Transepithelial Potential Difference
Healthy (intact) skin carriers a slightly negative charge
(Average skin potential -23.4 mV)
What occurs when skin is damaged?
an influx of (+) ions (Na+) interacts with (Cl-) which leads to a low-level bioelectric signal = current of injury
Current of Injury
- Negative chloride is typically sitting on top of the skin
- If you get it into the dermis, it is goes to shoot sodium up (+)
- This is what signals the derived platelet factors, which bring the so on and so on
What does a wound create?
- a low resistance pathway in which transepithelial potential (voltage) drives current out of the wound
- All types of tissue
- Disruption of these currents alters normal development, regeneration and wound healing
Injury current –> Role of E stim
- a moist wound environment is needed for the bioelectric system to function
- Dry tissue (necrosis) and infection can block these bioelectric signals thus disrupting the signals for repair process
Electrotaxis/Galvanotaxis
- Directional migration of cells in an electric
field - Some cells in the substratum migrate actively
to a specific pole
Which cells will migrate in an electric field
epithelial cells, neutrophils, macrophages, fibroblasts, endothelial cells, and nerve cells
Charge
– When an electrically neutral atom is acted upon by an outside force lending to loss or gain of electrons
– Measured in coulomb
Charge Density
Electrical charge per unit of cross-sectional area
Conductive Coupling
Electrical currents delivered directly or through a
pulsed electromagnetic field (PEMF)
what is a good conductive medium for superficial or small wounds
hydrogel
what should you use as a conductive medium for larger wounds
moisten the gauze with saline and pack the wound
Currents for wound healing
- Capacitive Coupled Electrical Currents (CCEC)
- Low Intensity Currents (LIC)
- Low intensity Direct Current (LIDC)
- Microcurrents (MC)
HVPC and LVPC
Phases of Healing
Inflammatory
Proliferative
Epithelialization
Maturation/Remodeling
Inflammatory Phase
- Initiates the wound repair process by its effect on the current of injury
- Neutrophils and macrophages both have a negative charge
- increases blood flow
- Promotes phagocytosis
- Enhances tissue oxygenation
- Reduces edema perhaps from reduced microvascular leakage
what type of charge attracts and stimulates neutrophils and macrophages
positive
infection in the inflammatory phase
if infection is present, neutrophils often become more positive therefore may want to utilize a negative bioelectric force
Proliferative Phase
- Stimulates fibroblasts which are positive
- Stimulates DNA and protein synthesis
- Increases ATP generation
- Improves membrane transport
- Produces better collagen matrix organization
Epithelialization
- Epithelial cells are negative
- Stimulates epidermal cell reproduction and
migration
Remodeling
- Produces a smoother, thinner scar
- Stimulates wound contraction
- Reduces scar hypertrophy
- Mostly seen with positive bioelectric flow
Types of wounds treated by e stim
- Pressure ulcers stage I through IV
- Diabetic ulcers due to pressure, insensitivity, and dysvascularity
- Arterial Ulcers
- Venous Ulcers
- Slow healing wounds
slow healing wounds treated by e stim
- ischemic ulcers
- vasculitic ulcers
- donor sites
- wound flaps
- burn wounds
- surgical wounds
How e stim can help wounds
- increase proliferation along wound edge
- HVPC and increase epithelialization
- Decreased thickness of hypertrophic scaring
How e stim can help edema
- block macromolecular leakage
- increased perfusion
