LINC: Similar Outcomes With Mechanical and Manual CPR

September 01, 2013

AMSTERDAM — Mechanical chest compressions with the LUCAS device (Physio-Control/Jolife) was as effective as but not more effective than manual compressions for delivering cardiopulmonary resuscitation (CPR) to patients in cardiac arrest in the LINC study.

Presenting the results here at the European Society of Cardiology (ESC) 2013 Congress today, Dr Sten Rubertsson (Uppsala University Hospital, Sweden) reported that the primary end point of four-hour survival was practically identical in the two groups. "While on one hand, I am disappointed that the mechanical device was not better than manual compressions, on the other hand, the fact that it was equally effective and showed no safety concerns means we now have scientific data to support its use," he commented to heartwire .

He explained that there was always a risk with treatments for cardiac arrest that they may improve survival with bad neurological outcomes, but that was not the case in this study. "There was only one patient out of 111 treated with the mechanical device who was left with a bad neurological outcome (clinical performance category [CPC] score of 3 or 4) compared with six of 104 patients given manual compressions. While this result was not statistically significant, as a statistician you look at the results one way, but as a clinician you interpret what you see," Rubertsson said.

He still sees a future for the device, saying it is particularly useful when prolonged CPR is needed, such as when a long journey to the hospital is necessary or if the patient is taken to the cath lab. "It is difficult to do CPR properly during transportation and when procedures are ongoing in the cath lab. The device makes it much easier," he added. He also pointed out that unlike the situation with manual compressions, the device allows compressions to continue when defibrillation is given.

Useful for Certain Subgroups

Discussant of the trial, Dr Patrick Goldstein (University Hospital of Lille, France), said that despite the neutral end points, the trial was positive for many reasons. "We know how difficult it is to perform a randomized study in a prehospital setting, and the investigators must be congratulated for achieving this.

"In addition, they showed good neurological outcomes in both groups--around 7.5% to 8.5% at six months. If we go back just five years these figures would not be over 3%. So we can see what improvements have been made in the field."

Goldstein said the neutral results suggested that mechanical compression would not be used routinely at present but may be useful in certain subgroups such as those with very long transport times, for non-heart-beating donors, and for patients on extracorporeal membrane oxygenation therapy.

The LINC study included 2589 patients from six European sites who had suffered an out-of-hospital cardiac arrest. Manual chest compressions were started on all patients as soon as paramedics arrived on the scene. Patients were then randomized to be kept on manual chest compressions (n=1289) or be switched to mechanical compressions with defibrillation during ongoing chest compressions (n=1300). In both groups, ventilation and drugs were given according to guidelines.

Results showed that four hours after the start of CPR, survival rates were similar in both groups. Later outcomes were also similar, including 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.

LINC Results

Outcome Mechanical compressions (%) Manual compressions (%)
4-h survival (primary end point) 23.6 23.7
ICU discharge 7.5 6.4
Hospital discharge 8.3 7.8
Good neurological outcome (CPC 1-2) at 1 mo 8.1 7.3
Good neurological outcome (CPC 1-2) at 6 mo 8.5 7.6

CPC=clinical performance category

Rubertsson noted that manual chest compressions often have insufficient depth, incorrect rate, and frequent interruptions, and even when done by experts deliver only approximately 30% of normal cardiac output, resulting in decreased blood flow to vital organs. "Mechanical compressions should theoretically improve CPR, but there is no definitive evidence from large randomized trials to show this."

He suggested that slight adjustments to the treatment algorithms might result in clinically significant differences in the future. "With the algorithm we used for mechanical CPR, we found that time to first defibrillation was delayed compared with 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."

Rubertsson noted that the LUCAS device is one of two mechanical compression devices available in Europe, the other one being Autopulse (Zoll). The LUCAS system is a piston-driven device with a suction cup designed to deliver compressions according to resuscitation guidelines.

Rubertsson believes that in future the CPR process will become more individualized than it is at present. "At the moment, it is recommended that everyone receives defibrillation every two minutes. But it would be preferable to use ECG patterns to identify the optimal time to defibrillate. That will be much easier to do if the patient is receiving mechanical compressions."

The LINC study was sponsored by Physio-Control/Jolife. Rubertsson has received consultation fees from Physio-Control/Jolife.

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