Systems and methods for determining a viscosity of a fluid

A method for determining a viscosity (η) of blood of a patient in a ventricular assist system, comprising:

• sensing a volumetric flow (Q) using a volumetric flow sensor of a determination device of the ventricular assist system, the volumetric flow sensor comprising a Doppler ultrasonic sensor arranged in a distal tip of a cannula of the determination device, the cannula, configured to be implanted in a body of the patient, wherein the ventricular assist system comprises:
• an impeller configured to convey blood from a lateral receiving interface of the cannula distal to the impeller to an outlet interface of the cannula;
• and
• a drive device coupled to the impeller, the drive device configured to drive the impeller at a rotational speed (ω);
• sensing a pressure difference (Δp) of blood in a region of the receiving interface and the outlet interface;
• and
• determining the viscosity (η) of the blood based on at least the sensed volumetric flow (Q) of the blood, the sensed pressure difference (Δp) of the blood, and either the rotational speed (ω) of the impeller or an electric power input Pel of a drive device for the impeller.

A non-transitory computer-readable storage medium comprising instructions that, when executed, direct a processor to perform a method comprising:

• sensing a volumetric flow (Q) using a volumetric flow sensor of a determination device of a ventricular assist system, the volumetric flow sensor comprising a Doppler ultrasonic sensor arranged in a distal tip of a cannula of the determination device, the cannula, configured to be implanted in a body of a patient, wherein the ventricular assist system comprises:
• an impeller configured to convey blood from a lateral receiving interface of the cannula that is distal to the impeller to an outlet interface of the cannula;
• and
• a drive device coupled to the impeller, the drive device configured to drive the impeller at a rotational speed (ω);
• sensing a pressure difference (Δp) of blood in a region of the receiving interface and the outlet interface;
• and
• determining a viscosity (η) of the blood based on at least the sensed volumetric flow (Q) of the blood, the sensed pressure difference (Δp) of the blood, and either the rotational speed (co) of the impeller or an electric power input Pel of a drive device for the impeller.