Load-cell based hospital bed control

• US 7,437,787 B2
• Filed: 08/03/2007
• Issued: 10/21/2008
• Est. Priority Date: 08/09/2004
• Status: Active Grant

• Current Assignee: Hill-Rom Services Incorporated (Baxter International Inc.)
• Original Assignee: Hill-Rom Services Incorporated (Baxter International Inc.)
• Inventors: Bhai, Aziz Ali
• Primary Examiner(s): Gibson; Randy W
• Application Number:
  US11/833,311
• Publication Number:
  US 20070268147A1
• Time in Patent Office: 445 Days
• Field of Search: 561/3, 561/5, 568/9, 177/144, 177/245, 340/666
• US Class Current: 5/613
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/1115 Monitoring leaving of a patient support, e.g. a bed or a wheelchair
• CPC Class Codes: A61G 2203/34 for pressure
• CPC Class Codes: A61G 2203/36 for motion
• CPC Class Codes: G01G 19/445 in a horizontal position
• CPC Class Codes: G16H 40/63 for local operation

Abstract

A system for monitoring a patient on a hospital bed includes load cells and a controller for detecting patient movement on, exit from, and impending exit from the hospital bed, including movement across or outside a virtual boundary or region located on the bed. The controller is configured to detect changes in the distribution of patient weight among the load cells. The controller is also configured to accommodate the installation or removal of medical equipment or other tare weights on the bed, head incline adjustment, and bed frame deformation or other changes in the system causing redistribution of weight among the load cells, while minimizing false alarms. A caregiver may select between various patient monitoring modes and remotely monitor patient movement relative to a reference load cell distribution, impending patient exit from the bed and patient exit from the bed. Pressures in an air mattress may be controlled based on signals from the load cells.

Claims

1. A patient support apparatus comprising

a frame,

an air mattress which is supported on a bed frame and which is configured to support an occupant, and

a system for controlling air pressure in a number of different zones of the air mattress, the system comprising a plurality of load cells coupled to the bed frame, each load cell being configured to produce a signal indicative of an amount of weight bearing upon that load cell, and a controller responsive to the signals produced by the plurality of load cells to determine a current distribution of occupant weight on each of the load cells, the controller being configured to control air pressure within any one or more of the number of different zones of the air mattress based on the current distribution of occupant weight on at least some of the plurality of load cells.

2. The patient support apparatus of claim 1, wherein the controller is configured to calculate a total weight of the occupant based on signals received from the plurality of load cells and air pressure within any one or more of the number of different zones of the air mattress is a function of the total weight.

3. The patient support apparatus of claim 1, wherein the controller is configured to monitor a position of a patient based on the signals produced by at least some of the plurality of load cells.

4. The patient support apparatus of claim 3, further comprising an alarm that is activated if a threshold condition is violated, the controller being configured to determine whether the threshold condition is violated based on the signals from at least some of the plurality of load cells and without calculating a center of gravity of the occupant.

5. The patient support apparatus of claim 4, wherein the alarm comprises at least one of a local alarm mounted to the bed frame and a remote alarm.

6. The patient support apparatus of claim 4, wherein the controller is configured to be selectively armed in at least two modes and the threshold condition is different depending upon which of the at least two modes is selected.

7. The patient support apparatus of claim 4, wherein the controller is configured to be selectively armed for activating the alarm when the threshold condition is violated and the controller is configured such that it can be armed only if the patient is within the safe arming zone as determined by the signals from at least some of the plurality of load cells.

8. The patient support apparatus of claim 1, wherein the controller is configured to determine whether the patient is moving toward a sitting up position based on the signals from at least some of the plurality of load cells.

9. The patient support apparatus of claim 1, wherein the controller is configured to determine whether the patient is rolling sideways from a prone position.

10. The patient support apparatus of claim 1, wherein a first plurality of sets of excessive patient movement conditions is stored in a memory of the controller, each of the first plurality of sets of excessive patient movement conditions defines first threshold values for each of the at least three load cells, the controller is configured to determine a total weight of the occupant on the bed, the controller is configured such that, for each of the first plurality of sets of excessive patient movement conditions, weight change values for at least some of the plurality of load cells is computed according to a patient movement model as a function of the total patient weight on the bed, and the controller is configured to determine that patient movement is excessive if at least some of the weight change values exceed corresponding ones of the first threshold values for at least one of the first plurality of sets of excessive patient movement conditions.

11. The patient support apparatus of claim 10, wherein the first threshold values comprise percentage weight values and the weight change values comprise percentage weight change values.

12. A patient support apparatus comprising

a frame,

an air mattress which is supported on the frame and which supports an occupant,

a plurality of load cells coupled to the bed frame, each load cell being configured to produce a signal indicative of an amount of weight bearing upon that load cell, and

a controller being responsive to the signals produced by the plurality of load cells to determine a current distribution of occupant weight on each of the load cells, the controller being configured to control air pressure within any one or more of the number of different zones of the air mattress based on the current distribution of occupant weight on at least some of the plurality of load cells, the controller also being configured to determine whether a patient position threshold condition is violated based on the signals from at least some of the plurality of load cells and without calculating a center of gravity of the occupant, the controller being configured to activate an alarm if the patient position threshold condition is violated.

13. The patient support apparatus of claim 12, wherein the alarm comprises at least one of a local alarm mounted to the bed frame and a remote alarm.

14. The patient support apparatus of claim 12, wherein the controller is configured to be selectively armed in at least two modes and the threshold condition is different depending upon which of the at least two modes is selected.

15. The patient support apparatus of claim 12, wherein the controller is configured to be selectively armed for activating the alarm when the threshold condition is violated and the controller is configured such that it can be armed only if the patient is within the safe arming zone as determined by the signals from at least some of the plurality of load cells.

16. The patient support apparatus of claim 12, wherein the controller is configured to determine whether the patient is moving toward a sitting up position based on the signals from at least some of the plurality of load cells.

17. The patient support apparatus of claim 12, wherein the controller is configured to determine whether the patient is rolling sideways from a prone position.