Patient Positioning Aid

Eduardo VargasEmmanuel Kordieh

Mikhail BritanOctober 28, 2005

Outline

• Background– RERC 2005-2006

• Imaging technologies: MRIs– Essential in understanding our project

• Current methods of approach

• Our Design

• Design Alternatives

• Specifications

• Protocol

Background

• RERC 2005-2006:– Aim: Versatile, low-cost, easy-to-adjust patient positioning

aid that works with a range of examination table…and meets the customer needs below.

• Patients with disabilities– Do not necessarily lack access; however, current conditions

make it very difficult for the user and therapist/clinician to perform proper examinations.

Patient Specifications• Bruce

– Renal failure, manual wheelchair• Joan

– Heart failure, old, weak, hard of hearing• Lloyd

– Type II Diabetes, overweight• Sophia

– On heparin, limited right arm function, uses a cane• Arnold

– Parkinson’s, Diabetes, suffers from slight to moderate tremors

• Dave– Limited use to right arm and leg, may use a scooter.

Imaging Technologies• Magnetic Resonance Imaging

– Magnet• Measured in tesla or gauss (1 tesla = 10,000 gauss)• Common modern-day use: 0.5-2.0 tesla (5,000-20,000 gauss)• Comparison: Earth = 0.5 tesla• 3 major kinds of magnets are used:

– Resistive» Very expensive to operate

– Permanent» Weight to magnetism ratio is inefficient.

– Superconducting (most common)» Wire through which current passes is bathed in liquid helium

452.4 degrees below zero.» Achieve the full range of 0.5-2.0 tesla

• Gradient magnets (3) are used to maintain a variable magnetic field (18-27 millitesla)

• Imaging is obtained through the variance in magnetic fields.

Imaging Technologies

• No Metals – can become dangerous projectiles.– Paperclips, pens, stethoscopes, IV poles, etc.

– Magnetism increases exponentially as distance decreases.

• No metal internally!– Pacemakers

– No metal in eyes

– Dental implants

– Aneurysm clips in the brain

Imaging Technologies• Magnetic Resonance Imaging

– Resonance• Radio frequency (RF)

– Comparable to that of many small radio stations (15-20kW)

– Specific to hydrogen atoms, causing them to spin, thus creating ‘resonance’.

– Imaging• Achieved by varying the magnetic fields in combination

to shutting off the RF.– Hydrogen atoms return to their natural state, giving off a

signal picked up by the coil.– This is sent to the computer and converted into an image

via Fourier transform; thus, create the ‘imaging’ component.

Drawbacks to MRIs• Many people that cannot be scanned (i.e. pacemakers, too big)• Certain people (our patients) have extreme hardship for testing.• Claustrophobia comes into play.• Machine makes tremendous amounts of noise (earplugs,

headphones)• Patients must remain very still for the entire duration (~ 20-

90minutes)– Slight movements can/will distort the image and thus will have to

be repeated.

This is due from a patientmerely swallowing duringtime of treatment.

• Expensive equipment = expensive examinations!!!

What’s the purpose of MRIs?• Non-invasive• Patient is given the ability to be diagnosed and

tested for:– Multiple sclerosis– Tumors (pituitary glands & brain)– Infections– Torn ligaments (wrist, knee, ankle)– Shoulder injuries– Tendonitis– Strokes in the early stages– Bone tumors, cysts, and bulging or herniated discs

• Imaging can be done in any plane (achieved by the gradient magnets).

Are you claustrophobic?

Imaging Technologies

Photons are emitted from tungsten

Are absorbed by denser bone tissue

X-Ray Machine

CAT-Scan

• Uses the same technology as conventional X-ray machine

• Soft tissue can be observe

Imaging Technologies

Current Methods of Approach

• Extremely basic

• Not patient specific.

• Often times this system fails = movement of patient = re-administrating of the MRI.

