Bioimpedance-based respiration monitoring with a defibrillator

Defibrillators often use an ac measurement to ensure safe electrode placement. Some defibrillators also utilize impedance measurements for ventilation monitoring. This paper investigates how such measurements can be optimized for high respiration sensitivity and finds that it is beneficial to add two extra electrodes in addition to the two defibrillator electrodes. This four electrode setup increases sensitivity and also allows respiration measurements at lower frequencies than the two electrode setup.