DE102009005048A1 - Inspiratory leakage volume determining method for use during provision of artificial respiration to patient, involves determining real total volume by subtracting inspiration time from inspiratory total volume - Google Patents

Abstract

The method involves measuring an inspiratory pressure average value between a measured expiration pressure and an inspiratory point pressure. A multiplication factor is determined from the determined inspiratory pressure average value. An expiration pressure leakage flow (2) is measured and stored. The determined multiplication factor is multiplied with an inspiration time (1) such that an inspiratory leakage volume (3) is determined. A real total volume (5) is determined by subtracting the inspiration time from an inspiratory total volume. An independent claim is also included for a device including a programmable microprocessor for automatically controlling a respirator.

Description

introduction

The The invention relates to a method for determining an inspiratory Leakage volume in artificial respiration under the Conditions of changing parasitic leaks and different Nominal losses, using the proposed calculations to the true inspiratory leakage volume is determined and from it resulting, referring to the measured inspiratory volume, the total volume (called real total volume) is calculated which actually participated in the gas exchange in the patient's lungs Has.

The The invention further relates to a device in the form a control unit for respirators, which the determined in the proposed method inspiratory leakage volume used to increase the supply of inspiratory volumes and pressure limits to control and correct.

definitions

The have in the following explanations mentioned technical terms within the scope of the present application and within the scope of the description mechanical ventilation following meaning and functions:

Inspiratory total volume (ventilation volume)

at artificial ventilation will be the replacement of the consumed Breathing air supported by ventilator. The The amount of air that is put into the lungs per breath is that inspiratory volume (hereinafter called "Vti").

Real tital volume

The Ventilation volume, which actually every breath in the lungs participated in the gas exchange and exhaled again is called (hereinafter "Vt P").

inspiratory pressure

Of the Pressure used in mechanical ventilation during inhalation in the Lung and the respiratory system (hereinafter referred to as "IPAP").

Inspiratory peak pressure

Of the maximum pressure during mechanical ventilation during inhalation achieved in the lungs and the respiratory system.

Mean inspirational pressure

Value, usually the mean airway pressure over indicates the total inspiratory time until the end of expiration. For the purposes of this invention, however, only the pressure curve during inspiratory time important, so here only the mean pressure value during the time Ti is used for calculations becomes.

Inspiration pressure relief

from Ventilator max. admitted pressure during inspiration to give the lungs a given volume of ventilation feed (hereinafter called "Pmax").

expiratory

Of the Pressure at machine ventilation at the end of exhalation in the lungs and respiratory system until the next inhalation held (hereinafter referred to as "PEEP").

inspiratory time

The Time in which the ventilation volume is administered to the lungs (hereinafter called "Ti").

Leckages

The opening within the ventilation system, out of the permanent or temporary a part of the air that is a lung in mechanical ventilation is supplied or exhaled by this, in the Environment escapes (hereinafter called "LÖ").

nominal leakage

The opening within the ventilator system with a defined size, from the constantly part of the air, which is a lung the mechanical ventilation should be supplied or the is exhaled by this, escapes into the environment. This nominal leakage is deliberately used in so-called open ventilation systems, even without a controlled exhalation valve an active exhalation of the lungs to allow and the CO2 from the exhaled air of the lungs rinse. This is done by a passive expiratory valve (see also Whisper Swivel) with one or more openings or a mask realized with corresponding openings. Depending on the manufacturer and type, there are differences in the leakage flow from 10% to 30% known.

Parasitic leakage

The opening within the ventilation system of unknown magnitude, from which, constantly or temporarily, part of the air which is to be supplied to a lung during mechanical ventilation or which is exhaled by it escapes into the environment. In non-invasive ventilation (also called mask ventilation), more or less frequently changing parasitic leaks occur at the contact points between the mask system used and the face of the ventilated patient. In invasive ventilation (via Trachiostoma), parasitic leaks are sometimes deliberately tolerated (eg when using special ventilation cannulas, unblocked cannula for ventilating children, partially unblocked cannulas to allow the patient to speak, etc.). These leaks are not constant and are subject to constant change.

Inspiratory leakage volume

The Amount of ventilation volume delivered by the ventilator in However, the direction of the lungs is lost on the way there Ambient air escapes.

Pressure-controlled ventilation

Ventilation mode, when the ventilator as long as a flow of air to the lungs is passed until a specified inspiratory pressure is reached, then held according to a predetermined time until the Exhalation is initiated.

