An optimal closed-loop control strategy for mechanical chest compression devices: A trade-off between the risk of chest injury and the benefit of enhanced blood flow

OBJECTIVES The widespread application of chest compression (CC) as a first aid measure inevitably has the potential for both harm and benefit. The present study was therefore undertaken to design an optimal CC closed-loop control strategy (OCCCS) for mechanical CC devices that will present an effective trade-off between the risk of chest injury and the benefit of blood flow during CPR. Additionally, to evaluate the CC performance of the OCCCS, the differences between the OCCCS and the traditional mechanical CC method (TMCM) of performing standard CC were explored. METHODS Using the computer simulation technique, partial pressure of end-tidal CO₂ (PETCO2) and human chest stiffness are simulated based on the Babbs' model in present study. PETCO2 was regarded as a benefit factor (BF), which was divided into 3 levels, while chest stiffness was regarded as a risk factor (RF), which was divided into 4 levels. A benefit versus risk index (BRI) was also constructed for the comprehensive evaluation of risk and benefit. An OCCCS was developed with the combination of the BF, RF, BRI and fuzzy control strategy. A comparison between the OCCCS and TMCM was then performed based on computer simulations. RESULTS The OCCCS obtained a greater BRI and a better trade-off between risk and benefit than the TMCM in 6 out of a total 9 cases, and the OCCCS also resulted in a significantly improved cardiac output (CO) and PETCO2 in 6 of the 9 cases. The mean BRI, CO and PETCO2 resulting from the OCCCS were 5.69, 1.45 L/min and 15.51 mmHg, respectively, while the mean BRI, CO and PETCO2 resulting from TMCM were 4.76, 1.18 L/min and 13.26 mmHg, respectively. CONCLUSIONS The OCCCS can provide safer and more effective CC during cardiopulmonary resuscitation (CPR) compared to the TMCM, and has great potential in the future mechanical CC device development.