When cardiac arrest occurs, conventional chest compression may enhance the blood flow to provide sufficient oxygen to vital organs. Various methods, such as the external cardiac compressor Zoll Auto-pulse and LUCAS chest compression system, have been applied to improve the efficiency and success rate. Unfortunately, several studies evaluated the success rate and prognosis between LUCAS and manual CPR but found that there was no meaningful difference between the two groups[14–16]. In addition, chest compression cannot be effectively applied under some circumstances, such as chest wall deformity, rib fracture, or hemopneumothorax.
Abdominal compression-decompression cardiopulmonary resuscitation was invented as an alternative compression method to augment blood return and cardiac output. This new method could do help in building circulatory and respiratory support and be used in cardiac arrest patients with sternum and thoracic rib fracture. However, little is known about whether patients with OHCA could benefit from combined chest compression with abdominal compression-decompression during CPR duration.
In the present study, we aimed to investigate the benefit of combining conventional chest compression and abdominal compression-decompression CPR for adult out-of-hospital cardiac arrest patients. The outcome of ROSC rates and survival to hospital admission rates of this randomized trial in 278 patients with an out-of-hospital cardiac arrest did not result in a statistical significance between the two groups. However, we found that patients receiving the combination method in CO-CPR had higher survival to hospital discharge rates, better neurological outcomes at discharge according to the CPC status, significant survival benefits compared with those receiving chest compression in STD-CPR.
In most cases of primary cardiopulmonary arrest, blood still contains some oxygen during the early period. Conventional chest compression cardiopulmonary resuscitation is based on using a "thoracic pump," this is accomplished by compressing the mid-sternum, which increases the pressure inside the thorax, and blood is pumped out of the heart to the peripheral tissues including the brain[12, 17]. In comparison, the abdominal compression-decompression technique is based on an "abdominal pump," model, which induces pressure changes within the abdominal cavity and promotes the return of blood from the abdominal cavity to fill the heart and be eventually pumped to the brain[18, 19]. A combination of abdominal compression-decompression and chest compression was previously shown to increase the venous refilling of the heart, which could generate an increased coronary perfusion pressure and an increase in the blood flow to vital organs[10, 20, 21]. In myocardial blood flow, a better 48-hour outcome was documented with the combination method compared with standard CPR[22–25]. Hans-Richard Arntz et al. reported that the Lifestick device could perform both abdominal compression-decompression and chest compression, improve the results of CPR, and reduce the rate of injury compared to conventional resuscitation. This finding suggests that patients may benefit from the combination of both chest compression and abdominal compression-decompression techniques. However, studies that compare the results and the use of different devices from different institutions might have heterogeneous results, and the results of these types of studies might have limited applicability. In our study, the combination of the two CPR methods improved the survival rates and the neurological outcomes at discharge, and there was a survival benefit at follow-up, which confirmed Hans-Richard Arntz et al.'s observations. However, the device in our study was smaller in volume, more straightforward in operation, and more accurate in the operating parameters.
A significant advantage in using the new device for the combination of conventional chest compression and abdominal compression-decompression was that the instrument is small, lightweight, and easy to operate and could be suitable for hospital and non-hospital use in a variety of settings, including medical, sanitation, ambulance, rescue, and health care institutions at all levels inside and outside of the hospital.
This study has several limitations. The study was performed at a single center; one limitation of the study may be the relatively small number of subjects. Due to the limited sample size, most cases of cardiac arrest occurred among older patients. Autopsies were not performed in non-survivors; therefore, we were not able to determine whether the abdominal compression-decompression technique resulted in abdominal injuries in this study. And the CO-CPR method requires one more rescuer than for STD-CPR.