Pressure controlled ventilation with target volume

pressure-controlled Ventilation, where the ventilator achieved the inspiratory Titalvolumen monitors and falls below, increases the inspiratory pressure within defined limits, as well as lowered again.

Volume-controlled ventilation

Ventilation mode, for the ventilator, a set ventilation volume is conducted to the lungs.

Volume-controlled ventilation with pressure regulation

volume controlled Ventilation, where the ventilator is within a fixed range Limits allow a higher or lower limit pressure, depending on whether the specified ventilation volume is administered could or not.

pressure curve

Of the Time course of the pressure in the ventilation system.

flow curve

Of the Time course of the air flow (flow) in the ventilation system.

ventilation cycle

To a complete Ventilation cycle is the inspiration, expiration and the respite until the beginning of the next inspiration.

Resistance

Of the Flow resistance that the airways oppose to the airflow.

compliance

The Elasticity of the lung.

State of the art

In the applications DE 10 2004 014 619 A1 and DE 10 2005 061 439 B3 various maneuvers are described, which must be performed in addition to the set ventilation in order to calculate a leakage, which leads to the influence and disturbance of the ventilation. In the application 10 2008 048 824.0, a comparable result is achieved by means of measured leakage openings and a ratio equation "Vti Leakage: Vte Leakage = Ti: Te", but with the aid of other methods. This invention is only in the testing phase and not yet available on the market. In the following description, although the same objective is pursued, but another approach is taken.

The ventilators on the market i. d. R. on a calculation and display of the inspiratory Titalvolumens (hereinafter called Vti). This is done by means of or patient-mounted sensor technology. Possibly. existing parasitic leaks remain unconsidered.

The (real) total volume (Vt P), which is active in the gas exchange in the Patient lung participates, agrees under the conditions of existing Leakage, usually with the ventilator did not even approximate Vti.

Occasionally, the ventilators incorporate leakage calculations that represent only a percentage difference between the measured inspiratory and expiratory volumes. These are only applicable to double-tube systems and can not be included in the volume volume or ventilator control and regulation in terms of volume or pressure regulation, as the inspirator's contribution to volume control or pressure regulation is limited and expiratory leakage can not be determined.

Separate Take into account controls of respirators in the regulation of permissible inspiratory pressure or the delivery of a ventilation volume that is changing Resistance and / or compliance of the lung. When parasitic There are leaks depending on their size z. T. significant deviations from a previously optimized ventilation. These deviations can lead to a considerable additional effort in the course of therapy, because the deviations the actual ventilation of the medically prescribed can only be detected by additional investigations. Only in retrospect, can so far accordingly manual adjustments to the ventilation parameters to adjust the ventilation artificial respiration or the support of the Be made spontaneous breathing.

To step in the known pressure-controlled ventilations coincident with the Changes in the resistance and / or compliance of the patient lung, parasitic leaks in the respiratory system, these become Changes in resistance and / or compliance in one automatic correction of a target volume or a pressure limit Pmax is not taken into account or misinterpreted as the pressure / flow curves and the measured volumes are corrupted by the leaks become.

at The known volume-controlled ventilations become parasitic Leaks are not balanced, as the leakages are not detected and thus can not be used to correct the control.

To step in volume modes with pressure regulation of a Pmax simultaneously with the Changes in the resistance and / or compliance of the lungs parasitic leaks in the respiratory system the ventilators do not do these changes qualify more because the measured pressure / flow curves and the measured Volumes corrupted by the parasitic leaks become. The measured Vti agrees with the actual Volume, which participates in the gas exchange, do not match, which inevitably leads to a misjudgment of one to be regulated Inspiratory volume and / or inspiratory pressure leads. For these reasons, so far are any volume of ventilation insufficiently suitable for non-invasive ventilation.

task

It Object of the present invention, a method for automatic Determination of the inspiratory leakage and thus for display the real tital volume (Vt P), which at each breath on the gas exchange in the lungs participates, to create.

Farther This Vt P is supposed to automatically affect the control of the Ventilation be used. The device for automatic control individual ventilation parameters taking into account the new Vt P is said to provide a more stable supply of fresh lung to the lungs Lead breathing gas.

embodiment

The The invention with reference to the method will be described below with reference to an embodiment described in the drawings.

The 2 to 4 are diagrams for a better understanding of the invention, but are used in the program parts of the control by means of numerical calculation formulas.

