perfusieindices

Perfusion indices, or perfusieindices in Dutch, are quantitative measures that describe the level of blood flow or perfusion in tissues, typically at peripheral sites. The term most commonly refers to the Perfusion Index (PI), a metric derived from photoplethysmography (PPG) signals used by many pulse oximeters.

The Perfusion Index is calculated as the ratio of the pulsatile component of the PPG signal to the non-pulsatile component from the same sensor. In practice, this yields a value that is often reported as a percentage or a unitless index. Higher PI values indicate stronger peripheral blood flow, while lower values suggest reduced perfusion. PI is influenced by factors such as vasomotor tone, temperature, sensor placement, probe site (finger, toe, or earlobe), arterial waveform quality, and motion.

Clinically, perfusion indices are used as part of non-invasive monitoring to assess peripheral perfusion status, guide sensor positioning, and track changes in perfusion during anesthesia, critical care, and neonatal care. They are not measures of blood pressure, cardiac output, or oxygen delivery, but can serve as a trend indicator for vasopressor therapy, fluid management, or detecting circulatory compromise.

Normal ranges vary by patient and device; typical PI values for adults may span a wide range (often from a few percent up to around 20%), and neonatal values can differ. Because PI is sensitive to technical and physiological factors, it should be interpreted cautiously and in conjunction with other vital signs and clinical context.