FLUIDIC RESPIRATOR CONTROL SYSTEM WITH PATIENT TRIGGERING RESPONSE MEANS

• US 3,834,382 A
• Filed: 09/05/1972
• Issued: 09/10/1974
• Est. Priority Date: 09/05/1972
• Status: Expired due to Term

• Current Assignee: Johnson Controls International BV (Johnson Controls International plc)
• Original Assignee: Alfred J. Pawlak, Warren A. Lederman
• Inventors: Lederman, Warren A., Pawlak, Alfred J.
• Primary Examiner(s): Gaudet, Richard A.
• Assistant Examiner(s): Dunne, G. F.
• Application Number:
  US05/286,293
• Time in Patent Office: 735 Days
• Field of Search: 128/145.5,145.6,145.8,188,142.2,142 137/624.11,624.12
• US Class Current: 128/204.24
• 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: Y10T 137/86389 Programmer or timer

Abstract

A respirator unit has patient triggering control means with an isolating fluidic repeater connected to an operational amplifying circuit employing a summing impact modulator and a feedback network. Two cascaded stages of differentiation connect the amplifying circuit to an output logic gate for controlling a control oscillator to initiate an inhalation cycle. An inhibit circuit includes a pair of pressure taps connected to spaced points on the flow line. Fluidic repeaters connect the taps to a fluidic comparator. A fluidic time delay means is connected to the output of the comparator and connected in common to the output logic gate to inhibit the triggering control means during the exhalation cycle. The fluidic oscillator includes a flip-flop circuit with output lines interconnected to control the exhalation and inhalation valves between the fluid air-oxygen mixer source and the patient. Inhalation and exhalation time adjustment means are provided. A positive pressure cutoff circuit includes a fluidic amplifier which produces a logic on-off type signal in accordance with the magnitude of patient pressure and is connected to the oscillator to terminate the inhalation cycle and initiate the exhalation cycle. An automatic selection switch means is provided to selectively deactivate the inhalation and exhalation time adjustment, and the triggering control means to control the respirator operating mode.

Claims

1. A respirator having a fluid source coupled to a valved flow means for carrying fluid to and from a patient, comprising a patient triggering circuit means for initiating the inhalation phase of the breathing cycle in response to inhalation flow by the patient, flow sensing means coupled to said valved means for detecting exhalation flow, said sensing means including a flow line having a flow in accordance with the direction of flow of said fluid with respect to the patient, a pressure sensing means coupled to said flow line and monitoring the pressure drop between two selected spaced points in said flow line, and coupling means connecting said pressure sensing means to said patient triggering circuit to inhibit the triggering circuit during exhalation flow.

2. A respirator control apparatus coupling a respirator having a fluid medium source and a valved control means for carrying fluid to and from a patient and establishing regulated breathing assistance for the patient through a flow means of the respirator, comprising flow sensing means having a flow line means connected to said flow means of the respirator and having flow in accordance with the direction of flow of said fluid in said flow means, and having monitoring means for connection to spaced points of the flow line means and establishing a signal in accordance with the pressure differential between said points and thereby the direction of flow of flUid with respect to the patient, a patient triggering control means having output means for connection to the flow means for actuating the flow means in accordance with the movement of the patient'"'"''"'"'s breathing faculties, and means connecting said sensing means to said control means to selectively inhibit said control means.

3. The respirator control apparatus of claim 2 wherein said flow sensing means includes a first pressure tap means connected to said flow line adjacent said respirator, a second pressure tap means connected to said flow line downstream of said first pressure tap means to define with said first tap means a pressure drop sensing means, and a first and a second fluidic repeater connected to the corresponding first and second pressure tap means to isolate the sensing means of the breathing flow means and establish a pair of positive pressure signals over the operating range of the respirator.

4. The respirator control apparatus of claim 3 wherein each repeater includes a diaphragm defining a closed input chamber and an output chamber, said output chamber being connected to a regulated supply and having an exhaust nozzle selectively opened and closed by the position of the diaphragm, means resiliently preloading the diaphragm to maintain a positive output pressure signal over the complete operating range of the respirator, and a fluidic comparator means establishing a selected output in response to flow associated with patient exhalation and a zero output associated with patient inhalation.

5. The respirator control apparatus of claim 4 having a time delay capacitor means connected to the output of the fluidic comparator means to inhibit the triggering control means until a stable exhalation period is created.

6. The respirator control apparatus of claim 4 operable over an ambient pressure range of -10 cm of H2O to +10 cm of H2O and wherein said repeater diaphragm includes an annular convolution and is preloaded by an adjustable spring means to maintain said positive output pressure signal over said pressure range, said fluidic comparator including an impact modulator having a pair of opposed nozzle means connected respectively one each to each of said output chambers and establishing said selected output, fluidic logic amplifiers connected to the output of the impact modulator, a time delay capacitor means connected to the output of the amplifiers, said triggering control means including a fluidic '"'"''"'"''"'"''"'"'Nor'"'"''"'"''"'"''"'"' gate having a first input connected to said capacitor means and to said modulator to inhibit the triggering control means until a stable exhalation period is created.

