METHOD AND SYSTEM TO CONTROL MECHANICAL LUNG VENTILATION

• US 20090114223A1
• Filed: 11/03/2008
• Published: 05/07/2009
• Est. Priority Date: 11/01/2007
• Status: Active Grant

• Current Assignee: Intermed Equipamento Médico Hospitalar Ltda. (Becton Dickinson & Co)
• Original Assignee: Intermed Equipamento Médico Hospitalar Ltda. (Becton Dickinson & Co)
• Inventors: BONASSA, JORGE
• Granted Patent: US 8,186,344 B2
• Time in Patent Office: Days
• US Class Current: 128/204.230
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/0833 T- or Y-type connectors, e.g. Y-piece
• CPC Class Codes: A61M 16/0858 Pressure sampling ports
• CPC Class Codes: A61M 16/204 used for inhalation control
• CPC Class Codes: A61M 16/205 used for exhalation control
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit

Abstract

The present disclosure refers to a system to control mechanical lung ventilation with volume band, more particularly a system to manage respiratory cycles in patients. Preferably, said respiratory cycles are controlled under pressure, so that the volumes as inspired by the patient are maintained within a volume range, comprising a lower volume limit and an upper volume limit, which are previously determined.

Claims

1. A method to control mechanical lung ventilation, comprising a safe band of volume as defined by a first lower volume limit and a first upper volume limit and comprising the steps of:

i) monitoring the volume as inspired by a patient during a respiratory cycle for an inspiratory time,

ii) detecting when the volume as inspired by the patient is outside the first limits defining the safe volume range, so that;

a) if it an inspired volume has reached the first upper volume limit, a flow and/or a pressure control valve is closed and an exhalation valve is opened, and

b) if the inspired volume is below the first lower limit;

b1) the number of cycles below said first lower limit within a pre-determined time interval is counted;

b2) the number of cycles below said first lower limit counted in step b1) is compared to a pre-defined or pre-adjusted reference value,

b3) if the number of cycles below said first lower limit counted in step b1) is equal to or higher than the pre-defined or pre-adjusted reference value, a pressure value is increased by a pre-defined pressure increase value, and

b4) steps b1)-b3) are repeated until the number of cycles below said first lower limit counted in step b1) is less than the pre-defined or pre-adjusted reference value.

2. The method of claim 1, characterized by being applied in controlled, assisted and/or spontaneous respiratory cycles.

3. The method of claim 1, characterized by a) the pressure being a controlled pressure and/or support pressure and b) the pressure increase of b3) is a controlled and/or assisted pressure increase and/or support pressure increase.

4. The method of claim 1, characterized by the exhalation valve only opening during step a) after an end of an adjusted inspiratory time.

5. The method of claim 1, characterized by the pressure increase value of b3) being established from a difference between an average volume inspired in cycles where the volume is outside of the safe band of volume and an average range value.

6. The method of claim 1, characterized by the pre-defined or pre-adjusted reference value being established from an analysis of a statistical distribution of a number of respiratory cycle volumes within a given period of time.

7. The method of claim 6, characterized by the pre-defined or pre-adjusted reference value being a number of respiratory cycles corresponding to the lower limit of a normal distribution in which a deviation is higher than two standard deviations of a sample.

8. The method of claim 6, characterized by the pre-defined or pre-adjusted reference value corresponding to a percentage of the total respiratory frequency.

9. The method of claim 1, characterized by a total pressure increase value of ii), b) being limited by a limit pressure.

10. The method of claim 1, characterized by the resulting increased pressure value of ii), b) being retroactively adjusted until returning to the initial pressure value.

11. The method of claim 10, characterized by the resulting pressure reduction being made by the following steps:

i) counting of the number of cycles within a second time interval, in which an inspiratory volume is below a second lower volume limit,

ii) comparing the number of cycles counted in i) and a second pre-defined and/or pre-determined reference value, and

iii) if number of cycles counted in i) is equal to or lower than the second pre-defined and/or pre-determined reference value, the pressure value is reduced by a pre-defined pressure decrease value.

12. The method of claim 11, characterized by the pressure reduction being a controlled or an assisted pressure reduction or a support pressure reduction.

13. The method of claim 11, characterized by the second lower volume limit being represented by the multiplication of the first lower volume limit by a factor K varying between 1.1 and 1.5.

