In Vivo and In Vitro Studies of a Chronic Oxygen Saturation Sensor

Abstract

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.

Rate Adaptive Cardiac Pacing Using Right Ventricular Venous Oxygen Saturation: Quantification of Chronotropic Behavior During Daily Activities and Maximal Exercise

“…Eight female patients with symptomatic sinoatrial disease received the dual sensor DDDR pace- Figure 3. Oxygen rate response curves (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). The pacing rate changes as a function of the percentage ofS^Oz decrease from the programmed rate response offset level.…”

The Development of a Control Method for a Total Artificial Heart Using Mixed Venous Oxygen Saturation

“…From a technological viewpoint, the practical technology of Sv o 2 measurement has already been established in the oxymetric catheter, rate responsive pacemaker, and blood gas monitoring system ( 4–7, 101113). The main problems to overcome for TAH control use are sensor stability, reliability, and durability ( 14).…”

“…We have proposed the possibility of applying mixed venous oxygen saturation (Sv o 2 ) as a suitable parameter for TAH control ( 3) because the Sv o 2 reflects the recipient's oxygen metabolic condition closely and sensitively. Moreover, the measurement of Sv o 2 has already been established in the oxymetric catheters and in the pacemakers using this parameter ( 4–7). Because Sv o 2 can also be measured through the transparent blood pump housing with near infrared rays, continuous monitoring may be possible for long periods without contact with the blood.…”

Utility of an Implantable Right Ventricular Oxygen Saturation-Sensing Pacemaker for Ambulatory Cardiopulmonary Monitoring

“…The technical details of the SvO2 sensor have been reported. 15 In brief, it consists of red (660 nm) and infrared (880 nm) light-emitting diodes, hermetically sealed in a sapphire capsule. The reflectance of the light from each is received and measured by a photodetector to generate a relative reflectance ratio.…”