Patent Publication Number: US-2009240160-A1

Title: Infant monitoring system

Description:
BACKGROUND 
     The present disclosure relates generally to monitoring, and more particularly to a system and method for monitoring infant vital sign(s). 
     Monitoring systems often detect movement of a person, such as an infant. As an example, it may be desirable for a caregiver to monitor a baby&#39;s movement for various reasons while the child sleeps. The systems may alert the caregiver if the child has not moved for some predetermined time. Such systems may utilize a piezoelectric crystal transducer to detect such random movements. 
     SUMMARY 
     An infant monitoring system according to embodiment(s) of the present disclosure include an accelerometer and an infant positioning member in operative communication with the accelerometer. The positioning member includes a positioning member top surface, a positioning member side surface, and a tension strip. 
     The positioning member top surface is configured for operative contact with an infant having a respiration rate and a heart beat occurring at a heart rate. The top surface receives and transmits, at least in the x-axis, a plurality of cardiac impulses exerted on the top surface responsive to the heart beat. 
     The positioning member side surface has an initial angular orientation with respect to the top surface. The accelerometer is operatively connected to the side surface and receives therefrom the impulses transmitted along the x-axis. The accelerometer may resolve the heart rate from the received impulses. 
     The tension strip, which is operatively connected to the positioning member top surface, has a substantially low bending stiffness and a substantially high tension stiffness. The strip bends longitudinally in response to periodic inhalation forces exerted on the top surface due to inhalations by the infant. The periodic longitudinal bending causes respective angular deflections of the positioning member side surface with respect to the initial angular orientation. 
     The accelerometer detects the respective angular deflections and resolves therefrom the respiration rate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features and advantages of embodiments of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to similar, though perhaps not identical components. For the sake of brevity, reference numerals or features having a previously described function may or may not be described in connection with other drawings in which they appear. 
         FIG. 1  is a semi-schematic perspective view depicting an embodiment of an infant monitoring system; 
         FIG. 2A  is a schematic front view of the embodiment of the infant monitoring system of  FIG. 1 ; 
         FIG. 2B  is an enlarged, cutaway, schematic front view of a portion of the embodiment of  FIG. 2A ; 
         FIG. 3  is a cutaway perspective view of another embodiment of an infant monitoring system; and 
         FIG. 4  is a flow diagram depicting an embodiment of a method for monitoring an infant. 
     
    
    
     DETAILED DESCRIPTION 
     Monitoring systems that detect random movement may be sensitive to any moving body, including other humans or animals in addition to the infant who is being monitored. Due to the fact that the system is looking for random movement, it may be difficult to know (with a sufficient degree of certainty) that the detected movement was actually caused by the infant. 
     Embodiment(s) of the infant monitoring system disclosed herein advantageously monitor a heart rate as well as a respiration rate of an infant in operative communication therewith. An accelerometer, which is connected to an infant positioning member, monitors infant bodily movements due to his/her heart beat and respiration and resolves the heart rate and the respiration rate therefrom. As such, embodiment(s) of the present infant monitoring system advantageously monitor infant circulation and respiration with a single accelerometer. Such a system looks for repetitive patterns of vital signs (heart and respiration rates) that are specific to the infant being monitored. It is believed that monitoring such specific patterns reduces the occurrence of false alarms often associated with other monitoring systems. 
     Furthermore, embodiments of the infant monitoring system disclosed herein may advantageously be portable. The positioning member (discussed further hereinbelow) may be placed on top of any infant sleeping surface, and may be easily removed by the care giver when the infant is to be relocated. Such a portable monitor may be used in a moving vehicle. Since the system is looking for specific infant vital signs, random noise from a moving vehicle may be filtered out relatively easily. 
     It is to be understood that the terms “top,” “bottom,” “side,” “front,” “x-axis,” “y-axis,” “z-axis” and/or like terms are not intended to be limited to, nor necessarily meant to convey a spatial orientation, but rather are used for illustrative purposes to differentiate views of the infant monitoring system, etc. It is to be further understood that embodiment(s) of the present disclosure may be assembled/used in any suitable and/or desirable spatial orientation. 
