Abstract: An ECG electrode impedance measuring approach is utilized which can determine, simultaneously, the condition of all electrodes in a three or five lead ECG monitoring configuration. A CPU automatically selects an ECG lead configuration in which all electrodes are attached to the patient and are below an impedance threshold. If the CPU cannot select a good ECG lead configuration, then the CPU signals a total lead failure. Electrode impedance is determined by passing a small DC current through each active electrode and the current is returned via the reference electrode. A comparator tests the resultant offset voltage induced between each active electrode and the reference. If the offset voltage exceeds a fixed threshold, then a flag is set and transferred to the CPU. The CPU can change the ECG lead configuration by issuing commands to an electrode lead switching network.