1

The basic functions of a conventional ventilator ( 1 ) are that the control and monitoring of all functions is CPU-based. The control program is made available in a memory area, where data collected during ventilation are stored for further use. Furthermore, a ventilator has a monitoring, on which predetermined and measured ventilation parameters are displayed numerically and / or graphically. Keypads, knobs, or touchscreen screens are used as the keypad for entering setpoints or recalling data during machine ventilation. The necessary for controlling actual values such. As pressure and flow are measured by means of electrical sensors inside the device or close to the patient. By means of controlling a turbine or compressed gas valves, the lung to be ventilated is supplied with a defined ventilation volume or a ventilation pressure over a defined time with a defined ventilation frequency. Typically, a modern ventilator has a detection (triggering device) that signals to the device that the patient needs additional breaths, which the device then supports.

In the program part 3 An existing PEEP leakage flow is automatically measured and stored. In the program part 4 is first determined with the aid of Pi medium of the multiplication factor M. With the following calculation formula is in the program part 5 the inspiratory leakage volume Vti leak is calculated: Vti leak = PEEP flow × Ti × M

The next step is in the program section 6 automatically calculated by subtraction between Vti and Vti leak the Vt P calculated. In the program part 7 is formed by automatic comparison between the setpoint in the form of a ventilation volume (Vt) or a target volume (target Vt) and the determined Vt P a correction value. This then automatically influences the control for the next breath.

Description of the facility

The Device according to the invention is designed that the determined Vti leakage is used to calculate the Vt P and this is automatically displayed in the monitoring, which allows a more accurate follow-up of artificial respiration.

The Device is designed to be used for the controller of pressure ventilation modes with integrated target Vt using this Function, now for the adaptation of the Pmax, not as hitherto possibly faulty Vti, but the determined Vt P is taken into account. The automatic adjustment, as a result, the Vti at the next Breath changes, can now be considered objectively respectively. The steps for adjusting the Pmax are not smaller than 0.5 mbar and not more than 3 mbar, depending on Amount of deviation. Deviates the determined Vt P despite corrective control at least 3 ventilation cycles in a row by more than 10% of the target Vt off, an audible and visual alarm as an indication of generates the user / operator of the device. A variably adjustable Alarm limit regarding the amount of deviation is planned. The function of automatic adjustment of Pmax, on the basis of the calculated Vt P is deactivatable for the cases where med. Problems of the ventilated patient This feature is not desired and / or contraindicated is.

For the control of volume ventilation modes is the device according to executed so that the determined Vt P for automatic Adjustment of the originally given Vt is used. The adjustment steps are not less than 5% and not greater than 10% of the given Vt, depending on from the amount of deviation. Volume modes that already have algorithms for adjusting the allowable inspiratory pressure Pmax, w. z. B. PRVC, are controlled so that to judge whether the Vt due to changes in resistance and / or compliance was not achieved, or whether these measurements are due to leaks that the calculated Vt P is used. The automatic adaptation of a Pmax takes place under objective aspects by comparing the Vt and the Vt P. The steps to adapt are not smaller than 0.5 mbar and not larger than 3 mbar, depending on the amount of deviation.

differs the determined Vt P despite corrective control for at least 3 ventilation cycles consecutively by more than 10% from the target Vt, an acoustic and visual alarm as an indication to the user / operator generated by the device. A variably adjustable alarm limit in terms of the amount of deviation is provided. The function of automatically adjusting the Pmax based on the calculated Vt P is deactivatable, for the cases in which med. Problems of the ventilated patient this function not wanted and / or contraindicated.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102004014619 A1 [0025]
• - DE 102005061439 B3 [0025]

Claims (2)

Method for the automatic determination of an inspiratory leakage volume, characterized in that, using known methods for measuring a leakage flow, a novel multiplication factor M, which is measured from a first-time determined inspiratory pressure mean, which is measured between a measured PEEP and a peak inspiratory pressure, with the inspiratory time Ti, whereby an inspiratory leakage volume is determined, with the aid of which, by subtracting this from the inspiratory volume of the stomach, the real total volume of the stomach is determined. Device with a programmable microprocessor for automatic control of a ventilator, thereby characterized in that using claim 1, the automatic Regulation of a volume to be delivered or a regulated one Ventilation pressure limitation in artificial respiration under Consideration of occurring parasitic leaks and different nominal leakages and the real total volume is displayed.