     Referring now to  FIG. 1 , the infant monitoring system  10  includes a positioning member  14  having a positioning member top surface  14   t  and a positioning member side surface  14   s.  The positioning member may be at least partially formed from open/closed cell foam or elastomeric materials. In an embodiment, at least a portion of the positioning member  14  is substantially protected by a positioning member cover  16 , as shown in  FIG. 3 . The cover  16  may substantially protect a portion of the positioning member  14 , or the entire positioning member  14 , from, for example, liquid and/or soiling. As non-limiting examples, the cover  16  may be formed at least partially from rubber and/or fabric. The cover  16  may be removable, semi-removable, or non-removable with respect to the positioning member  14 . 
     The positioning member  14  may have any suitable geometric shape. As non-limiting examples, the positioning member  14  may be substantially round or rectangular. In an embodiment where the positioning member  14  is substantially round or oval, the positioning member  14  has a single side surface  14   s . In an embodiment where the positioning member  14  is substantially square or rectangular, the positioning member includes a second positioning member side surface  14   s ′. In other embodiments, it is to be understood that the positioning member may have more than two side surfaces  14   s.  Referring also to  FIG. 2B , the side surface  14   s  has an initial angular orientation φ with respect to the top surface  14   t . The initial angular orientation φ may be defined as the angle formed between the top surface  14   t  and the side surface  14   s  as viewed along the z-axis. In the embodiment depicted in  FIGS. 1 ,  2 A and  2 B, the side surface  14   s  meets the top surface  14   t  substantially at a right angle and, thus, the initial angular orientation φ is approximately 90 degrees. 
     The positioning member top surface  14   t  is configured for operative contact with an infant. It is to be understood that clothing, bedding, and/or the like may be disposed between the infant and the top surface  14   t  during use/operation of the infant monitoring system  10 . Placing the infant substantially near the center of the positioning member  14  (i.e., approximately halfway between the side surfaces  14   s,    14   s ′) may be desirable to prevent the infant from shifting off of the positioning member  14 , which shifting may prevent the infant monitoring system  10  from properly functioning. Top surface  14   t  may have any shape suitable for operative contact with the infant. As non-limiting examples, the top surface  14   t  may be substantially flat (either horizontal or tilted) or substantially concave. In an embodiment, the top surface  14   t  is configured to substantially maintain the position of the infant on the positioning member  14  while the infant is in operative communication therewith. As an example, the top surface  14   t  depicted in  FIG. 3  is contoured to substantially mirror an infant&#39;s shape. 
     Referring back to  FIG. 1 , cardiac impulses may be exerted on the top surface  14   t  by the infant in response to the infant&#39;s heart beat. The top surface  14   t  receives and transmits, at least in the x-axis, the cardiac impulses. As such, the cardiac impulses are transmitted, by the top surface  14   t,  substantially toward the positioning member side surface  14   s.  Generally, the cardiac impulses are communicated to an accelerometer  18  as a mechanical vibration/impulse. The frequency of the signal is within a range to which the accelerometers  18  is very sensitive, and, as such, may be easily resolved. 
     The accelerometer  18  is in operative communication with the positioning member side surface  14   s.  In an embodiment, the accelerometer  18  is not a piezoelectric device. Non-limiting examples of suitable accelerometers  18  include silicone capacitive accelerometers or microelectromechanical system (MEMS) inclinometers. The accelerometer  18  receives the cardiac impulses transmitted along the x-axis from the positioning member top surface  14   t . In an embodiment, the accelerometer  18  resolves the infant&#39;s heart rate based upon the received cardiac impulses. In another embodiment, the accelerometer  18  is in operative communication with a component  22 , which receives a signal indicative of the cardiac impulses from the accelerometer  18  and resolves the heart rate therefrom. The accelerometer may be substantially insensitive to substantially low-frequency (e.g., ranging from about 0.2 to about 0.8 hertz) movement in the z-axis resulting from infant inhalations. 
     In an embodiment, the heart rate is resolved by monitoring the number of cardiac impulses received by the accelerometer  18  during a predetermined length of time. The number of received cardiac impulses may then be divided by the predetermined length of time to calculate the heart rate. 
