Cardiopulmonary coupling analysis using smart wearables and mobile computing

Cardiopulmonary coupling (CPC) analysis links heart and respiration rates to assess sleep-related parameters. Typically, the CPC is measured using multi-lead electrocardiography (ECG) and ECG-derived respiration (EDR). Novel textile shirts with embedded ECG sensors offer convenient and continuously monitored sleep at home. We investigate the feasibility of a shirt with textile sensors (Pro- Kit, Hexoskin, Quebec, Canada) for CPC analysis by mobile computing. ECG data is continuously transmitted from the shirt to a smartphone via Bluetooth Low Energy (BLE). We customize a CPC algorithm and use twelve whole-night recordings from four volunteers to perform qualitative and quantitative analysis. We compare EDR with respiratory inductive plethysmography (RIP). In average, EDR and RIP differ 17.22%. After one night, the batteries are reduced to approx. 70% (shirt) and 90% (smartphone). The run time for CPC processing is approx. 3 min. Hence, smart wearables in combination with mobile computing show technical feasibility for CPC analysis. Eventually, this could yield a useful solution for sleep analysis of non-expert users in a private environment.

Second Ventilatory Threshold Assessed by Heart Rate Variability in a Multiple Shuttle Run Test

Many studies have focused on heart rate variability in association with ventilatory thresholds. The purpose of the current study was to consider the ECG-derived respiration and the high frequency product of heart rate variability as applicable methods to assess the second ventilatory threshold (VT2). Fifteen healthy young soccer players participated in the study. Respiratory gases and ECGs were collected during an incremental laboratory test and in a multistage shuttle run test until exhaustion. VΤ2 was individually calculated using the deflection point of ventilatory equivalents. In addition, VT2 was assessed both by the deflection point of ECG-derived respiration and high frequency product. Results showed no statistically significant differences between VT2, and the threshold as determined with high frequency product and ECG-derived respiration (F(2,28)=0.83, p=0.45, η2=0.05). A significant intraclass correlation was observed for ECG-derived respiration (r=0.94) and high frequency product (r=0.95) with VT2. Similarly, Bland Altman analysis showed a considerable agreement between VT2 vs. ECG-derived respiration (mean difference of −0.06 km·h−1, 95% CL: ±0.40) and VT2 vs. high frequency product (mean difference of 0.02 km·h−1, 95% CL: ±0.38). This study suggests that, high frequency product and ECG-derived respiration are indeed reliable heart rate variability indices determining VT2 in a field shuttle run test