## 5 Conclusions  
This study the need to improve the energy accuracy of AED used in emergency patients such as SCA. The results of the study showed that changes in thoracic impedance due to various factors such as patient status and first aid process had a negative effect on the energy delivery of the AED. The experiment was conducted based on the international standard IEC60601-2-4:2010 of medical devices. The electric shock energy error was measured by changing the impedance of each adult mode and pediatric mode of the AED. When the impedance is changed and set to adult mode, the first peak current of the shock energy is set to 55.4 (A), at least 8.4 (A), and the first peak current is set to 32.2 (A) and at least 4.8 (A) when the pediatric mode is set. Experimental results show that the change in the thoracic impedance of the patient is inversely proportional to the decrease in the peak current of the electric energy applied by the AED.  
The AED analyzes ECG and thoracic impedance of early emergency patients through pads to provide information on whether defibrillation is necessary and decisions of adult or pediatric mode. However, thoracic impedance can change in the process of first aid treatment to patients. The changing thoracic impedance can be improved by various measure such as correcting the electric shock energy by analyzing the change of impedance by continuously applying a specific Alternating Current (AC) signal to the human body through the pad. This can increase the survival rate of patients with cardiac arrest by delivering accurate electric energy required for the patient.  
In the Guidance for Medical Device Performance Test published by the Korea Food and Drug administration in 2010, the test criteria for the accuracy of output energy among the performance evaluation items of AEDs are \(\pm\) 3 J or \(\pm\) 15% [28]. However, most of the AEDs installed in public places are used by non-professional medical personnel. Therefore, the test performance standards for AEDs should be stricter. Especially in the case of children, the elderly, and pregnant women, the performance deterioration due to the energy error for the thoracic impedance change can have a big designation for life. Therefore, the pad of the AED is required to analyze the changes in the thoracic impedance of the patient in real time and to revise the electric shock energy. In the case of ventricular fibrillation emergency patients, the probability of defibrillation success is reduced by about 10% every minute, so quick and accurate response to cardiac arrest is the most important part of protecting life. Since the AED used in this way is a medical device developed for all the public to use, continuous research should be conducted to demonstrate accurate performance to emergency patients even when non-specialized medical personnel use it according to its purpose and goal performance.  
Figure 5: Relationship between impedance and peak current in adult mode and pediatric mode, respectively.  
**Author Contributions:** Conceptualization, T.-J.H.; methodology, H.-G.P.; validation, H.-G.P.; formal analysis, T.-J.H.; investigation, T.-J.H.; resources, S.-K.P.; data curation, T.-J.H.; writing--original draft preparation, T.-J.H.; writing--review and editing, S.-G.P.; visualization, T.-J.H.; supervision, S.-G.P.; project administration, S.-G.P.; funding acquisition, H.-G.P. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was supported by Changwon National University in 2020-2021.  
**Conflicts of Interest:** The authors declare no conflict of interest.