Breathing Activity Monitoring And Alarm Device

Abstract

An activity detecting means for detecting the movement of an animate object which includes a permanent magnet attached to the object. A pickup coil is provided around the area of movement of the object so that movements of the magnet induce a voltage in the coil. The output of the coil is delivered to circuit means which generates pulses when receiving the signal from the coil. An alarm means is operated by the pulses to provide an alarm signal which flashes off and on with each pulse received, but remains on when no pulse is received. Thus, the alarm means indicates the movement of the object by the flashing signal and indicates no movement by a continuous signal.

Description

The invention relates to an activity detecting means and more particularly to a means for detecting and monitoring the movements of an animate subject, such as the breathing of an infant which may be subject to Apnea Neonatorum and providing an alarm if breathing stops.

Episodes characterized by sudden unexpected cessation of respiratory movement are familiar to all who care for premature infants. These attacks of apnea usually occur without warning. This problem (Apnea Neonatorum) has been reported frequently in medical literature and everyone involved with the care of infants is concerned with it.

The invention is most useful in providing a means of detecting apnea. For this purpose a small permanent magnet is fastened to the infant's diaphragm or stomach region as by taping. The magnet is caused to move with each respiratory motion. A flat pickup coil is placed proximately to the infant, such as under the infant's bed pad or at the side of the incubator. The motion of the magnet causes a very small voltage to be induced in the receiving or pickup coil. In the absence of motion, there is no induced voltage. The voltage generated is then amplified by a tuned amplifier which is designed to reject high frequency components which could be caused by adjacent motors and other powerline caused interferences, while amplifying the signal component caused by the infant's respiration.

After passing through the amplifier the signal is passed through a band pass filter further eliminating undesirable components caused by interference. After rectification of the filtered signal it is delivered to a Schmitt trigger and other associated circuits for generating pulses which operate an alarm means. The alarm means provides a visual or audible signal which goes off and on in synchronism with the respiratory motion of the infant. If the respiratory motion stops, the alarm signal becomes steady.

Thus, a principal object of the invention is to provide a means which allows the monitoring of the movements of an animate subject without restricting the subject or connecting wires or such means thereto.

Another object of the invention is to provide a new and improved activity detecting means which monitors the movement of an animate subject and provides an alarm upon the occurrence of a predetermined condition.

Another object of the invention is to provide a new and improved activity detecting means most suitable for monitoring infants subject to Apnea Neonatorum, for detecting over a continuous period of time, the breathing activity of the infant, providing a flashing alarm in synchronism with the breathing rate, and providing a continuous alarm signal when breathing ceases.

Another object of the invention is to provide a highly reliable and effective means for monitoring the activity of an animate subject.

The foregoing and other objects of the invention will become more apparent as the following detailed description of the invention is read in conjunction with the drawings, in which:

FIG. 1 is a perspective view of a crib or incubator for an infant including the activity detecting means of the invention,

FIG. 2 is a schematic diagram in block form of the invention,

FIG. 3 is a circuit diagram of one form of the alarm means of the detecting means of the invention, and

FIGS. 4a to 4e inclusive are respective graphs illustrating the wave form of the various signals generated by the components of the diagram shown in FIG. 2.

Like reference numerals designate like parts throughout the several views.

FIG. 1 is a perspective view of a bed which may be a crib or incubator 10 including the invention. The crib 10 is provided with a base 12 having legs 14. A rectangular board 16 is pivotally supported upon the base 12 by a pair of bolts 18 at each end, for allowing the board 16 to be rocked from side to side. An infant 20 supported by the crib 10 may rest upon a crib mattress 22 which is supported by the board 16.

A pickup coil 24 comprising a large plurality of fine windings may be encased within a flat sheet 26 of plastic material and is preferably positioned under and surrounding the infant 20, by being received between the board 16 and mattress 22. The pickup coil 24 is illustrated by the dashed lines in FIG. 1.

The infant which is to have its breathing monitored, has secured with its abdomen, as by taping, a small permanent magnet 28. The magnet thus will move up and down respectively, as the infant inhales and exhales each time it breathes. Of course when the infant 20 is placed in the incubator, a closure means 30 is also provided and a source of oxygen is supplied to the infant. Thus, for the purpose of monitoring the breathing of the infant 20, no wires or any other such means need be attached to the infant and the breathing activity of the infant 20 is detected by the movement of the magnet 28 which generates voltage signals in the pickup coil 24 of a detecting means 32 which may be supported at the underside of the horizontal frame 34 of the structure 12. A lead 36 delivers the signal generated in the pickup coil 24 to the detecting means 32, while a pair of leads 38 from the detecting means 32 may be secured to an arm 40 of the infant 20 in spaced relationship at 42, 44 for applying electrical stimuli to the infant when required. The detecting means 32 also includes a motor and rocker arm 46 which is energized for rocking the pivotally secured board 16 and moving the infant 20 when a failure in breathing is detected for stimulating the infant to resume normal breathing activity.

