## 3 Results
### CPR Performance with No-Feedback and with Real-Time Feedback System  
#### 3.1.1 Chest Compression Depth  
The medical participants performed infant CPR using the TT compression technique see Figure 5a. The mean value of chest compression depth during no performance feedback was 32.8 \(\pm\) 2.6 mm compared to the chest compression depth parameter mean value of 38.2 \(\pm\) 2.7 mm with feedback performance. During CPR, there was an improvement in the compression depth parameter with performance feedback of approximately 16% compared to the CPR performance without feedback. The median values of the compression depth parameter with and without feedback were 33 mm and 38 mm, respectively. The difference and percentage of difference between the no feedback and feedback groups were 5% and 15%, respectively. There was a significant difference in the compression depth parameter when assisted with performance feedback compared to unassisted performance (\(p\)-value \(<\) 0.05). In addition, when medically trained participants performed infant CPR using the TF compression technique, see Figure 5a. The mean value of the chest compression depth parameter without feedback was 30.2 \(\pm\) 2.07 mm compared to the chest compression depth parameter mean value of 36.8 \(\pm\) 1.13 mm with performance feedback. During CPR, there was an improvement in the compression depth parameter with feedback of approximately 22% compared to the CPR performance without feedback. The median values of the compression depth parameter with no feedback and feedback performance were 30 mm and 37 mm, respectively. The difference and percentage of difference between the no feedback and feedback group were 7% and 23%. There was a significant difference in the compression depth parameter with feedback-assisted performance compared to unassisted performance (\(p\) < 0.05). Figure 4: The overall system design of the infant CPR real-time feedback system. Figure 5: Mean value of the four CPR parameters achieved during no feedback and feedback CPR performance using TT and TF compression technique (**a**) the chest compression depth parameter; (**b**) the chest release force parameter; (**c**) the chest compression rate parameter; (**d**) the compression duty cycle parameter; and the dashed line represents the guideline range of each CPR parameter. Related to lay participants, when infant CPR was performed using the TT compression technique, see Figure 5a. The mean value of the chest compression depth parameter with no performance feedback was 30.28 \(\pm\) 3.30 mm compared to the chest compression depth parameter mean value of 36.84 \(\pm\) 2.16 mm with performance feedback. During CPR, there was an improvement in the compression depth parameter with the performance feedback of approximately 22% compared to CPR performance without feedback. The median values of the compression depth parameter during no feedback and feedback performance were 31 mm and 37 mm, respectively. The difference and percentage of difference between the no feedback and feedback group were 6% and 19%. There was a significant difference in the compression depth parameter with feedback-assisted performance compared to the unassisted performance (\(p\)-value \(<\) 0.05). In addition, when the lay participants performed infant CPR using the TF compression technique, see Figure 5a. The mean value of chest compression depth parameter during no feedback performance was 29.76 \(\pm\) 2.17 mm compared to the chest compression depth parameter mean value of 36 \(\pm\) 1.87 mm during feedback performance. During CPR, there was an improvement in the compression depth parameter with the feedback performance of approximately 21% compared to the CPR performance without feedback. The median values of the compression depth parameter with no feedback and feedback performances were 30 mm and 36 mm, respectively. The difference and percentage of difference between the no feedback and feedback group were 6% and 20%.