Patent ID: 8346353

Claim:
A medical system comprising: an implantable medical lead adapted for implantation in a patient, said implantable medical lead carrying at least one optical sensor comprising a light source configured to emit light in vivo at a predetermined wavelength and at a predetermined intensity, said optical sensor further comprising a light detector, said implantable medical lead being configured to direct the light emitted by said light source into lung tissue of the patient; and an edema detection circuit connected to said implantable medical lead, said edema detection circuit being configured to activate said light source to emit light during at least one measurement session at said predetermined wavelength and said predetermined intensity and, with said light detector, to detect said light after said light interacts with said lung tissue, the light detected by the light detector having a detected light intensity value, and to evaluate said detected light intensity value by comparing said detected light intensity value with a reference intensity value to obtain a comparison result, and to emit an edema detection circuit output indicating incipient edema when said comparison result is consistent with incipient edema.