Referring now to the block diagram of FIG. 2 for a more detailed explanation of the operation of the detecting means 32, the movement of the magnet 28 with the breathing or movement of the infant 20 results in the magnetic lines of flux from the magnet 28 increasing or decreasing through the pickup coil 24. The pickup coil 24 provides an output voltage which is related to the rate of change of magnetic flux therethrough, the output voltage being either positive or negative, depending upon whether the lines of flux are increasing or decreasing through the pickup coil 24.

The amplifier 48 receives and amplifies the signals from the pickup coil 24, and may be tuned to minimize or attenuate signals which are outside the desired frequency range of the desired information signals. The output signal from the amplifier 48 is then received by the band pass filter 50 which further acts to attenuate signals below 0.5 Hertz and above 20 Hertz, while passing the signals between these limits to the signal rectifier 52. The signal rectifier 52 passes all positive going signals and inverts negative going signals, so that all of the output signals are positive going. Such signals are delivered to the input 53 of a Schmitt trigger 54 which has a pulse forming function delivering a substantially rectangular output signal for each input pulse signal having a predetermined minimum amplitude. Since the duration of the output pulse from the Schmitt trigger 54 depends upon the duration of the input signal, the output signals from the Schmitt trigger 54 are delivered to a monostable multivibrator 56 which is triggered by each of the input signals, to deliver a respective output signal of standard amplitude and duration.

The multivibrator 56 delivers its output by a line 58 to an alarm means 60. The alarm means 60 provides a visible or audible signal which goes off and on with each pulse of the signal from the multivibrator. The signal of the alarm may be a light which flashes off and on or a buzzer which goes off and on. In addition, the alarm means provides a continuous signal, such as the light or buzzer remaining on, if no signal is delivered to the alarm means by the multivibrator. Thus, since for each breath of the infant, a pulse is generated for the inhalation as well as the exhalation, the signal of the alarm means goes off and on in synchronism with the breathing of the infant. This not only indicates that the infant is breathing, but also provides an indication of the breathing rate. In addition, the flashing signal provides an indication that the detecting means is operating. However, if the infant stops breathing, no signal is provided by the multivibrator and the signal is continuously on to provide an indication that assistance is required.

The detecting means 32 may also be provided with means to deliver a voltage stimulus to the infant through the leads 38 and/or activate the motor and arm 46 to rock the bed for causing the infant to resume normal breathing at the earliest possible time. Such means may be activated manually by an attendant or automatically when the alarm means indicated that breathing has ceased by providing a continuous signal.

It has been found that a shock to the infant such as delivery of a voltage stimulant or the rocking of the infant is sufficient to cause the infant to resume its natural breathing activity. The important factor, however, is that action must be taken immediately since failure to do so will result in the death of the infant by its failure to breathe. Thus, a most essential factor is the constant monitoring of the infant's breathing, since the failure to know that the infant has ceased its breathing activity is fatal. With the resumption of breathing of the infant 20, the magnet 28 resumes corresponding reciprocating motion generating output voltage signals in the pickup coil 24 which after amplification is rectified by the wave signal rectifier 52 are again delivered to the Schmitt trigger 54. This provides a signal pulse from the multivibrator 56 so that the alarm means 60 again provides the off and on signal.

Referring to FIG. 3, there is shown one form of the alarm means 60. As shown, alarm means 60 comprises two transistors 62 and 64. The line 58 from the multivibrator 56 is connected through a resistor 66 to the base of transistor 62. The collector of the transistor 62 is connected to the base of transistor 64. The collector of transistor 62 is also connected through a resistor 68 to the positive side of a low voltage source of direct current. The emitter of transistor 62 is connected to the negative side of the direct current source. The collector of transistor 64 is connected through a resistor 70 and the signal means, a light bulb 72, to the positive side of the direct current source. The emitter of transistor 64 is connected to the negative side of the direct current source.

In the operation of the alarm means 60, the pulses from the multivibrator 56 are delivered to the transistor 62 which produces an inverted pulse. The inverted pulses are delivered to the transistor 64 which acts as a switch. The transistor 64 turns the light bulb 72 off when the transistor 64 receives a pulse, but leaves the light bulb on at all other times. Thus, during the period of each pulse from the multivibrator 56, the light bulb is switched off, but the light bulb is on between pulses or when no pulse is received. Thus, the light bulb is switched off and on with each breath of the infant and stays on if the infant ceases breathing.

Refer now to FIGS. 4a to 4e inclusive which are respective schematic representations of signals produced by the detecting means 32 illustrating their wave form and their time relationships.

