US2831181A - Respiration monitoring device - Google Patents

Description

Filed Jan. 27, 1956 ALARM 1N VEN TOR.

H oro 1d Warn er Adorney United States Patent RESPIRATION MQNITORING DEVICE Harold Warner, Holmes, Pa.

Application January 27, 1956, Serial No. 561,808

8 Claims. (Cl. 349-213) The present invention relates to novel and improved electronic detection apparatus and more particularly to novel and improved electronic detection apparatus for use in providing ample warning of an appreciable change of rate, or cessation, of the respiratory process of a human being or other living pulmonary organism.

in the care and treatment of incubator or normal infants and other patients likely to suffer respiratory anomalies, it often becomes necessary and desirable to monitor with care the respiratory action of the patient and to provide a prompt and reliable Warning or alarm when the respiration cycle falters. In the past, this vigilance has ordinarily been maintained by the nursing staffs of the hospitals or other available attendants, who periodically observe and inspect the condition of the patient in accordance with a predetermined schedule. It has been found, however, that on occasion respiratory difficulties, such as aspiration of the contents of the stomach, a mucous bronchial occlusion, or some other complication, develop immediately or shortly after such a check or; inspection. Remedial measures taken after discovery of the same during the next period of inspection are often too late to effect resuscitation of the patient.

Accordingly, it is a principal object of the present invention to provide a novel and improved respiration monitoring device which provides an automatic and prompt warning or alarm when an appreciable change of rate, or the cessation of respiration of the patient occurs.

It is a further object of the present invention to provide novel and improved respiration detection apparatus which is reliable and effective in operation and yet relatively simple and economical in construction.

Other objects and advantages of the subject invention will become more readily apparent from the following description:

In the drawing which is illustrative of the invention:

Figure I is a side elevational view of a preferred embodiment of the present invention, showing a preferred manner in which the same is positioned adjacent to the nasal passages of the patients face.

Figure II is a detailed view of the sensing element shown in Figure I.

Figure 111 is a preferred schematic diagram of the electrical circuits of the invention shown in Figure I.

A preferred embodiment of the invention isillustrated in Figures I-III of the drawings. As shown in Figure I,

the mask assembly or the like 3 is preferably secured.

to the infants or patients face by suitable conventional straps or the like 4 and includes the plastic nosepiece element 5, which preferably encloses the lower extremity of the nose, and the tubular cylindrical portion 6, which extends'downward from the nasal passages of the patients nose. The opening 7 in the mask assembly adjacent to the bottom of the nosepiece provides a bypass air passage and insures free and unrestricted breathing of the patient.

The sensing element or the like 8, which forms an important part of the present invention, is securely positioned within the tubular extremity 6 of themaskas-- sembly in any suitable manner and electrically connect ed to amplifier integrator alarm chassis 13 through conductors 14 and 15.

mask assembly 3 and the atmosphere.

The details of a preferred embodiment of shown therein, the sensing element 8 is preferably 'c'onnected in the cathode circuit of tube V-lA. 'Theplate--' circuit of tube V-1A extends from the positive volt supply line 17 through the decoupling resistor R5, the" load resistor R1, the tube V-lA, and the sensing element 8 to ground. The control grid of tube V1A' is preferably tied to ground. The plate of tube V-lA is coupled to the control grid of tube V-lB through condenser C1 and resistor R2. The plate circuit of tube V-1B extends from the positive 120 volt supply line 17 through resistors'R5 and R4, the tube V-1B, and resistor R3 to ground. "Decoupling condenser C6 is preferably connected as shown" 7 between the junction of resistors R4 and R5 and'grouridt- V-2A, and resistor R7 to ground. The plate of tube V-ZA is coupled to the control grid of tube V-2B through condenser C3 and resistor R9. The plate circuit o'ftube V-ZB extends from the positive 120 volt supply line 17 through resistor R8, the tube V-ZB, and resistor" R10 to Patented Apr. 15, 1958v the ampli-" fier integrator and alarm circuits of the present inven' tion are illustrated in Figure III of the drawing... A's

ground. The plate of tube V-ZB is coupled to the con-'f trol grid of tube V-3A through condenser C4 and resis'tor" R11. Tube V-3A is'a cathode follower whose platefcir cuit extends from the 120 volt supply line 17 through resistor R13, the tube V-3A, and resistor R12 to the negative 70 volt supply line18. Resistor R11 is pref erably returned to the negative 4 volt supply line 19.

Decoupling condenser C5 is connected from the plate of tube V-3A to ground. The cathode of tube V-3A is directly connected to the cathode of tubeV-3B. The

plate and control grid, electrically joined, of the tube V-3B feed condenser C7, which is shunted by poten tiometer R14. Condenser C7 and variable resistor R14 comprise a time constant in the control grid circuit of:

thyratron tube V-4. The plate circuit of tube V-4 ex-'- tends from the 120 volt supply line 17 through resistor.-

R16, relay coil K1, and switch SW1 to ground. The,

plate and control grid of tube V-3B are di rectly"con,-;-;

nected to the control grid of tube V-4. The normally alarm device.

and target circuit of tube V 5 extends from the 120 vb supply line 17 through resistor R16, resistorlR19 aridgthe I tube V-S to ground. I

In operation, the sensing element 8 is hat'e'ibjfhe quiescent current of tubeV-1A to a value somewhat above ambient temperature. Respiratory or tidal air moving past this heated filament 9 displaces the heated layers of still air,,thereby lowering the thermal impedance. This a C; causes: as rapid' cooling of the filament 9, thereby sharply lowering its resistance. Since the value of resistance. in the cathode circuit of tube V-1A determines the amount of plate current flow, this varying resistance as a function oftransient respiratoryair movementmanifests. itself in a varying-or A. C. plate voltage impressed across resistorRl.

