Patent ID: 6839587

Claim:
A leads-off indicator for an ECG apparatus comprising: (a) a plurality of electrodes adapted for attachment to a patient's body at predetermined locations for picking up signals and noise, said locations including the left arm (LA), right arm (RA), left leg (LL), right leg (RL) and chest (V) to define lead vector I as a potential difference between RA and LA electrodes, lead vector II as a potential difference between RA and LL electrodes, lead vector III as a potential difference between LA and LL electrodes and precordal vector V as a potential difference between V electrode and an average of the ECG signals at RA, LA and LL electrodes; (b) detector means coupled to said plurality of electrodes for first detecting whether the RL electrode is connected to the patient and, if so, applying a drive signal to the patient, via the RL electrode, the drive signal being derived from ECG signals and ambient noise picked up by the LL, LA and RA electrodes; and (c) means for comparing a level of ambient noise on each of said vectors to assess whether a particular one of the RA, LA and LL electrodes is not properly contacting the patient.