7. The respirator control apparatus of claim 2 wherein said triggering control means includes a diaphragm fluidic repeater having a deadended input chamber connected to said flow sensing line and an output chamber with an exhaust means regulated by a common chamber diaphragm, an operational amplifier including a fluidic amplifier means connected to the output of the repeater and a feedback network including adjustable resistance means connected to said fluidic amplifier means, a first fluidic differentiator connected to the output of said fluidic amplifier means, a second fluidic differentiator connected to the output of the first differentiator, a logic gate connected to the output of said second differentiator to control the flow means.

8. The respirator of claim 7 including a diaphragm amplifier having a deadended input chamber connected to the output of the fluidic amplifier means and an output chamber connected to said feedback network and to said first fluidic differentiator.

9. The respirator of claim 2 wherein the flow means includes inhalation valve means and exhalation valve means and a fluidic variable pulse width oscillator coupled to alternately activate the inhalation valve means and the exhalation valve means, said oscillator having an inhalation time adjustment means and an exhalation time adjustment means, each oF said adjustment means including a capacitive means and an adjustable bleed restrictor means connected to said capacitive means.

10. The respirator of claim 9 wherein said fluidic variable pulse width oscillator includes a pair of '"'"''"'"''"'"''"'"'Nor'"'"''"'"''"'"''"'"' gates connected to define a fluidic flip-flop circuit with a pair of output lines connected to the opposite of said gates and to alternately activate the inhalation valve means and the exhalation valve means, said inhalation time adjustment means and exhalation time adjustment means being connected to said '"'"''"'"''"'"''"'"'Nor'"'"''"'"''"'"''"'"' gates to actuate said flip-flop circuit.

11. The respirator of claim 9 having a positive pressure cutoff means connected to said flow line and to a set pressure source means and connected to said oscillator to terminate the inhalation cycle at a selected inhalation pressure, and said triggering control means connected to said oscillator to initiate the inhalation phase of the breathing cycle.

12. The respirator of claim 11 having a selector switch means connected to said oscillator and to said triggering control means and having a first position to inhibit the inhalation adjustment means and the exhalation adjustment means and having a second position inhibiting the triggering control means and a third non-inhibiting position.

13. The respirator control apparatus of claim 2 operable over an ambient pressure range of -10 cm of H2O to +10 cm of H2O and having a first pressure tap means connected to said flow line adjacent said respirator, a second pressure tap means connected to said flow line downstream of said first pressure tap means, a first and a second fluidic repeater connected to the corresponding first and second pressure tap means, each repeater including a diaphragm having an annular convolution and defining a closed input chamber and an output chamber, said output chamber being connected to a regulated supply and having an exhaust nozzle selectively opened and closed by the position of the diaphragm, a spring means resiliently preloading the diaphragm to maintain a positive output pressure signal over the complete operating range of the respirator, a fluidic comparator including an impact modulator having a pair of opposed nozzle means connected respectively one each to each of said output chambers and establishing a selected output in response to flow associated with patient exhalation and a zero output associated with patient inhalation, fluidic logic amplifying gate means connected to the output of the comparator, a time delay capacitor means connected to the output of the gate means, said triggering control means including an output fluidic '"'"''"'"''"'"''"'"'Nor'"'"''"'"''"'"''"'"' gate having a first input connected to said capacitor means and to gate means to inhibit the triggering control means during the exhalation cycle, said triggering control means including a third fluidic repeater corresponding to said first and second repeaters and having an input chamber connected to said flow sensing line, an operational amplifier including a fluidic impact modulator having first and second nozzle means in opposed relation with the first nozzle means connected to the output of the third repeater and the second nozzle means connected to a feedback network, said feedback network including adjustable pin valve means, a diaphragm amplifier having a deadended input chamber connected to the output of the impact modulator and an output chamber connected to said feedback network, a first fluidic differentiator including an impact modulator with a pair of opposed nozzles connected in common to the output of said last-named diaphragm amplifier and having a fluidic capacitor between one of said nozzles and the common connection, a second fluidic differentiator having a corresponding impact modulator to said first and having a common connection to the output of the first differentiator and having a fluidic capacitor in the connection to the opposite one of said nozzle means, and a logic inverter gate cOnnecting the output of said second differentiator to a second input of said output fluidic NOR gate.

14. The respirator of claim 13 wherein the flow means includes inhalation valve means and exhalation valve means and including a fluidic variable pulse width oscillator having a pair of NOR gates connected to define a fluidic flip-flop circuit with a pair of output lines connected to one of said gates and coupled to alternately activate the inhalation valve means and the exhalation valve means, said oscillator having an inhalation time adjustment means and an exhalation time adjustment means, each of said adjustment means including a capacitive means and an adjustable bleed restrictor means connected to said capacitive means, a positive pressure cutoff means including an impact modulator connected to said flow line and to a set pressure source means and connected to a first of said gates of said oscillator to terminate the inhalation cycle at a selected inhalation pressure, said triggering control means having said output fluidic '"'"''"'"''"'"''"'"'Nor'"'"''"'"''"'"''"'"' gate means connected to the second of said gates of said oscillator to initiate an inhalation cycle, and a selector switch means connected to said oscillator and to said triggering control means and having a first position to inhibit the inhalation adjustment means and the exhalation adjustment means and having a second position inhibiting the triggering control means and a third non-inhibiting position, said selector switch means being constructed to establish fluidic control signals, said oscillator and triggering control means having logic gates, said switch means being connected to said logic gates for selective inhibiting of said oscillator and said triggering control means.