Flow Line Break Alarm Device

Abstract

A portable alarm device is attached to interfitting coupling portions in a therapeutic apparatus, such as, the metal or plastic coupling portions between a respirator hose and tracheostomy tube, the device including normally engaging electric contacts on the coupling portions which separate with the coupling portions to sense a break. One contact is connected to the patient's body, the other contact connected to a low-power electric pulse generating circuit for triggering an electric switch, the latter being adapted to activate the alarm element when the contacts disconnect to alert hospital personnel.

Description

This invention relates to alarm devices and, more particularly, to electric alarm devices suitable for use with therapeutic apparatus, such as, the coupling portions of a respirator flow line and tracheostomy tube assembly for indicating a break therebetween.

A variety of types of flow lines are presently in use as an integral part of commercially available therapeutic apparatus. In many instances, particularly when treatment with such apparatus is carried out over extended periods of time, it is not practical to have an attendant present at all times; yet it is readily apparent that a failure in therapeutic apparatus such as an undetected break in an oxygen line may be seriously harmful or even fatal to the patient.

One typical example is the respirator hose and tube employed in a tracheostomy which continuously delivers a negative and positive oxygen pressure. While some types of alarm devices for detecting breaks in airflow lines have theretofore been provided such as pressure responsive devices they have not proved entirely satisfactory for all applications.

Accordingly an object of this invention is to provide a simplified, reliable, lightweight, safe and easy to use electric alarm device.

Another object of this invention is to provide an electric alarm device which is extremely sensitive and is readily conformable for use with various types of therapeutic apparatus.

A further object of this invention is to provide an electric alarm device suitable for use in the presence of oxygen without danger of sparking for the purpose of alerting hospital personnel when there is a break in the coupling between a respirator flow line and a tracheostomy tube attached to a patient.

It is a still further object of this invention to provide a portable alarm device which is easily transportable to the point of use and is readily attachable to releasable flow line couplings of the type utilized between a respirator supply hose and tracheostomy tube inserted into the trachea of a patient.

Other objects, advantages and capabilities of the present invention will become more apparent from a consideration of the following description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of an alarm device embodying features of the present invention attached to line coupling portions between a respirator supply line and a plastic tracheostomy tube shown partially retracted from the trachea of a patient, the coupling portions being shown in a separated position;

FIG. 2 is a perspective view of the alarm device shown in FIG. 1 attached to coupling portions between a respirator supply line and metal tracheostomy tube with the coupling portions shown in an interfitting connected position and the tracheostomy tube inserted into the trachea of a patient; and

FIG. 3 is an electric circuit diagram of an alarm circuit which is preferably contained in the portable box shown in FIGS. 1 and 2.

Referring now to the drawings, there is shown by way of illustrative example in FIG. 1 a typical airflow system for tracheostomy usage wherein a respirator supply represented at 3 has a flexible hose outlet or line 4 which is adapted to be detachably coupled to a tracheostomy tube 6, the latter being normally attached to the neck of a patient P with one end inserted into the trachea designated at T. Although the tracheostomy tube 6 is shown partially retracted in FIG. 1, a flange member 8 is disposed on the tracheostomy tube and in normal use is tied around the back of the patient's neck to secure the tracheostomy tube 6 in fully inserted position. The respirator supply 3 may be one of a variety of known oxygen sources of the inspirator-expirator type capable of alternately producing a positive and negative pressure in the output line for inspiration and expiration.

A releasable connection or coupling is provided between the supply hose 4 and the intake end of the tracheostomy tube 6 to permit repeated cleaning and care of the trachea of the patient. This coupling requires ease of separation, and a typical form is a friction-fitting type coupling as shown comprising an elbow-shaped female portion 11 at the discharge end of the supply hose 4 and a male portion 12 at the intake end of the tracheostomy tube which interconnect or interfit to form a detachable coupling.

The tracheostomy tube 6 and associated flange 8 may be conventionally formed either of an electrically nonconductive or insulative material, usually plastic, as depicted in FIG. 1; or they are often composed of an electrically conductive material, such as, metal as depicted in FIG. 2, and the tube and flange are designated by numerals 15 and 16, respectively. The female coupling portions 11 in both forms are preferably composed of an insulative material, such as, a plastic with the male coupling end 17 of the metal tracheostomy tube 15 also being of a conductive metal forming an extension of the tracheostomy tube.

In accordance with the present invention, the electric alarm or signal apparatus devised for the airflow tracheostomy systems described broadly is capable of sensing a leak or break in the airflow line to the tracheostomy tube, and more specifically a separation in the friction-fitting coupling portions, and of activating an alarm element which can be heard by hospital personnel at a point remote from the patient. To this end, the sensing portion or sensor arrangement of the alarm device associated with the tracheostomy tube of FIG. 1 includes an electric contact 19, herein referred to as the first electric contact, supported on the female coupling portion 11; and another electric contact, referred to as the second electric contact, is supported on the male coupling portion 12. Essentially, the first and second contacts engage one another when the coupling portions are physically connected and are movable to an electrically disconnected position when the coupling portions are separated.

