Conserving device for use in oxygen delivery and therapy

• US 6,220,244 B1
• Filed: 09/15/1998
• Issued: 04/24/2001
• Est. Priority Date: 09/15/1998
• Status: Expired due to Term

• Current Assignee: Patrick L. Mclaughlin
• Original Assignee: Patrick L. Mclaughlin
• Inventors: McLaughlin, Patrick L.
• Primary Examiner(s): Dawson, Glenn K.
• Application Number:
  US09/153,545
• Time in Patent Office: 952 Days
• Field of Search: 128/204.18, 128/204.21, 128/204.23, 128/204.26, 128/205.24, 128/207.16
• US Class Current: 128/204.23
• 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 16/0051 with alarm devices
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/0677 Gas-saving devices therefor
• CPC Class Codes: A61M 2016/0024 with an on-off output signal, e.g. from a switch

Abstract

A method and apparatus for conserving oxygen provided for oxygen therapy. The oxygen conserving delivery system includes a sensor for detecting inspiration efforts, and a microcontroller which is triggered by the sensor to open a valve to allow the flow of oxygen to the patient. The system includes a cross-field excitation/detection inspiration sensor using an adaptive full-wave signal detector/tracer. The system also includes a method for conserving energy by a unique combination of start and sustain drive lines coupled to the valve control. The system is able to compensate for variations in battery condition, inlet gas pressures, variations in valve tolerances, and the absence of gas pressure in a fault condition. Finally, a self-adaptive inspiration depth tracking ability ensures constant oxygen delivery volume even when there are variations in inspiration depths rather than changes in respiration rates. This ability enables the system to provide oxygen at a depth and a rate which is a best fit for a patient'"'"'s oxygen needs when at rest or at work.

Claims

1. An oxygen conserving delivery system operative to regulate a flow of oxygen during an inspiration event of a respiratory cycle, and comprising:

a valve assembly including a valve for receiving oxygen, and having an output port;

an inspiration sensor assembly coupled at a first port to the output port of the valve assembly, having a second port;

a signal generator for generating a signal on a sensor output line of the inspiration sensor assembly when an inspiration event is detected by the inspiration sensor assembly;

a single respiration tube coupled to the second port of the inspiration sensor assembly;

a microcontroller for regulating operation of the oxygen conserving delivery system, wherein the microcontroller is coupled to the valve assembly via a start drive line which when actuated provides sufficient power to the valve assembly to initially open the valve, and coupled to the valve assembly via a sustain drive line which when actuated provides less power to the valve assembly suffering only to maintain the valve in an open position, and wherein the microcontroller receives input from the sensor output line when the inspiration event is detected;

a power source for providing power to the oxygen conserving delivery system; and

a means for regulating a respiration rate of oxygen supplied by the oxygen conserving delivery system between no delivery of oxygen and a maximum delivery rate of oxygen.

2. The oxygen conserving delivery system as defined in claim 1 wherein the system further comprises a plurality of status indicators to provide feedback to an operator of the system of a status thereof.

3. The oxygen conserving delivery system as defined in claim 2 wherein the plurality of status indicators are comprised of:

a plurality of visual status indicators; and

an audio status indicator, wherein the audio status indicator can provide a same type of information to the operator as is provided by the plurality of visual status indicators.

4. The oxygen conserving delivery system as defined in claim 3 wherein the plurality of visual status indicators further comprises:

a flow fault status indicator which is actuated when a flow of oxygen to the patient is interrupted;

an apnea status indicator which is actuated when the inspiration sensor assembly does not detect a second inspiration event within a predetermined time period after detecting a first inspiration event; and

a positive flow status indicator which is actuated by normal operation of the oxygen conserving device, and which functions to at least provide feedback to the operator that said system is functioning properly.

5. The oxygen conserving delivery system as defined in claim 4 wherein the system further comprises a dedicated low battery detection circuit for determining when the battery is providing voltage below the predetermined voltage level.

6. The oxygen conserving delivery system as defined in claim 3 wherein the plurality of visual status indicators further comprises:

a low battery status indicator which is actuated when a battery providing power to the system falls below a predetermined voltage level; and

a voltage integrity indicator which is actuated when the voltage to the oxygen conserving delivery system is not being consistently delivered such that normal operation cannot be guaranteed.

7. The oxygen conserving delivery system as defined in claim 3 wherein the microcontroller includes a memory for storing a plurality of different signals which when used to drive the audio status indicator, can provide audibly distinct sounds, each of which is associated with a particular condition of said system.

8. The oxygen conserving delivery system as defined in claim 1 wherein the power source further comprises a battery so that the oxygen conserving delivery system is mobile.

9. The oxygen conserving delivery system as defined in claim 8 wherein the valve assembly further comprises means for reverse shunting reflected electromotive energy from the valve back to the battery.