Key to Success

• Integration of old with the new

Our design

• Bed-topper mattress– Initially filled with air– Patient lays down– Beads contour body– Deflation occurs– Contour stays as a solid entity– Clinician allows air back into the system– Ready for the next patient

Alternative designs – Air Flotation Device• Air flotation mattress with automatic

sensor. • Determines body weight and position and

molds mattress accordingly.• Firmness adjustable from ultra soft to

super firm. • Internal computer continuously monitors

firmness level. • Solid state sensor adjusts individual air

tubes for degree of support at pressure points. Standard hospital bed sizes.

• Damask or vinyl cover.

A closer look

1) 2)

3) 4)

220kg person = 1078Pa 127mbar = 12954Pa112mbar = 11424Pa

 

●Virtually maintenance-free operation in continuous duty service  ●Quiet operation; as low as 75 dB(A)

● Compact, lightweight design● Handles vacuum and/or pressure applications.

HP Maximum Vacuumin H20 mbar

Maximum Pressure

in H20 mbar

8.5 127 112

Foam – Alternative Design

Foam Mattress Pad

• Laminar

Types of Foam1. Open cellular

• interconnected pores or cells and are suitable for filtration applications

2. Closed cellular• Closed cellular foams do not have interconnected pores or cells,

but are useful for buoyancy or flotation applications

3. Flexible• Flexible foams can bend, flex or absorb impacts without

cracking or delaminating

4. Rigid• Rigid foams feature a matrix with very little or no flexibility

5. Reticular • Reticular foams have a very open structure with a matrix

consisting of an interconnecting network of thin material strands

6. Syntactic • Syntactic foams consist of rigid microspheres or glass micro-

balloons held together by a plastic or resin matrix

Foam Specifications

Average weight has 0.9-1.0 support pressure PSI

Flexible Foams

• High-Resiliency (HR)– Mostly used commercial

• Standard Urethanes– Natural Latex Foam

• Visco-Elastic– Memory Foam

• Creates a warmer sensation• Contours to the shape of anything

• How do you determine foam density?– Density is just how much a piece of foam weighs per unit

area.

• What is the ILD?- The ILD stands for Indentation Load Deflection.

- It's the number that really refers to the firmness of a piece of foam.

Mechanical properties that we should know

• Bulk density • depends upon the theoretical density of the foam and its

actual porosity after packaging

• Tensile strength • of stress required to fail or break the foam under tension

loading conditions.

• Tensile modulus • is a material constant that indicates the variation in strain

produced under an applied tensile load

• Elongation• the percent deformation occurring during a tensile or other

mechanical test

• Thermal conductivity• Dielectric strength

Materials – Pros & Cons

Coverings• Naugahyde

– A vinyl-coated, waterproof and durable fabric.

• Nylon/Sailcloth– Also known as para-pak. A smooth, silky nylon material.

• Knit– A stretchy woven materialóused.

• Lycra/Neoprene– Similar to double-knit material; however, it has a laminated rubber

backingósimilar to wetsuit material.

• Shelterite– A vinyl-coated fabric, waterproof and durableósimilar to naugahyde

except that it has a ridge texture.

• Cordura– A woven-like nylon material with breathability.

• Darlex/Dartex/Darflex– A four way stretch fabric that is water resistant and breathable.

Protocol – Where we’re headed

Choosing our design• Meet with:

– Dr. Wagshul, Head of Radiology Department – Stony Brook University

– Mrs. Metzger, Head Nurse Stony Brook Hospital

• Explore material properties under imaging environments.

References• http://electronics.howstuffworks.com/mri2.htm• http://www.magmedix.com/products/positioning/vertebral_positioning.html

• Invest Radiol. 1992 Dec;27(12):1005-8.Related Articles, Links –

Effect of prone versus supine patient positioning on pelvic magnetic resonance image quality.

http://www.abledata.com/abledata.cfm?pageid=19327&top=13012&deep=2&trail=22,12999,13008

http://www.emedicine.com/pmr/topic179.htmhttp://electronics.howstuffworks.com/mri11.htmhttp://www.freedomdesigns.com/info_catalog_page114.htmlhttp://www.adaptivemall.com/versaformplus.html

http://www.sunmatecushions.com/select.htmhttp://www.seatingdynamics.com.au

Any questions?

Brainstorming Begins…