If your heart suddenly stopped, how long should rescue workers try to save you? Should you be taken to the hospital even if you can't be revived and are likely to die?
Canadian researchers say they've devised a test that helps rescue workers spot those futile cases and save a frantic trip to the hospital.
Some paramedics with advanced training — those who can give drugs and start IVs — already are allowed to stop giving CPR if their efforts fail and they have consulted a doctor, said lead researcher, Dr. Laurie J. Morrison of the University of Toronto.
But 60 percent of Americans and Canadians, mostly in rural areas, are served by rescue workers who only have basic skills and don't have that option, she said.
"Now they make no decisions whatsoever," Morrison said. "They just start the resuscitation, put them in the back of the ambulance and drive."
Taking such lost causes to the hospital ties up ambulances and emergency departments and the race to get there is hazardous for rescue workers and other motorists, researchers said.
The three-point test
Morrison said her group studied the issue after she was approached by two frustrated paramedics. The researchers reviewed old cases, devised a three-point rule, then tested it in urban and rural areas of Ontario. Their findings are in Thursday's New England Journal of Medicine.
Few people survive a cardiac arrest, which is caused by an abnormal heart rhythm and brought on by a heart attack or heart disease, electrocution, drowning or choking. The victim loses consciousness and stops breathing. More than 300,000 Americans die of cardiac arrest each year.
In the Canadian experiment, only 41 of 1,240 patients, or 3 percent, survived. All were given cardiopulmonary resuscitation at the scene, hooked up to a defibrillator to try to shock their hearts back into normal rhythm and taken to the hospital.
Later, the rescue workers filled out a form, applying the three-criteria test to each case to see if it would have signaled that CPR be stopped. Termination was advised if a pulse couldn't be restored, if the defibrillator determined that an electric shock shouldn't be given, and if the cardiac arrest wasn't witnessed by a rescue worker.
The researchers said the test closely predicted who was likely to die. Overall, 776 patients met the three criteria, and all except four died, a survival rate of 0.5 percent.
If the test were applied, it would reduce by about two-thirds the number of patients taken to the hospital, the researchers said.
When two more criteria were added — paramedic arrival time of more than 8 minutes and the attack wasn't witnessed by a bystander — the test worked even better.
Morrison said surveys suggest that families often accept the decision to stop CPR.
Dr. Gordon Ewy, of the University of Arizona College of Medicine, said the guidelines are needed but shouldn't replace medical judgment and won't necessarily apply in every case.
"They're transporting patients that have practically no chance of survival," said Ewy, who wrote an accompanying editorial. "I think that this publication is extremely important because it gives guidelines for that."
Revised CPR guidelines
The experiment was done before the American Heart Association revised its CPR guidelines last year, putting more emphasis on chest compression than mouth-to-mouth resuscitation. The researchers say the new CPR will likely help revive more people, but their guidelines would still identify those unlikely to survive.
Michael Perkins, director of the Coshocton County Emergency Medical Services in rural northeast Ohio, said there are certain circumstances where emergency medical technicians should be able to decide to stop CPR. He said his paramedics can make that call, but he said the majority of patients are still taken to the hospital.
"As a paramedic, myself included, if you make that commitment to start, you don't want to stop until you get to the hospital," said Perkins.