A novel signal processing method for the measurement of venous refilling time

Methods in vogue for the measurement of venous refilling time (VRT), based on the photo-plethysmographic (PPG) principle, employ a feedback compensation technique to remove the influence of the colour of a patient's skin. Hence these methods require a “standardization phase” for every measurement. Based on an appropriate model for the propagation of light through skin and tissue, a novel signal processing method is proposed for the measurement of VRT. The proposed technique renders the measurement of VRT independent of not only the colour of the skin of a patient but also of source intensity and detector sensitivity. Test results obtained from a prototype unit, built under the LabVIEW virtual environment, establish the validity of the model and the proposed signal processing technique.