Use of Mechanical CPR for Cardiac Arrest
November 2023
Author: Reena Sheth, MD PGY3
Peer Reviewers: Shriman Balasubramanian, DO PGY-3
Faculty Editor: Adam Blumenberg, MD, Assistant Professor of Emergency Medicine at Columbia University Medical Center
The authors of this article have no industry relationships or conflicts of interest to disclose.
Case 1:
A 55-year-old man with CAD calls 911 from home for chest pain. A 12-lead ECG by EMS confirms an anterior STEMI. En route to the hospital, the patient goes into V-fib arrest, and ACLS is initiated immediately.
On arrival to the ED, chest compressions are continued using the LUCAS, which allows for the medical team to focus on other tasks. The patient remains in refractory V-fib, so the ECMO team is activated and the patient is successfully cannulated onto VA-ECMO while receiving automated chest compressions and transported to the cath lab.
He is discharged home after 2 weeks with a favorable neurologic outcome.
Case 2:
A 63-year-old woman with a history of ESRD codes while boarding in the ED. She is in PEA arrest. Your team consists of yourself, 2 nurses, and an ER tech.
One of the nurses tries to place the LUCAS but is having trouble with the attachments, leading to a considerable pause in chest compressions. The other nurse tries to help, leading to a delay in epinephrine administration.
Once placed, you note that the piston is malpositioned, and is compressing the epigastric region. While you attempt to intubate, gastric contents fill the airway. There is further delay of chest compressions while the device is repositioned.
The patient’s end-tidal CO2 never rises above 15. Despite maximal medical therapy, there is no return of spontaneous circulation after 30 minutes and the patient is pronounced deceased.
Background
Amongst all the advancements in resuscitation over the past decade, one thing has not changed–the importance of early, high quality, uninterrupted chest compressions in cardiac arrest continues to be a core predictor of survival and meaningful neurologic outcome. Conventional CPR, however, is not without its challenges–there is variation in quality of compressions between providers, and practical matters such as provider fatigue, limited staffing, and limited physical space can pose obstacles to delivering high-quality compressions.
Mechanical CPR (mCPR) devices provide an appealing potential solution to many of these pitfalls–it seems intuitive that an automated device should be better able to provide consistent, uninterrupted chest compressions for prolonged periods of time, which should theoretically lead to better outcomes. However the literature does not support this theory, and moreover, many ED clinicians have likely encountered scenarios like Case 2 above, where the mCPR device seems to do everything but high-quality chest compressions. This article will review some of the literature surrounding mCPR use and its efficacy, safety, and impact on patient-centered outcomes.
Types of mCPR Devices
There are two main types of mCPR devices available: the automated piston device (i.e. Stryker Physio-Control LUCAS) and load-distributing band devices (i.e. Zoll AutoPulse). These devices are commonly used for out-of-hospital cardiac arrest (OHCA) by EMS personnel, and are increasingly being used in Emergency Departments as well. The LUCAS does not have a weight limit, but the patient’s body habitus must allow for the device to lock into place. The AutoPulse has a maximum weight allowance of 136 kg. mCPR devices cost between $10,000-20,000, not including costs for upkeep and training5,11.
Table 1. Comparison of the most common commercially available mCPR devices in the United States.
Figure 1. Left) LUCAS chest compression system (image from lucas-cpr.com); Right) AutoPulse resuscitation system (image from zoll.com)
What does the literature say?
There are several RCTs that have compared mCPR to conventional CPR. The majority of studies are for out-of-hospital cardiac arrest (OHCA), while the data for ED or in-hospital cardiac arrest (IHCA) is considerably more sparse.
The LINC trial published in JAMA in 20148 was a multicenter RCT with 2589 OHCA patients comparing outcomes between manual CPR and mCPR using the LUCAS. Despite improved flow fractions with mCPR, there was no significant difference in survival with favorable neurological outcome (CPC score 1 or 2) at 4 hours and 6 months. The CIRC trial, published in Resuscitation in 201410 was a RCT with 4753 OHCA patients comparing manual CPR and mCPR using the Zoll AutoPulse, and demonstrated no significant difference in survival to hospital discharge. The LINC and CIRC trials were both industry-sponsored.
The PARAMEDIC trial7 was a non-industry-sponsored RCT consisting of 4471 patients with OHCA comparing the LUCAS to manual compressions, and similarly did not show 30-day survival benefit of mCPR. Subsequent meta-analyses1,9 have reinforced this conclusion.
For IHCA, high-quality literature is limited. The most recent randomized controlled trial, COMPRESS-RCT (2021)2 (not industry sponsored), was a UK-based study that randomized 127 patients with IHCA with a non-shockable rhythm to compare mCPR with a LUCAS device to manual CPR. There was no significant difference in ROSC, survival to hospital discharge, and survival with favorable neurological outcome between the two groups. This trial was limited by a relatively small study cohort and very low survival rates in both arms of the trial. Of note, this was a feasibility study and the primary goal was to determine if a larger IHCA RCT would be possible in the future, not to assess efficacy of mCPR.
