Circulation: Out-of-hospital cardiac arrest survival rates similar after standard CPR or chest compr
A simpler version of bystander-delivered cardiopulmonary resuscitation (CPR) that skips mouth-to-mouth resuscitation may be just as effective for out-of-hospital cardiac arrest victims as standard CPR, according to two studies published online on Dec. 18 in Circulation: Journal of the American Heart Association.

“If you hesitate to do CPR, remember that chest compressions only is better than doing nothing,” said Katarina Bohm, RN, whose 15-year retrospective study of 11,275 out-of-hospital cardiac arrests, compiled in the Swedish Cardiac Arrest Register, found similar one-month survival from standard CPR (St-CPR) which includes mouth-to-mouth resuscitation and chest compressions and the simpler version, which uses only chest compressions (CC-CPR). She and colleagues conducted the research at Prehospital Center, department of cardiology in Stockholm, Sweden.

In a separate five-year prospective cohort study in Japan’s Osaka district researchers analyzed 4,902 witnessed cardiac arrests. They found higher one-year survival with favorable neurological outcome when bystanders provided either the simpler version of CC-CPR or St-CPR compared to no CPR when emergency medical personnel arrived within 15 minutes to provide additional treatment.

The Japanese study also suggested that CC-CPR may be superior to St-CPR when provided within five minutes of cardiac arrest, and rescue breathing may be of some help for very prolonged cardiac arrests. The study was the first investigation of CPR methods in which time frame was a central hypothesis, said Taku Iwami, MD, PhD, an assistant professor at Kyoto University Health Service.

The patients in Bohm’s retrospective study experienced out-of-hospital cardiac arrest from a variety of causes, including heart rhythm disturbances and drowning, from 1990 through 2005. Of the patients, 73 percent (8,209) received St-CPR and 10 percent (1,145) received CC-CPR from bystanders. Survival among the St-CPR group was 7.2 percent compared to 6.7 percent for CC-CPR cases—a statistically insignificant difference, Bohm said. The outcome from each method remained similar even after researchers adjusted for differences between the two groups at baseline, such as age and gender, and for differences in ambulance arrival time.

In Bohm’s study, 1,921 patients (17 percent of the total) had received only mouth-to-mouth resuscitation, without any chest compressions. Although excluded from the comparison of St-CPR and CC-CPR, that group had the lowest one-month survival (4.5 percent), the researchers said.

Both studies sought to address the poor overall survival from out-of-hospital cardiac arrest, and the need to improve the chain of survival.

In the Osaka study of 4,902 witnessed cardiac arrests in which cardiac problems were thought to be the cause, 783 patients received St-CPR and 544 received CC-CPR.

“For cases in which CPR was needed for less than 15 minutes, one-year survival with favorable neurological outcome was virtually the same: 4.3 percent (19/ 441) for the simpler CC-CPR, and 4.1 percent (25/617) for St-CPR, which is significantly higher than that in cases who received no CPR (2.1 percent),” Iwami said. “The difference between the two methods fell short of statistical significance, but CC-only CPR had better outcomes than no CPR.”

For cases in which CPR was needed for more than 16 minutes, one-year survival with favorable neurological outcome was very poor irrespective of type of CPR: 0 percent (0/92) for the simpler CC-CPR, 2.2 percent (3/139) for St-CPR, and 0.3 percent (2/624) for no bystander  CPR. Although mouth-to-mouth resuscitation may be of some help for very prolonged cardiac arrests, the data show that there are few victims who actually received the benefit of bystander started mouth-to-mouth resuscitation, he said.

One of the limitations of the Japanese study is the lack of data on the quality of chest compressions—its force, rate and continuity without interruption.

“Currently, the rate of bystander CPR remains low, perhaps because conventional CPR requires that bystanders perform a complicated task in an emotionally intense situation.  CC-CPR is a much simpler technique that is easier to teach, learn, remember and perform. It is impressive that over 40 percent bystanders chose to perform cardiac-only resuscitation despite no training programs for cardiac-only resuscitation,” Iwami said.

The Swedish Heart and Lung Foundation and Stockholm County Council funded Bohm’s study. Iwami’s study was supported by a grant from the Japanese Ministry of Education, Science, Sports and Culture and the Ministry of Health, Labor and Welfare.