Respiratory ventilator with automatic flow calibration

• US 6,135,967 A
• Filed: 04/26/1999
• Issued: 10/24/2000
• Est. Priority Date: 04/26/1999
• Status: Active Grant

• Current Assignee: Bird Products Corporation (Becton, Dickinson & Co)
• Original Assignee: Bird Products Corporation (Becton, Dickinson & Co)
• Inventors: MacDonald, John Judson, Fiorenza, Anthony Joseph
• Primary Examiner(s): O'Connor, Cary
• Assistant Examiner(s): CARTER, RYAN CHRISTOPHER
• Application Number:
  US09/299,780
• Time in Patent Office: 547 Days
• Field of Search: 600/529, 600/538, 600/543, 128/200.24, 128/204.21, 128/204.26
• US Class Current: 600/529
• 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 16/021 operated by electrical means A61M16/202 – A61M16/205 take precedence
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/702 automatically during use

Abstract

A respiratory ventilator and methodology thereof for automatically calibrating respiration gas flow delivery. The ventilator includes a gas flow calibration member having a reader component for recording inspiratory and exhalation gas volume with exhalation time, and for measuring a plurality of incremental exhalation gas flow values in a plurality of incremental time periods during a single exhalation. The gas flow calibration member includes a composite calculator component for determining an average of consecutive composite flow values, and a scanner calculator component for scanning in reverse order the plurality of consecutive composite flow values and calculating a new flow calibration value where a preselected number of consecutive composite flow values fall within a pre-selected flow rate. Thereafter, the gas delivery member is calibrated in accord with the determined new flow calibration value.

Claims

1. A respiratory ventilator for monitoring breath flow and automatically regulating and calibrating respiration gas flow delivery in accord with such monitored breath flow, the ventilator comprising:

a) a respiratory gas delivery member having a calibrateable gas flow adjuster and a calibrateable gas pressure adjuster, wherein said flow and pressure adjusters regulate delivery of respiratory gas; and

b) a gas flow calibration member in communication with the gas flow adjuster and gas pressure adjuster for calibrating said adjusters to thereby regulate delivery of respiratory gas, said gas flow calibration member comprising;

1) a reader component for recording inspiratory gas volume, exhalation gas volume, and exhalation time of an individual breath, and for measuring a plurality of incremental exhalation gas flow values in a plurality of incremental time periods during exhalation of said individual breath and averaging as a set of consecutive flow values a pre-selected number of said flow values;

2) a composite calculator component for determining an average composite flow value of a plurality of consecutive sets of flow values and thereafter determining and saving an average aggregate flow value of a plurality of consecutive composite flow values, and additionally for determining a volume flow calibration value as the difference between inspired and exhaled gas volume divided by exhalation time; and

3) a scanner calculator component for scanning in reverse order the plurality of consecutive composite flow values and calculating a new flow calibration value where a pre-selected number of consecutive composite flow values fall within a pre-selected flow rate, and thereafter for calibration of the gas flow adjuster and gas pressure adjuster.

2. A respiratory ventilator as claimed in claim 1 wherein each incremental time period is two milliseconds.

3. A respiratory ventilator as claimed in claim 2 wherein the pre-selected number of flow values of each set is determined from three consecutive flow values.

4. A respiratory ventilator as claimed in claim 3 wherein the average composite flow value is determined from 15 consecutive sets.

5. A respiratory ventilator as claimed in claim 4 wherein the pre-selected number of composite flow values for calculating a new flow calibration is 60 and the pre-selected flow rate is ±

2.5 liters per minute per millisecond.

6. A respiratory ventilator for monitoring breath flow and automatically regulating and calibrating respiration gas flow delivery in accord with such monitored breath flow, the ventilator comprising:

a) a respiratory gas delivery member having a calibrateable gas flow adjuster and a calibrateable gas pressure adjuster, wherein said flow and pressure adjusters regulate delivery of respiratory gas; and

b) a gas flow calibration member in communication with the gas flow adjuster and gas pressure adjuster for calibrating said adjusters to thereby regulate delivery of respiratory gas, said gas flow calibration member comprising;

1) a reader component for recording inspiratory gas volume, exhalation gas volume, and exhalation time of an individual breath, and for measuring a plurality of incremental exhalation gas flow values in a plurality of consecutive two millisecond time periods during exhalation of said individual breath and averaging as a set of flow values three consecutive flow values;

