PATIENT MONITORING SYSTEM

TECHNICAL FIELD

The present invention generally relates to a patient monitoring system that monitors a patient on a time basis.

BACKGROUND OF THE INVENTION

In-patient care, one concern is the formation of bed sores or decubitus sores resulting from the patient remaining in bed for extended periods of time. The most common solution is to turn the patient. Typically a patient who is susceptible to such sores may need to be turned every two hours and, in some cases, more frequently. This process of monitoring a patient to reduce the likelihood of the patient developing such sores will generally be referred to as "wound care." To ensure that adequate wound care is performed or to make sure that the patient is moving sufficiently on their own, a system for monitoring a patient on a time basis is needed.

SUMMARY OF THE INVENTION

In general, the present invention provides, a patient monitoring system used in connection with a mattress, the system including a controller, a sensor in communication with the controller and adapted to detect movement on the mattress, a timer in communication with the controller, and an alarm in communication with the controller, wherein the controller is adapted to communicate an alarm signal after a selected period of time has passed without sensing any movement on the mattress.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a to plan view of the patient migration monitor according to the concepts of the present invention showing a single chamber migration sensor having a pair of insertable ends located near the lateral edges of a mattress;

Fig. 2 is a partially fragmented sectional side elevational view, as might be seen along line 2-2 in Fig. 1 , depicting details of one insertable end;

Fig. 3 is a partially fragmented partially sectional end view as might be seen along line 3-3 in Fig. 1;

Fig. 4 is a patient migration monitor according to the concepts of the present invention having two migration sensors shown near the edges of a mattress having a first end insertable within the mattress for detecting patient movement and a second end connected to a sensor that detects changes in the internal pressure within the sensor and reports the same to a controller;

Fig. 5 is a partially fragmented side elevational view of the mattress depicted in Fig. 4 shown on a pivotable bed frame depicting a portion of the mattress in an elevated position;

Fig. 5a is an enlarged fragmented sectional side elevational view showing details of the migration sensor, when a portion of the mattress is raised;

Fig. 6 is a patient migration monitor according to the concepts of the present invention having an array of migration sensors within the mattress;

Fig. 7 is a partially schematic section side elevational view of a migration sensor according to the concepts of the present invention, where the sensor defines a chamber that has been filled with foam;

Fig. 8 is a partially schematic section side elevational view of a migration sensor according to the concepts of the present invention, where a pump communicates with the sensor's chamber to over inflate the chamber;

Fig.9 is an operational diagram depicting a controller according to the concepts of the present invention that monitors a patient on a time basis; and

Fig. 10 is a flow chart depicting operation of a controller according to the concepts of the present invention that monitors a patient on a time basis.

DETAILED DESCRIPTION OF THE INVENTION The present invention generally provides a patient monitoring system used in connection with a mattress, overlay, cover, cushion, or pad, on which a patient is at least partially supported, collectively referred to herein as a "mattress". The mattress may be used in connection with any supporting frame including, without limitation, a bed, chair, or sofa. More particularly, the present invention relates to a monitoring system that incorporates a migration sensor that includes a member that defines a chamber fluidly connected to a pressure sensor. The migration sensor is placed in proximity to a patient such that movement of the patient applies a force to the member, which is detected by the sensor as a pressure change. Pressure changes are monitored by a controller and reported

to a care giver to help alert the care giver of a potentially dangerous condition, for example a patient attempting to exit the mattress or moving to a position where they might fall from the mattress. Use of the terms patient and care giver should be understood as any person and are not limiting. They are merely used to provide context in the sense that a patient is the person being monitored by the care giver. This monitoring could occur in any setting including, for example, hospitals, managed care facilities, emergency shelters, or a home.

One embodiment of a patient monitoring system according to the concepts of the present invention is shown, as an example, in the drawings and generally indicated by the numeral 10. System 10 includes a migration sensor, generally indicated by the numeral 15. Migration sensor includes a member 20 that defines a chamber 25. A pressure sensor 30 is placed in sensing communication with the member 20. As a result, changes in the external forces on the member 20 are detected as pressure changes within the chamber 25 by the pressure sensor 30.

To that end, the member 20 may be constructed of a compressible material including, but not limited to, nylon, vinyl, rubber, and similar materials. As an option, the member 20 may be constructed of a material that gives the member 20 a softness substantially equal to or less than that of the surrounding mattress material. When using a member 20 having a softness substantially equal to or less than the softness of the mattress, the therapeutic value of the mattress is improved because the member 20 will not create a pressure point in the mattress.

