Masimo signal extraction pulse oximetry

Objective. To describe a new pulse oximetry technology and measurement para digm developed by Masimo Corporation. Introduction. Patient motion, poor ti ssue perfusion, excessive ambient light, and electrosurgical unit interfere nce reduce conventional pulse oximeter (CPO) measurement integrity. Patient motion frequently generates erroneous pulse oximetry values for saturation and pulse rate. Motion-induced measurement error is due in part to widespr ead implementation of a theoretical pulse oximetry model which assumes that arterial blood is the only light-absorbing pulsatile component in the opti cal path. Methods. Masimo Signal Extraction Technology (SET (R)) pulse oxim etry begins with conventional red and infrared photoplethysmographic signal s, and then employs a constellation of advanced techniques including radiof requency and light-shielded optical sensors, digital signal processing, and adaptive filtration, to measure SpO(2) accurately during challenging clini cal conditions. In contrast to CPO which calculates O-2 saturation from the ratio of transmitted pulsatile red and infrared light, Masimo SET pulse ox imetry uses a new conceptual model of light absorption for pulse oximetry a nd employs the discrete saturation transform (DST) to isolate individual "s aturation components" in the optical pathway. Typically, when the tissue un der analysis is stationary, only the single saturation component produced b y pulsatile arterial blood is present. In contrast, during patient motion, movement of non-arterial components (for example, venous blood) can be iden tified as additional saturation components (with a lower O-2 saturation). W hen conditions of the Masimo model are met, the saturation component corres ponding to the highest O-2 saturation is reported by the instrument as SpO( 2). Conclusion. The technological strategies implemented in Masimo SET puls e oximetry effectively permit continuous monitoring of SpO(2) during challe nging clinical conditions of motion and poor tissue perfusion.