A Novel Point-of-Care Smartphone Based System for Monitoring the Cardiac and Respiratory Systems

Figures

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  Figure 1. The smartphone-based ECG acquisition system, or “cvrPhone”. The Bluetooth-enabled ECG acquisition system is composed of three commercially available parts: An analog-to-digital (AD) converter, a microcontroller board and, and a Bluetooth module. (A) Flow-diagram of the 12-lead ECG signals from the torso to smartphone. Ten electrodes are placed on the torso for the recording of 8 ECG leads (Leads I and II and six precordial leads). The AD converter amplifies and digitizes the 8 ECG leads. Then the signals are transmitted to the smartphone through the HC-05 Bluetooth module, and the remaining leads (Leads III, aVR, aVL and aVF) are calculated. (B) Real-time display of selected three ECG signals on the smartphone screen.

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  Figure 2. Estimation of the respiration rate (RR) and tidal volume (TV). Different RRs and TVs were obtained by adjusting the mechanical ventilator and using the reading in its display as the gold-standard. (A) The respiration rate was randomly changed from 14 to 10 to 12 to 8 to 13 to 6 to 11 to 7 to 9 breaths/min, while the TV was 500 ml and the heart rate was ~122 bpm. (B) The TV was changed from 250 to 0 to 820 to 0 to 540 to 0 to 760 ml (marked by the thick red lines), while the RR was 14 breaths/min.

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  Figure 3. Assessment of apnea. (A) Estimation of the respiration rate (RR) during an apneic event. The RR was changed from 9 breaths/min to 0 breaths/min (ventilator-off) to 14 breaths/min, and the tidal volume (TV) was changed from 760 ml to 0 ml (ventilator-off) to 300 ml. (B) Estimation of the TV during an apneic event. The TV was 250 and 690 ml, and the RR was 14 and 6 breaths/min, before and after the apneic event, respectively. The apnea period occurs from 2 min and 53 sec to 4 min and 43 sec.

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  Figure 4. Temporal changes of the ischemic index after coronary artery occlusion. (A) Beat-by-beat ischemic index estimation before and after coronary artery occlusion (t > 0 min), of lead V6. (B) One-minute, running median ischemic index estimation. (C) Summary results of beat-by-beat, ischemic index estimation (n = 9 records from 6 animals). There is a statistically significant (p < 0.018) increase of the ischemic index after coronary artery occlusion. Each bar graph represents 5, 25, 50, 75 and 95 percentiles of ischemic indices beat-by-beat estimated for all animals for 1 minute time span. (D) Summary results of beat-by-beat, ischemic index estimation preceding ventricular tachycardia (n = 3). The ischemic index distributions that are significantly increased after occlusion compared to baseline, are indicated by an asterisk (p < 0.028).

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  Figure 5. ECG signals displaying spontaneous transition to ventricular tachycardia after coronary artery occlusion, which occurred 298 sec after the occlusion.

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  Figure 6. Real-time display of the respiration rate, tidal volume and ischemic index. Each red dot represents a 1 min running median estimated value obtained every 30 sec.