Ih general, the member 20 may be fluid-tight, but some fluid loss is permissible. As will be appreciated, changes in the chamber pressure caused by patient migration will still be detected by the sensor 30 even if a loss of fluid is occurring. If necessary, losses may be compensated for by periodically refilling the member 20 with fluid. To that end, an air supply, including, but not limited to a pump P (Fig. 8), may be fluidly connected to the member 20: When using a pump P, to minimize losses through the pump P, a valve V may be used to close off the pump P from the member 20 after the desired inflation of the chamber 25 is achieved.

The member 20 maybe given any desired shape and may be of any suitable size. In the example shown in Fig. 1, a member having an elongate tubular shape is shown. As best shown in Fig. 3, the member 20 may have a circular cross-section. Returning to Fig. 1, member 20 may have a first end 21 and a second end 22 that are located on opposite sides of the mattress centerline C. While the ends 21,22 are shown at the lateral outward

edges 23,24 of the mattress 12, it will be appreciated that the member 20 may be located at any position relative to the mattress 12. For example, as shown in Fig. 1, the member 20 may be located at the periphery 26 of the mattress 12, or as shown in Fig. 6, member 20 may be located at positions inboard of the mattress periphery 26. The ends 21 , 22 or individual members 20, when multiple members 20 are used, may be arranged symmetrically about the mattress centerline C or in an unsymmetrical fashion.

Also, member 20 may have any length. For example, member 20 may extend the entire length of the mattress 12 or a selected portion of the mattress 12. For example, the member 20 may have a length that allows it to be adjacent to the patient's torso. Locating the member 20 at the upper end 14 of the mattress 12 near the patient's torso is believed to provide earlier detection of movement that might lead to a dangerous condition because the patient' s torso is closest to the edge of the mattress 12. In the example shown in Fig. 1, the member 20 extends from one end of the mattress 12 to a point near or beyond the mattress's transverse center-line TC. Alternatively, when used in connection with an articulating mattress, as shown for example in Figs. 4- 5 A, that is hinged on an axis A, the member 20 may be located near or extend beyond the axis A to provide information relating to the incline of the mattress 12 as will discussed more completely below.

With reference to Fig. 1 , the member 20 is placed in proximity to the patient, as by attaching the member 20 to the mattress 12. For purposes of this invention, "attachment" of the member 20 may include any mechanical attachment of the member 20 to the mattress 12, insertion of the member 20 within a receiver formed in the mattress 12 or an adjacent structure, or simply laying the member 20 on or beneath the mattress 12. As shown in Fig. 1 , member 20 may also be attached by inserting the member 20 within a member support 35 that is attached to the mattress 12. In general, the member support 35 may be any member suitable for supporting the member 20. In the example shown, member support 35 is a bolster 36 that defines a receiver 37 for the member 20. The member support 35 may be constructed of materials commonly used to construct mattresses. For example, as shown in Fig. 3, the member support 35 may be constructed of foam.

In the example shown, member support 35 defines a cylindrical shaped receiver 37 at a depth D from the upper surface 38 of the member support 35. Depending on the

material used to construct the member support 35 and the level of sensitivity desired, the depth D at which the receiver 37 is located may be increased or decreased.

Also, while the receiver may have a length corresponding to the portion of the migration sensor 15 that is inserted into the receiver 37, as shown, the support 35 may alternatively define a receiver 37 that extends the entire length L of the support 35. This provides flexibility in that the migration sensor 15 may be inserted at either end of the support 35 and facilitates the use of extrusion methods of forming the support 35. The support 35 allows forces to be transmitted from the patient to the migration sensor 15 and may be made flexible to facilitate the transmission of these forces. As best shown in Fig. 3, to facilitate radial insertion of the migration member 20 when axial insertion is not possible, for example, when the receiver 37 does not open outward at an end of the support 35 or mattress 12 or simply to provide an alternative to axial insertion, the support 35 may be provided with a slot 39 that extends radially outward from the receiver 37. Legs 41 on either side of the slot 39 may be flexed outwardly to allow radial insertion of the member 20. In the example shown, the slot 39 extends downward from the receiver 37.

