In vivo and in vitro studies of a chronic oxygen saturation sensor.
An oxygen saturation sensor, for the purpose of chronically controlling the heart rhythm produced by a pacemaker, should be specific to oxygen saturation and should be minimally affected by the harsh blood environment. For the sensor type we tested we found: (1) one sensor failure in 205.5 canine-months of chronic implantation (n = 11, range 4 to 50 months); (2) hematocrit-induced error of less than 5 percentage points of SvO2 over the range of 50% to 80% SvO2 and 15% to 45% hematocrit; (3) carboxyhemoglobin (HbCO)-induced error of less than 4 percentage points of SvO2 with HbCO up to 20%; (4) a fibrotic sheath-induced error of less than 3 percentage points of SvO2 in the range of 50% to 80% SvO2 due to fibrotic sheath thicknesses up to 0.22 mm; (5) no significant error induced by velocity variations local to the sensor; (6) no significant error due to temperature in the range of 30 degrees to 42 degrees C; and (7) that the sensor could be as close as 0.3mm to the ventricular wall and still only produce an error of 5% SvO2.
Seifert
G P
GP
Advanced Concept Department, Medtronic, Inc., Minneapolis, Minnesota 55432.
Moore
A A
AA
Graves
K L
KL
Lahtinen
S P
SP
D000818:Animals; D015374:Biosensing Techniques; D001783:Blood Flow Velocity; D001831:Body Temperature; D002263:Carboxyhemoglobin; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004285:Dogs; D004567:Electrodes, Implanted; D004867:Equipment Design; D005260:Female; D006339:Heart Rate; D006352:Heart Ventricles; D006400:Hematocrit; D066298:In Vitro Techniques; D008297:Male; D010092:Oximetry / Q000295:instrumentation*; D010138:Pacemaker, Artificial
D002263:Carboxyhemoglobin