WO2009144628A1

WO2009144628A1 - System for determining a medication dosage in airway disorders

Info

Publication number: WO2009144628A1
Application number: PCT/IB2009/052099
Authority: WO
Inventors: Maryam Atakhorrami; Teunis J. Vink
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2008-05-28
Filing date: 2009-05-20
Publication date: 2009-12-03

Abstract

A system (10) for determining a medication dosage in airway disorders, the system (10) comprising a mouthpiece (11), an NO-sensor (12), means for measuring an airflow obstruction, a memory (13), a personalization module and a medication dosage prescription module. The mouthpiece (11) is arranged for receiving exhaled air during an exhalation. The NO sensor (12) is coupled to the mouthpiece (11) for measuring an NO concentration of the exhaled air. The memory (13) stores the measured NO concentration, and a corresponding measured airflow obstruction level. The personalization module determines a personal reference level and at least one personal threshold. The personal reference level of exhaled NO is based on NO concentrations and corresponding airflow obstruction levels stored in the memory (13). The at least one personal NO threshold (T1) is based on the personal reference level of exhaled NO. The medication dosage prescription module prescribes a medication dosage based on the NO concentration and the at least one personal NO threshold (T1).

Description

System for determining a medication dosage in airway disorders

FIELD OF THE INVENTION

This invention relates to a system for determining a medication dosage in airway disorders.

BACKGROUND OF THE INVENTION

Published US patent application US 2005/053549 describes a method for management of asthma and other respiratory conditions using exhaled nitric oxide (NO) readings to measure airway inflammation, thereby allowing precise titration of medication. The method of US 2005/053549 can also be used to measure patient compliance with prescribed treatment regimes.

It is a problem of the method of US 2005/053549 that it is mainly used for assisting a physician in determining a treatment program for the patient and does not provide a safe and easy to use device for enabling the patient to take an optimal dosage of the medication. More important, the method in US 2005/053549 only compares current exhaled NO values to previous measurement values. These previous measurement values may be exceptional and thus less useful values for use as a reference.

OBJECT OF THE INVENTION

It is an object of the invention to provide a system for more reliably determining the medication dosage.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, this object is achieved by providing a system for determining a medication dosage in airway disorders, the system comprising a mouthpiece, an NO sensor, means for measuring an airflow obstruction level, a memory, a personalization module and a medication prescription module. The mouthpiece receives exhaled air during an exhalation. The NO sensor is coupled to the mouthpiece for measuring an NO concentration of the exhaled air. The measured NO concentration and a corresponding measured airflow obstruction level is stored in the memory. The personalization module determines a personal reference level of exhaled NO based on NO concentrations and corresponding airflow obstruction levels stored in the memory. The personalization module further determines at least one personal NO threshold (Tl) based on the personal reference level of exhaled NO. The medication dosage prescription module prescribes a medication dosage based on the NO concentration and the at least one personal NO threshold (Tl). A problem with measurements in known systems appears to be that the measured NO concentration may depend on the amount of airway obstruction in the patient, while the amount of airway obstruction may vary from day to day irrespective of the inflammatory status of the airways. The system according to the invention mitigates this problem.

The personal reference level of exhaled NO is used as a starting point of the medication prescription algorithm. Preferably, the personal reference level is based on multiple exhaled NO and measurements and airflow obstruction measurements performed at different moments in time and with different levels of airflow obstruction. For example, one or two weeks of daily measurements may be stored and the minimum exhaled NO level or the average of a number of relatively low exhaled NO levels in this period is then used for determining the personal reference level of exhaled NO. NO measurements may be corrected for the measured corresponding airflow obstruction levels or may only be taken into account if the corresponding airflow obstruction level is within a predetermined range. The means for measuring an airflow obstruction level may, e.g., be a peak expiratory flow meter or other spirometric test equipment. For example, the means for measuring the airflow obstruction level may be used for determining the exhaled NO level when airway obstruction is minimal.

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Figure 1 schematically shows an embodiment of a device according to the invention, and

Figure 2 shows a flow diagram of a method of operation for the system according to the invention.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 schematically shows an embodiment of a device 10 according to the invention. The device 10 comprises a mouthpiece 11 for allowing the user to exhale air into the device 10. The exhaled air is led through the device 10 to an NO sensor 12. The NO sensor 12 determines the concentration of NO (nitric oxide) in the exhaled air. The measured values of exhaled NO are used for managing the treatment of airway disorders. The exhaled NO values may be used for monitoring the effectiveness of a treatment as well as for prescribing a future medication dosage. The measured NO concentrations may be stored in a memory 13. Preferably the measured NO concentrations are stored together with a relevant day and time of the corresponding measurement. Data processor 14 uses the stored NO concentrations to determine the personal reference level of exhaled NO. For example, the processor 14 may select the lowest NO concentration measured over a predefined period of, e.g., one or two weeks as the personal reference level. Alternatively, the processor may average two or more measured NO concentrations. The device 10 further comprises means (not shown) for measuring an airflow obstruction level, such as a peak expiratory flow meter or other spirometric test equipment. Values for the assessed obstruction of the airways are also stored in the memory 13. Airway obstruction levels are preferably stored together with corresponding NO measurements or with a date and time of the measurement, such that it becomes possible to relate airway obstruction levels to exhaled NO concentrations at the same moment in time. The airway obstruction levels may then be taken into account when determining the personal reference level of exhaled NO. For example, the personal reference level of exhaled NO may be defined as the NO concentration in exhaled air when the airflow obstruction level is minimal or exhaled NO levels may be disregarded or compensated when the airflow obstruction level is not within a predetermined range. Based on the personal reference level of exhaled NO, one or more personal NO thresholds are determined by the processor 14. The personal NO threshold is used for determining whether a user should increase, decrease or maintain a certain medication dosage. For example, exhaled NO levels above a first threshold (Tl) may indicate that the medication dosage should be increased by a certain amount. Even higher exhaled NO levels may result in prescribing even higher medication dosages or a suggestion to contact a doctor. The medication prescription is provided to the user via a user interface, e.g., comprising a display 15 for displaying information digitally. Alternatively an analogue dosage indicator or synthesized audio may be used for prescribing a medication dosage. The device 10 may further comprise some buttons, sliders or other user interface elements 16 to enable the user to operate the device or browse through an operation menu or a presentation of data on the display 15.

