RE: bi phasic defib

["Tom Brazelton, MD, MPH" <brazeltoniii@facstaff.wisc.edu>]

Title: RE: bi phasic defib

I don't know if this will help the discussion but here's a copy of our state EMS-C recommendations for AED use from the AHA:

> November 28, 2001
>
> The American Heart Association's Emergency Cardiovascular Care
> Committee, Wisconsin Region, would like to make the following
> recommendation to the EMS for Children Committee, DHFS regarding
> pediatric defibrillation:
>
> Note:  If the child is 8 years old and 55 pounds or above,
> the AED should be used for VF if that is all that is available.
>
> 1. To try to limit the amount of myocardial
> damage that may occur from the use of higher energy levels EMS
> provider should consider modifying the amount of energy that is
> ultimately delivered to the patient.  When feasible EMS providers
> should program their AEDs to deliver 200 J initially followed by a
> second defibrillation of 200 J and the third defibrillation to deliver
> 300 J.  This modification should not delay time to
> defibrillation. ALS providers should continue to use defibrillators
> capable of appropriate energy adjustment and follow current AHA PALS
> guideline for resuscitation. To improve pediatric out-of-hospital
> care, EMS providers should be optimally trained and equipped to care
> for the pediatric patient.
> 2. As new equipment is purchased, EMS systems
> should be aware and take into consideration that research is ongoing
> in the pediatric defibrillation field and the AHA Pediatric Life
> Support Committee are ready to change their current recommendations
> when sufficient data exists to do so.
> 3. These recommendations are based on the
> following data and the current American Heart Association Position
> Statement:
>
> … Sudden
> cardiopulmonary arrest in infants and children is much less common
> than sudden cardiac arrest in adults.  The causes of cardiac
> arrest in infants and children are numerous and vary by age, and the
> underlying health of the child. Cardiac arrest is rarely a sudden
> event but rather a terminal event related to the progression of shock
> or respiratory failure.
>
> … Although VF is not a
> common arrhythmia in children it is not a rare occurrence. 
> Pediatric VF may be more prevalent than previously believed.  VF
> has been identified as the initial rhythm in as many as 20% of
> pediatric cardiac arrests.  The true incidence of this arrhythmia
> is unknown.  Until recently, pediatric patients often did not
> receive early rhythm identification.  The use of AEDs was limited
> in patients that were less than 12 years of age or weighing less than
> 90 pounds. EMTs were directed to perform basic life support with CPR
> until an ALS unit arrived or until the child was transported to an
> Emergency Department. This delay in identifying the initial rhythm at
> the onset of arrest may have masked the true prevalence of ventricular
> fibrillation (VF) in children.  We know from research that VF
> deteriorates over time.  From studies done in the adult
> population it has been shown that VF tends to convert to asystole
> within a few minutes.   We also know from studies done in
> adult cardiac arrest that survival rates after VF cardiac arrest
> decrease about 7% to 10% with every minute that defibrillation is
> delayed.
>
> … In several studies,
> pediatric patients with VF who receive defibrillation at the scene
> have a higher resuscitation rate, up to 38%, and are more likely to be
> discharged from the hospital with good neurological outcomes than
> pediatric patients who present in non-VF rhythms. Based on these facts
> it is imperative that EMS providers be able to identify and promptly
> treat life threatening ventricular arrhythmias.
>
> … One of the issues
> surrounding the use of AEDs in the pediatric population is: "What is
> the appropriate energy level to use for defibrillation?"  The
> answer is:  "We don't know". There is inadequate data to
> formulate a definitive answer.  Experiences with the use of AEDs
> in children are limited.    Currently available
> monophasic and biphasic AEDs deliver energy doses  (120-200 J)
> that exceed the recommended dose of 2 to 4 J/kg in children ages
> approximately 8 to 12 years of age. The initial delivered dose from
> these AEDs would correlate to less than 10 J/kg in this
> subpopulation.  Data from animal studies suggest that this may be
> a safe dose.
> … Current research
> confirms that biphasic shock energies <200 J appears to be safe and
> effective at lower energy doses in adults.  Biphasic waveforms
> require lower energy use in adults but there is inadequate data to
> recommend a biphasic energy dose for the treatment of VF in
> children.
> If references are needed please contact Terry Block
> at terry.block@heart.org.

Tom Brazelton, MD, MPH

Advisory Board, WI EMS-C

PICU, UW Children's

Madison, WI