Lecture 24 - Wound healing and biophysical agents Flashcards
What is the definition for chronic wound?
A wound that deviates from the expected sequence of repaire in terms of time, appearance and response to aggresive and appropriate treatment
Factors that impede healing (9)
- Low blood oxygen content (due to poor circulation)
- Excessive physical strain (immobilation-> movement)
- Infection
- Foreign body not removed from the wound
- Sustained pressure – affecting the blood flow
- Age, level of mobility (immobility)
- Patient nutrition
- Systemic disease (diabetes, spinal cord injury)
- Medications
What medications impede healing and why?
Corticosteroids
anti-inflammatory effect stabilizes cellular membranes;
inhibits the production of prostaglandins
Non-steroidal anti-inflammatories (NSAIDS) aspirin, ibuprofene – inhibit prostaglandin
Lack of what vitamines impede healing?
Vitamin C – hydroxylation during the synthesis of collagen
Vitamin A – increases the availability of macrophages
Zinc – increases epithelialization
Types of chronic wound (6)
Pressure ulcers
Lower extremity - Diabetic foot ulcers neuropathic Leg ulcers: - Venous insufficiancy - Arterial insufficiancy
Inflammatory
Malignant
Post-surgical
Post-traumatic
Pressure ulcers etiology?
Localized areas of tissue necrosis that develop when soft tissue is compressed between a bony prominence and an external surface for a prolonged period
Neuropathic ulcers definition, prevalence and etiology
Definition: secondary to peripheral neuropathy
Prevalence: most common in diabetics
Etiology: - Sensory: no feedback about tissue trauma - Motor: abnormal foot mechanics - Autonomic Decreased blood flow Decreased hydration
To what are due venous ulcers ?
Blood flow:
Compromised
Back flows due to incompetent valves
What is primary cause (1) and predisposing factors to arterial ulcers (5)?
Primary cause is arteriosclerosis of medium or large arteries
Predisposing factors
- Smoking
- Diabetes
- Hyperlipidemia
- Hypertension
- Genetics
Explain stage 1 of wound development
STAGE I
Redness or blue-gray discoloration over the pressure area
In dark-skinned people, the area may appear drier
Usually reversible at this stage if the pressure ’d
Explain stage 2 of wound development
STAGE II
Skin is reddened and may or may not be broken
Abrasions, blisters (cloques) , or a shallow crater at the site
Epidermis alone or both the epidermis and the dermis
If neglected, further and deeper damage occurs
Explain stage III of wound development
All the layers of the skin are destroyed and a deep crater forms
Explain stage IV
The ulcer extends through the skin and subcutaneous tissues, and may involve bone, muscle, and other structures
The patient will experience fluid loss and pain
Great risk for infection
Theurapeutic effects of HVPC (6)
increase microcirculation
decrease and prevent edema
increase re-oxygenation
Antibacterial effects
Bioelectrical effects
Galvanotaxis
Cellular effects
Explain bioelectrical potential
Skin surface is electronegative
Average surface charge = -23.4mV
Maintains tissue health
Deeper epidermal cells and dermis are + ve
Thus wound cavity is positive
After injury, the injured site sets up a ‘current of injury’ (- ve surface & +ve wound) = Skin Battery
Estim applied over the dermal wound enhances the healing process
What is the process of galvanotaxis
HVGS enhances wound healing by causing inflammatory, phagocytic and repair cells to migrate to wound
Different stages of repair respond to currents of different polarity, positive bioelectric charge is used for __a__ and negative bioelectrical charge is used for __b__.
& what cells are implicated
a. early stages of healing, Neutrophils, macrophages, epidermal cells
b. later stages of healing, neutrophils, fibroblasts
Cellular effects of HVPC (5)
Stimulate tissue formation
collagen synthesis
ATP output
increase capillary density
increase collagen organization
increase wound strength
Releases growth factors (e.g., increase fibroblasts)
Indications for HVPC (4)
Chronic wounds: most types
Pressure ulcers Diabetic
PVD
Failure to heal using conventional care
No clinical signs of healing after 14 days
PMHx of impaired healing
Issues of healability
Factors affecting healability (4)
Medical status
Anemia, malnutrition, hyperglycemia
Blood flow
Patient compliance to treatment
Chronicity of ulcer
Likelihood of healing decreases significantly with time
Application of HVPC (3 steps)
- Remove petroleum and metal residue
- Remove foreign/necrotic materials: Debridement + Irrigate wound
3. Apply conducting agent/electrode Aluminium foil in saline soaked gauze metallic gauze single use electrode Hydrogel