2) a composite calculator component for determining an average composite flow value of 15 consecutive sets of flow values and thereafter determining and saving an average aggregate flow value of a plurality of consecutive composite flow values, and additionally for determining a volume flow calibration value as the difference between inspired and exhaled gas volume divided by exhalation time; and

3) a scanner calculator component for scanning in reverse order the plurality of composite flow values and calculating a new flow calibration value where 60 consecutive composite flow values fall within a flow rate of ±

2.5 liters per minute per millisecond or where less than 60 consecutive composite flow values fall within a flow rate of ±

2.5 liters per minute per millisecond and wherein (i) an existing flow calibration value is greater than an existing bias flow plus 2.5 liters per minute, (ii) the volume flow calibration value is less than said bias flow plus 2.5 liters per minute, and (iii) said existing flow calibration value minus said volume flow calibration value is greater than 3.1 liters per minute, and thereafter for calibration of the gas flow adjuster and gas pressure adjuster to a flow calibration value equal to said volume flow calibration value minus 1.0 liter per minute.

7. A method for monitoring breath flow and regulating and calibrating respiration gas flow delivery by a ventilator in accord with such monitored breath flow, the method comprising:

a) activating a ventilator comprising a respiratory gas delivery member having a calibrateable gas flow adjuster and a calibrateable gas pressure adjuster, wherein said flow and pressure adjusters regulate delivery of respiratory gas;

b) recording inspiratory gas volume, exhalation gas volume, and exhalation time of an individual breath, and measuring a plurality of incremental exhalation gas flow values in a plurality of incremental time periods during exhalation of said individual breath and averaging as a set of consecutive flow values a pre-selected number of said flow values;

c) determining an average composite flow value of a plurality of consecutive sets of flow values and thereafter determining and saving an average aggregate flow value of a plurality of consecutive composite flow values, and additionally determining a volume flow calibration value as the difference between inspired and exhaled gas volume divided by exhalation time;

d) scanning in reverse order the plurality of consecutive composite flow values and calculating a new flow calibration value where a pre-selected number of consecutive composite flow values fall within a pre-selected flow rate; and

e) automatically transmitting the new flow calibration value to the gas flow adjuster and gas pressure adjuster of the ventilator to thereby regulate delivery of respiratory gas.

8. A method for monitoring breath flow and regulating and calibrating respiration gas flow delivery as claimed in claim 7 wherein each incremental time period is two milliseconds.

9. A method for monitoring breath flow and regulating and calibrating respiration gas flow delivery as claimed in claim 8 wherein the pre-selected number of flow values of each set is determined from three consecutive flow values.

10. A method for monitoring breath flow and regulating and calibrating respiration gas flow delivery as claimed in claim 9 wherein the average composite flow value is determined from 15 consecutive sets.

11. A method for monitoring breath flow and regulating and calibrating respiration gas flow delivery as claimed in claim 10 wherein the pre-selected number of composite flow values for calculating a new flow calibration is 60 and the pre-selected flow rate is ±

2.5 liters per minute per millisecond.

12. A method for monitoring breath flow and regulating and calibrating respiration gas flow delivery by a ventilator in accord with such monitored breath flow, the method comprising:

a) recording inspiratory gas volume, exhalation gas volume, and exhalation time of an individual breath, and measuring a plurality of incremental exhalation gas flow values in a plurality of consecutive two millisecond time periods during exhalation of said individual breath and averaging as a set of flow values three consecutive flow values;

2) determining an average composite flow value of 15 consecutive sets of flow values and thereafter determining and saving an average aggregate flow value of a plurality of consecutive composite flow values, and additionally determining a volume flow calibration value as the difference between inspired and exhaled gas volume divided by exhalation time; and

3) scanning in reverse order the plurality of composite flow values and calculating a new flow calibration value where 60 consecutive composite flow values fall within a flow rate of ±

2.5 liters per minute per millisecond or where less than 60 consecutive composite flow values fall within a flow rate of ±

2.5 liters per minute per millisecond and wherein (i) an existing flow calibration value is greater than an existing bias flow plus 2.5 liters per minute, (ii) the volume flow calibration value is less than said bias flow plus 2.5 liters per minute, and (iii) said existing flow calibration value minus said volume flow calibration value is greater than 3.1 liters per minute, and thereafter calibrating a gas flow adjuster and gas pressure adjuster of the ventilator to a flow calibration value equal to said volume flow calibration value minus 1.0 liter per minute.