Pressure measuring system

Abstract

A pressure measuring system, including a tube system having at least one first device for measuring pressure in a fluid. The at least one first device includes a coupling element, at least one pressure transducer and at least one measuring chamber, which can be filled with a fluid. Between the first device and the feed of the fluid, the tube system has a second device for regulating a fluid flow, the second device having a tube section through which fluid can flow and at least one tube clamp, which can be set in the regulation positions open, closed and perfused.

Claims

1. Method for the automatic filling and correction of hydrostatic pressure of a pressure-measuring system, comprising: selecting a pressure-measuring system with at least a first measuring lumen which can be filled with a fluid, and having at least first and second pressure-measuring devices and at least two flow regulation devices, wherein the pressure measuring system includes (A) a tube system that defines the first measuring lumen, (B) the at least first and second pressure-measuring devices and (C) the at least two flow regulation devices, and is connectable to (a) a fluid reservoir serving as a supply of fluid and to (b) at least one catheter lumen of at least one catheter, and a mechanism for conveying the fluid through the tube system and into the at least one catheter, wherein each of the at least first and second pressure-measuring devices includes a pressure transducer membrane and a measuring chamber which can be filled with fluid, wherein the tube system further includes at least one coupling element which mechanically connects each measuring chamber via its respective membrane with a measuring area of a pressure transducer and each measuring chamber has at least two connection points for a fluid flow and, positioned between the first pressure measuring device and the supply of the fluid, the tube system has a first flow regulation device for regulating fluid flow with a perfusion tube section made of a flexible material and having a perfusion tube section lumen through which fluid can flow and has a first tube clamp into which the tube section is inserted, and the first flow regulation device can be set to regulation positions open, closed and perfused, wherein in the closed position the perfusion tube section lumen is completely squeezed closed and in the perfused position, through a spacer in the inside of the tube section the perfusion tube section lumen is partly open even when squeezed by the first tube clamp; wherein one of selected the flow regulation devices being the first flow regulation device with the perfusion tube section and corresponding first tube clamp, and the other flow regulation device having a second tube section and a second tube clamp, with the first measuring lumen connecting the first pressure measuring device to one catheter lumen and a second measuring lumen connecting the second pressure measuring-device to another catheter lumen; measuring a rest pressure on each pressure transducer with the tube system and measuring lumens filled with air and connected to (a) the fluid reservoir serving as a supply of fluid and to (b) at least one catheter lumen of at least one catheter; setting at least one of the first and second tube clamps into the closed regulation position; setting another of the first and second tube clamps into the open regulation position and filling the tube system and one of the measuring lumens with liquid from a fluid reservoir; setting at least one of the first and second tube clamps into the closed regulation position and correcting the hydrostatic pressure exerted by the height difference between at least one of (i) the pressure transducer and the measuring chamber and (ii) the measuring lumen and the measuring location by comparison with the previously determined rest pressure; and setting at least the first tube clamp into the perfused regulation position.

2. The method according to claim 1, wherein the measured rest pressure for each measuring lumen is transmitted to a control device and from several measurements a mean rest pressure is determined.

3. The method according to claim 2, wherein the correction of the hydrostatic pressure exerted by the height difference between each measuring chamber and the pressure transducer sensor takes place through comparison with the mean rest pressure.

4. The method according to claim 1 wherein a quantity of liquid used for filling corresponds to the volume of the tube system and the measuring lumens.

5. The method according to claim 4, wherein the filling process is automatically ended when a quantity that corresponds to the volume of the tube system and the measuring lumens has been pumped out of the fluid reservoir into the tube system and the measuring lumens.

6. The method according to claim 4 wherein the quantity of liquid pumped into the tube system and each measuring lumen is determined by revolutions of a roller wheel of the mechanism for conveying or via a volume transducer.

7. The method according to claim 1 wherein before filling of the tube system and each measuring lumen, the corresponding tube clamp is automatically set to the open regulation position and after filling is set back into the closed regulation position.

8. The method according to claim 1 wherein the individual processing stages are carried out automatically after the start of the process.

9. The method according to claim 1 wherein the second flow regulation device is a non-perfusion flow regulation device and the second tube section is a non-perfusion tube section having a non-perfusion tube section lumen, with the second tube clamp having a basic housing with a second accommodating area for the second, non-perfusion tube section and a clamping element that can be moved between open and closed regulation positions, and wherein the clamping element in interaction with sections of the second accommodating area as pressing points in at least one closed regulation position acts on the second tube section and its non-perfusion tube section lumen by squeezing.

