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

[trauma at emergencyunit.com]

A lot of work is currently being undertaken into CPR, ventilation and
defibrillation, some by my group. 

There are several things coming out. Firstly, it is pointless electrocuting
a heart that can't make any sort of mechanical twitch. As time passes after
cardiac arrest, the heart gradually fills with blood - until it completely
fills the pericardium. Hence a shock early, when the heart can respond, is
likely to defibrillate. However, once the heart has lost its ability to
react mechanically (visible as fine VF) the chances of defibrillation are
very slim. See Leonard Cobb JAMA 1999;281: 1102-8, which seems to address
the issue in the original posting) What we now know is that the heart needs
CPR to empty it. We are piloting Protocol C, where paramedics give 100
compressions in an unwitnessed arrest before shocking (if shockable,
obviously). They then immediately give another 100 compressions. This
decompresses the heart and provides MUCH better organ perfusion. (see Berg
et al. Circulation 2001; 104: 2465) We only have preliminary data, but in
2003 we had 2 walk out of hospital after prehospital cardiac arrest and last
year we had around 17.

Cooling is important, mechanical chest compressors (LUCAS and Autopulse) are
coming in fast (although we need to understand their effect on ventilation)
and some of the new work I can't tell you about on fast Fourier analysis of
the ECG waveform may be even more useful.

BFM

-----Original Message-----
From: trauma-list-bounces at trauma.org [mailto:trauma-list-bounces at trauma.org]
On Behalf Of Mike Smertka
Sent: 08 October 2007 13:04
To: Trauma &amp, Critical Care mailing list
Subject: Re: cpr,this is the original post that prompted my questions about
CPR


 
   
  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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