Thisvoltage is applied to the control grid of tube V.1B.

through condenser C1. The signal is then amplified by the. circuits. of tubes. V1B, V2A, and V-ZB until the small value of signal existing in the cathode circuitof tube V'-.1'A is increased to a value sufiicient to drive cathode follower tube V-SA. The. signal voltage developed across plate load resistor R8 is impressed through condenser C4 andacross resistor R11 on to. the grid of tube, V-.3A. The cathode circuit of tube V-3A returns toancgativeJO, volt D. C. supply. line 18 to permit signal voltage at the. cathode. of, tube V-3A. to drop below ground. Similarly, the control. gridv circuit of tube V-3A isreturncd; to. anegative 4-vtolt D. C. supply line 19 to fix; the, quiescent voltage at the cathode to zero. Tracing throughthis circuit then, anegative going signal at the control grid of tube V-3A causesanegative going signal at low impedance, at the cathode of. tube V3A. This signal charges capacitor C7-negatively through diode tube V-3B, This negative voltage. existing across condenser Q7 maintains a. c t-oil bias on the control grid of thyratrontube V-4, Variable resistor R14 actsto control the r-ate ofgdischarge of condenser C7, andtherefore determines thelength of time thyratron tube, V-.4 is held cut-oft following the last respiratory efiort. It can be seen, then, that respiration fails, the bias voltage maintained across condenser C7 is discharged within a. predetermined time asset by variable resistor R14, and the thyratron tube, V.4 fires, actuating relay K1 and energizing the alarm circuit. Electron ray eye tubeV-S is included in conventional circuitry, driven also from the cathode of tube V-3A. The purpose of this tube V5 is toenable hospital personnel to visually monitor respiration rate. Condenser C6 and resistor R5, and condenser C5 and resistor R13, are decoupling networks to prevent regenerative feedback.

While preferred embodiments of the invention have been-disclosed, the description isintended to be, illustrative only and, it isto be understood that changes and variations may be made without departing from the spirit and scope of thevinvention as definedby the appended claims.

I claim:

1. Apparatus for sensing and detecting variations in the respiratory function of a patient, comprising an electrical resistive element sensitive to respiratory tidalair; means for positioning the said element in the path of the respiratory tidal air of the patient; an electrical circuit which includes an electrical energy source for the element, and the sensitive element itself; means forzamplifying changes of the AC component, in the flow of current throughthe sensitive element to a value sufficient to charge a capacitor from a low impedance source to a value negative enough to act as a cutoff bias on an alarm circuit, which is-energized when the AC component ofthe flow of current through the aforesaid sensitive element changes or reduces to zero.

2'. In electronic apparatus for sensing and detecting changes in the respiratory function of a patient; a thermally sensitive resistive device comprising a tubular glass envelope; a thermally sensitive wire mounted within the envelope; electrically conductive end caps mounted upon opposite extremities of the envelope, each of the said end caps having an aperture disposed therein which together with the interior of the envelope provide a .continuous axial air passage through the device; and means 5 for electrically connecting the end caps to opposite extremities, of. the. thermally sensitive wire.

3. Apparatus for detecting a change in the respiratory action of a pulmonary organism, said apparatus comprising an element sensitive to thermal variations of its surrounding atmosphere; means for positioning the element in the path of the respiratory tidal air of the organism; and means for detecting the effect of thermal changes on the said element.

4. Apparatus for detecting a change in the respiratory action of a pulmonary organism, said apparatus comprising an element sensitive to thermal variations of its surrounding atmosphere; means for positioning the ele ment in the path of the respiratory tidal air of the organism; and means for detecting the effect of thermal changes on the said element; and an alarm device which is coupled to the detecting means and which becomes energized when a predetermined thermal change in the elements surrounding atmosphere occurs, said thermal change caused by displacement of atmosphere proximal to the element by the respiratory tidal air.

5. Apparatus for detecting a change in the respiratory action of a pulmonary organism, said apparatus comprising-a thermally sensitive element; means causing the temperature of the element to diflier from the ambient temperature; means for positioning the element in the path of the respiratory tidal air of the organism; and means to detect the efiect of variations of the temperature of the element.-

6. Apparatus for detecting a change in the respiratory action of a pulmonary organism, said apparatus comprising a thermally sensitive element; means to elevate the temperature of the element above the ambient temperature; means for positioning the element in the path of the respiratory tidal airof the organism; means for detecting the efiectof temperature variations of the element; and an alarm device which is coupled to the detecting means and which becomes energized when the said temperature variations of the element vary from a predetermined magnitude.

7. Apparatus for detecting a change in the respiratory action of a pulmonary organism, said apparatus comprising a thermally sensitive electrical impedance element; a source of electrical energy; an electrical circuit which includes in series the energy source and the impedance element; means for positioning the impedance element in the path of the respiratory tidal air of the organism; means for detecting variations in the impedance of the impedance element; and an alarm device which is coupled to the detecting means and which becomes energized when the impedance variations of the impedance element vary from a predetermined value.

8. Apparatus for detecting a change in the respiratory action of a pulmonary organism, said. apparatus comprising a thermally sensitive electrical resistor; 21 source of electrical energy; an electron tube having an anode, a cathode, and a control grid; means connecting the source, the tube and the resistor in electrical, series; means for positioning the resistor in the path of the respiratory tidal air of the organism; means for detecting variations in the flow ofcurrent through the tube; and an alarm device which is coupled tothe detecting means and which becomesenergized when the variations in the tube current vary from a predetermined amount.

References Cited in the file of this patent UNITED STATES PATENTS 2,193,945 Strauss et al Mar. 19, 1940 2,435,181 Lindsay Ian. 27, 1948 2,473,922 Tobias June 21, 1949

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