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Mon Oct 8 13:04:29 BST 2007

  With all the work AHA has put into it, this seemed like a waste of money and potentially people. But this is where my questions come from. The reason I posted the questions is because if the concepts about delayed resuscitation are correct and it is the reoxygenation of the acidotic cell that trigers cell death in certain circumstances, that would make many current practices only valid if the cells have not reached that state. So in a witnessed arrest or a short down time, say in a hospital or when bystander cpr is initiated, it makes no difference. But in an out of hospital arrest where cpr is not performed, it might make a big difference. But if you are allowing more acid to build up waiting to defib, what is the point of delaying the defib? AHA says the heart may go into refractory vfib. But even without a delayed resus. mentality, if you contiinue to let anaerobic metabolism continue, because cpr is not halting it, aren't you just risking your electrical therapy not
 being effective?

  Personally I would think CPR until defib is a good idea, but suggesting to delay a defib seems like a poor idea to me.

  Apologies if this has already been posted in the past

Should Rescuers Give CPR Before Defib?

Barbara Turnbull
The Toronto Star

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.

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Joe Nemeth <joe.nemeth at mcgill.ca> wrote:

JOE IN CAPS...

Hello everyone,
>
> I posed a question about the topic of delayed resuscitation and
> oxygenation on the EMS-L list and hoped maybe somebody here could answer my
> questions.
>
> 1. Does effective CPR adequetly perfuse the body enough to stop/reverse
> anaerobic metabolism in the Brain/kidnetys/heart/liver?

NO....

>
> 2. What causes an apoptotic rxn when o2 is reindroduced? My only guess
> is a capsase chain in the mitochondria. Possibly from the others in the cell
> as well. By I lean towards mitochondria.

DON'T CARE...MAKES FOR GREAT CONVERSATION AT THE DINNER TABLE BUT...AT 
BEDSIDE DON'T CARE....
>
> 3. Would continued/exteded CPR prior to defib then be more harmful?

LIKE THE PRIOR POST...LATEST "EVIDENCE" IS TO "PUSH A LITTLE" PRIOR TO 
DEFIB AFTER UNWITNESSED ARREST...

JOE
MCgILL UNIVERSITY
MONTREAL

>
> I accept that immediate cpr, would perfuse enough heart and brain to
> stop acidosis there, but what about the liver especially?
>
> I ask because of a study that was recently announced about possibly
> delaying defib longer for more cpr. I am very skeptical about that. I know
> that refractory v-fib is likely from the AHA study if during prolonged
> downtime the heart is defibed without reoxgenation. But how does all this
> play out?

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cpr, this is the original post that prompted my questions about CPR