Methods and apparatus for varying the back-up rate for a ventilator

• US 7,628,151 B2
• Filed: 07/17/2007
• Issued: 12/08/2009
• Est. Priority Date: 03/07/2003
• Status: Active Grant

• Current Assignee: ResMed Pty Ltd. (ResMed Incorporated)
• Original Assignee: Resmed Limited (ResMed Incorporated)
• Inventors: Bassin, David John
• Primary Examiner(s): Douglas; Steven O
• Application Number:
  US11/778,895
• Publication Number:
  US 20080011302A1
• Time in Patent Office: 875 Days
• Field of Search: 128/204.18, 128/204.21, 128/204.23, 128/204.26
• US Class Current: 128/204.18
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/0003 Accessories therefor, e.g. sensors, vibrators, negative pressure
• CPC Class Codes: A61M 16/0066 Blowers or centrifugal pumps
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/04 Tracheal tubes catheters in general A61M25/00
• CPC Class Codes: A61M 16/06 Respiratory or anaesthetic masks
• CPC Class Codes: A61M 16/0875 Connecting tubes
• CPC Class Codes: A61M 16/20 Valves specially adapted to medical respiratory devices
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: A61M 2205/502 User interfaces, e.g. screens or keyboards
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/40 Respiratory characteristics

Abstract

A ventilator device delivers ventilatory support to a patient in a back up timed mode when patient respiration is not detected or a spontaneous mode when patient respiration is detected. The timing threshold governing the back-up mode is chosen to deviate from normal expected respiration time for the patient to promote patient initiated ventilation in the spontaneous mode but permit back-up ventilation in the event of apnea. Automated adjustments to the timing threshold during the timed mode are made from the less vigilant timing threshold to a more vigilant threshold at or near a timing of normal expected breathing of the patient. Such adjustments may be made from a minimum to a maximum vigilance timing settings or incrementally there between as a function of time in the timed mode which is preferably the number of delivered machine breaths.

Claims

1. A method for providing back-up support ventilation for a patient comprising the steps of:

delivering pressure support ventilation to the patient during inspiratory and expiratory portions of the breathing cycles of the patient,

detecting recurrent respiratory events in cycles of the patient'"'"'s respiration,

controlling delivery of pressure support ventilation in the absence of detection for a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event,

decreasing said threshold time interval in the event of the absence of detection during a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event, and

increasing said threshold time interval in the event of the detection of a second recurrent respiratory event subsequent to a first recurrent respiratory event before expiration of a threshold time interval.

2. The method of claim 1 wherein the threshold time interval is adjusted in a manner that varies with the number of cycles of ventilation that are delivered.

3. The method of claim 1 further comprising the step of determining adequacy of the patient'"'"'s ventilation and further adjusting said threshold time interval as a function of the adequacy of the patient'"'"'s ventilation.

4. The method of claim 3 wherein said function of the adequacy of the patient'"'"'s ventilation is dependent upon the ratio of a measured ventilation and a target ventilation.

5. A method for providing back-up support ventilation for a patient comprising the steps of:

delivering pressure support ventilation to the patient during inspiratory and expiratory portions of the breathing cycles of the patient,

detecting recurrent respiratory events in cycles of the patient'"'"'s respiration,

controlling delivery of pressure support ventilation in the absence of detection for a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event,

adjusting said threshold time interval in a direction that is more likely to have the ventilation support interfere with the spontaneous breathing of the patient in the event of the absence of detection during a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event, and

adjusting said threshold time interval in a direction that is less likely to have the ventilation support interfere with the spontaneous breathing of the patient in the event of the detection of a second recurrent respiratory event subsequent to a first recurrent respiratory event before expiration of a threshold time interval.

6. The method of claim 5 wherein the threshold time interval is adjusted in a manner that varies with the number of cycles of ventilation that are delivered.

