By Barbara Turnbull
Toronto Star
Copyright 2007 The Toronto Star
ONTARIO, Canada — In the critical moments after a heart stops, should paddle-wielding rescuers shock fast? Or slow?
That’s the life-or-death question a new, North America-wide study of nearly 15,000 emergency patients will try to answer. Researchers are examining the benefits of defibrillating victims within 30 seconds of their collapse in cardiac arrest, versus first performing three minutes of cardiopulmonary resuscitation, or CPR, before the shock.
St. Michael’s Hospital is one of 43 Ontario hospitals participating in the $15-million undertaking that involves 11 major centres and their myriad emergency-care services.
The mind-boggling logistics involve the co-operation and extra training of about 36,000 emergency medical service workers who will administer one of four combinations of treatment, including the pre-defibrillation 30-second or three-minute CPR. As well, the medical workers will also use a new device designed to increase blood flow during CPR — or a placebo — in the research.
“Most of us who do this kind of research are very excited, because (we’ll be able to) answer questions we could never answer before,” says Dr. Paul Dorian, a cardiologist at St. Mike’s and one of the hospital’s key investigators for the study.
Up to 20,000 Canadians suffer cardiac arrests outside of hospitals each year. Only about 5 per cent survive; most die en route to the hospital.
Dorian cites the sheer numbers of study participants, both professionals and patients, as a key factor in the study’s success. Ottawa and Vancouver, as well as nine U.S. centres, have signed on to take part in ROC-PRIMED (Resuscitation Outcomes Consortium — Prehospital Resuscitation Using an Impedance Valve and Early Versus Delayed Analysis Trial).
In Ontario, scientists and physicians have joined with emergency workers in Peel Region, Muskoka District and Toronto to launch the trial — a world first.
The motivation for the study is straightforward and dramatic: elapsed time can be as critical as the treatment in saving someone who collapses with a suspected heart problem.
When 74-year-old Mississauga resident John MacLean collapsed during a Leafs-Penguins overtime game at the Air Canada Centre last March, the capacity crowd was silenced and play was halted. Fortunately for MacLean, a nurse sitting nearby leapt to his aid and started CPR. He was resuscitated and taken to hospital, where he underwent triple-bypass surgery.
Traditionally, medical personnel would try to shock a collapsed victim as quickly as possible, sometimes within 30 seconds.
“Now there is research that suggests maybe this isn’t the right thing, maybe you shouldn’t shock them right away; you should wait three minutes and be doing CPR,” Dorian says, indicating recent studies in Seattle and Norway.
“It turns out that when somebody has been unconscious for more than a couple of minutes and you shock their heart right away, the heart may not be ready to receive this electrical shock,” he says.
“The way to prime (the heart) is to do some minutes of CPR before you give the shock, so the heart ... will start to beat more effectively.
“But we don’t know which is right,” Dorian adds.
Small, targeted studies of longer, pre-paddle defibrillation have had surprising outcomes, showing better survival rates. The results have made the large and random effort of PRIMED more important.
All patients will continue to get the best care currently available, researchers promise. New EMS guidelines for cardiac arrest and CPR are already improving survival rates for victims which, after they were treated and released from Toronto hospitals, climbed to 5.6 per cent from 3.8 per cent — and to 19 per cent from 13 per cent for patients with an erratic or disorganized heart rhythm — in 2006 and 2007.
In addition to the pre-shock CPR, the study will test the new Impedance Threshold Device (ITD), which is attached to the face mask and breathing tube used for collapse victims, and increases the vacuum-like effect of CPR.
For the study, every paramedic will add a valve to the treatment of an emergency patient — half will be placebos. Also determined at random, half of collapse patients will be treated with the current 30 seconds of CPR and half will receive CPR for three minutes before defibrillation.
The treatments have been refined to cause no added risk to patients. Permission for participation in the study is acquired after the emergency treatment.
“Most of the time the sudden cardiac death is caused by a rapidly life-threatening cardiac rhythm called ventricular fibrillation,” Dorian explains. “It’s an electrical problem, if you will, that kills people.
“These are generally individuals who have a history of heart disease, but they don’t even know it ... Despite getting relatively prompt treatment, it is often that these individuals die anyway.”
Two years ago cardiologists, emergency doctors and doctors who work with paramedics conceived the Resuscitation Outcomes Consortium. It involves public safety agencies, regional hospitals, community health care institutions, medical centres and emergency medical support workers in the 11 locations.Peel Region was the first to get rolling in June, followed by Muskoka District. The rest of the GTA is to begin within the next three months. It was the high level of collaboration among emergency medical services in the GTA that made it first out of the starting gate, Dorian says.
“We are unbelievably lucky in Toronto, because the entire enterprise – from the paramedics, the firemen, the organization that runs the emergency medical, to the doctors (and researchers) who are involved – we have a fantastic culture of co-operation,” Dorian says.
Verena Jones, educator for Peel’s paramedics, says she was surprised at the passion for the project. “It shows their dedication and professionalism to their patients, and people in the region of Peel and the service itself,” she says, crediting Peel’s medical director, Dr. Sheldon Cheskes’ personal interest and individual feedback to the paramedics for part of the enthusiasm.
Since June, about 125 patients in Peel have been part of the study.
Expected to wrap up next year, the study is being funded by the Canadian Institutes of Health Research and the U.S. National Institutes of Health, along with other foundations in both countries.