     The positioning member top surface  14   t  is operatively connected to one or more tension strips  26 , each having a substantially low bending stiffness and a substantially high tension stiffness. In an embodiment, the tension strip  26  is formed from an adhesive backed thin polyester film. It is to be understood that the tension strip  26  may be formed from any thin material which provides sufficient lateral stiffness and minimal bending stiffness. Generally, the tension strip  26  provides bending stiffness that is comfortable for the user, and has sufficient lateral stiffness to provide ample rotational movement which an accelerometer  18  is able to resolve. Such lateral and bending stiffness may be achieved by skinning an open/closed cell material, such as a two density urethane foam product. In an embodiment having a plurality of tension strips  26 , the tension strips  26  are disposed substantially parallel with each other. The tension strip  26  may be connected to the top surface  14   t  or may be embedded within the body of the positioning member  14  near the top surface  14   t  or such that the tension strip  26  acts on the top surface  14   t,  as will be discussed further below. The tension strip  26  may extend along the top surface  14   t  substantially to the side surface  14   s  or may, alternately, extend to the side surface  14   s  and, further, a portion of the distance along the side surface  14   s  (i.e., along the y-axis). The tension strip  26  responds to inhalation forces exerted on the top surface  14   t,  which are responsive to infant inhalations, by bending longitudinally (i.e., substantially about the z-axis). 
     Referring now to  FIGS. 1 ,  2 A and  2 B together, the longitudinal bending of the tension strip  26  causes an angular deflection Θ of the positioning member top surface  14   t  with respect to the initial angular orientation φ, which angular deflection Θ is shown in phantom in  FIG. 2B . The accelerometer  18  detects the angular deflection Θ and resolves the respiration rate therefrom. In an embodiment, the component  22  receives a signal from the accelerometer  18  indicative of the angular deflection η and resolves the respiration rate therefrom. It is to be understood that a single accelerometer (and not more than one accelerometer) may both receive the cardiac impulses and detect the angular deflections Θ. As such, the single accelerometer  18  may resolve the heart rate and the respiration rate. 
     In an embodiment, each angular deflection Θ that is larger than a predetermined angle is associated with an infant inhalation. Generally, the angular deflection Θ is large enough to be resolved by the accelerometer  18 . The repeating nature of the signal and its frequency/frequency stability indicate that the deflection is an inhalation signal. The respiration rate may be resolved by monitoring the number of inhalations detected by the accelerometer  18  during a predetermined length of time. The number of received inhalations may then be divided by the predetermined length of time to calculate the respiration rate. 
     It is to be understood that longitudinal bending occurs when an inhalation force, caused by an infant&#39;s expanding lungs and, thus, abdomen, press on a portion of the tension strip  26 , substantially in the y-axis. As such, the inhalation force presses on a portion of the top surface  14   t  (i.e., substantially along the y-axis), which causes the longitudinal bending of the tension strip  26  having the substantially low bending stiffness. Further, since the tension strip  26  has a substantially high tension stiffness, the longitudinal bending causes the tension strip  26  to “act on” or pull, in the x-axis, the top of the positioning member  14  toward the point of receipt of the inhalation force (e.g., substantially near the longitudinal center of the tension strip  26 ). It is to be understood that the angular deflection Θ occurs when the longitudinal bending compresses the positioning member top  14   t  while the bottom remains substantially non-deformed. 
     Referring to  FIG. 3 , an alert system  30  may be in operative communication with the accelerometer  18 . It is to be understood that  FIG. 3  depicts another embodiment of the positioning member  14 . 
     The alert system  30  emits an alarm if the heart rate and/or the respiration rate extends beyond a respective predetermined range. In an embodiment, the alarm is emitted from a transmitter  34  in operative communication with the accelerometer  18 . In another embodiment, the alert system  30  transmits a signal from the transmitter  34  to a receiver  38  via a wired or wireless connection, which signal triggers emission of the alarm from the receiver  38 . It is to be understood that an alert system  30  may include two or more receivers  38  which may emit the alarm substantially simultaneously upon triggering. The transmitter  34  and the receiver  38  may be powered by a power cord, a replaceable power source, such as one or more batteries, and/or a rechargeable power source. 
     The alarm may include an audible alarm, a visual alarm, and/or a tactile alarm. In an embodiment, the alarm is audibly output (played, provided, etc.) via speakers in operative communication with the transmitter  34  and/or the receiver  38 . In a non-limiting example, the audible alarm includes a verbal message and/or one or more sounds, such as beeps. In another embodiment, the transmitter  34  and/or the receiver  38  includes a notification panel which digitally displays a visual notice to the user. In a non-limiting example, the visual notice may include a textual message and/or a blinking light. In yet another embodiment, the alarm is a tactile alarm, which vibrates the receiver  38 , which may be embodied, for example, as a wristband, a clip (e.g., configured for attachment to personal garments, bedding, etc.), and/or the like. It is to be understood that the alarm may be presented on divergent media, such as, for example, an alarm that is both visual and audible, and is presented to a user substantially simultaneously. 