FIG. 4a graphically discloses the output voltage signal 80 from the pickup coil 24. The signal 80 comprises positive portions 82 and negative portions 84 corresponding respectively to when the infant is either inhaling or exhaling during each breathing cycle. With reference to the time scale given in seconds at 86, it is apparent that the infant is taking a breath approximately each second and a half, providing a rate of 40 breaths per minute which is within the normal range.

FIG. 4b graphically illustrated the rectified wave form 88 of the signal from the rectifier 52. In this connection it is noted that each of the negative pulses 84 of FIG. 4a have been rectified as a pulse 90 whereas the positive pulses 82 are also delivered as positive pulses from the output of the rectifier 52.

FIG. 4c graphically illustrates the delivery of an output pulse 92 by the Schmitt trigger 54 upon the receipt of a positive signal from the rectifier 52, while FIG. 4d discloses the delivery of output pulses 94 upon the receipt of the output signal 92 from the Schmitt trigger 54. It is noted again that the Schmitt trigger 54 delivers an output signal upon receiving a positive going input signal having a minimum voltage amplitude. The duration of the output pulse signal from

FIG. 4e graphically illustrates the delivery of the DC current signal 96 to the light bulb or other type of alarm device upon receipt of a positive signal from the multivibrator 56 by the alarm means 58. Each pulse 94 from the multivibrator 56 cuts off the flow of the DC current signal to the light bulb so that the light bulb flashes off and on with each pulse 94. From FIG. 4a it is noted that the breathing activity of the infant 20 ceases for a time after the signal pulse 98 from the pickup coil 24. Thus, the multivibrator 56 discontinues delivering signals after the pulse 100 as shown in FIG. 4d. As shown in FIG. 4e, the DC current is then continuously supplied to the light bulb so that the light bulb remains on providing the attendant with an indication that the infant has ceased breathing. A voltage stimulus may be applied to the infant and/or the crib 10 may be rocked to start the breating of the infant again.

Upon the resumption of breathing activity by the infant the pickup coil again delivers output signals, the first such pulse signal 102 being illustrated in FIG. 4a. The production of the pulse signal 102 results in the initiation of output signals from the rectifier 52, the first such pulse being shown at 104 in FIG. 4b. The pulse 104 is delivered to the Schmitt trigger 54 which generates the pulse 106 as shown in FIG. 4c. The generation of the output signals from the Schmitt trigger 54 results in the generation of output signals 108 from the multivibrator 56 illustrated in FIG. 4d which are delivered to the alarm means 60. As illustrated in FIG. 4e, this starts the flashing of the light bulb again.

Although the invention has been particularly illustrated with regard to the detection of the cessation of normal breathing by infants, the problem being medically designated Apnea Neonatorum, it will be obvious to those skilled in the art that the invention may find wide application with appropriate modification to meet the individual design circumstances but without substantial departure from the essence of the invention. Thus, in a situation where it is desired to monitor the motions of animals for various scientific studies, the application of magnetic means 28 to the animal and the appropriate placement of a pickup coil will allow the detection of the animal's various movements and observation of the same without interfering with the animal's normal activities, such as would be the result where wires or other encumbrances are attached to the animal.

Claims

What is claimed is:

1. An activity detecting means providing a magnetic field comprising a first means for being secured with an animate body whose breathing activity is to be monitored, second means for detecting the movement of said magnetic field of said first means and delivering an output signal responsive to said movement and third means receiving and processing the output signal of said detecting means for providing a monitoring signal which goes off and on and is responsive to the breathing activity of the animate body and an alarm signal which remains on in the absence of such activity.

2. The means of claim 1 in which said first means is a permanent magnet and said second means includes a magnetic pickup coil for being fixed with a frame of reference with respect to which the movement of said animate body, at the location where said magnetic means is secured, is to be monitored.

3. The means of claim 2 in which said third means includes pulse forming means responsive to signal derived from said second means for producing output pulses, and alarm means actuated by the output pulses to turn the alarm signal off and on.

4. The means of claim 3 in which said third means includes means receiving and rectifying the output signal form said first means and delivering said rectified signal to said pulse forming means for producing said output pulses.

5. The means of claim 4 in which the alarm means includes means for providing a visual or audible signal and means actuated by the pulses from the means for providing output pulses for turning the visual or audible signal off and on.

6. The means of claim 5 in which the means for providing a visual or audible signal is connected to a source of current to provide said signal, and the means for turning said signal off and on is a switching means which is actuated by said pulses to turn the visual or audible signal off during the occurrence of each pulse.

7. The means of claim 6 in which said switching means includes a transistor connected in the circuit between the visual or audible means and the source of current and actuated by the pulses from the means for producing output pulses.