With regards to safety, several trials have demonstrated increased risk of thoracic injury while using mechanical compression devices, such as rib/ sternal fracture, hematoma, or pneumothorax. Koster et al4 and Khan et al3 both found higher risk of injury with use of the AutoPulse when compared to the LUCAS and to conventional CPR.
Interestingly, quantified time to deployment and pauses associated with device placement is not consistently reported in much of the literature comparing mCPR to conventional CPR, even though time to intervention is frequently cited as a potential explanation for the absence of mortality benefit with use of mCPR devices. In the COMPRESS-RCT trial, median time from CPR start to deployment was 11 minutes, with a mean pause of 7.43 seconds for back plate placement and a 9.83 second pause for placement of the upper part of the device. These pauses were non-consecutive, and the study had specifically trained teams with a pit-stop approach for assembling the device to minimize gaps in compressions. A sub-10 second pause seems acceptable, but lack of appropriately-trained personnel may substantially affect the duration of these interruptions. Bonnes et al. found a correlation between earlier device deployment and improved outcomes.
Bottom Line
The bottom line is that despite the perceived benefits, the literature suggests that there is no associated improvement in survival with mCPR use, particularly for OHCA. More data is needed in the in-hospital setting.
Pauses in compressions associated with device placement or troubleshooting may be a plausible explanation for the absence of survival benefit– thus highlighting the importance of appropriate training for medical personnel utilizing these devices. As a modifiable factor, focusing quality improvement efforts in this area has potential for significant impact. Another potential downside is that some devices, particularly the AutoPulse, may be more prone to causing thoracoabdominal injury. There are also operational issues that can affect use of the device, as they need general upkeep, cleaning, charged batteries, etc.
In some scenarios (pre-hospital, limited physical space, low-staff settings) mCPR may be useful, and it may also potentially facilitate more definitive interventions, such as ECPR or PCI.
The decision to utilize conventional versus mechanical CPR should be made on a case-by-case basis depending on patient characteristics, staffing, resources, and anticipated hospital course. The potential for equipment malfunction, malpositioning, or delays while placing the device should be taken into account.
References
Bonnes JL, Brouwer MA, Navarese EP, et al. Manual Cardiopulmonary Resuscitation Versus CPR Including a Mechanical Chest Compression Device in Out-of-Hospital Cardiac Arrest: A Comprehensive Meta-analysis From Randomized and Observational Studies. Ann Emerg Med. 2016;67(3):349-360.e3. https://pubmed.ncbi.nlm.nih.gov/26607332/
Couper K, Quinn T, Booth K, et al. Mechanical versus manual chest compressions in the treatment of in-hospital cardiac arrest patients in a non-shockable rhythm: A multi-centre feasibility randomised controlled trial (COMPRESS-RCT). Resuscitation. 2021;158:228-235. https://pubmed.ncbi.nlm.nih.gov/33038438/
Khan SU, Lone AN, Talluri S, Khan MZ, Khan MU, Kaluski E. Efficacy and safety of mechanical versus manual compression in cardiac arrest - A Bayesian network meta-analysis. Resuscitation. 2018;130:182-188. https://pubmed.ncbi.nlm.nih.gov/29746986/
Koster RW, Beenen LF, van der Boom EB, et al. Safety of mechanical chest compression devices AutoPulse and LUCAS in cardiac arrest: a randomized clinical trial for non-inferiority. Eur Heart J. 2017;38(40):3006-3013. https://pubmed.ncbi.nlm.nih.gov/29088439/
LUCAS Chest Compression System. Product Specifications. Accessed November 1, 2023. https://www.lucas-cpr.com/product_specifications/
Mitchell OJL, Shi X, Abella BS, Girotra S. Mechanical Cardiopulmonary Resuscitation During In-Hospital Cardiac Arrest. J Am Heart Assoc. 2023;12(7):e027726. https://www.ahajournals.org/doi/10.1161/JAHA.122.027726
Perkins GD, Lall R, Quinn T, et al. Mechanical versus manual chest compression for out-of-hospital cardiac arrest (PARAMEDIC): a pragmatic, cluster randomised controlled trial. Lancet. 2015;385(9972):947-955. https://pubmed.ncbi.nlm.nih.gov/25467566/
Rubertsson S, Lindgren E, Smekal D, et al. Mechanical chest compressions and simultaneous defibrillation vs conventional cardiopulmonary resuscitation in out-of-hospital cardiac arrest: the LINC randomized trial. JAMA. 2014;311(1):53-61. https://jamanetwork.com/journals/jama/fullarticle/1774037
Wang PL, Brooks SC. Mechanical versus manual chest compressions for cardiac arrest. Cochrane Database Syst Rev. 2018;8(8):CD007260. https://pubmed.ncbi.nlm.nih.gov/30125048/
Wik L, Olsen JA, Persse D, et al. Manual vs. integrated automatic load-distributing band CPR with equal survival after out of hospital cardiac arrest. The randomized CIRC trial [published correction appears in Resuscitation. 2014 Sep;85(9):1306]. Resuscitation. 2014;85(6):741-748. https://pubmed.ncbi.nlm.nih.gov/24642406/
Zoll. AutoPulse Resuscitation System. Accessed November 1, 2023. https://www.zoll.com/products/automated-cpr/autopulse-for-ems
