September 3, 2013

Mechanical Chest Compressions As Effective As CPR

April Flowers for redOrbit.com - Your Universe Online

A new study from Uppsala University and the European Society of Cardiology (ESC) shows that mechanical chest compressions are as equally effective as manual CPR. The LINC study, published in the journal Resuscitation, included 2,589 patients from six European sites who had suffered an out-of-hospital cardiac arrest and needed resuscitation.

"The study was designed to show a better 4-hour survival in the group treated with mechanical chest compressions, and this was not achieved," said lead investigator Sten Rubertsson, MD, PhD, professor and specialist consultant at Uppsala University and Uppsala University Hospital.

"But we now have the scientific support to allow us to use mechanical chest compressions and defibrillate during ongoing compressions," he said. Rubertsson added that this could possibly increase the efficiency and safety of emergency personnel delivering care during medical transport of patients.

For all patients in the study, manual chest compressions were started as soon as EMS personnel arrived on the scene, then they were randomized to either be kept on manual chest compressions (n=1289) or be switched to mechanical compressions with defibrillation during ongoing chest compressions (n=1300). EMS personnel used the LUCAS Chest Compression System - a piston-driven device with a suction cup designed to deliver compressions according to resuscitation guidelines.

Ventilation and drug therapies were given to both groups according to guidelines. Four hours after the initiation of CPR, the results show that survival rates were similar in both the mechanical (23.6 percent) and manual CPR groups (23.7 percent).

The researchers found that later outcomes were also similar. These outcomes included the rate of restoration of spontaneous circulation (ROSC), the number of patients who arrived at the emergency room with a palpable pulse, the number of patients who survived until discharge from intensive care, and neurological outcomes at one and six months.

According to prevailing theory, mechanical chest compressions should have an advantage over manual because manual chest compressions often have insufficient depth, incorrect rate and frequent interruptions.

"The efficacy of traditional manual chest compression is heavily dependent on the skills and endurance of rescuers, and is compromised by periods of hands-off time and transportation interruptions," explained Dr. Rubertsson. Even at high efficiency it delivers only approximately 30 percent of normal cardiac output, resulting in decreased blood flow to vital organs."

To date, however, there is no definitive evidence from large randomized trials to show that mechanical chest compressions have improved CPR.

Mechanical chest compressions have been compared with mechanical compressions from the LUCAS device in two previous pilot studies of out-of-hospital cardiac arrest patients. Neither study found any significant difference between the two groups of patients. The study populations were small, however, which limited the effectiveness of the results.

The Uppsala study results suggest clinical equipoise, although slight adjustments to the treatment algorithms might result in clinically significant differences in the future, according to Rubertsson.

"With the algorithm we used for mechanical CPR we found that time to first defibrillation was delayed compared to manual CPR and this could explain why we were not able to show improved outcome. Therefore in the future we will recommend defibrillation without delay, before deployment of the device."

Regarding safety, Rubertsson said, "I would say that we can deem the device is safe, based upon the low number of severe adverse events and adverse events reported in the study.”

"Survivors at 6 months had good neurologic outcome (99 percent in the mechanical group and 94 percent in the manual) and in a previously published pilot study of 85 patients we did not find any difference between groups in injuries at autopsy. What remains to be finally analyzed is the cohort of 200 patients within LINC that underwent autopsy."

The findings, showing equal efficacy for both manual and mechanical compressions, are an added benefit to Emergency Medical Systems (EMS) workers.

"EMS workers can now use a device to provide CPR which means they have an extra pair of hands available for other possible interventions," said Dr. Rubertsson. "Safety during transportation in the ambulance can also be improved since now the crew can have safety belts and still provide CPR."

Rubertsson cautioned that the results are only applicable to the LUCAS machine and should not be extrapolated to other mechanical chest compressors.