# Feedback Devices for Cardiopulmonary Resuscitation: A Narrative Review
## 2 Classification of Feedback Devices for Cardiopulmonary Resuscitation
### Integration of Feedback Devices with Defibrillator and Related Equipment  
Real CPR HelpTM is an enhanced functionality integrated into Zoll's AED Plus, utilizing accelerometer technology within the ZOLL defibrillator electrodes, furnishing real-time feedback concerning the accuracy of CPR compression in terms of depth and frequency. Audio and visual prompts guide the operator through the CPR process. Notably, unlike the autonomous small free-standing AVF device discussed in Section 2.1, the utilization of Real CPR HelpTM is contingent upon its integration with the CPR Dashboard; it cannot function independently. The CPR Dashboard, in addition to presenting data on compression depth and frequency, also exhibits an indicator illustrating coronary perfusion pressure. This inclusion offers a more intuitive representation of the patient's circulatory effectiveness. A comparative study conducted on the effectiveness of Real CPR HelpTM demonstrated noteworthy outcomes. The overall quality of CPR demonstrated a marked improvement with the implementation of Real CPR HelpTM. The proportion of participants who achieved sufficient compression depth surged from 25% to 78.1%, and the percentage of participants executing compression with proper technique increased from 50% to 86.5% [39]. Current Limitations of Cardiopulmonary Resuscitation Closed-Loop Feedback Devices and Future Development  
To improve the quality and success rate of CPR and provide effective guidance for rescuers, as well as personalize chest compression for cardiac arrest patients, feedback devices for CPR are continuously being developed. These feedback devices have achieved significant results in terms of improving the quality of CPR and increasing the survival rate of cardiac arrest patients. However, some limitations and problems still remain. * _Limited Application Scenario_ The application scenario for these devices is limited, and their reliability is questionable in special environments such as earthquakes, fires, explosions, mine collapses, traffic accidents, uneven support surfaces, soft compressible situations, and patient transport. The measurement results during artificial CPR may not be accurate when using a manual chest compression auditory feedback device, and the reliability of the device is questioned. * _A Non-Intuitive Feedback Mode_ The closed-loop feedback mode used in these devices is not intuitive, and its practicality is moderate. The moving parts of the pressure sensor may cause harm to the rescuers, and additional force may be required to perform chest compression due to the obstruction of the device. This increases the fatigue of the rescuers, making it harder for them to provide effective CPR. Due to the feedback device generally providing indications of compression through indicator lights, it takes time for unfamiliar users to learn and understand, which may delay the time of on-site rescue. * _Limitations of Feedback Parameters_ Artificial chest compression audio-visual feedback devices primarily provide feedback on the quality of CPR, such as compression rate and depth. However, they do not assess the patient's physiological response to CPR, presenting a limitation in the scope of their feedback. * _Limited Contribution to Improving Chest Compression Quality_ The current audio-visual feedback devices on the market are only able to provide feedback on the depth and frequency of the compression, and some products can only provide feedback on the depth. During chest compression, body posture, hand placement, and compression position significantly influence the quality of cardiopulmonary resuscitation (CPR). However, the current audio-visual feedback devices lack the ability to comprehensively assess and provide guidance on these critical aspects. As a result, the effective utilization of such devices requires individuals who have undergone relevant training. Furthermore, these current audio-visual feedback devices are unable to provide personalized guidance based on the unique differences of individual patients.