1. New Minimally-Invasive Bed-Ridden Patient Weighing System
Amy Rosenthal, Nicole Typaldos, Emily Jaeger
Mentor: Dr. Frank CP Yin

2. Background Patient’s weight is critical to care
Uncomfortable for patients to be weighed
Difficult and time consuming for nurses to move patients
Nurses often estimate weight to avoid the hassle
May become unsafe to weigh certain patients
Obesity has increased to over 35% of the population1
1. United States. Center for Disease Control and Prevention. Department of Health and Human Services. Prevalence of Obesity in the United States, By Cynthia L. Ogden, Margaret D. Carroll, Brian K. Kit, and Katherine M. Flegal. Vol. 83. Hyattsville, MD: National Center for Health and Statistics, CDC. Web. 23 Sept

3. Problem Patients can be lifted Scale built into bed Bed can be weighed
Uncomfortable
Unsafe for patient and nurse
Difficult
Complicated
Scale built into bed
Nurses forget to tare
Poor repeatability
Nurses are expected to do calculation
Bed can be weighed
Difficult to move the bed
Uncomfortable for patient to move
Large weight of the bed must be subtracted off causing less accuracy

4. Scope
Design a device for weighing bedridden patients within 0.23 kg (0.5 lbs) and with minimal movement of patient to avoid the discomfort for patients and hassle for nurses.
A single user with no additional training will be able to operate the device and determine the weight of the patient within 5 minutes of seeking the information so weighing can be done efficiently without taking the current minute standard.
The device design will not interfere with normal patient care.
Adults and obese patients weighing 22.7 kg to kg (50 lbs to 1000 lbs) should be able to remain comfortable while weight is monitored.
Some automatic capabilities will be added to ease continual patient weight monitoring including an automatic readout for use in hospitals.
The device will cost a maximum of $10,000.

5. Current Patents Attached to the bed
Design raises bed on a leg attached to a force transducer that takes weight1
1. Neuman, Eli. Weighting Device for Bedridden Patients. Tedea-Huntleigh Intl. Ltd., assaignee Patent May 1998

6. Current Patents Mobile scale
Design slides under hospital bed and then weighs both bed and patient and then the bed weight is subtracted1
Design has scale wheeled against patient bed, but still requires moving patient2
Design goes under bed mattress to give reading3
1. Ashpes, Adam T., Rynd, Richard. Mobile Hospital Bed Scale. EZE Weigh, LLC., assignee. Patent Nov. 1999
2. Stultz, Frederick L., and Clark, George C. Scale for Weighing Hospital Patients in their Horizontal Position. Acme Sclae Company, assignee. Patent Feb 1997
3. Hasty, Byron E. and Carbona, John A. Portable Scale. CH Administration Inc., assginee. Patent Feb

7. Current Patents Veterinary scales
Design pulls cables taught when table is in lowest position, letting force transducer measure weight1
Design has a platform suspended at four corners with tensile load cells that give signal proportional to force2
1.Rosenberg, Philip M., and Rosenberg, Alexander J. Veterinary Examination Table. Animal Veterinary Products, Inc.,
assignee. Patent RE Dec
2. Schneider, H. Allen. Animal Scale. Weigh Right Electronic Systems, Inc., assignee. Patent Sept. 1981

8. Stryker Hospital Beds Bariatric Hospital Beds Critical Care Beds
Model: Bari 10A
In bed scale standard with kg (1000lb) range
Critical Care Beds
Models: InTouch, Epic II
Integrated scale only comes standard in InTouch model
Maximum weight capacity of only 228 kg (500lb)
Med/Surge Beds
Models: S3, GoBed II
Integrated one-touch scale optional in both models
Ability to weigh patient in any position
Stryker.

9. Hill-Rom Hospital Beds
Bariatric Beds
TriFlex II-Optional In-bed scale
Maximum capacity kg (1000 lb) capacity
Excel Care ES – In-bed scale standard
Accuracy of 1% of patient weight when sleep deck in supine position
Maximum capacity of kg (1000 lb) capacity
TotalCare Bariatric Plus – Integrated scale standard
Accuracy of 1% of patient weight up to kg (400 lb)
Functional up to 227 kg (500 lb)
Hill-Rom.

10. Hill-Rom Hospital Beds
Non-Bariatric Beds
VersaCare – In-bed scale standard
Accuracy of 1% of patient’s weight, even with head elevated
CareAssist ES – optional integrated scale
Accuracy within 1 kg (2.2 lb) or 1.1% of patient’s weight, whichever is greater
Repeatability is within 2% of patient’s weight
Functional up to 227 kg (500 lb)
Hill-Rom.

11. Hoyer Lift Scales
Variety of models with capacities ranging around 500 to 700 lbs
Need to buy the lift and the scale separately
Lift slings can be either a chair or a stretcher lift
Commonly used
Portable

12. Design Specifications: Force
Range: kg kg (50 lbs to 1000 lbs)
Sensitivity: 0.23 kg (0.5 lbs)
Repeatability: Variance of less than 0.25 kg
Force transducers linear over 44 N to 5000 N

13. Design Specification: Safety
Shockproof
Waterproof
Can be sterilized
Current leakage of less that 100 microamp

14. Design Specifications: Device
Size: fit within normal bed dimensions (91 x 213 cm)
Portable: May be carried by a single nurse, less than 35lbs
Digital readout of weight
Option to remove or add the object’s weight (i.e. to account for removal or addition blankets)
Interface with computer or standalone device
Display output in units of kg or lbs
Efficient: less than 5 minutes to operate and single output for easy reading
Made for adults and obese patients
Power source: 120 V AC or convert to DC
Temperature range: Perform in 10°C to 37°C (50°F to 100°F)

15. Design Specifications
Minimal movement of patient
No change to patient’s comfort

16. Load Cell Equations Converts force into an electrical signal.
Force deforms a strain gauge which measures the strain as an electrical signal, as a strain causes a change in the electrical resistance
Strain gauge in form of Wheatstone bridge

17. Load Cell Equation
Electrical signal output must be amplified by instrumentation amplifier

18. Mass Equation Weight = mass x acceleration due to gravity
g = 9.81 m/s2 = acceleration due to gravity

19. Current Nurse Calculations for Weight by Bed
Freitag, Elke, et al. "Determination of body weight and height for critically ill patients admitted to the intensive care unit: A quality improvement project." Australian Critical Care 23 (2010):

20. Team Organization Amy Nicole Emily First Presentation
Second Presentation
Third Presentation
Computer Programming
Hospital Contact
Client Contact
Designs
Electrical Component
Mechanical Aspect

21. Timeline to work on project1 2 3 4 5 6 7 8 9 10 11 12 13 14
Initial Process
Background Research
Literature
Patents
Social Impact
Interviews
Problem Definition
Project Scope
Specifications
Metrics
Concept Generation
Brainstorming
Comination Table
Design Alternatives
Project Choice
Design Requirements
DesignSafe
Project Development
Draft Due
Timeline to work on project

22. Due Dates Course Assignments 1st 2nd 3rd 4th 5th 6th 7th 8th 9th 10th
Preliminary Report
Preliminary Presentation
Progress Report
Progress Presentation
Final Report
Final Presentation
Design Webpage
Poster Presentation
Final Due Date
Initial Draft
Timeline to work on project

23. Questions?