour measurement protocol.  
Figure 6: (**A**) Clinical set-up consisting of the two FOT devices and their input and recorded signals. Resmon PRO is a standalone device with two parts: device (1) and an arm holder (2). It is provided with a touchscreen display (3) to interact with the user and a USB port (4) to save the acquired data. The 4P-FOT device at lower frequencies is mounted on a height-adjustable table (5) and is connected to a laptop (6) with built-in programs and a user interface. For each measurement, a singe-use mouthpiece (8) is connected to slot (7). (**B**) The EQV real-time physiological signals that monitor sensor and the recorded signals.