10. The method according to claim 1 wherein the at least one coupling element has a clamping edge and at least one rotatably borne pressing roller and each of the at least one measuring chamber has two webs arranged opposite each other, wherein one of the webs engages the clamping edge and the other web engages into the pressing roller.

11. The method according to claim 1 wherein at least one of (i) the first and second tube clamps, (ii) the coupling element, and (iii) the measuring chambers are at least in sections made of a material selected from a group which includes duroplastic or thermoplastic synthetic materials.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the structure of a measuring system in accordance with the prior art;

(2) FIG. 2 shows the structure of a pressure measuring system in accordance with the present invention;

(3) FIGS. 3a-3h show detailed views of the device for regulating the volumetric flow

(4) FIG. 4 shows a detailed view of the pump tube for the pressure-measuring system in accordance with the invention;

(5) FIG. 5 shows an exploded view of the assembly of the pressure dome cassette with the pressure measuring sensors;

(6) FIGS. 6a to 6d show detailed views of the dome cassette and its locking arrangement on the pressure measuring sensors;

(7) FIG. 7 shows a measuring protocol of automatic venting and zeroing of the pressure measuring system in accordance with the invention.

DETAILED DESCRIPTION OF THE CURRENTLY PREFERRED EMBODIMENTS

(8) FIG. 1 schematically shows the structure of a device for measuring pressure with water-filled disposable catheters. In addition to the bag with a solution for infusion 1 and a pressure cuff 2, a pressure transducer 3 and two-way valves 4 before the pressure sensors 6 are shown. Connected to these are three-way valves 5 and the corresponding tubes are designated as P.sub.ura 7, P.sub.ves and P.sub.abd 9. Via the pressure transmission hoses 10 the solution for infusion is supplied from the bag 1 to the rectal catheter 11 and the urethral pressure profile (UPP) catheter 12. In addition from the bottle 16 with, for example, a saline solution, via the roller pump 14 and the drip chamber 13, the saline solution is supplied to the UPP catheter 12 from the bottle 16.

(9) The preparation and measuring procedure is carried out as follows:

(10) a) The pump tube 15 is inserted into the pump 14 and the spike connection 12 of the tube inserted into the bottle stopper. The pump 14 is switched on until the drip chamber 13 of the bottle 16 is half filled and the tube is filled with saline solution completely free of bubbles.

(11) b) The three pressure measurement indicators 6 are placed in the holders and connected to the perfusion tube 18between the perfusion tube and one pressure measurement indicator a flow transducer 3 is inserted. The spike connection 19 of the perfusion tube 18 is inserted into the water bags 1.

(12) c) The pressure transmission hoses 10 are connected to the pressure measurement indicators 6.

(13) d) All two-way 4 and three-way valves 5 are closed and the pressure cuff 2 is pumped up to pressurise the water bags 1.

(14) e) To vent the pressure transmission tubes the two-way 4 and three-way valves 5 of the pressure transducer are set to open and are filled, without bubbles, to the top with water and the two-way valve 2 is closed again. This procedure must be carried out individually for all three pressure transmission lines.

(15) f) The three-way valves 9 are now individually turned into the 90 position in order to electronically adjust the pressure channel to atmospheric pressure by pressing a button. The three-way valves 5 are then turned to the open position again.

(16) g) The two catheters 11, 12 are placed in the urethra and rectum of the patient and connected to the pressure transmission lines and the pump tube 10.

(17) h) The three-way valves 5 must now be individually opened again individually in order to vent the two lumens of the transurethral catheter 12 up to the tip and to fill the balloon of the rectal catheter 11.

(18) i) The measured pressures are checked and, if necessary, zeroed by software. The system is now ready for measurement.

(19) In FIG. 2 the set-up of a pressure measuring system in accordance with the invention is shown.

(20) With reference number 21 this figure shows the pump tube leading to the pressure dome cassette 25 with the Luer locks for the connection of catheters 28 and 29. The spike connector 30 for standard infusion bottles 20 is also shown. 29 denotes the transurethral and 28 the rectal catheter (possible also any number of catheters or measuring volumes) which are supplied with the fluid via the lines 26 (three stages) and 27. Arranged adjoining this is the locking mechanism of the dome cassette 25. Arranged in the area denoted as 24 are four (possibly any number) of tube clips with the statuses open, closed and perfused. A roller pump 22 for conveying the medium through the tube system is shown. The system also has a control system 31 with a fully automated algorithm for venting the tube system with catheters, determining rest pressure and zeroing the measuring system using the functionality of the individual components.

(21) In FIGS. 3a-3h various settings (open, closed, perfused) of the device 41 for regulating the volumetric flow, i.e. the tube clamp are shown.