Contacts 19 and 20 may be disposed on the coupling portions in a number of ways to effect the desired electric connection and disconnection therebetween. For convenience of assembly onto the coupling portions presently in use on the tracheostomy tube and respirator hose and for effecting a good electric connection between contacts, a preferred arrangement for the first contact 19 in FIG. 1 and 2 is to utilize an insulated wire wound in a plurality of turns to define a helical coil designated 21 in surrounding relation to one end of the female coupling portion 11, the end loop or turn having its insulation removed so as to be bare or exposed. The second electric contact 20 for the form of FIG. 1 may be noninsulated wired wound in a plurality of turns or loops defining a helical coil designated 22 of approximately the same diameter as coil 21 in surrounding relation to the male coupling portion 12, the end loop of the wire adjacent the exposed end loop forming the contact 19 being similarly exposed. The helical coil members on the coupling portions are aligned so as to compress or bias the contacts 19 and 20 together when the coupling portions are connected.

The first contact 19 is electrically connected to the electric alarm actuating circuitry contained in a portable box 23 shown in FIGS. 1 and 2 by means of an electric lead preferably a coaxial cable 24, having an alligator-type clip 25 mounted at its extended end. In the preferred coil arrangement shown, the other end of coil 21 is secured to the alligator-type clip 25, for instance, by soldering. In the assembly shown the alligator-type clip 25 is clamped to the female joint portion 11 to hold the coil 21 and cable 24 in a proper position.

The second contact 20 for the plastic tracheostomy tube 6 is electrically connected through coil 22 to a skin electrode 27 which may be attached and grounded to the body of the patient as by tape 28. When the metal type tracheostomy tube 15 of FIG. 2 is employed a second contact designated 29 need only be a piece of electrically conductive material mounted on the outer surface of the intake end of the male joint portion 17 which will engage the bared wire or contact element 19 when the coupling portions are connected. The end surface of the metal male joint portion 17 could also define the second electric contact. The metal tracheostomy tube 15 suitably contacts the patient's body to perform the same function as the skin electrode 27 shown in the arrangement of FIG. 1.

The box 23 or container for the electric alarm actuating circuitry and alarm element may be of a variety of configurations but for the instant tracheostomy application it is important that it be of a lightweight metal such as aluminum. The top of the box serves as a combined panel and support for an on-off switch 31, a reset button 32 and a speaker 33, described more fully hereinafter in connection with the circuit diagram of FIG. 3.

The electric alarm-actuating circuitry shown in FIG. 3 may be generally characterized as a relaxation oscillator type pulsing circuit which comprises a low voltage DC power source illustrated as two batteries 35 and 36 connected in series having the on-off switch 31 connected therein. A series circuit is connected across the power source including resistors 37 and 38, a negative resistance element shown in the form of a neon lamp 39, a capacitor 41 connected between one electrode of the lamp and a variable tap on load resistor 42. Capacitor 46 is connected between the other electrode of the lamp and one end terminal designated 44 of the load resistor 42, the other end terminal being designated 45, and a capacitor 47 is connected to the lamp electrode common to resistor 38. One end of the inner solid cylindrical conductor of the coaxial cable 24 has its outer conductor connected to the common ground or zero potential portion of the circuit. As shown in FIG. 3 the alligator clip is connected to the other end of the inner conductor of cable 24 and through contacts 19 and 20 to the patient's body, through the skin electrode 27 shown in FIG. 3, or alternately to the metal tracheostomy tube 15 of FIG. 2.

The alarm element 48 is connected in a series circuit including the cathode and anode of an electronic solid state switch element 49, preferably a silicon-controlled rectifier, and a reset switch 32, and which circuit is connected across battery 36 and on-off switch 31. The gate and cathode elements of the SCR 49 are connected across load resistor 42, and specifically terminal 44 is connected to the anode through switch 32 and terminal 45 to the gate. A preselected positive firing voltage applied between the gate and cathode elements will cause the SCR 49 to conduct between the cathode and anode thereby applying the voltage of battery 36 to the alarm element 48. An alarm element 48 which is suitable for the circuit above described is a Mallory Tone-Alert, manufactured by P. R. Mallory and Company, Inc. of Indianapolis, Ind., having a speaker 33 for transmitting the sound to hospital personnel. However, it is understood that a variety of warning devices such as a relay, light for bell may be used.

