Method for determining a physiological parameter using a PPG signal with reduced influence of venous pulsatility

A non-transitory computer readable medium storing a program causing a computer to execute a method comprising:

• using a PPG sensor device to measure a single PPG signal on a user, the single PPG signal comprising at least an arterial pulsatility component and a venous pulsatility component, the single PPG signal containing at least two cardiac cycles;
• identifying individual PPG pulses from the single PPG signal, each individual PPG pulse corresponding to a cardiac cycle and having a non-modulated component and a time-modulated component;
• for each individual PPG pulse, determining a set of at least one venous pulse feature indicative of the contribution of venous pulsatility to the time-modulated component of the individual PPG pulse from at least a waveform parameter characterizing a shape of the individual PPG pulse;
• assigning a weighting factor to each pulse, comprising calculating the weighting factor by using a weighting function comprising a mathematical operator inputted with said set of at least one venous pulse feature;
• computing a weighted-average PPG pulse by using the individual PPG pulses and their respective weighting factors;
• and
• determining the physiological parameter by using the weighted-average PPG pulse.

A photoplethysmography (PPG) sensor device comprising a light source and a light receiver and configured to measure a single PPG signal comprising a non-modulated component and a time-modulated component, wherein the time-modulated component comprises at least an arterial pulsatility component and a venous pulsatility component;

• the PPG sensor device further comprising a processing module configured to execute a method comprising:
• measuring the single PPG signal on a user, the single PPG signal containing at least two cardiac cycles;
• identifying individual PPG pulses from the single PPG signal, each individual PPG pulse corresponding to a cardiac cycle and having the non-modulated component and the time-modulated component;
• for each individual PPG pulse, determining a set of at least one venous pulse feature indicative of the contribution of venous pulsatility to the time-modulated component of the individual PPG pulse from at least a waveform parameter characterizing a shape of the individual PPG pulse;
• assigning a weighting factor to each pulse, comprising calculating the weighting factor by using a weighting function comprising a mathematical operator inputted with said set of at least one venous pulse feature;
• computing a weighted-average PPG pulse by using the individual PPG pulses and their respective weighting factors;
• and
• determining the physiological parameter by using the weighted-average PPG pulse.

A method for determining a physiological parameter, comprising the steps of:

• providing a photoplethysmography (PPG) sensor device configured to measure a single PPG signal comprising a non-modulated component and a time-modulated component, wherein the time-modulated component comprises at least an arterial pulsatility component and a venous pulsatility component;
• using the PPG sensor device to measure the single PPG signal on a user, the single PPG signal containing at least two cardiac cycles;
• identifying individual PPG pulses from the single PPG signal, each individual PPG pulse corresponding to a cardiac cycle;
• for each individual PPG pulse, determining a set of at least one venous-related feature indicative of the contribution of venous pulsatility to the time-modulated component of the individual PPG pulse from at least a waveform parameter characterizing a shape of the individual PPG pulse;
• assigning a weighting factor to each pulse, comprising calculating the weighting factor by using a weighting function comprising a mathematical operator inputted with said set of at least one venous-related feature;
• computing a weighted-average PPG pulse by using the individual PPG pulses and their respective weighting factors;
• and
• determining the physiological parameter by using the weighted-average PPG pulse;
• wherein the weighted-average PPG pulse pwa(t) is calculated by:
• p
• w
• ⁢
• a
• (
• t
• )
• =
• [
• ∑
• k
• =
• 1
• K
• ⁢
• w
• k
• ·
• p
• k
• (
• t
• )
• ]
• ∑
• k
• =
• 1
• K
• ⁢
• w
• k
• where pk(t) represents the kth identified PPG pulse and wk is the weighting factor associated with the kth identified PPG pulse.