Figs.7 and 8 depict examples of members 20, but are not to be considered limiting. The member 20 maybe made compressible as by having crushable zones or, as discussed above, by selecting a material that will deform under suitable force. As shown in Figs. 7 and 8, a thin membrane may be used to construct the member 20. To increase the sensitivity of the member 20, as shown in Fig. 7, the member's chamber 23 may be filled with a porous material 40 including, but not limited to, foam. Alternatively, a pump P may be used to maintain the member 20 in an over inflated condition. A valve V may be used to close the conduit to the pump P to avoid fluid loss back through the pump P. As mentioned, a sensor 30 is in sensing communication with member 20. To that end, member 20 may provided with an opening 28 that opens to the sensor 30. Other methods of sensing the pressure or changes in pressure within member 20 may be used as well. In the example shown in Fig. 1 , a conduit 31 extends from member 20 to the sensor 30 to fluidly connect the member 20 to the sensor 30. As shown in Fig. 4, the member 20 may directly connect to the sensor 30 with the opening formed at the member's second end 22.

The sensor 30, in turn, communicates with a controller C, which monitors changes in the member's pressure and notifies the care giver. The term controller encompasses any

device capable of receiving pressure information from the pressure sensor 30 and notifying the care giver. The controller C may be simple in the sense that any change in pressure is communicated to the caregiver by activating an alarm, described more completely below. In this example, the controller C acts much like a switch. Alternatively, the controller C may be programmable and include a processor and memory if necessary.

The controller C may be programmed with instructions to alert a care giver only under certain circumstances. For example, controller C may be programmed with a selected threshold pressure. The controller C may, then, compare the sensed pressure to the selected threshold pressure. In comparing the sensed pressure to the threshold pressure the controller C may warn the care giver in a variety of ways. In one example, the selected threshold is programmed to indicate a dangerous condition. If the controller C detects a pressure equal to or exceeding this pressure it may activate an alarm or otherwise communicates this condition to a care giver. Alternatively, the controller C may be programmed to incrementally alert the care giver as the sensed pressure approaches the threshold. Along these lines, the controller C may be programmed to signal the care giver with increasing frequency or intensity as the threshold is approached. Since some changes in pressure may be considered permissible, the controller C may be programmed with a base pressure value that must be exceeded before the controller C notifies the care giver. The controller C may notify the user by communicating an alarm signal to an existing system within the care giver facility, for example, a nurse call or similar system.

Notification may be in any perceptible form including for example, visual, audible, or tactile forms. For sake of simplicity, the device used to notify the caregiver will be referred to as an alarm AL. The alarm AL may form part of the controller C or, as shown in Fig. 6, may be separate from the controller C. Optionally, the alarm AL may be located remotely from the mattress 12, for example at a central care giver's station. Thealarm AL may be mobile and carried by a care giver. Multiple alarms AL may be used together, as well. For example, the controller C may simultaneously signal an alarm within the controller C and a remote alarm AL. Any known device capable of receiving a signal from the controller C and notifying the care giver may be used as an alarm AL. Or, a custom alarm AL may be designed. In Fig. 6, communication between the controller C and alarm AL is schematically shown, and may occur in any manner including but not limited to electrical, optical, and wireless forms.

Alarm AL may be any suitable device for generating a perceptible form of notice. For example, alarm AL may include, but not be limited to, a speaker that generates an audible tone, bell, or recorded voice or other audible cue; a light, an LED, a display screen, or other viewable device; or a vibrating unit, Braille reader, or other tactile device. As an alternative or in addition to the above described systems, controller C may be programmed, such that, at a selected pressure range corresponds to a selected risk level. Upon detecting pressures within the respective ranges, the controller C itself, or through alarm AL, notifies the care giver of the selected risk level. One example, which is not considered limiting, provides low, medium, and high risk levels associated with increasing pressure ranges. As a further alternative, the actual pressure value may be communicated to the care giver.

When communicating more complex information, the controller C or alarm AL will include a suitable audible, visual, or tactile device for communicating the risk level, such as those described above with respect to the alarm AL. Other examples, which are not considered limiting, would be visual displays or simply a "display", including, but not limited to, a numeric or alpha-numeric LED, series of lights associated with a printed scale, or a monitor.

