Summary Of Studies Of Waveform Safety & Effectiveness - Welch Allyn AED 10 User Manual

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Summary Of Studies Of Waveform Safety & Effectiveness
Introduction
Over 30 years ago, Medical Research Laboratories (MRL) patented a unique monophasic
truncated exponential waveform, which utilized a low peak current, impedance
compensated defibrillation waveform. The MRL monophasic waveform was developed as
an alternative to the monophasic damped sine (MDS) waveform (often referred to as the
Edmark waveform) defibrillator, which was associated with higher peak currents and did
not actively compensate for varying patient impedances. In fact, the MRL monophasic
waveform defibrillator delivers less than half of the peak current of an MDS waveform
defibrillator at equal delivered energies. A new defibrillator (the Welch Allyn AED 10) has
been introduced, which offers a biphasic truncated exponential waveform that
incorporates MRL's original low peak current, impedance compensation design. The MRL
Orbital™ biphasic truncated exponential waveform has been extensively tested in multiple
scientific safety and effectiveness studies. Over 524 fibrillation/defibrillation shock
episodes have been conducted using the MRL Orbital Biphasic waveform comparing it to
MDS, MTS and another commercially available 2kV biphasic (360 J capable) defibrillators.
Results of three of the scientific safety and effectiveness studies are summarized below.
Study 1
Objective
To evaluate the MRL Orbital Biphasic waveform defibrillator against a monophasic
damped sinusoidal waveform defibrillator.
Methods
A canine model (n=5, 71±7 lbs) was used in a study that was approved by the Institutional
Animal Care and Use Committee. The animals were anesthetized with 20 mpk sodium
pentothal i.v., and maintained as required through an intravenous catheter in the foreleg.
The external jugular vein was cannulated and a bipolar pacing catheter was introduced
under fluoroscopic control and advanced into the right ventricle. The femoral artery was
cannulated and an intra-arterial line was placed for continuous measurement of arterial
blood pressure. The chest was shaved and defibrillating patch electrodes (R2 part number
3200-1715) were placed on the left and right chest walls.
Fibrillation was induced by delivering 60 Hz current to the right ventricular electrode. The
energy required to defibrillate was determined by a protocol that has been used in several
other biphasic comparison studies. An initial shock strength of 50 to 70 joules was used. If
successful, VF is reinduced after a 4-minute rest period, and the shock strength is
reduced by approximately 20% for the next defibrillation attempt. If the initial shock fails, a
rescue shock is delivered, and after a rest period, VF is again induced. The energy is now
increased about 20% for the next defibrillation attempt. This procedure was continued
until at least 3 reversals in result were observed with each waveform. Two ED50
estimation procedures were run in parallel, with the device being used alternated on each
shock. In practice, actual clinical units were used, so the energy steps were limited to
those selectable on the devices tested.
Welch Allyn AED 10 Automatic External Defibrillator