Improved survival with timely admin of mechanical CPR in out-of-hospital cardiac arrest
Early mechanical cardiopulmonary resuscitation (CPR) with a LUCAS 2 device administered by emergency ambulance crew in patients with out-of-hospital cardiac arrest (OHCA) resulted in improved survival compared with manual CPR, results from the MECCA* study showed.
In this prospective study, 14 ambulances were randomized to the mechanical CPR arm while 32 ambulances were allocated to the manual CPR arm. Participants were aged ≥21 years (n=1,191); 889 and 302 underwent manual and mechanical CPR, respectively.
The LUCAS 2 device was adjusted to continuously provide 100 compressions per minute, with ventilation delivered by crew at every tenth compression. Manual CPR was initially administered prior to insertion of device.
“The mechanical device takes the place of one person, freeing the ambulance staff of a pair of hands to perform other tasks,” said the researchers.
The primary outcome, return of spontaneous circulation (ROSC), was comparable between patients undergoing manual and mechanical CPR (29.2 percent vs 31.1 percent; odds ratio [OR], 1.09, 95 percent confidence interval, 0.82–1.45; p=0.537). [Singapore Med J 2017;58:424-431]
Findings were also comparable between manual and mechanical CPR in terms of 24-hour survival (11.2 percent vs 13.2 percent; OR, 1.20; p=0.352), survival to discharge (3.6 percent vs 4.3 percent; OR, 1.20; p=0.579), and 30-day survival (3.0 percent vs 4.0 percent; OR, 1.32; p=0.430).
In the as-treated population comprising 923 and 255 patients treated with manual and mechanical CPR, respectively, survival was higher among patients treated with mechanical compared with manual CPR (OR, 1.32; p=0.081).
Timing of mechanical CPR delivery also affected the findings with patients who received mechanical CPR early (within 5 minutes of collapse, n=206) having improved ROSC (36.9 percent vs 28.0 percent [manual CPR] and 24.5 percent [late mechanical CPR]), 24-hour survival (15.5, 10.6, and 8.2 percent, respectively), survival to discharge (5.8, 2.9, and 2.0 percent, respectively), and 30-day survival (5.8, 2.4, and 0 percent, respectively).
After adjusting for multiple variables, survival was greater among patients who received early mechanical CPR compared with manual CPR (OR, 1.47; p=0.026).
“These results indicate that, compared to the use of manual CPR only, the survival effect of the LUCAS CPR device was significantly greater when applied early, on-site, before the patient is moved into the ambulance, and within 5 minutes of starting resuscitation,” said the researchers.
“For OHCA, there is a need for a consistent level of good quality, early CPR with minimal interruptions until achievement of ROSC. Manual CPR in out-of-hospital and in-hospital environments is beset with many quality issues and frequent interruptions … [and] mechanical CPR devices were introduced to specifically address the various interruptions in provision of good quality manual CPR,” they said.
“[D]ue consideration should [also] be given to enable the ambulance team to carry the mechanical CPR device to the patient in every instance, so as to minimize delay in application. Future efforts to reduce the size and weight of mechanical CPR devices may allow for greater portability and earlier application,” said the researchers.
The researchers acknowledged study limitations such as the inability to standardize resuscitation protocols upon patient admission to hospital and lack of data on cerebral performance postresuscitation, and recommended that future studies investigate the impact conferred by efficient use of mechanical CPR devices in OHCA.
According to study author Professor V. Anantharaman, a senior consultant at the Department of Emergency Medicine, Singapore General Hospital, mechanical CPR is already frequently used among emergency crew in Singapore.
“[T]heir prompt use of mechanical CPR immediately after encountering cardiac arrest patients has contributed to improved survival rates in the country. However, one needs to bear in mind that not every patient with cardiac arrest will survive after application of a mechanical CPR device. Survival is dependent on many factors, only one of which is the early application of CPR,” he said.
“The use of the mechanical device will better ensure that the quality of CPR, if started early, will be consistent with the national prescribed standards. Other factors, such as public bystander CPR, calling the emergency ambulance  early within the first 1 to 3 minutes after collapse, early use of the automated external defibrillator [AED], and giving way to emergency ambulances and their crew will also help in improving survival outcomes,” he said.