WFDB Applications Guide - PhysioNet

EDR(1) WFDB Applications Guide EDR(1)
NAME
edr − derive a respiration signal from an ECG
SYNOPSIS
edr -r record -i annotator [ options ... ]
DESCRIPTION
edr derives asample of a respiratory signal for each QRS complex inthe input ECG, by measuring the
mean electrical axis (in two-channel mode) or the projection of that axis onto the lead axis (in single-channel
mode). See the references below for details of the algorithm.
edr reads the signal and annotation files specified by record and annotator, and writes another annotation
file, which is a copy ofthe input annotation file except that the num field of each beat annotation is
replaced by an EDR sample.
If the beat annotations are not located at the QRS peaks, it will be necessary to set the window limits (the
offsets relative to the annotations between which the raw measurements for the EDR are taken), using the
-d option. By default, edr behaves asifthe option -d -0.04 0.04 has been given (in other words, measurements
are taken over an80mswindow beginning 40 ms (.04 seconds) before the annotation, and ending 40
ms after the annotation); this default is reasonable if the QRS annotations have been placed on or near the
QRS peaks or centroids. If edr is supplied with annotations generated by sqrs, oranother method that
places the annotations near the PQ junction (the beginning of the QRS complex), the option -d 0 0.08 is
recommended.
For ECGs sampled at relatively low rates (e.g., 100-128 Hz, as is common for many long-term ECG recordings),
it may be advantageous to base the EDR on the T-wave rather than the QRS complex, by choosing a
window such as -d -0.08 0.28 or -d -0.12 0.32 (for annotations placed at the QRS peaks or PQ junctions
respectively), since this permits an axis estimation based on a larger number of samples. Note that the use
of a negative value for dt1, asinthese examples, allows the beginning of the EDR measurement window to
be placed after the QRS annotation.
Options include:
-d dt1 dt2
Set the EDR measurement window relative to QRS annotations (defaults: dt1 =0.04 (seconds
before annotation), dt2 =0.04 (seconds after annotation).
-f time Begin at the specified time (default: the beginning of the record).
-h Print a usage summary.
-o ann Use ann as the output annotator name (default: edr).
-s signal-list
Analyze only the signals named in the signal-list (one or more input signal numbers, separated by
spaces; default: analyze signals 0 and 1). If the signal-list contains more than two signals, only
the first two are analyzed.
-t time Stop at the specified time.
-v Verbose mode: print individual measurements.
ENVIRONMENT
It may be necessary to set and export the shell variable WFDB (see setwfdb(1)).
Example
edr -r 100 -i atr -f 0 -t 5:0
This command creates an annotation file named edr.100, containing a copy ofthe reference (atr) annotation
file for the first five minutes of record 100, with EDR measurements for each annotated beat in the
num fields of the output annotation file.
AVAILABILITY
edr is available as part of PhysioToolkit under the GPL (see SOURCE below).
20 28 October 2002 EDR 1.0