(22) In the upper row 3a to 3c a view from above of a corresponding device 41 is shown, in which the tube 42 is inserted. In the tube in the lower half, a thread 43 in the form of a spacer can be seen. In addition, the clamping element 44 and, interacting with it, the counter-wall 45 of the device 41 is shown. In FIG. 3a the open position, in FIG. 3b the completely close position and in FIG. 3c the so-called perfused, i.e. slight open, position is shown.

(23) FIGS. 3d to 3f show cross-sectional views from FIGS. 3a to 3c along the relevant lines A-A, B-B and C-C. Here too the inserted tube 42 with the space 43 can be seen which is placed in the accommodating section 46 of the device 41. Reference number 44 denotes the clamping element which is arranged on a rotatable guide 47. The latter can interact with the wall section 45 in the various position (see 3c and 3f), wherein in accordance with the view show here, in the position according to FIGS. 3b and 3e the tube is completely close and in the position according to FIGS. 3c and 3f the tube is slightly open, although the clamping element 44 interacts with the counter-wall 45. However, in spite of squeezing of the tube, the spacer 43 brings about a slight fluid flow. In FIGS. 3g and 3h detailed views of the two positions 3e and 3h are shown in order to illustrate the difference between closed and perfused. The slight opening of the tube can be clearly seen in FIG. 3h.

(24) Such a device 41 can also be called a tube clamp. The tube clamps replace the two-way and three-way valves used in conventional pressure measurement. They also act as a perfusion regulator for pressure measurement channels that have to be perfused (urethral pressure in urodynamic). The clamps can be brought into the positions open, closed and perfused by simply turning about the axis with any actuator.

(25) Position open: in this position the filling medium can pass the tube clamp unhindered. It is the start and end position for all channels in which the tube system can be simply inserted or removed, is also used for venting the measuring channels and is the normal operating state of the infusion channel.

(26) Position closed: in this position the tube is completely clamped and even at pressure differences up to 2 bars it is impassable for the fluid. It is the operating state for already vented measuring channels and the temporary initial state for the infusion channel when the measuring channels are vented or perfused.

(27) Position perfused: in this position, largely independently of the admission pressure, only very small quantities of the filling medium (max. 8 ml/min) can pass the clamping point. This is achieved in that even though the tube is clamped with fully force in similar manner to the closed position, in the wall of the tube a small opining is always kept free by a spacer, such a thread, which brings about a capillary reduction of the filling medium flow. This position is used for channels which require perfusion (urethral pressure).

(28) Integrated in the pump tubeas shown in FIG. 4are the infusion tube 21, the venting hoses 34 to 36 for the threepossibly any number ofpressure channels and the dome cassette 25. The pump/infusion tube 21 also has a spiked connection 30 for an infusion bag and Luer locks 37 for connection of the catheter. When using the system with a roller pump the tube system has a suitable compressible tube segment 31 in this segment which it integrated into the tube system through appropriate connectors 32. Via the distributor 23 the tube system is dispersed over the four hoses 33 to 36 shown here. In addition to the actual tube 42, the tube 33 also comprises the spacer 43 as can be seen in the detailed view in FIG. 4.

(29) Particularly advantageous in the present invention is the integration of threepossibly any numberof domes in a dome cassette and the common coupling of the channels to the sensors via a pressing roller and the clamping edge. Webs integrated into the dome cassette act on the pressing roller and clamping edge side as spring elements, which produce the required pressing pressure of the membranes, which are preferably arranged on the base section of the pressure domes, on the sensors.

(30) This design has the great advantage over the conventional solution with individual domes that production is very much more cost-effective and handling is extremely simplified. Instead of placing each dome individually on its sensor as in the previous solutions, it is sufficient to insert the cassette which through the subsequent pressing of a button is turned with the pressing roller into the closed position via an actuator. The previously high number of required sterile components is reduced to a single disposable product.

(31) As in many areas of application the sensor can be placed above the measuring locations in the body, as a result of the hydrostatic force of the water column negative pressures (lower than atmospheric pressure) also occur in the dome which are then not measured through pressure on the sensor surface but through tension. To produce the suction effect required for this the contacting between the membranes and sensor must be completely airtight. For this a pressing force is required.

(32) FIG. 5 shows an exploded view of the assembly of the pressure dome cassette 51 with the pressure measurement sensors 54. In addition to the dome cassette 51, the pressing roller 52, the holder 53 with the clamping edge 55 can be seen. Reference number 56 denotes the positions in relation to the dome cassette 51 which are fitted with a pressure measurement indicator. In position 57 no pressure measurement indicator is envisaged.

