SE453884B - SET AND DEVICE FOR DETERMINING ATMINSTONE TWO PNEUMATIC LUNG PARAMETERS - Google Patents

Description

453 884 Due to the large spread of the measured values in the breathing air flow, in hitherto known devices the calculated or indicated pneumatic lung parameters have had too little accuracy for many monitoring end needles. The object of this invention is to provide a method and a device of the type stated in the introduction. whereby the desired pneumatic lung parameters can be quickly determined with high accuracy.

This object is fulfilled by a method and a device of that kind. as stated in the appended claims, wherein the method and the device exhibit the characteristics stated in the main claim and the claim 2, respectively, of claim 2.

In the practical design of the device, the signals generated by pressure and flow sensors are measured in an electronic circuit, and by integrating the flow measurement or direct measurement, the volume is determined. The greats. which forms a value triplet is then available as electrical voltages and is scanned accordingly.

For assigning the triplet values with respect to the inhalation or exhalation phase, the device flexibly tests the flow profile. If the flow for some time is equal to 0 and suddenly becomes> 0, then the beginning of the exhalation is assumed to exist. and in connection therewith, the required value triplets p, V, Ü, which are generally in the highest possible number, are gradually fed during the exhalation phase. whereby also the magnitude values of the rising course of the flow must be included. These serve to recognize and distinguish between the inhalation and exhalation phases. In the exhalation phase, the value maximum of the flow normally occurs approximately 50 ms after the beginning of the exhalation. The scan time period, ie the time period during which the value triplets are gradually fed in, must be at least equal to the time constants of the lung. 453 884 On for example the values of RI. Rz. C and Po must be passed. then this can be done starting from the linear equation system. in which equation the coefficients are formed by four value triplets (p. Ü and V). The linear system of equations is solvable only on two of the quantities p. Ü and V from case to case are not linearly dependent.

This direct determination includes all network errors, and in addition the calculation fails on any of the three quantities p, Ü and V is constant. On nan still consumes a plurality, especially a variety, of value triplets. then the above-mentioned linear system of equations can be expressed by the 'least squares method' as follows: í = n __. to | 1 2 _ E \ ïí + R1. Vi + R 2. . V. V). t! u In this case, the instantaneous value of the flux V0 means the volume of the inflated lung at the end of the inhalation, the instantaneous value of the pressure in front of the nun Po the alveolar residual pressure R the linear part of the respiratory tract resistance 453 884 ie inverted the value of the elasticity of the lung.

Then the required number of value triplets is gradually ingested. is calculated and indicated by the specified system of equations from n gradually loaded network value triplets the network-technically optimal values for RI. R2. C and Po. The device may, after each breath, indicate the values of RI, R2, C and Po applicable to that breath.

The flow is preferably measured in the exhalation branch, but the measurement is also feasible in the inhalation branch or in the general respiratory air line.

The device also works if the patient would not be connected to the device for supplying breathing gas. but would only be inhaled and exhaled via a mains pipe, and by means of the corresponding valve control it is ensured that at the beginning of the exhalation p> 0 and p fall. while | Ü | stiger. The usefulness of the device is further given. on the patient is supplied with breathing gas during spontaneous or INV or Släv conditions, similar to PEEP.

In simpler embodiments of the device, only two pneumatic lung parameters can be ordered, if applicable. pre- 1 linear part and compliance C. while omitting the quadratic part of the respiratory tract node R of the respiratory tract node R and the alveolar residual pressure Po.

The determination affects p, Û or V either during the inhalation or during the exhalation phase. Nor is it necessary that an end plate for inhalation or exhalation is achieved for p, Ü or V: The existence of a linear exhalation notch does not form any precondition for the usability of the device. which remains useful even for non-linear exhalation resistances.

The accuracy of the measurement result decreases the number of value triplets scanned. This number is almost the greater, the greater the measurement errors in the individual stock quantities p. V and V. 453 884 With reference to the accompanying drawing, a suitable embodiment of the device according to the invention is described below, for example. The figure of the drawing shows the block diagram of the device.

In an exhalation branch 1, which consists of a corresponding valve device, there is a flow sensor 2. whose output signal is consisted of a network value unit 3 of flow quantity Ü and by integration is transferred to a volume quantity V.

In a continuous breathing air line 4 a pressure sensor 5 is arranged, the output quantity of which is also supplied to the network value unit 3 and son p is incubated. In the light value unit 3 the quantities p, Û and V are thus present at all times by scanning from a downprop equipped with a microprocessor calculation device 6. son genon monitoring of the magnitude values of the flow as a supplement determines the beginning of the desired network phase (inhalation or exhalation).

The value triplets scanned by a scanning device 7 during the mains phase, approximately 250 value triplets, are taken into a erasable memory device 8. at the end of each mains phase the value triplets are transferred from the memory device 8 to the computing device 6, where the linear equation system is calculated. the optimum value of the pneumatic lung parasites R1, R2. C and Po. son shall be maintained, and indicated in an indicating device 9.

The exhalation branch 1 and inhalation branch 10 of the common breathing air line 4 are in the present case connected to an apparatus 11 for supplying breathing gas.

Claims (5)

10 15 20 25 30 35 453 884 Patent claims 1. l. Method for determining at least two of the following. pneumatic lung parameters. namely, the linear portion (RL) of the airway resistor, the square portion (R2) of the airway resistor. compliance (C) and the alveolar residual pressure (Po). in particular in connection with an apparatus (II) for supplying breathing gas. an input signals from a pressure sensor (5) and a flow meter (2) from the breathing air line (4) are supplied to a device for carrying out the method during the measuring process, and a time-controlled integrator from the flow signal forms a corresponding volume signal or whereby volume determination takes place. by means of a volume measuring device. and further from these signals the desired pneumatic lung parameters are determined. The fact that the instantaneous values for pressure, flow and volume are determined as value triplets, that the desired measuring phase (inhalation and / or exhalation) is present is determined from a measuring quantity for 10 PPP. that a predetermined number of these value triplets are gradually fed into a memory device (8), that the contents of the memory are queried and the desired pneumatic lung parameters are calculated from per se known linear equation systems, and that the memory device (8) is deleted and the process repeated from the beginning. Device for carrying out the method according to claim 1, characterized in that a scanning device (7) is provided, which at intervals scans associated signals for pressure, flow and volume as value triplets and within each breathing cycle inputs at least two such value triplets in a periodic erasable memory device (8). and that a computing device (6) is provided, which is connected to the scanning device (7) and the memory device (8). and which, from the value triplets stored afterwards, calculates the desired lung parameters from per se known linear systems of equations. and that this calculation device (6) is connected to an indicating (9) and / or control device, which indicates the lung parameters and / or emits them for controlling an apparatus for supplying breathing gas. 453 884 Device according to Claim 2, characterized in that at least 50 value triplets are scanned within a breathing cycle. 4. Device according to claim 2 or 3, characterized in that the scanning of the value triplets takes place exclusively during the inhalation or exhalation part of the breathing cycle. 4 Device according to claim 2, characterized in that the computing device (6) comprises a microprocessor.