7. The method of claim 5 further comprising the step of determining adequacy of the patient'"'"'s ventilation and further adjusting said threshold time interval as a function of the adequacy of the patient'"'"'s ventilation.

8. The method of claim 7 wherein said function of the adequacy of the patient'"'"'s ventilation is dependent upon the ratio of a measured ventilation and a target ventilation.

9. Apparatus for providing back-up support ventilation for a patient comprising:

means for delivering pressure support ventilation to the patient during inspiratory and expiratory portions of the breathing cycles of the patient,

means for detecting recurrent respiratory events in cycles of the patient'"'"'s respiration, and

means for controlling delivery of pressure support ventilation in the absence of detection for a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event, wherein

said controlling means decreases said threshold time interval in the event of the absence of detection during a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event, and

said controlling means increases said threshold time interval in the event of the detection of a second recurrent respiratory event subsequent to a first recurrent respiratory event before expiration of a threshold time interval.

10. The apparatus of claim 9 wherein said controlling means adjusts the threshold time interval in a manner that varies with the number of cycles of ventilation that are delivered.

11. The apparatus of claim 9 wherein said controlling means further determines the adequacy of the patient'"'"'s ventilation and further adjusts said threshold time interval as a function of the adequacy of the patient'"'"'s ventilation.

12. The apparatus of claim 11 wherein said function of the adequacy of the patient'"'"'s ventilation is dependent upon the ratio of a measured ventilation and a target ventilation.

13. Apparatus for providing back-up support ventilation for a patient comprising:

means for delivering pressure support ventilation to the patient during inspiratory and expiratory portions of the breathing cycles of the patient,

means for detecting recurrent respiratory events in cycles of the patient'"'"'s respiration, and

means for controlling delivery of pressure support ventilation in the absence of detection for a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event, wherein

said controlling means adjusts said threshold time interval in a direction that is more likely to have the ventilation support interfere with the spontaneous breathing of the patient in the event of the absence of detection during a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event, and

said controlling means adjusts said threshold time interval in a direction that is less likely to have the ventilation support interfere with the spontaneous breathing of the patient in the event of the detection of a second recurrent respiratory event subsequent to a first recurrent respiratory event before expiration of a threshold time interval.

14. The apparatus of claim 13 wherein said controlling means adjusts the threshold time interval in a manner that varies with the number of cycles of ventilation that are delivered.

15. The apparatus of claim 13 wherein said controlling means further determines the adequacy of the patient'"'"'s ventilation and further adjusts said threshold time interval as a function of the adequacy of the patient'"'"'s ventilation.

16. The apparatus of claim 15 wherein said function of the adequacy of the patient'"'"'s ventilation is dependent upon the ratio of a measured ventilation and a target ventilation.

17. A method for providing back-up support ventilation for a patient comprising the steps of:

delivering pressure support ventilation to the patient during inspiratory and expiratory portions of the breathing cycles of the patient,

detecting recurrent respiratory events in cycles of the patient'"'"'s respiration,

controlling delivery of pressure support ventilation in the absence of detection for a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event,

decreasing said threshold time interval with an increase in the number of absences of detection during a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event, and

increasing said threshold time interval with a decrease in the number of detections of a second recurrent respiratory event subsequent to a first recurrent respiratory event before expiration of a threshold time interval.

18. Apparatus for providing back-up support ventilation for a patient comprising:

means for delivering pressure support ventilation to the patient during inspiratory and expiratory portions of the breathing cycles of the patient,

means for detecting recurrent respiratory events in cycles of the patient'"'"'s respiration, and

means for controlling delivery of pressure support ventilation in the absence of detection for a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event, wherein

said controlling means decreases said threshold time interval with an increase in the number of absences of detection during a threshold time interval of a second recurrent respiratory event subsequent to a first recurrent respiratory event, and

said controlling means increases said threshold time interval with a decrease in the number of detection of a second recurrent respiratory event subsequent to a first recurrent respiratory event before expiration of a threshold time interval.