Die nichtinvasive, pulsspektroskopische Bestimmung der Hämoglobinkonzentration im Blut

Mehr zum Buch

Pulse oximetry is a non-invasive method for measuring arterial oxygen saturation, while hemoglobin concentration (cHb) is typically determined through invasive blood sampling. Despite various non-invasive techniques proposed in literature, none have gained widespread clinical acceptance. This study introduces a non-invasive method for cHb determination, analyzing its accuracy compared to pulse oximetry and identifying factors that hinder precision. Three main factors were identified: 1) Tissue filters the light from LEDs, and thermal drift in LED wavelengths affects measurements, making non-invasive cHb determination reliant on LED temperature and tissue properties, unlike pulse oximetry. 2) The method operates only in transmission mode, requiring a change in measurement volume from the arterial blood pulse, which means accuracy is highly dependent on sensor placement and geometry. 3) The mean light path in tissue varies with hemoglobin concentration and blood content, making it impossible to determine cHb accurately with just two wavelengths. Incorporating a third wavelength improves the model. A study involving 139 subjects undergoing blood donation or transfusion was conducted, comparing non-invasive cHb values to invasive reference values. The non-invasive method showed a root mean square (RMS) error of 1.42 g/dl, improving to 1.20 g/dl after excluding poor-quality signals. While promising, the accuracy does not fu