     As an example, the alert system may emit the alarm if the respiration rate extends beyond the predetermined range, which predetermined range may be from about 12 breaths per minute to about 60 breaths per minute. As another non-limiting example, the predetermined range for the respiration rate may be from about 30 breaths per minute to about 60 breaths per minute. In still another example, the alert system may emit the alarm if the heart rate extends beyond the predetermined range, which predetermined range may be from about 60 beats per minute to about 150 beats per minute. As another non-limiting example, the predetermined range for the heart rate may be from about 100 beats per minute to about 120 beats per minute. 
     It is to be understood that the predetermined range may vary from person to person, and may depend, at least in part, on the age of the person and/or the shape in which the person is in. For an infant ranging in age from zero to six months, the predetermined respiration rate range may be from about 30 breaths per minute to about 50 breaths per minute and the predetermined heart rate range may be from about 120 beats per minute to about 140 beats per minute. For an infant ranging in range from about six months to about twelve months, the predetermined respiration rate range may be from about 25 breaths per minute to about 40 breaths per minute and the predetermined heart rate range may be from about 95 beats per minute to about 120 beats per minute. Generally, the older the infant is, the lower the respiration and heart rates are. Furthermore, such ranges may be increased or decreased if the infant, for example, suffers from a heart and/or respiratory condition. 
     If it is desirable to monitor an adult&#39;s vital signs using the monitoring system  10 , the predetermined ranges may be less than those of an infant. For example, the predetermined respiration rate range for an adult may be from about 15 breaths per minutes to about 20 breaths per minute, and the predetermined heart rate range for an adult may be from about 70 beats per minutes to about 85 beats per minute. 
     The transmitter  34  may be operatively connected to the positioning member  14  in a removable manner. As a non-limiting example, the transmitter  34  may be situated in a pocket  42  formed in the positioning member  14 . In the embodiment depicted in  FIG. 3 , the transmitter  34  is situated in a pocket  42  formed in an attachment member  46 . The attachment member  46  may releasably connect the positioning member  14  to a substantially stationary apparatus, such as a crib. In an embodiment, the attachment member  46  utilizes one or more of a snap, button, hook-and-eye, hook-and-loop, and/or the like to attach the positioning member  14  to the substantially stationary apparatus. The attachment member  46  may be formed from flexible and/or rigid materials. 
     In an embodiment, the infant monitoring system  10  includes components to operate as an audio monitor. As such, the transmitter  34  may include a speaker to pick up noises, which noises (or a signal indicative thereof) may be transmitted to the receiver  38  and output therefrom audibly, visually, and/or tactilely. 
     Referring to  FIG. 4 , an embodiment of a method of monitoring an infant includes situating the infant in operative communication with the top surface  14   t  of an infant positioning member  14 , as depicted at reference numeral  202 ; receiving, at the top surface  14   t , a plurality of cardiac impulses exerted in response to the infant&#39;s heart beat, as depicted at reference numeral  204 ; and transmitting, in the x-axis, the plurality of cardiac impulses, as depicted at reference numeral  206 . The accelerometer  18  realizes the transmitted impulses, as depicted at reference numeral  208 ; and the heart rate is resolved in response to the realized impulses, as depicted at reference numeral  210 . The embodiment further includes detecting, at the accelerometer  18 , a plurality of respective angular deflections Θ of the side surface  14   s  with respect to the initial angular orientation φ, as depicted at reference numeral  212 ; and resolving the respiration rate in response to the detected respective angular deflections Θ, as depicted at reference numeral  214 . 
     It is to be understood that the terms “connect/connected/connection” and/or the like are broadly defined herein to encompass a variety of divergent connected arrangements and assembly techniques. These arrangements and techniques include, but are not limited to (1) the direct communication between one component and another component with no intervening components therebetween; and (2) the communication of one component and another component with one or more components therebetween, provided that the one component being “connected to” the other component is somehow in operative communication with the other component (notwithstanding the presence of one or more additional components therebetween). Additionally, two components may be permanently, semi-permanently, or releasably engaged with and/or connected to one another. 
     While several embodiments have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting.