Field of the invention

The invention relates to a device for monitoring physic-chemical parameters of an organic fluid, which is particularly adapted to be mounted to an extracorporeal circuit in which a patient's blood circulates.

Background art

Monitoring of partial oxygen pressure (hereinafter p0 ₂ ), partial carbon dioxide pressure (hereinafter pC0 ₂ ), pH and pressure of biological fluids in circuits for extracorporeal circulation of an organic fluid, such as blood, is critical in therapies that require the fluid to be monitored or treated to flow through the tubing that forms an extracorporeal circuit.

Particularly, monitoring of the above-mentioned physico-chemical parameters has a key role especially when, during execution of such therapies, an external support is needed to entirely or partially replace the respiratory function and/or the cardiac pump function of the patient, using special machines known as heart-lung machines.

In the prior art, parameters are monitored using special sensors arranged along the tubing of extracorporeal circuits, and controlled by an electronic controller that collects and displays data.

Each sensor has such characteristics as to allow monitoring of a particular parameter and schematically comprises a sensing part, consisting for instance of a hydrophobic and elastically deformable membrane which is designed to contact the fluid to be monitored, and an electronic transducer circuit that converts the stresses applied to the membrane into electronic signals to be transmitted to the connection and monitoring controller.

The membrane or equivalent sensitive element has hydrophobic properties to prevent fluid from flowing therethrough, thereby avoiding both contact with and damage of the electronic circuit and contamination of the organic fluid being monitored.

As mentioned above, each sensor is specially designed to detect one of the physico-chemical parameters of the organic fluid. Thus, for example, the pressure of a biological fluid is monitored by interposing a deformable membrane between the fluid and a sensor that measures the difference between ambient pressure, which is considered as a zero reference value, and the pressure acting upon a semiconductor transducer, which in turn produces a value for electric resistance generated on the semiconductor.

On the other hand, changes in the concentration of oxygen dissolved in the biological fluid are determined by a technique that measures the attenuation of luminescence of a luminescent substance according to the concentration of oxygen in the fluid, i.e. a technique in which a light generated by light sources having known wavelengths is reflected by a matrix that contains a fluorophore in contact with the biological fluid, and generates an optical signal proportional to oxygen concentration, which is picked up by a light-sensitive transistor.

Also, pH and pC0 ₂ are typically measured, in the prior art, by measuring the amount of hydrogen ions H+ dissolved in the organic fluid being monitored, and the amount of dissolved carbon dioxide is determined by calculating the inverse proportion using an algorithm for reversible chemical reactions.

One of the most advanced methods used in these sensors is based on the use of a fluorescent chromophore, whose emission intensity is directly proportional to the amount of ions H+.

When fluorescent chromophores are excited by a light having a predetermined frequency, such chromophores, also known as fluorophores, emit a fluorescent light that may be picked up by a transducer and converted thereby into a quantitative electric signal.

An optical sensor for determining the pH value is known from EP 906,566.

According to this document, the optical sensor comprises a membrane on a transparent support material, which membrane is made of polyurethane, polyurea-urethane, or a polyurea composition containing a pH sensitive fluorescein compound. An instrument for continuous and instantaneous measurement of substances in a biological fluid is disclosed in FR 28661 18.

According to this document, the measuring instrument has a cavity including a measuring chamber through which a biological fluid flows between an inlet and an outlet.

The chamber contains an ISFET (Ion Sensitive Field Effect Transistor) chemical sensor, which is sensitive to a substance contained in the biological fluid.

Further optical sensors are known, for instance, from W01996EP004426, US200400031 63, US 5,536,783.

The above described prior art suffers from certain drawbacks.

One drawback is that all the sensors that have to be used for generally monitoring the physico-chemical condition of a patient undergoing therapeutic treatment by means of an extracorporeal circuit in which an organic fluid to be monitored such as blood circulates, are located at discrete points in the circuit, whereby each of these locations has to be equipped with a special connector for a particular sensor, as well as a connecting cable for transferring the data for the collected parameters between the sensor and an electronic controller that receives and displays such data.

It shall be understood that, for full control of the organic condition of the patient, these sensors have to be located both on the venous line of the circuit that comes from the patient, and on the arterial line that returns to the patient, once the organic fluid has been treated with the required therapies.

Therefore, the great number of connectors and the numbers and lengths of the connecting cables increase the cost and inconvenience of use of the extracorporeal circuit.

Furthermore, in case of malfunction of a sensor, particularly a sensor designed to detect pressure, the latter has to be disconnected from the connecting cable, removed and replaced by a new sensor of the same type, otherwise monitoring of the relevant physic-chemical parameter should be stopped, thereby preventing full control of patient conditions.

Disclosure of the invention It is an object of the present invention to improve the prior art.

Another object of the invention is to provide a device for monitoring physic— chemical parameters of an organic fluid that allows constant monitoring of an organic fluid and avoids the requirement for a great number of independent connectors for the individual sensors to be arranged along the tubes of the extracorporeal circuits, thereby simplifying their structure.

Another object of the invention is to provide a device for monitoring physico-chemical parameters of an organic fluid that, in case of failure of one of the pressure sensors, allows either quick replacement thereof or the addition of a sensor of the same type beside the malfunctioning sensor, for substantially seamless monitoring of patient conditions.

In one aspect, the invention relates to an device for monitoring physico-chemical parameters of an organic fluid according to the features of claim 1 .

Therefore, the invention provides the following advantages:

- combining a plurality of separate sensors in a single housing, and connecting them to units for downloading the collected data, which are also accommodated in the single housing, and are connected to the electronic controller by a very small number of connecting cables; - quickly restoring the best parameter sensing conditions, even in case of failure of one of the pressure sensors;

- simplifying extracorporeal circuits; and

- reducing the cost and size of the latter.

Brief description of the drawings

Further characteristics and advantages of the invention will be more readily apparent upon reading of the detailed description of a preferred nonexclusive embodiment of a device for monitoring physico-chemical parameters of an organic fluid, which is shown as a non-limiting, illustrative example in the annexed drawings, in which:

FIG. 1 is a front perspective schematic view of a simplified embodiment of a device for monitoring physico-chemical parameters of an organic fluid of the invention, which is adapted for use on a single line of an extracorporeal circuit;

FIG. 2 is a rear perspective schematic view of a second more complete embodiment of a device for monitoring physico-chemical parameters of an organic fluid of the invention, which is adapted for use on a dual line of an extracorporeal circuit;

FIG. 3 is a front perspective schematic view of the monitoring device of Figure 2;

FIG. 4 shows a scheme of an extracorporeal circuit for filtering and oxygenating a patient's blood, with the monitoring device of Figure 2 mounted thereto;

FIG. 5 is a front perspective schematic view of a third even more complete embodiment of a device for monitoring physico-chemical parameters of an organic fluid of the invention;

FIG. 6 is a corresponding rear perspective view of the monitoring device of Figure 5.

Detailed description of one preferred embodiment Referring to Figure 1 , numeral 1 generally designates a device for monitoring physico-chemical parameters of an organic fluid, namely blood, hereinafter simply referred to as monitoring device, in a simplified embodiment adapted for use on a single line of an extracorporeal circuit 500 known to the skilled person.

The device 1 comprises a three-dimensional body 2, namely a substantially cylindrical body 2, which defines a passageway section having an inlet 3 for the organic fluid to be monitored and an outlet 4 for the monitored fluid that flows in the body 2 in the direction of arrows "F1 ", through an inner detection chamber, not shown.

Housings are successively formed at the inner detection chamber in the body 2, for corresponding sensors designed to sense parameters of the organic fluid to be monitored.

The housings are through housings, which means that they extend through the outer wall of the body 2 to allow communication between the inner detection chamber and the sensing parts of the sensors in the housings.

Namely, in the simplified embodiment, the device 1 comprises a raised quadrangular housing 4 for a sensor that senses the pressure of venous or arterial blood flowing from or back to a patient "P", and three more circular housings 6, 7, 8, successively arranged along a longitudinal axis of the body 2, and having connection and retention elements 10 for corresponding sensors, better described below, as well as an additional raised housing 9, substantially identical to the housing 5.

All the sensors in the housings 6, 7, 8 are connected to a data collection board, generally referenced 1 1 , which in turn interfaces with a mainboard, that provides and displays the collected data on a screen of a monitoring unit.

Likewise, the pressure sensors 5 and 9 are connected to a dedicated data collection board, generally referenced 1 2, which in turn interfaces with a mainboard, that provides and displays the collected data on a screen of a monitoring unit.

More in detail, the housing 5 and the housing 9, as mentioned above, are designed to accommodate a pressure sensor each, whereas the housing 6, the housing 7 and the housing 8 are designed to accommodate a pH sensor, a partial oxygen pressure (p0 ₂ ) sensor and a partial carbon dioxide (pC0 ₂ ) sensor respectively.

Referring to Figure 3, the device for monitoring physico-chemical parameters of an organic fluid, referenced 1 00 in the most complete embodiment, is shown to comprise two bodies 200 and 201 substantially having the same shape and joined together in parallel relation, with intermediate connecting ribs, referenced 120, thereby forming a substantially integral and easy-to-handle device.

Therefore, in this embodiment the device 1 00 has two passage lines for the fluid to be monitored which, like in the previous embodiment, both have respective inlets and outlets, referenced 1 50, 151 , 1 52 and 153.

Thus, the device 100 allows monitoring of a fluid, such as the blood of a patient "P" both on a venous line 501 that comes therefrom, and on an arterial line 502 that returns thereto, as schematically shown in Figure 4.

Still referring to Figure 3, the body 200 is substantially similar to that of the above described simplified embodiment, whereas the body 201 has two raised housings only, for as many sensors.

More in detail, the body 200 has a housing 1 05 and a housing 109 for receiving pressure sensors, here arterial pressure sensors, a housing 106 for an arterial blood pH sensor, a housing 1 07 for an arterial blood partial oxygen pressure (p0 ₂ ) sensor and a housing 1 08 for an arterial blood partial carbon dioxide (pC0 ₂ ) sensor.

On the other hand, the body 201 has a housing 1 12 and a housing

1 1 3 for receiving respective venous blood pressure sensors, sensing the pressure of venous blood flowing from the patient.

Also in this embodiment, all pressure sensors are connected to a data collection board 21 2, and the three additional sensors are connected to a similar data collection board 1 1 1 .

The monitoring device of the invention may be also provided in a third even more complete embodiment, as shown in Figures 5 and 6.

It will be appreciated that the monitoring device, here designated by numeral 600, has a section substantially identical to the second embodiment, referenced "S1 ", and a second extension section "S2".

In Figures 5 and 6, the parts that are also contained in the second embodiment of the monitoring device are designated by the same numerals, for simplicity.

A portion of the extension section "S2" is made of a transparent material, to allow visual detection of the flow of organic flow in the monitoring device 600.

More in detail, this portion comprises a plurality of windows 601 having respective flat surfaces, for an optical detection unit to move close thereto, and detect, e.g. by the emission of beams of treated light, additional chemical and physical parameters of the organic fluid.

Indicatively, the section "S2" may be used to detect oxygen saturation, temperature, hematocrit and/or hemoglobin on the venous line that comes from the patient, i.e. on the body 201 , whereas oxygen saturation and temperature of the organic fluid may be detected on the arterial line directed to the patient.

The operation of the device for monitoring physico-chemical parameters of an organic fluid is described below with reference to the most complete embodiment 100, i.e. the one that includes two parallel passage lines for the fluid, namely blood, defined by the two bodies 200 and 201 .

The device 1 is mounted to an extracorporeal circuit 500 and the venous line 501 and the arterial line 502 are connected to the inlet 153 of the body 201 and to the outlet 150 of the body 200 respectively.

A conduit 503 is connected to the outlet 152 of the body 201 for connection to a venous blood treatment device, which comprises, for instance, a filtering unit 504, a pump 508 and a thermal and oxygenation treatment unit 505.

A return conduit 506 extending from the filter unit on the arterial line

507 is connected to the inlet 1 51 of the body 200.

When blood flow in the extracorporeal circuit 500 is at steady state, the sensors on the bodies 200 and 201 allow detection of physico-chemical parameters as blood flows through the inner detection chambers of the two bodies 200 and 201 and transmission of detected data to the respective data collection boards.

These collection boards 1 1 , 12 and 1 1 1 and 21 2 are usually connected to a further main board, which is not shown because it is mounted to a display a control unit also not shown, whereby the medical staff can see the parameters of the blood being monitored.

Since the sensors for detection of physico-chemical parameters of both venous and arterial blood (or another organic fluid) are combined in a single device, they may be readily connected to their respective boards 1 1 and 12 or 1 1 1 and 21 2, without requiring a multiplicity of connecting cables in disorderly arrangement along the tubes of the extracorporeal circuit 500, and hence providing a less bulky and considerably more easy-to-handle device.

Furthermore, the number of housings for pressure sensors on the bodies 200 and 201 may depend on particular needs and allow seamless monitoring of the relevant parameter, even in case of failure, because at least two pressure sensors are provided for each hydraulic conduit, which are normally engaged by the monitoring system.

Furthermore, the coupling and retaining members 1 0 in all sensor housings allow quick mounting of sensors.

The third embodiment of the monitoring device allows the operator to bring a known optical detection unit close to one of the windows 601 , which unit radiates a treated light beam through the transparent walls of the windows 601 , to propagate light through the organic fluid, as the latter circulates, and hence detect the desired parameters.

Finally, the device for monitoring physico-chemical parameters of an organic fluid according to the invention, both in its simplified and more complete embodiments, has a substantially integral construction, whereby it can be easily mounted to specially designed housings on therapeutic treatment equipment, and thus may be conveniently located and reached by the medical staff.

The invention has been found to fulfill the intended objects.

The invention so conceived is susceptible to changes and variants within the inventive concept.

Also, all the details may be replaced by other technical equivalent elements.

In practice, any material, shape and size may be used as needed, without departure from the scope as defined by the following claims.