10. The oxygen conserving delivery system as defined in claim 9 wherein the means for reverse shunting electro-motive energy further comprises using quenching arrestors to thereby eliminate any potential for a spark which must be prevented when operating in an oxygen rich environment.

11. The oxygen conserving delivery system as defined in claim 1 wherein the inspiration sensor assembly further comprises:

a first stationary plate;

a second stationary plate;

a canter plate which capacitively couples the first stationary plate to the second stationary plate, wherein a increase in pressure results in an increase in capacitively coupled current to flow from the first stationary plate to the second stationary plate, wherein a decrease in pressure results in a decrease in capacitively coupled current to flow from the first stationary plate to the second stationary plate, and wherein the canter plate is electrically coupled to a full-wave rectifier and current amplifier.

12. The oxygen conserving delivery system as defined in claim 11 wherein the inspiration sensor assembly further comprises:

a first comparator for generating a repetitive signal to thereby excite the first stationary plate; and

a second comparator for generating an output signal which transitions from a first state to a second state when an inspiration event is detected, and which transitions from the first state to the second state when

     1) gas pressure from the valve, when said valve is open, resets the canter plate, or

     2) the inspiration sensor assembly detects an end of an inspiration effort.

13. The oxygen conserving delivery system as defined in claim 1 wherein the inspiration sensor assembly further comprises:

an excitation circuit for providing a predetermined clock signal;

an inspiration sensor for receiving input from the excitation circuit, and which is sensitive to pressure changes which cause the inspiration sensor to generate a first output signal which is indicative of pressure thereon;

a first rectifying and buffering circuit for processing a positive half of the first output signal and thereby generating a second output signal;

a first low pass filter which receives the second output signal and generates a third output signal;

a first high pass filter which receives the third output signal and generates a fourth output signal;

a positive reference signal which is modified by the fourth output signal to thereby generate a fifth output signal; and

a detector circuit for receiving the fifth output signal and capable of detecting pressure changes in the inspiration sensor that are indicative of an inspiration effort.

14. The oxygen conserving delivery system as defined in claim 13 wherein the inspiration sensor assembly further comprises:

the inspiration sensor for receiving input from the excitation circuit, and which is sensitive to pressure changes which cause the inspiration sensor to generate a first output signal which is indicative of pressure thereon;

a second rectifying and buffering circuit for processing a negative half of the first output signal and thereby generating a sixth output signal;

a second low pass filter which receives the sixth output signal and generates a seventh output signal;

a second high pass filter which receives the seventh output signal and generates an eighth output signal;

a negative reference signal which is modified by the eighth output signal to thereby generate a ninth output signal; and

the detector circuit for receiving the ninth output signal and capable of detecting pressure changes in the inspiration sensor that are indicative of an inspiration effort.

15. The oxygen conserving delivery system as defined in claim 1 wherein the system further comprises a barometer for detecting changes in altitude, wherein the barometer provides a signal to the microcontroller when a sufficient change is detected in altitude to warrant a modification in oxygen delivery to the patient.

16. The oxygen conserving delivery system as defined in claim 1 wherein the valve is further comprised of a valve which is normally closed.

17. The oxygen conserving delivery system as defined in claim 1 wherein the system further comprises:

a memory for the microcontroller which once programmed cannot be erased, and which stores program instructions for controlling the microcontroller; and

a look-up data table stored in the memory and which contains data regarding an oxygen delivery schedule that is responsive to an index of average inspiration rates and average inspiration dwell times.

18. The oxygen conserving delivery system as defined in claim 17 wherein the system further comprises the look-up data table stored in the memory which also contains data regarding an index of inspiration depths to thereby obtain the oxygen delivery schedule.

19. A method for supplying oxygen to a patient'"'"'s respiratory system during a respiration cycle which includes inhalation, said method comprising the steps of:

(1) providing an oxygen conserving delivery system which includes a valve assembly, an inspiration sensor assembly, a microcontroller for positively controlling operation of the valve assembly and the inspiration sensor assembly, and a power source for mobile operation of said system;

(2) providing sufficient energy to open a valve of the valve assembly; and

(3) providing a lesser amount of energy to the valve assembly when the valve is completely opened, wherein said lesser amount of energy is sufficient to maintain the valve in an open position until the microcontroller determines that the valve is to be closed, and wherein said method of opening the valve compensates for variations in power source condition, inlet pressures to the system, variations in valve tolerances, and an absence of oxygen pressure.

20. The method as defined in claim 19 wherein the method further comprises the steps of:

(1) reverse shunting reflected electro-motive energy from the valve back to the battery; and

(2) eliminating a possibility of a spark resulting from power being released from transistors that are supplying energy to open the valve, by providing quenching resistors in a circuit providing the reverse shunting.