[TheForge] Re: Generators

[TodEstesRN at aol.com]

In a message dated 9/2/2004 7:00:47 AM Central Daylight Time, 
phlip at 99main.com writes:
Probably could- there's certainly enough juice in one for the job. Problem
is, that they're very expensive (although prices are coming down), and the
current AEDs won't zap anyone unless they show certain types of heart
rhythms- they won't flash a flat-line.

Defibrillators function not by jump-starting the heart, as is so frequently
supposed, but by changing its rhythm from a non-useful rhythm (rather as if
you had your spark plugs in your car in the wrong order) to a useful rhythm
(as if you magicly got the order right),

Saint Phlip,
CoD
Hi Saint Phlip!

You are right about the AED. AED and SAED's will deliver energy only when 
specific inputs match the rhythm parameters that they have built in. I.E. Vent. 
Tach, Vent Fib. etc.
I was thinking of a Monitor/Defibrillator which can deliver energy whenever 
the provider chooses.  Yes, they are expensive, if you buy one. I was just 
going to have the ambulance relocate to my drive. To connect I was thinking of 
using the wires that usually go to a set of disposable hands free pads. Used 
Defib units go for around $3000 if you are going to use it on a patient. If you 
are only using it for training it is much less.  Still way too expensive.  I 
haven't looked at EBAY though. LOL.

Defibrillation takes advantage of four properties of the heart muscle 
(myocardium).  First myocardium (like other muscle tissue) may be stimulated to 
contract due to external stimuli like electricity.  Second the myocardium once 
stimulated will quickly spread the signal to the rest of the heart fibers due to 
the cardiac muscle fibers that instead of lined up in layers are more like a 
mesh. Connecting the cardiac muscle fiber cells together are specialized 
intercalcated disks that speed conduction and provide a physical link fiber to fiber. 
Third unlike skeletal muscle cardiac muscle once contracted will not react to 
further stimuli until the muscle fiber is repolarized. This waiting period it 
called the refractory period.  Lastly the myocardium can stimulate its own 
fibers to beat without any stimuli this is automaticity.  
When you defibrillate you induce an external action potential potential that 
causes all the cardiac muscle fibers to contract at the same time. This sends 
all the heart muscle right to the refractory period which no further stimuli 
will be accepted.  In other words the heart makes one big beat then stops 
beating. With luck the sinoatrial node in the right atrium will start to send 
stimuli to the atria and the heart will start beating in a more normal rhythm.  In 
practice if you see V-Tach with no pulse sometimes this works.  In my 
experience in V-Fib when you defibrillate sometimes you get asystole. Of course 
oxygen, ventilation, fluids and drugs are given too.  Have a heart learn CPR.



Time enough for sleep in the grave.
Tod Estes