Figs.4-5 A depict an alternate patient monitoring system, generally indicated by the number 110. Patient monitoring system 110 is similar to the system 10 and thus like numbers will be used to refer to like components. As shown in Fig.4, system 110 differs from system 10 in that it includes multiple migration sensors, generally indicated by the number 115. As in the previous embodiment, each migration sensor 115 includes a member 120 that defines a chamber 125, and is in fluid communication with a sensor 130. In this embodiment, individual pressure changes within the members 120 may be independently sensed at multiple locations. In the example shown, a pair of members 120 is used, but any number of migration sensors 115 may be used. To that end, pressures (P ₁ , P ₂ ) are detected by a pair of sensors 130, which respectively report the pressures (P ₁ , P ₂ ) to controller C. By monitoring the changes in pressure at the individual member locations more information about the patient's movements may be defined. For example, in the embodiment shown, an increase in pressure in a single member could indicate which side of the mattress 112 the patient is moving toward. Also, detection of simultaneous changes in the pressures within individual members 120 may indicate that the angle of the mattress 112 is being changed ruling out a dangerous condition, as described more completely

below. To avoid false alarms caused by changes in the mattress angle, controller C may be programmed to reset after the detection of simultaneous pressure changes in separate migration sensors 115 located on opposite sides of the mattress 112. For example, upon detecting such changes in pressure, the controller C may be programmed to zero the pressure values detected at the simultaneously changing migration sensors 115 to filter out pressure changes not associated with the patient.

In the example shown, one migration sensor 115 is located at each lateral outward extremity 113 of mattress 112. As discussed in the previous embodiment, the migration sensor 115 may be incorporated as part of the mattress 112 or be separately attached. In the latter case, a migration sensor support, generally indicated by the number 135, may be provided and attached or positioned adjacent the mattress 112 in any known manner, for example, snaps, Velcro, buttons, or other mechanical fasteners, or adhesives, welds, and the like. Support 135 may be similar to the support 135 described above and include an elongate member that defines a receiver 137 adapted to receive the migration sensor 115. While the receiver 137 may have a length corresponding to the portion of the migration sensor 115 that is inserted into the receiver 137, the support 135 may define a receiver 137 that extends the entire length of the support 135. This provides flexibility in that the migration sensor 115 may be inserted at either end of the support 135 and facilitates the use of extrusion methods of forming the support 135. The support 135 allows forces to be transmitted from the patient to the migration sensor 115 and may be made flexible to facilitate the transmission of these forces. In the example shown, support 135 is constructed of foam. As discussed, the type of support material or depth D at which the receiver 137 is located may be altered to increase or decrease the migration sensor's sensitivity to the patient's movement. In the depicted example, members 120 are used in connection with an articulating mattress 112. The articulating mattress 112 folds or bends along an axis A. It will be appreciated that in some mattresses more than one axis may be provided. The length and position of the migration sensor 115 maybe adjusted to compensate for pressure changes along these axes in the same manner as the single axis case described below. With plural migration sensors 115, articulation of the bed or mattress 112 may be detected as a pressure change within migration sensors 115 located on opposite sides of the mattress 112. As shown in Fig.5A, the change in the mattress 112 angle α causes the member 120 to bend at an (β) or otherwise compresses the member 120 near the axis A. In contrast to

a patient rolling toward the edge of the mattress 112, compression caused by a change in the mattress angle, will be detected on opposite sides of the mattress 112. It will be appreciated that the pressure change will be detected by both migration sensors 115 at roughly the same time. It is foreseeable that the pressure changes at each migration sensor 115 may not occur exactly at the same time. Consequently, reference to this condition as a "substantially simultaneous" change in pressure at plural migration sensors 115 will be understood as including pressure changes that occur exactly at the same time or with some delay between the detected pressure changes at plural migration sensors 115. In detecting these changes, the goal is to rule out false alarm conditions. To that end, the controller C may be programmed with a permissible delay between pressure readings at plural migration sensors 115 as indicative of a change in mattress angle, for example, 5 seconds.

This example is not limiting, as the care giver may enter any time period that it deems to be a safe window for the controller C to rule out conditions that might create a false alarm.

To avoid a false alarm, upon detecting a substantially simultaneous change in pressure at plural migration sensors 115 located on opposite sides of the center line CL, controller C may be programmed to automatically recalibrate itself to zero pressure so that a false alarm is not triggered. If the condition triggering the substantially simultaneous pressure changes is ongoing, for example, the mattress angle is being changed over a period of time, the controller may be programmed to continue to recalibrate to zero until the substantially simultaneous change in pressures at plural migration sensors 115 ends.

Alternatively, the controller may be programmed to alert the caregiver that the patient is changing the angle of the mattress 112 or otherwise provide notice that would cause the caregiver to investigate the patient's status without indicating an immediately dangerous condition. Since the pressure changes caused by changing the mattress angle are expected to be roughly the same, despite the simultaneous change in pressure at each migration sensor 115, the controller C may still notify the care giver of a dangerous condition if the pressures at each migration sensor 115 are different.