Figure 2 shows a flow diagram of an exemplary method of operation for the system according to the invention. The value of exhaled NO and airflow obstruction are obtained and stored by relevant day and time (step 21). Anti- inflammatory asthma management for individuals starts after a trial of inhaled glucocortisteroid (ICS) drug for a number of days (e.g. Beclomethasone for 5 days) as prescribed by doctor or suggested by the NO-sensing device 10 (step 22). One can also use the combination medication such as Adviar. The values of exhaled NO and peak expiratory flow (PEF) are registered every day in the morning (step 23). The device 10 may ask the user whether he or she experiences any side effects (step 24) and may suggest to call a doctor if required (step 25). The personal reference value of exhaled NO (eNOo) may be obtained when PEF is at its maximum predicted level (step 26). The personal reference value is the key parameter used in the algorithm of titration of ICS. This algorithm may, e.g., be as follows: First we define two thresholds Tl and T2 as a multiplication function of eNOo.

These values will be defined for each individual, with the help of a medical doctor or a medical device. Tl < T2 (e.g. Tl = 1.5 eNOo and T2 = 2.5 eNOo). For example, Tl describes the no action limit and T2 describes a 'consult physician' limit. We can define 4 different regimes that the frequent measurement of exhaled NO (daily, weekly, etc) should be compared to: i) No action regime: if the measured level of exhaled NO remains in the interval of eNOO < Tl, the ICS dose is kept constant. ii) Step-up regime: In interval of Tl < eNO < T2, then increase the ICS dose as prescribed by the medical help, e.g., with some percentage. iii) Step-down regime: In interval of exhaled NO <T1 then decrease the ICS dose as prescribed by the Medical help, e.g., with some percentage. iv) Refer to medical doctor if the level of exhaled NO > T2.

For example, the device first checks whether the exhaled No level is in the fourth regime (step 28) and if so, will suggest to call a doctor (step 29). Alternatively, the device 10 itself may automatically alarm a doctor via, e.g., GSM, SMS or e-mail. If the exhaled NO level is below T2, the device determines what medication dosage to suggest (step 30) and communicates the prescription to the user (step 31), e.g., via a display.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS:

1. A system (10) for determining a medication dosage in airway disorders, the system (10) comprising: a mouthpiece (11) for receiving exhaled air during an exhalation, an NO sensor (12), coupled to the mouthpiece (11) for measuring an NO concentration of the exhaled air, means for measuring an airflow obstruction level, a memory (13) for storing the measured NO concentration, and a corresponding measured airflow obstruction level a personalization module for determining: a personal reference level of exhaled NO based on NO concentrations and corresponding airflow obstruction levels stored in the memory (13), and at least one personal NO threshold (Tl) based on the personal reference level of exhaled NO, and a medication dosage prescription module for prescribing a medication dosage based on the NO concentration and the at least one personal NO threshold (Tl).

2. A system (10) for determining a medication dosage in airway disorders as claimed in claim 1, the personalization module further being arranged for determining a further personal NO threshold (T2) based on the personal reference level of exhaled NO and the prescribing the medication dosage is further based on the further personal threshold (T2).

3. A system (10) for determining a medication dosage in airway disorders as claimed in claim 2, the medication dosage prescription module being arranged for: prescribing a medication dosage decrease when the concentration of NO is below the personal reference level of exhaled NO, prescribing a medication dosage stabilization when the concentration of NO is between the personal reference level of exhaled NO and the at least one personal NO threshold (Tl), prescribing a medication dosage increase when the concentration of NO is between the at least one personal NO threshold (Tl) and the further personal threshold (T2), activating an alarm mode when the concentration of NO exceeds the further personal threshold (T2).

4. A system (10) for determining a medication dosage in airway disorders as claimed in claim 1 , wherein the means for determining the airflow obstruction level is a peak expiratory flow meter, coupled to the mouthpiece (11).

5. A system (10) for determining a medication dosage in airway disorders as claimed in claim 1, wherein the personal reference level of exhaled NO is defined as the stored NO concentration corresponding to the lowest stored airflow obstruction level.