Among all comers, the likelihood of survival was less than 10% after 10 minutes, less than 5% after 20 minutes, and less than 1% after 40+ minutes. The likelihood of survival with favorable neurologic outcome was even lower.

The findings stem from an analysis of data from the Get With The Guidelines–Resuscitation (GWTG-R) quality improvement program of the American Heart Association (AHA).

This study provides "new information and much more granular data" on duration of CPR and outcomes, "but it's not going to turn into a simple — 'this is the number of minutes we continue resuscitation for your father or for you,'" author Robert Berg, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, told theheart.org | Medscape Cardiology.

Matthew Tomey, MD, who wasn't involved in the study, said the findings are "consistent with knowledge that likelihood of favorable outcomes decays rapidly as resuscitation extends without return of spontaneous circulation. The data may be helpful for clinicians involved in hospital code teams to prognosticate and to counsel families."

Still, "the statistics derived from this large dataset should not, in my opinion, be used to generate bright lines or define hard stops for resuscitation," Tomey, assistant professor of medicine (cardiology), Icahn School of Medicine at Mount Sinai, New York City, told theheart.org | Medscape Cardiology. "To do so would be to reject the individuality and dignity of a person experiencing cardiac arrest."

The study was published online on February 7, 2024, in The BMJ.

Each year in the United States, roughly 300,000 adults suffer in-hospital cardiac arrest, with only about one quarter surviving to hospital discharge.

A previous observational study using the GWTG-R registry showed that duration of resuscitative efforts varies across hospitals, and patients at hospitals with longer CPR attempts are more apt to survive and be discharged than patients at hospitals with shorter attempt periods.

Yet, less is known about the duration of CPR and patient outcomes after in-hospital cardiac arrest. An expert panel took up this issue in 2020 but was unable to make recommendations on when to stop CPR for in-hospital cardiac arrest.

To help fill the knowledge gap, Berg and colleagues quantified the time-dependent probabilities of favorable outcomes as a function of duration of CPR on outcomes for 348,996 US adults (mean age, 67 years) who suffered in-hospital cardiac arrest between 2000 and 2021.

Roughly two thirds of the cohort (233,551 patients, 67%) achieved return of spontaneous circulation with a median interval of 7 minutes (interquartile range [IQR], 3-13) between start of chest compressions and first return of spontaneous circulation.

The remaining 115,445 patients (33%) did not achieve return of spontaneous circulation with a median interval of 20 minutes (IQR,14-30) between starting and stopping chest compressions.

Altogether, 8799 patients (23%) survived to hospital discharge.

At 1-minute CPR duration, the probabilities of survival and favorable functional outcome among patients were 22% and 15%, respectively. Favorable functional outcome was defined as a cerebral performance category score of 1 (good cerebral performance) or 2 (moderate cerebral disability).

But as duration of CPR increased, the probabilities of survival and favorable functional outcome decreased quickly and were < 1% at 39 minutes and at 32 minutes of CPR, respectively.

In terms of clinical features of in-hospital cardiac arrest, patients younger than 60 years with witnessed arrest and initial shockable rhythm would likely benefit from longer duration of CPR than those with older age, unwitnessed, and with initially non-shockable rhythm, the researchers reported.

"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 CPR," they wrote.

The data could have a "substantial impact on how people think about and operationalize time of duration of CPR for their specific patients," Berg told theheart.org | Medscape Cardiology.

The researchers acknowledged the difficulty in collecting time variables during CPR and said "the precision of the collected time variables is an important limitation." They also couldn't account for the severity of underlying pre-arrest comorbidities, which could have played a role in time to termination of resuscitation.

Tomey noted that "even with very brief resuscitation efforts, the absolute likelihood of a good outcome after in-hospital cardiac arrest is very low. This speaks, in part, to the severity of illness observed in patients who experience cardiac arrest in the hospital."

"It also serves to remind us that a key strategy to reduce in-hospital mortality associated with cardiac arrest is to avoid cardiac arrest in the first place. Early identification of vulnerability and clinical deterioration can create opportunities to disrupt the downward spirals that culminate in cardiac arrest," Tomey told theheart.org | Medscape Cardiology.

Support for the study was provided by the AHA, Society for Academic Emergency Medicine Foundation, and the National Heart, Lung, and Blood Institute of the National Institutes of Health. Berg and Tomey had no relevant conflicts of interest.