Fig.6 schematically depicts a patient monitoring system, generally indicated by the number 210, where the receivers 237 are formed within the mattress 212, and the members 220 are inserted therein. Members 220 could also be placed beneath the mattress 212 in the same configurations. In the example, a single member 220 having four ends is used. Alternatively, as described with respect to system 110, multiple members 220 may be used each separately communicating with the controller C.

Fig. 6 also depicts an example of a transversely extending member 220A, which like the previously described member 220, may be placed within a transverse receiver TbIK. While shown near the foot of the mattress 212, the transverse member 220A may be located at any point along the length of the mattress 212. Member 220A, while not particularly suited for detecting rolling movement of the patient, may be used to detect pressure changes in local areas on the mattress. For example, member 220A may be used to detect a patient exiting the mattress 212, which might be seen as the pressure being removed from member 220A. A sharp increase in pressure followed by its release might also indicate that a patient has exited the mattress 212. Controller C may be programmed to detect such conditions at member 220A and notify the care giver, as described in the previous embodiments.

As shown in Fig. 9, controller C may further include or be placed in communication with a timer T that monitors a patient on a time basis, hi one example, the timer T monitors a patient for an "absolute" time period meaning that the controller is programmed to notify the caregiver, for example via an alarm AL, after a fixed period of time passes on timer T. Alternatively, controller C may be programmed to monitor the patient for a "dynamic" time period meaning that the controller C monitors the amount of time based on a trigger. The trigger TR may be a signal from a sensor M. For example, controller C may include a sensor that monitors patient movement. If patient movement is sensed by controller C, the timer T starts and does not stop until additional movement is detected. In this example, a signal communicated from the sensor M to the controller C would cause controller to restart or reset the dynamic period. Alternatively, a signal from the care giver can act as a trigger TR. For example, the care giver may press a button or otherwise activate an input I in communication with controller C to initially activate or restart the timer T after checking on the patient. Controller C may be programmed such that if a selected period of time, which will be referred to as a dynamic period, passes between triggering events, such as movement or care giver activation, the controller C notifies the care giver via an alarm AL.

As a variation on the above example, the controller C may begin the dynamic time period after input I is activated by the caregiver and notify the caregiver if nothing occurs during the time period via an alarm AL. In other words, if after the input I is activated, the dynamic time period expires without another triggering event such as movement or caregiver activation, the controller C activates the alarm AL. This method of operation

may be useful when an alarm has sounded based on expiration of an absolute or dynamic time period causing the caregiver to activate an input I to silence the alarm AL. For example, the caregiver may deactivate the alarm AL or simply press a mute button. The alarm AL may have sounded to notify the caregiver that a patient needed to be turned or other patient movement was required. To ensure that this turning or movement has occurred, a dynamic period may be triggered by the caregiver's input for purposes of detecting whether or not this movement occurred. Therefore, if the dynamic time period expires without the movement sensor detecting movement on the mattress. If the dynamic time period expires without detecting movement, controller C alerts the caregiver via the alarm AL. If movement, however, is detected, the controller stops the dynamic timer and may begin the absolute timer for the next care-giving period.

The absolute and dynamic time functions may be combined with a selected time period set for each function. For example, the controller C may include a first time period or absolute time period, where an alert is sent to the care giver after a selected period of time passes on timer T. Controller C might be programmed with a second time period or dynamic time period used to monitor the time between patient movements. For example, if no movement is detected within the dynamic time period, the controller C alerts the caregiver. If a movement occurs within the dynamic time period, the controller may be programmed to restart the time period upon detecting movement. In detecting movement, a pressure sensor according to the concepts of the present invention may be used in addition to any other sensor adapted to detect patient movement including load cells, pressure switches, optical sensors, and other devices known in the art. These devices will collectively be referred to as a "movement sensor" herein. Alert to the caregiver may be communicated in the same fashion as described in the previous embodiments to an alarm AL, as described above. The absolute and dynamic time periods may be programmed into the controller C by the manufacturer or controller C may be made programmable to allow the care giver to customize these time periods. It will be appreciated that different patients may require differing levels of care of different care levels may be required based on whether a patient is unconscious, and accordingly different time periods for each may be programmed into controller C. Controller C may be a single unit monitoring several patients or a controller C may be associated with each mattress so that each patient is monitored by a separate controller C. A flow chart

invention is included in Fig. 10 as one example and is not to be considered limiting.

While a full and complete description of the invention has been set forth in accordance with the dictates of the patent statutes, it should be understood that various modifications can be made to the described invention without departing from the spirit hereof or the scope of the appended claims.