Page 100 - Critical Care Notes

4223_Tab02_045-106 29/08/14 10:00 AM Page 94

CV

Determining Rate and Measurement
To figure out rate (regular rhythms only), you can do one
of the following:
Count the number of QRS complexes Irregular
(regular rhythms only) in a 6-sec strip rhythms
and multiply by 10. should be
counted for
Divide the number of large boxes an entire
between two R waves into 300. minute.
Remember the number sequence below and find an
R wave that falls on a heavy line. Starting from the
next heavy line, count 300, 150, 100, and so forth,
and whatever line the next R wave falls on is the
heart rate (see below for example).
1st R wave 300 150 100 75 60 50 43

Next R wave here Next R wave here
would be 150 bpm. would be 60 bpm.
Inherent rates of different cardiac regions:
SA Node......................60–100 bpm

AV Node......................40–60 bpm
Ventricles....................20–40 bpm
One small box
represents
One big box represents 0.04 sec and
0.20 sec and is 5 mm 2 . is 1 mm 2 .

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