In sequence of operation with the circuit elements connected as shown, the contacts 19 and 20 are closed to establish an essentially zero or ground reference potential at capacitor 46. With the battery polarity as illustrated, negative pulses are formed across load resistor 42 at its tap by the charging and discharging of capacitor 41, and positive pulses are formed across load resistor 42 by the charging and discharging of capacitor 41 which in effect add algebraically to form an instantaneous voltage between the gate and anode of the SCR. An adjustment of the tap on resistor 42 regulates this voltage level. When the contacts open, the electrical connection to ground or zero potential for the relaxation oscillator circuit is removed and results in a sufficient change in the sum of the positive and negative pulses to fire the SCR 49.

Initially the circuit resistor 42 is set with nothing connected in series with capacitor 45, i.e., when the contacts are open. Under this condition pairing of the positive and negative pulses is just great enough to fire the SCR. When additional capacitors of the cable 24 are added to the circuit, the oscillator circuit is sufficiently altered to hold the SCR off. When the SCR fires it will continue to conduct until the current flow in the cathode is momentarily broken. Reset switch 32 is used to perform the function after firing. With the use of low voltage DC batteries a typical circuit of this type will draw on the order of 20 microamperes when the SCR is not conducting and 9 to 14 microamperes when fired. A positive voltage of 0.8 volt or slightly more across resistor 42 fires the SCR.

The single coaxial type cable 24 connected to one contact is preferred for simplicity of attachment but it is understood that a second cable connected to the other contact and grounded to the box could be used in place of the body electrode or metal tracheostomy tube ground. Further the present device using electric pulses to indicate a line break is suitable for wireless transmission wherein such pulses may be modulated and transmitted as radio waves to a distant receiving station.

While the present invention has been described with reference to particular structure there is no intent to limit the spirit and scope of the present invention to such structure except as defined by the appended claims.

Claims

We claim:

1. An alarm device for signaling a line separation comprising interfitting male and female line coupling portions in the flow line between a tracheostomy tube and a respirator hose,

sensing means including first and second electric contacts arranged for support on said male and female line-coupling portions and being aligned for electric connection with each other when the coupling portions are joined for disconnection when the coupling portions are separated,

an alarm element, and

electric circuit means coupled to said alarm element and responsive to the disconnection of said contacts for actuating said alarm element.

2. An alarm device as set forth in claim 1 wherein one of electric contacts is connected to an electrode and includes means for attachment to the body of a patient to ground said circuit means to said patient when said contacts are closed.

3. An alarm device as set forth in claim 1 further including a coaxial cable arranged to clamp on one of said coupling portions to connect one of said electric contacts to said electric circuit means.

4. An alarm device as set forth in claim 1 wherein at least one of said electric contacts is an exposed wire loop at one end of a coil of insulated wire slidably mounted on one of said coupling portions.

5. An alarm device as set forth in claim 1 wherein one of said coupling portions is formed of an insulative material and said associated contact is an end loop of a coil of wire wound on said coupling portion.

6. An alarm device as set forth in claim 5 wherein said coil of wire is connected to a skin electrode including means for fastening to the body of a patient.

7. An alarm device as set forth in claim 1 wherein the tracheostomy tube and associated coupling portion is formed of an electrically conductive material and having means forming one of said contacts for connecting the circuit means to the body of the patient.

8. An alarm device as set forth in claim 1 wherein said electric circuit means includes a relaxation oscillator circuit for simultaneously generating pulses of an opposite polarity which are applied across the electrodes of an electronic switch element in the circuit of the alarm element for triggering said switch element when the contacts are separated.

9. An alarm device as set forth in claim 8 wherein said electronic switch element is a silicon controlled rectifier.

10. An alarm device as set forth in claim 8 wherein said oscillator circuit includes a negative resistance element and capacitors connected thereto and interconnected with a load resistor across which said pulses are formed.

11. An electric alarm device for signaling a line separation, comprising male and female line-coupling portions in the flow line between a tracheostomy tube and a respirator hose,

an electric contact arranged for support on each of said coupling portions to be engageable with each other when said coupling portions are joined and disengaged when said coupling portions are separated, and

electronic circuit means including an audible alarm element and electric power source for the alarm element and means connected to one of said contact elements to alternately connect the power source to the alarm element when the contacts are in engagement and disconnect the power source from the alarm element when the contacts are separated.

12. An alarm device for signaling a line separation comprising interfitting male and female line coupling portions in the flow line between a tracheostomy tube and a respirator hose,

an electric contact arranged for slidable movement on each of the coupling portions to be electrically connected with each other when the coupling portions are connected and to be disconnected when the coupling portions are separated,

a first electric circuit including a power supply, an audible alarm element and a low voltage electronic switch arranged to turn on the alarm element when triggered, and

a second electric circuit connected to one of said contacts and the electronic switch having means for generating a plurality of electric pulses which sufficiently change in amplitude when said contacts separate to trigger said switch for activating said alarm element.