Hospitals should audit the length of their cardiac arrest resucitations, doctors say. (Rafiq Maqbool/Associated Press)

Some people who suffer cardiac arrests in hospital might survive better if doctors and nurses gave longer resuscitations, a new study suggests.

It's estimated that between one and five of every 1,000 hospitalized patients in developed countries will have a cardiac arrest, but fewer than 20 per cent survive to leave hospital alive.

Researchers used data from what they call the world’s largest registry of cardiac arrests in hospital from the American Heart Association to compare the length of resuscitation efforts and survival for 64, 339 patients with cardiac arrests at 435 U.S. hospitals between 2000 and 2009.

The median resuscitation duration was 17 minutes, meaning half were longer and half were shorter, the researchers said in Wednesday's issue of the medical journal The Lancet. Overall, hospitals with the longest resuscitation durations had higher survival rates.

"We are unable to provide a specific cutoff from these data and are hesitant to speculate," Brahmajee Nallamothu from the Ann Arbor VA Medical Center and University of Michigan and his co-authors concluded.

"Clinical judgment will always be needed for this aspect of care, since the benefits of increasing the length of resuscitative measures should be balanced with the potential downside of futile care. Prolongation of resuscitation attempts by 10 or 15 minutes might have only slight effects on resources once efforts have already began, but could improve outcomes."

The researchers ranked the hospitals into five groups based on the median length of resuscitation attempts in non-survivors.

Times varied widely between hospitals.

But factors that couldn’t be measured, such as the quality of chest compressions, could make a difference, the researchers noted.

The findings might not be representative of all hospitals, since those in the study tended to be large, they added.

A journal commentary published with the study praised the researchers for using a large database and for taking variables into account that affect outcome after cardiac arrest, such as other medical conditions that the patients had, the time and location of the cardiac arrest.

Brain findings reassuring

The study's findings reassure clinicians that longer resuscitation attempts to do not seem to worsen neurological injury in survivors, British commentators Jerry Nolan from the Royal United Hospital NHS Trust in Bath and Jasmeet Soar from Southmead Hospital in Bristol said.

"To improve outcomes, all hospitals should audit their cardiac arrests and benchmark outcomes as part of a quality improvement program," Nolan and Soar suggested.

"Duration of resuscitation attempts should be established on a case-by-case basis."

Similarly, the Heart and Stroke Foundation of Canada said in an email that in hospitals, the decision to stop resuscitation efforts rests with the treating physician.

The Canadian foundation is part of an international group that lists several factors in making the decision including:

• Witnessed versus unwitnessed arrest.
• Time to CPR.
• Initial arrest rhythm.
• Time to defibrillation.

One of the study's authors received a grant from Medtronic, a medical technology company.