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Effects Of A Support Surface On Homeostasis

References
EFFECTS OF A SUPPORT SURFACE ON HOMEOSTASIS
James G. Spahn, MD, FACS; EHOB, Inc., Indianapolis, IN;
1.
Krasner D, Kane D. Chronic wound care: a clinical source book for healthcare professionals. Wayne (PA):
Christie Duncan, BSN, RN, CWOCN; EHOB, Inc., Indianapolis, IN.
Health Management Publications, Inc.; 1997. p. 1.
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Bryant RA. Acute and chronic wounds: nursing management. St. Louis (MO): Mosby; 1992. p. 106.
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Bennett RG, O’Sullivan J, DeVito EM, et al. The incresing medical malpractice risk related to pressure
Statement of the problem
ulcers in the United States. J AmerGeriatr Soc 2000; 48:73-81.
Poor support surface choices can be clinically and financially devastating to both patient and facility, yet the vari-
4.
McCance KL, Huether SE. Pathophysiology: the biologic basis for disease in adults and children. St. Louis:
ety of surfaces available can make the process overwhelming. This educational piece will identify endothelial
Mosby; 1998.
damage as the true culprit in tissue necrosis and show how to choose support surfaces that prevent endothelial
5.
Beiser A. Physics. Menlo Park (CA): Addison-Wesley; 1991.
damage and facilitate homeostasis.
6.
Beiser A. Theories and problems of applied physics. 2nd ed. New York: McGraw-Hill; 1988.
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Bennet CE. College physics. 6th ed. New York: Harper & Row; 1967.
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Besancon RM. The encyclopedia of physics. New York (NY): VanNostrand Reinhold; 1990.
Rationale
9.
Baharestani M. Pressure ulcers in an age of managed care: A nursing perspective. Ostomy/Wound
Support surfaces are key factors in pressure ulcer management and prevention. Unfortunately surface choices
Management 1999 45(5):18-40.
are often based upon prior experience, verbal suggestion, or written materials, rather than a true understanding
10.
Blue Cross and Blue Shield Association. Tec Special Report: Pressure-reducing support surfaces in the
of the therapy or its effect on the soft tissue. Understanding the pathophysiology behind pressure ulcer develop-
prevention and treatment of pressure ulcers: Group 2 technologies BlueCross BlueShield Association, Kaiser
ment will assist caregivers in choosing support surfaces that facilitate the body’s ability to maintain a stable inter-
Permanente; 1998.
nal environment (homeostasis).
11.
Cuddigan J, Frantz R. Pressure ulcer research: Pressure ulcer treatment. Advances in Wound Care 1998;
11(6): 294-300.
Methodology
12.
Maklebust, J. An update on horizantal support surfaces. Ostomy/Wound Management 1999; 45, 1A (Suppl):
A literature review was performed to examine the key mechanical and physiologic factors relating to tissue necro-
70S-77S.
sis and pressure ulcer development. The sources studied were internationally renowned textbooks of medical
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Fauci AS, Braunwald E, Isselbacher KJ, et at. Harrison’s principles of internal medicine. New York: McGraw-
Hill; 1998.
physiology, pathophysiology, chemistry, and physics.
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Hirshberg J, Rees RS, Marchant B, Dean S. Osteomyelitis related to pressure ulcers: the cost of neglect.
Advances in Wound Care 2000; 13(1): 25.
Results
15.
Guyton AC, Hall JE. Textbook of medical physiology. Philadelphia: Saunders; 1996.
Homeostasis is significantly impaired when blood vessels are crimped by gradient pressure and shear. This
16.
Kelley WN. Textbook of internal medicine. 3rd ed. Philadelphia: Lippincott-Raven; 1997.
mechanical stress causes a change in blood flow from laminar to turbulent, which increases the risk for endothe-
17.
Marieb EN. Human anatomy & physiology. Menlo Park (CA): Benjamin/Cummings; 1998.
lial damage. Endothelial damage is the key factor leading to tissue necrosis. The laws of physics show that flota-
18.
