Wearable tonometer

A system for determining the arterial blood pressure of a patient, comprising:

• a) a tonometer arranged to generate a tonometric curve and comprising:
• a bracelet configured to be applied to a wrist of a patient;
• a detection group mounted on said bracelet and configured to detect a pressure signal, said detection group comprising a plurality of pressure sensors arranged to detect a respective pressure signal associated with the blood pressure wave of the patient, at least a pressure sensor of said plurality being configured to be positioned in proximity of a radial artery of the patient, at an opposite side of a radial bone;
• a touching group configured to be interposed between said detection group and said radial artery of said patient, said touching group comprising a plurality of protuberant members, each protuberant member of said plurality of protuberant members being configured to be positioned into contact with skin of said patient to exert a predetermined force F on said radial artery, and to transmit the received pressure pulses to a respective pressure sensor associated with said radial artery;
• a processing unit arranged to process said pressure signal detected by said detection group to determine the blood pressure wave of the patient;
• wherein said touching group comprises a predetermined material having an elastic constant greater than elastic constant of the radial artery, in that said touching group comprises a base portion that is integral to said detection group and a plurality of connection portions, each of which is arranged to elastically connect a respective protuberant member to said base portion, and in that each said connection portion of said plurality comprises a plurality of connection arms configured to have a controlled elastic flexibility along a predetermined direction orthogonal to said base portion, such that each protuberant member of said plurality is suitable to elastically move along said direction orthogonal to said base portion;
• and
• wherein said connection arms are S-shaped, each of said connection arms being configured to lay in a rest position on a plane orthogonal to said movement direction of said protuberant members;
• b) an ECG device arranged to generate an electrocardiographic curve;
• c) an oscillometric device arranged to measure an arterial blood pressure value PA3(ti) by an oscillometric technique;
• and
• d) a microcontroller arranged to process said electrocardiographic curve and said tonometric curve at determined instants for determining the pulse transit time, which is the delay between said electrocardiographic curve and said tonometric curve, said microcontroller being arranged to associate said computed delay to a determined reference value of the arterial blood pressure and to measure at said determined instants (ti), a difference ΔPA(ti) between a value PA1(ti) of the arterial blood pressure of the patient, that is estimated by using the pulse transit time, and a value PA2(ti) of the arterial blood pressure that is estimated by said tonometric curve, said microcontroller arranged to operate said oscillometric device, and to associate said arterial blood pressure value PA3(ti) both to the value PA2(ti) of arterial blood pressure that is estimated by the tonometric curve, and to the value PA1(ti) of arterial blood pressure that is estimated by pulse transit time.