Question: chest compressions, electrical activity

[GoldShadow]

I was on another forum where there was an argument about electrical activity of the heart during chest compressions during CPR.

Somebody said that a chest compression actually elicits electrical activity in the heart (even in asystole), and that an EKG would show a spike or some electrical activity in response to a chest compression. However, I was under the impression that chest compressions are simply a mechanical method of circulating blood and that they have no effect on electrical activity of the heart.

Could somebody more knowledgeable clear this up?

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[TerraMedicX]

You're sorta right. Chest compressions are purely mechanical in nature. Some people are confused by the fact that you see a prominent EKG spike with each compression. These spikes are artifact from the mechanical movement of the chest during compression, but that being said, artifact occurs because ANY movement of muscles produces a small electrical discharge, which is what the EKG shows. So chest compressions do not produce any inherent electrical activity in the heart, just in the muscles of the chest, and more importantly, can not effect the electrical rhythm of the heart directly.

Nate.

 

[jbar]

Chest compressions do help to oxygenate the heart muscle, so in a way they increase the ability of the muscle to generate electricity. (No 02, no ATP, no Na/K pump, no electrical potential.) I agree with Terra that what you see on the ECG is due to mechanical movement, but it would make sense that if you were able to record the electrical activity of a heart undergoing CPR it would be generating more electricity than the same heart without compressions. This is assuming that the heart muscle is still viable, and producing some amount of electricity (since by definition asystole is the absence of detectible net electrical current. There is a difference between the current that can be detected via skin electrodes and electrodes directly implanted in the heart muscle, such as in an animal model.)
I haven't seen any research one way or the other on this one, so that above is me just trying to use the physiology I know. Anyone who has sources please post, thanks.

 

[howelljolly]

I vote no. The "v-tach" you see on the monitor during chest compressions probably has nothing to do with the heart, and everything to do with the chest wall movement.

If you are an unprofessional a medic as I am, you can try an experiment.

With the hands-off paddles on the chest of a person who is asystolic, and pronounced... If you rapidly drum your hands on the right anterior shoulder, you can simulate v-fib on the monitor.

When I took the defibrillation upgrade, and dinosaurs roamed the earth, the instructor mentioned this was a way that some sociopathic EMTs had forced their AED to shock.

On the other hand, Ive seen an Emergency Physician who would give all his arrest patients a precordial thump. Sometimes, you'd see one perfect QRS complex show up on a background of asystole. He used it as a prognostic factor relating to how aggressively he'd work the arrest.

 

[BostonEMT]

On the other hand, Ive seen an Emergency Physician who would give all his arrest patients a precordial thump. Sometimes, you'd see one perfect QRS complex show up on a background of asystole. He used it as a prognostic factor relating to how aggressively he'd work the arrest.

Heh. Interesting.

 

[NPEMTIV]

On the other hand, Ive seen an Emergency Physician who would give all his arrest patients a precordial thump. Sometimes, you'd see one perfect QRS complex show up on a background of asystole. He used it as a prognostic factor relating to how aggressively he'd work the arrest.

I've seen this as well. I agree with the technique personally.