CPR can save lives, but its ability to restore heart function goes from slim to none in a shockingly short time, a new study finds.

How short? A person’s chance of surviving cardiac arrest while receiving CPR declines from 22% after one minute of chest compressions to less than 1% after 39 minutes of compressions, researchers report Feb. 7 in the BMJ.

Meanwhile, the chance of escaping major brain damage from cardiac arrest declines from 15% after one minute of CPR to less than 1% after 32 minutes with no re-established heartbeat.

These results could help guide the grim decision of when to stop applying CPR to a patient whose heart is not responding.

“The findings provide resuscitation teams, patients and their surrogates with insights into the likelihood of favorable outcomes if patients pending the first return of spontaneous circulation continue to receive further cardiopulmonary resuscitation,” concluded the study led by Dr. Masashi Okubo, a clinical assistant professor of emergency medicine at the University of Pittsburgh.

About 300,000 cardiac arrests happen in a hospital every year, researchers noted, and about 25% of those patients survive to hospital discharge.

In the study, Okubo’s team measured CPR duration for nearly 350,000 U.S. adults who had an in-hospital cardiac arrest between 2000 and 2021, using the largest dataset of such cases available in the world.

They found that two-thirds of patients (67%) responded to CPR within an average of seven minutes, while 33% failed to re-establish a heartbeat after an average 20 minutes of CPR.

Overall, about 23% of cardiac arrest patients survived to hospital discharge in this study.

“Most termination of resuscitation occurred before the time point of traditional medical futility,” or the point at which survival odds are less than 1%, the researchers noted in a journal news release. 

“Further research is needed to evaluate whether patients’ outcomes would improve with prolonged cardiopulmonary resuscitation before termination of resuscitation,” the team continued.

They proposed a future clinical trial in which one group of patients receives CPR for as long as their doctors deem necessary, while a second group receives CPR for a predetermined — and likely longer — amount of time.

More information

The American Heart Association has more about CPR.

SOURCE: BMJ, news release, Feb. 7, 2024

Source: HealthDay