Porth CM. Pathophysiology-concepts of altered health status. Philadelpia: Lippincott; 1998
tion 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.
The Clinical Leader in Medical Devices for Patient Care
-Guyton AC, Hall JE. Textbook of medical
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EFFECTS OF A SUPPORT SURFACE ON HOMEOSTASIS
Gradient Pressure & Shear
Pressure Ulcer Development Cascade
Mechanical Stress delivered by a support surface will result in
volumetric support or distortion.
(Mechanical Stress)
Soft Tissue Distortion
Promote
(Strain)
Homeostasis
Change in capillary flow
VOLUMETRIC SUPPORT
(Decreased Velocity, Laminar to Turbulent)
Turbulent flow
Disruption of intravascular
causes pelting
cellular movement
(center to periphery)
Endothelial Damage
Endothelial
(Microtrauma secondary to pelting by platelets and neutrophils)
damage
DISTORTION WITH
secondary to
ENDOTHELIAL DAMAGE
Promote
oxygen free rad-
Cells activated
Pressure Ulcer
icals and enzy-
(Endothelium, platelets and neutrophils)
Development
matic activity
Adapted from Figure 17-13
Oxygen Free Radicals and enzymes released
Endothelial Cell Injury
Why flotation therapy? (Volumetric support)
Increased Capillary Permeability
h If the human body is 3-dimensional, then;
Why Static Air?
Flotation
(due to damage)
h Volumetric support is needed to maintain
Volume of body sinks into static air chamber
Therapy Facts
proper tissue orientation, then;
compressing and displacing volume of air in
Fluids leak out of vessel
Gross Anatomy
A static fluid media (gas, liquid, sol) is needed
chamber until pressure in chamber* is enough
h
h Contouring is
to float the body in a flexible container that is
to support weight of body (Archimedes,
The body is 3-Dimenstional
properly filled or inflated, and;
Boyle’s Law, Newton’s Third Law) in a perpen-
not equal to
dicular, non-gradient fashion (Pascal’s
Flotation
Stasis
h Static air is preferred to liquid or sol because
Principle), delivering volumetric support of the
it has less density and no viscosity.
Therapy
soft tissue (Hooke’s).
* Intra-Chamber Pressure
h
Coagulation
Dynamic
fluids do
not deliver
Ischemia
Flotation
therapy.
Endothelium retracts
with no damage
Decreased oxygen causes anaerobic metabolism
h Overinflation
or overfilling
of a static
Acidosis
media con-
Future Studies Needed
tainer will
(Too much lactic acid)
not deliver
Hospital Bed
By Industry
Flotation
On board
4" Foam
Simulation (3” high
Therapy
density foam, air mat-
Cell Injury/Death
tress and bed clothing.)
Chemotaxis
Nature’s Flotation
Conclusion
Margination
Inflammatory
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 clini-
Diapedesis
Response
cally 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 endothe-
Extravasation
lial 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
Maintain Autoregulation
clinicians to choose support surface products that prevent endothelial damage and facilitate the autoregulatory
h Clinical Protocols
Phagocytosis
h Nutrition
h Mobilization
functions of the body (homeostasis). Support surface selection is greatly simplified for caregivers who under-
h Ambulate
h Turn
stand the key factors in pressure ulcer development. Since we are unable to eliminate gravity, we must minimize
h Passive Range of Motion
h Support Surface
its effects on soft tissue when a patient is placed on a support surface. Thus, as part of a comprehensive care
Interstitial Edema
h Bed, Chair, Cart, ER, OR
h Incontinence Care
plan and protocol, caregivers must match the product to the patient12, not the patient to the product and should
h Wound Care
h Continuum of Care
h Treatment of other general medical
consider only support surfaces that provide volumetric support, not distortion, to the soft tissue at risk.
conditions
Decreased Perfusion
DO NO HARM!
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