EFFECTS OF A SUPPORT SURFACE ON HOMEOSTASIS
References
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James G. Spahn, MD, FACS; EHOB, Inc., Indianapolis, IN;
Christie Duncan, BSN, RN, CWOCN; EHOB, Inc., Indianapolis, IN.
Statement of the problem
Poor support surface choices can be clinically and financially devastating to both patient and facility, yet the variety of surfaces available can make the process overwhelming. This educational piece will identify endothelial
damage as the true culprit in tissue necrosis and show how to choose support surfaces that prevent endothelial
damage and facilitate homeostasis.
Rationale
Support surfaces are key factors in pressure ulcer management and prevention. Unfortunately surface choices
are often based upon prior experience, verbal suggestion, or written materials, rather than a true understanding
of the therapy or its effect on the soft tissue. Understanding the pathophysiology behind pressure ulcer development will assist caregivers in choosing support surfaces that facilitate the body’s ability to maintain a stable internal environment (homeostasis).
Methodology
A literature review was performed to examine the key mechanical and physiologic factors relating to tissue necrosis and pressure ulcer development. The sources studied were internationally renowned textbooks of medical
physiology, pathophysiology, chemistry, and physics.
Results
Homeostasis is significantly impaired when blood vessels are crimped by gradient pressure and shear. This
mechanical stress causes a change in blood flow from laminar to turbulent, which increases the risk for endothelial damage. Endothelial damage is the key factor leading to tissue necrosis. The laws of physics show that flotation therapy provides volumetric support (non-gradient pressure) of soft tissue.
Terminology
Homeostasis- The body’s ability to maintain relatively stable internal conditions even though
the outside world changes continuously.
Autoregulation- The ability of tissue to regulate its own blood flow.
Automaticity- The reciprocal interplay of the 75-100 trillion cells of the body working for the
benefit of all.
Endothelium- Simple squamous epithelial cells that line the blood vessels.
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-Guyton AC, Hall JE. Textbook of medical
physiology. Philadelphia: Saunders; 1996.
EFFECTS OF A SUPPORT SURFACE ON HOMEOSTASIS
Pressure Ulcer Development Cascade
Mechanical Stress delivered by a support surface will result in
volumetric support or distortion.
Gradient Pressure & Shear
(Mechanical Stress)
Soft Tissue Distortion
Promote
(Strain)
Homeostasis
VOLUMETRIC SUPPORT
Change in capillary flow
(Decreased Velocity, Laminar to Turbulent)
Turbulent flow
causes pelting
Disruption of intravascular
cellular movement
(center to periphery)
Endothelial Damage
Adapted from Figure 17-13
Endothelial
damage
secondary to
oxygen free radicals and enzymatic activity
(Microtrauma secondary to pelting by platelets and neutrophils)
DISTORTION WITH
ENDOTHELIAL DAMAGE
Cells activated
Promote
Pressure Ulcer
Development
(Endothelium, platelets and neutrophils)
Oxygen Free Radicals and enzymes released
Endothelial Cell Injury
Why flotation therapy? (Volumetric support)
Increased Capillary Permeability
❉ If the human body is 3-dimensional, then;
❉ Volumetric support is needed to maintain
(due to damage)
proper tissue orientation, then;
Fluids leak out of vessel
Gross Anatomy
❉ A static fluid media (gas, liquid, sol) is needed
to float the body in a flexible container that is
properly filled or inflated, and;
The body is 3-Dimenstional
❉ Static air is preferred to liquid or sol because
Stasis
it has less density and no viscosity.
Why Static Air?
Volume of body sinks into static air chamber
compressing and displacing volume of air in
chamber until pressure in chamber* is enough
to support weight of body (Archimedes,
Boyle’s Law, Newton’s Third Law) in a perpendicular, non-gradient fashion (Pascal’s
Principle), delivering volumetric support of the
soft tissue (Hooke’s).
Flotation
Therapy Facts
❉ Contouring is
not equal to
Flotation
Therapy
* Intra-Chamber Pressure
❉ Dynamic
Coagulation
fluids do
not deliver
Flotation
therapy.
Ischemia
Endothelium retracts
with no damage
❉ Overinflation
Decreased oxygen causes anaerobic metabolism
Acidosis
(Too much lactic acid)
Cell Injury/Death
Chemotaxis
Inflammatory
Response
On board
Nature’s Flotation
Margination
Diapedesis
Extravasation
Maintain Autoregulation
Phagocytosis
Interstitial Edema
Decreased Perfusion
❉ Clinical Protocols
❉ Nutrition
❉ Mobilization
❉ Ambulate
❉ Turn
❉ Passive Range of Motion
❉ Support Surface
❉ Bed, Chair, Cart, ER, OR
❉ Incontinence Care
❉ Wound Care
❉ Continuum of Care
❉ Treatment of other general medical
conditions
4" Foam
Hospital Bed
Simulation (3” high
density foam, air mattress and bed clothing.)
Future Studies Needed
By Industry
or overfilling
of a static
media container will
not deliver
Flotation
Therapy
Conclusion
Clinicians are held accountable to proven clinical standards of care as well as cost-effective care. Increased
expenditure does not always guarantee better outcomes. 9, 10, 11, 12 Poor support surface choices can be clinically and financially devastating to both patient and facility, yet the variety of surfaces available can make the
process overwhelming. As shown above, the true culprit in tissue ischemia necrosis (pressure ulcer) is endothelial damage. In the normal inflammatory response, endothelial cells are unharmed whereas in pressure ulcer
development, they are injured. Understanding the pathophysiology of support surface-induced ischemia will lead
clinicians to choose support surface products that prevent endothelial damage and facilitate the autoregulatory
functions of the body (homeostasis). Support surface selection is greatly simplified for caregivers who understand the key factors in pressure ulcer development. Since we are unable to eliminate gravity, we must minimize
its effects on soft tissue when a patient is placed on a support surface. Thus, as part of a comprehensive care
plan and protocol, caregivers must match the product to the patient12, not the patient to the product and should
consider only support surfaces that provide volumetric support, not distortion, to the soft tissue at risk.
DO NO HARM!
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