Controlling an alarm in a medical instrument

• US 8,622,902 B2
• Filed: 01/19/2009
• Issued: 01/07/2014
• Est. Priority Date: 01/21/2008
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Woehrle, Dieter
• Primary Examiner(s): Thomson, Bill
• Assistant Examiner(s): SORIANO, BOBBY GILES
• Application Number:
  US12/863,008
• Publication Number:
  US 20100324377A1
• Time in Patent Office: 1,814 Days
• Field of Search: 600300-301, 34053912-53914, 705 2- 4
• US Class Current: 600/301
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02455 provided with high/low alarm devices
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2230/00 Measuring parameters of the user
• CPC Class Codes: A61N 1/37258 Alerting the patient
• CPC Class Codes: G16H 40/63 for local operation

Abstract

The invention concerns a method for controlling an alarm in a medical instrument or system, the medical instrument or system detecting at least one physiological parameter of the patient. The present value of the physiological parameter is consecutively detected and an alarm delay is determined as a function of at least one detected value of the physiological parameter wherein the function yields a shorter alarm delay for increasing values of the deviation from a normal value and a longer alarm delay for decreasing values of the deviation from the normal value. Further, the duration the value of the physiological parameter exceeds or under-runs at least one predefined threshold for the physiological parameter defining an upper or lower limit for a normal range of the physiological parameter, respectively, is measured and the alarm is generated when the duration the determined value of the physiological parameter exceeds or under-runs the predefined threshold exceeds the alarm delay. This method allows for the avoidance of nuisance alarms while still indicating severe conditions of the monitored patient reliably.

Claims

1. A method for controlling an alarm unit in a medical instrument or system, the medical instrument or system detecting at least one physiological parameter of the patient, the method comprising:

with the medical instrument or system, consecutively detecting a present value of the physiological parameter;

with a determination unit, after detecting the present value of the physiological parameter, determining an alarm delay as a function of at least one detected value of the physiological parameter wherein the function yields a shorter alarm delay if the degree by which two consecutively determined values of the physiological parameter deviate from a normal value increases, and wherein the function yields a longer alarm delay if the degree by which two consecutively determined values of the physiological parameter deviate from the normal value decreases;

measuring a time the physiological parameter has exceeded or under-run at least one predefined threshold for the physiological parameter defining an upper or lower limit for a normal range of the physiological parameter, respectively;

starting a limit violation counter running after a first of multiple directly consecutive events of detected present values of the physiological parameter that exceed or under-run the threshold, respectively, and wherein the value of the alarm delay is continuously updated according to the function of at least the detected value of the physiological parameter;

determining the value of the limit violation counter when a detected present value of the physiological parameter has returned into a normal range, a reduction value is calculated as a function of the detected present value of the limit violation counter and/or the degree by which the detected present value of the physiological parameter exceeds or under-runs the predefined threshold, and the reduction value is decremented in time; and

controlling the alarm unit to generate an alarm when the time of the physiological parameter exceeds or under-runs the predefined threshold, respectively, exceeds the alarm delay.

2. The method according to claim 1, wherein the most recently detected value of the physiological parameter is used for determining the alarm delay.

3. The method according to claim 1, wherein the determination unit considers the degree by which the detected value exceeds or under-runs the predefined threshold, respectively, and wherein the function yields a longer alarm delay for a lesser degree of exceeding or under-running the predefined threshold, respectively, and vice versa.

4. The method according to claim 1, wherein a maximum alarm delay and/or a minimum alarm delay are defined.

5. The method according to claim 1, wherein the reduction value is equal to the value of the limit violation counter when the detected present value of the physiological parameter has returned into the normal range.

6. The method according to claim 1, wherein a subsequently alarm delay is reduced by the present reduction value.

7. The method according to claim 1, wherein the alarm condition is only cleared when the reduction value has reached zero.

8. The method according to claim 1, wherein the alarm condition is cleared when the detected present value of the physiological parameter has returned into the normal range.

9. A medical instrument or system for detecting a physiological parameter and controlling an alarm, comprising

a detector for consecutively detecting the present value of at least one physiological parameter of the patient;

a determination unit for determining an alarm delay as a function of at least one detected value of the physiological parameter, wherein the function yields a shorter alarm delay if the degree by which two consecutively determined values of the physiological parameter deviate from a normal value increases, and wherein the function yields a longer alarm delay if the degree by which two consecutively determined values of the physiological parameter deviate from the normal value decreases,

a timer for counting the time the physiological parameter has exceeded or under-run at least one predefined threshold for the physiological parameter defining an upper or lower limit for a normal range of the physiological parameter, respectively; and

an alarm unit for generating the alarm when the time the physiological parameter has exceeded or under-run the predefined threshold, respectively, exceeds the alarm delay, wherein a limit violation counter starts running after the first of multiple directly consecutive events of detected present values of the physiological parameter that exceed or under-run the threshold, respectively, and wherein the value of the alarm delay is continuously updated according to a function of at least the detected value of the physiological parameter; and

wherein the value of the limit violation counter is determined when the detected present value of the of the physiological parameter has returned into the normal range, a reduction value is calculated as a function of the value of the limit violation counter and/or the degree by which the detected value of the physiological parameter has exceeded or under-run the predefined threshold, and the reduction value is decremented in time.