(33) FIGS. 6a to 6d show detailed views of the dome cassette 25 and locking arrangement on the pressure measurement sensors. In FIG. 6a a side view of the dome cassette 25 is shown in which the connections 60, the pressing web 61 and parts of the fluid domes 62 can be seen. In FIG. 6b a view from above of the dome cassette 25 is shown in which the other connections 63 and the rear pressing web 64 can also be seen. FIG. 6c is a further side view in which in addition to the two connections 60 and 63 the two pressing webs 61 and 64 and the angle arrangement of the supply lines 60 and 63 with regard to each other with angle and with regard to the base with angle are shown.

(34) FIG. 6d shows the arrangement of the dome cassette 25 on the pressure measurement indicators, wherein the dome cassette 25 is aligned via the pressing web 61 in the holder 53 and fixed by means of the pressing roller 52 and its axial slit in combination with turning. The holder 53 also comprises the guide 69 and 68 as a direct or indirect component part of the holder, which in the corresponding positions also comprises the pressure measurement indicator (not shown here). In addition to the holder, in this view the connections 60 and 63 can also be seen, wherein the connection 60 also has a Luer lock 65.

(35) In FIG. 7 by way of the process stages the course of the pressure at the corresponding positions or settings of the components is shown. P.sub.ura, P.sub.ves, and P.sub.abd stand for the pressure in the corresponding pressure domes, V.sub.inf and Q.sub.inf for the infusion volume tune and the fluid flow and clamp pump, clamp P.sub.ura clamp and P.sub.abd and clamp P.sub.ves for the switching position of the corresponding tube clamp. The process is described as an example below:

(36) 1) The user places the dome cassette 25 of the pump tube 21 into the device and inserts the spike connection 30 into the infusion bag 20.

(37) 2) The locking mechanism is closed, whereby through the pressing pressure of the domes 25 on the sensors a pressure offset occurs.

(38) 3) The pressure offset is automatically balanced out (zeroed) after a material relaxation time of 5-10 seconds. At the same times the tube clamps 24 of the pressure channels 26 and 27 are closed.

(39) 4) The user places the transurethral catheter 29 in the bladder and the rectal catheter 28 in the rectum of the patient (if this has not already been done) and connects the pump tube 21 and the pressure transmission tubes with the Luer locks of the dome cassette 25. As of this moment the user can check the correct placement of the catheter 28, 29 by means of rest pressure values shown on the device, which are now measured via the air columns of the pressure transmission tubes and catheter lumen.

(40) 5) If the rest pressures show plausible values, the user starts the fully automatic venting and zeroing procedure by pressing a button on the device, whereupon the entire infusion line is vented.

(41) 6) In the hatched time interval all the measuring changes measure the rest pressure at the relevant measuring site via the air column. In order to minimise any fluctuations through movement of the patients or disturbances the average value measured by the channel during this period is calculated and subsequently use as the rest pressure value for zeroing.

(42) 7) As the volume of the infusion line (tube plus filling volume of the catheter) is precisely known and the quantity of the filling medium conveyed through the volume transducer and rotations of the rolling wheel of the pump 22 is constantly measured, the venting can be fully automatically ended when the water column reaches the filling lumen output. The pump tube clamp 24 is closed.

(43) 8, 10, 12) The venting of the pressure transmission tubes than always takes place sequentially in the same way. The relevant tube clamp is opened, while all the others are closed and the pump conveys the filling medium at a defined filling rate through the relevant pressure transmission line. It should be noted, that during filling, due to the increasing water column a hydrostatic and also a dynamic component are increasingly added and no longer is the actual pressure at the measuring location determined.

(44) 9, 11, 13) As the volumes of the pressure transmission lines are known and the filling quantity is constantly measured the venting process can be fully automatically ended when the water column has reached the measuring lumen outputs. The pump 22 is stopped and the relevant tube clamp 24 closed. At this moment the device measures the current pressure at the measuring location in the body plus a hydrostatic pressure resulting from the unknown difference in height between the measuring location and the sensor. This is now fully automatically calculated by setting the measuring channel to the rest pressure measured via the air column in (6) by means of the software.

(45) 14, 15) The correct placement of the catheter is checked in a final stage by asking the patient to cough and comparing the resulting pressures peaks. For this the tube clamps 24 of all channels which required perfusion for the measurement (P.sub.ura in urodynamics) are automatically set to the perfusion setting and the pump 22 to perfusion speed.

(46) 16) The preparatory phase is completed and the actual measurement can begin.