14. The method of claim 11, characterized by the pressure reduction value being equal to or lower than the pressure rise value.

15. The method of claim 2, characterized by the following control parameters being defined in controlled and assisted respiratory cycles:

Respiratory Frequency FR;

Sensitivity S;

Inhalation Time TI, Controlled Pressure PC, Minimum Controlled Value VCMin and Maximum Controlled Volume VCMax.

16. The method of claim 2, characterized by the following control parameters being defined in spontaneous respiratory cycles:

Support Pressure, Minimum Spontaneous Volume, Maximum Spontaneous Volume.

17. The method of claim 2, characterized by also defining the Exhalation Pressure of the patient.

18. The method of claim 2, characterized by the inspiratory flow F(t) and the inspired volume ∫

F(t) dt within the interval dt for pressure controlled cycles being given by;

PC−

PEEP=F(t)·

R+∫

F(t)dt/C

in which;

R;

Resistance of airways

C;

Compliance of the respiratory system.

19. The method of claim 2, characterized by the inspiratory flow F(t) and the inspired volume ∫

F(t) dt within the interval dt for assisted cycles being given by;

PC+Effort−

PEEP=F(t)·

R+∫

F(t)dt/C

in which;

R;

Resistance of airways

C;

Compliance of the respiratory system

Effort;

Inspiratory effort by the patient.

20. The method of claim 2, characterized by the inspiratory flow F(t) and the inspired volume ∫

F(t) dt within the interval dt for spontaneous cycles being given by;

PS+Effort−

PEEP=F(t)·

R+∫

F(t)dt/C

in which;

R;

Resistance of airways

C;

Compliance of the respiratory system

Effort;

Inspiratory effort by the patient.

21. An apparatus for controlling a mechanical lung ventilator comprising a flow and pressure control valve connected to a gas source, an inspiratory tube connected to a patient through a “

Y”

type connector that is connected within an expiratory tube interconnected to an exhalation valve, a flow transducer located downstream from the flow and pressure control valve and a pressure transducer that send signals to a central control unit provided with a control panel to control flow, pressure and exhalation valves, the apparatus being adapted to provide a safe volume range comprising a lower volume limit and an upper volume limit.

22. The apparatus of claim 21, wherein the flow, pressure and exhalation control valves are servo controlled by a microprocessor.

23. The apparatus of claim 22, wherein the flow, pressure and exhalation control valves are activated by solenoids and/or pneumatics.

24. The apparatus of claim 22, wherein the flow and pressure valve is a compressor or a turbine.

25. The apparatus of claim 22, wherein the exhalation valve is a simple orifice in the patient'"'"'s connection.

26. The apparatus of claim 21, adapted for control and assisted respiratory cycles having control parameters of Respiratory Frequency, Sensitivity, Inhalation Time, Controlled Pressure, Minimum Controlled Value, and Maximum Controlled Volume.

27. The apparatus of claim 21, adapted for spontaneous respiratory cycles having control parameters of Support Pressure, Minimum Spontaneous Volume, and Maximum Spontaneous Volume.

28. The apparatus of claim 21, adapted to provide a control parameter of a Positive End Expiratory Pressure.

29. The apparatus of claim 21, wherein the inspiratory flow and the inspired volume within a time interval for pressure controlled cycle is given by:

PC−

PEEP=F(t)·

R+∫

F(t)dt/C

wherein R is the resistance of airways, C is the compliance of the patients respiratory system, ∫

F(t) is the inspired volume, and F(t) is the inspiratory flow.

30. The apparatus of claim 21, wherein the inspiratory flow and the inspired volume within a time interval for assisted cycles is given by:

PC+Effort−

PEEP=F(t)·

R+∫

F(t)·

dt/C

wherein R is the resistance of airways, C is the compliance of the patients respiratory system, Effort is the inspiratory effort by the patient, ∫

F(t) is the inspired volume, and F(t) is the inspiratory flow.

31. The apparatus of claim 21, wherein the inspiratory flow and the inspired volume within a time interval for spontaneous cycles is given by:

PS+Effort−

PEEP=F(t)·

R+∫

F(t)dt/C

wherein R is the resistance of airways, C is the compliance of the patients respiratory system, Effort is the inspiratory effort by the patient, ∫

F(t) is the inspired volume, and F(t) is the inspiratory flow.