User`s guide

How the PageWriter 200/300pi Measures ECGs
3-6 Understanding ECG Analysis and the Predictive Instruments Applications
late group and global atrial rhythm parameters. If no conclusive result is
achieved, no atrial rhythm parameters are calculated.
Global Measurements
The global measurements for the ECG, including the frontal and horizontal
plane axis measurements, are reported to the right of the lead measurements in
the Morphology Analysis section of the Extended Measurements report.
These interval, duration, and segment measurements are weighted averages of
the lead measurements. The global rate reported is the mean ventricular rate
over the entire ECG unless the ECG criteria program determines that one of
the group mean ventricular rates is more representative of the underlying
rhythm.
Axis Measurements
Although when making axis measurements manually, it is most convenient to
use waveform amplitudes, using areas yields more accurate results. The Page-
Writer 200/300pi uses the waveform areas from the lead measurements in cal-
culating the P, QRS and T axes, while the sum of the ST onset, middle and end
amplitudes is used in calculating the ST axis. For the frontal plane axis mea-
surements, which use the limb leads, nine lead pairs, all at least 60 degrees
apart, are used to estimate the axes. The resulting estimates are examined to
ensure that they converge to a single result. If so, they are averaged to form
the representative axis measurement. The horizontal plane axis measure-
ments, which use leads V1-V6, are calculated similarly from seven lead pairs.
The representative measurements are reported on the Extended Measurements
report.