Systems and methods for modified pulse transit time measurement

A method comprising:

• selecting at least two signal channels corresponding to an arterial signal, the at least two signal channels associated with corresponding optical sensors of the wearable blood metrics measurement apparatus;
• obtaining first signal data from a first channel of the at least two signal channels over a predetermined period of time;
• obtaining second signal data from a second channel of the at least two signal channels over the predetermined period of time;
• applying a frequency transform function to each of the first signal data and the second signal data to transform the first signal data and the second signal data to a frequency domain;
• determining a first phase value for a first frequency component of the first signal data in the frequency domain;
• determining a second phase value for a second frequency component of the second signal data in the frequency domain;
• determining a phase difference value between the first phase value and the second phase value;
• determining a time shift value between the first signal data and the second signal data based on the phase difference value;
• determining a modified pulse transmit time based on the time shift value between the first signal data and the second signal data, the modified pulse transit time representing a transit time for a pressure wavefront to travel from a first optical sensor of the corresponding optical sensors and a second optical sensor of the corresponding optical sensors;
• determining a pulse wave velocity based on the modified pulse transit time;
• calculating an arterial blood pressure value based on the pulse wave velocity;
• and
• providing a message including or being based on the arterial blood pressure value.

A non-transitory computer readable medium comprising instructions that, when executed, cause one or more processors to perform:

• selecting at least two signal channels corresponding to an arterial signal, the at least two signal channels associated with corresponding optical sensors of the wearable blood metrics measurement apparatus;
• obtaining first signal data from a first channel of the at least two signal channels over a predetermined period of time;
• obtaining second signal data from a second channel of the at least two signal channels over the predetermined period of time;
• applying a frequency transform function to each of the first signal data and the second signal data to transform the first signal data and the second signal data to a frequency domain;
• determining a first phase value for a first frequency component of the first signal data in the frequency domain;
• determining a second phase value for a second frequency component of the second signal data in the frequency domain;
• determining a phase difference value between the first phase value and the second phase value;
• determining a time shift value between the first signal data and the second signal data based on the phase difference value;
• determining a modified pulse transmit time based on the time shift value between the first signal data and the second signal data, the modified pulse transit time representing a transit time for a pressure wavefront to travel from a first optical sensor of the corresponding optical sensors and a second optical sensor of the corresponding optical sensors;
• determining a pulse wave velocity based on the modified pulse transit time;
• calculating an arterial blood pressure value based on the pulse wave velocity;
• and
• providing a message including or being based on the arterial blood pressure value.