Re: Respiration and Electrocardiograms [HAPP-L]

[Jennifer Mansfield-Jones <j_mansfi@xxxxxxxx>]

On Sat, 25 Jan 2003 KHoehn@xxxxxxxxxxxxx wrote:
> The change in voltage observed in the Biopac figure could simply be due to
> movement of the electrodes during the repiration so that their positions
> relative to the ECG vector have changed.  I doubt that that is
> reproducible, but the change in heart rate is almost always present.

Is it possible that expansion of the lungs is changing electrical
resistance of the chest enough to alter wave amplitude?  There's
certainly some resistance change or an impedance pneumograph
wouldn't work.  I'm assuming recording artifacts have been ruled out
here... it's remarkably easy for slow sampling speeds to do odd
things to the amplitude of the R wave.  I've attached a powerlab
screen capture that shows the breathing effect: the second channel
is a stretch-based transducer of breathing motions.  Down should be
inhalation on channel 2. 

regards,
-=-=-=-=-                                                 -=-=-=-=-
Jennifer Mansfield-Jones                      j_mansfi@xxxxxxxx
Department of Biology, UNCG                            437 Eberhart
P. O. Box 26174                                      (336) 256-1038 
Greensboro, NC  27402-6174       


Content-Type: IMAGE/GIF; name="pic2.gif"
Content-ID: <Pine.GSO.3.96.1030128123314.18860A@maggie>
Content-Description: 

Attachment converted: Road:pic2.gif (GIFf/prvw) (0003BAA8)