Monitoring Respiration Rate
For the respiratory measurement (Resp), the monitor measures the thoracic impedance between two
ECG electrodes on the patient's chest. Changes in the impedance due to thoracic movement produce
the Resp waveform on the monitor screen. The monitor counts the waveform cycles to calculate the
respiration rate (RR).
Lead Placement for Monitoring Resp
Correct patient skin preparation techniques for electrode placement are important for Resp
measurement: you will find this information in the chapter on ECG.
The Resp measurement uses the standard ECG cable sets and lead placements. You can use any of the
different types of ECG cable sets - 3-lead, 5-lead, 6-lead or 10-lead, using either standard or EASI™
placement - to measure Resp, as long as you use ICU ECG cables.
The Resp signal is always measured between two of the ECG electrodes. If you are using standard ECG
electrode placement, Resp is measured between the RA and LL electrodes. If you are using EASI™
ECG electrode placement, Resp is measured between the I and A electrodes.
Optimizing Lead Placement for Resp
If you want to measure Resp and you are already measuring ECG, you may need to optimize
placement of the two electrodes between which Resp will be measured for some patients. Repositioning
ECG electrodes from standard positions, especially when you are using EASI™ ECG electrode
placement, results in changes in the ECG waveform and may influence ST and arrhythmia
Cardiac activity that affects the Resp waveform is called cardiac overlay. It happens when the Resp
electrodes pick up impedance changes caused by the rhythmic blood flow. Correct electrode placement
can help to reduce cardiac overlay: avoid the liver area and the ventricles of the heart in the line
between the respiratory electrodes. This is particularly important for neonates.