Lecture 23 - Wound Healing and Biophysical Agents Flashcards
what modalities are used for wound healing?
1) Electrical Stimulation Therapy
–High Voltage Pulsed Current
–Low-Intensity Direct Current
2) Therapeutic Ultrasound
–Conventional
–Low-Frequency
3) Light Therapy
–Ultraviolet
–Infrared
–Low Level LASER
4) Negative Pressure
5) Hydrotherapy
6) Intermittent Pneumatic Compression (next lecture)
what are 4 types of chronic pressure wounds?
- Pressure Ulcers
- Venous Ulcers
- Arterial Ulcers
- Neuropathic Ulcers
what are potential physiological effects of wound healing using different modalities? (chart)
Only modality having evidence to support its use for wound healing?
electrical stimulation therapy
The current weight of the evidence supports the use of both LIDC and HVPC for speeding tissue healing.
–Venous ulcers
–Ischemic ulcers
–Pressure ulcers
–Burns
describe the “skin battery”
what happens to the electrical flow following a skin injury? “currents of injury” slide
Cathode = electrode from which a conventional current leaves a polarized electrical device. (This definition can be recalled by using the mnemonic CCD for cathode current departs.)
Conventional current describes the direction in which positive electronic charges move, making the cathode the positive electrode (i.e. repels +ve charges, attracts –ve charges)
Electrons have a negative charge, so the movement of electrons is opposite to the conventional current flow (electrons flow into the device’s cathode). * correction* positive is cathode!!
what is the electrical basis for Electrical Therapy Wound Healing? proposed effects?
Manipulation of the Currents of Injury
Positively charged electrode (cathode) over a wound
- Negatively charged cells and ions will be drawn toward the electrode
- Positively charged cells and ions will be repelled
Negatively charged electrode (anode) over a wound
- Positively charged cells and ions will be drawn toward the electrode
- Negatively charged cells and ions will be repelled
Cells that migrate to a positive bioelectric charge
–Neutrophils
–Macrophages
–Epidermal cells
Cells that migrate to a negative bioelectric charge
–Neutrophils (if wound infected or inflamed)
–Fibroblasts
*Different stages of repair respond to currents of different polarity
define: galvanotaxis
Galvanotaxis: the process of attracting charged cells to an electric field of opposite polarity
what are the indications of electric wound therapy?
1.Chronic wounds: most types
–Pressure ulcers
–Diabetic
–PVD (peripheral vascular disease)
2.Failure to heal using conventional care
–No clinical signs of healing after 14 days
3.PMHx of impaired healing
describe what influences the “healability” in terms of wound healing with electric therapy
1) Medical status – Anemia, malnutrition, hyperglycemia
2) Blood flow
3) Patient compliance
4) Chronicity of ulcer – Likelihood of healing decreases significantly with time
*Ankle Brachial Pressure Index (ABPI) is a measure of the fall in blood pressure in the arteries supplying the legs and as such is used to detect evidence of blockages. Normal = 0.9, abnormal below 0.8, severe PVD below 0.5)
describe High-Volt Pulsed Current (HVPC) vs Low-Intensity Direct Current (LIDC)
Low-Intensity Direct Current (LIDC)
- amplitude less than 1 mA (10–3A)
- a.k.a. microcurrent, low-volt pulsed current, microelectrical neuromuscular stimulator, or microelectrical stimulation
describe electrode placement for electrotherapy
describe the Effect of Current based on the treatment goal of electrotherapy
describe the how to conduct the electrotherapy process
* Metals usually not allowed but Silverlon ok because bound to dressing
what is the protocol for high-volt pulsed current? (in terms of frequency, intensity, and duration for the phases of healing)
what are contraindications of electrotherapy?
Same as any electrical modality with the addition of:
–Osteomyelitis
–Heavy metal residue (be aware of ingredients in wound care products)
what are the applications (freq, duty cycle etc) for conventional ultrasound
Based on Acoustic Streaming
Typical Application:
–3 MHz
–20% duty cycle
–0.1-0.2 W/cm2
–3-5 times/week
what have studies shown about how conventional ultrasound works to treat wounds?
In Vitro studies have shown:
–alterations in the amount of calcium uptake and growth factor production (inflammatory phase)
–increased fibroblast activity (collagen deposition) (proliferative phase)
–increased rate of angiogenesis (formation of capillary beds and blood vessels (proliferative phase)
“… there is presently no evidence of a benefit of using ultrasound therapy in the treatment of pressure ulcers …” Ontario Health Quality (2009) p.124
conventional us application method
describe the application of low frequency ultrasound and what research says about it
- no contact vs direct contact
Same principles as conventional US, different machine:
–frequency of 20 to 40 kHz
Non-contact low frequency ultrasound (NCLFUS)
–Uses a fine saline mist (a.k.a. MIST therapy)
–Intensity: 0.2 to 0.6 W/cm2
–Frequency of 40 kHz.
–Limited, but promising research (faster wound healing, bacterial reduction)
Direct contact, higher intensity form
–frequency of 22 to 35 kHz
–probe in direct contact with the tissue
–intended as a debridement tool (ultrasound-assisted wound debridement)
–One prospective RCT showed it to be as effective as traditional wound debridement
what is UV light effective for treating?
Ultraviolet light (UVA and UVB) is an effective modality for treating skin disorders (psoriasis, vitiligo, lichen planus, dermatitis, and more) is overwhelmingly positive.
Ultraviolet light may:
–increase epithelial cell turnover
–remove slough
–stimulate granulation and epithermal growth
–destroy bacteria
For wound healing
–Primary use of UV light is UVC (the shortest wavelength, generally blocked by the ozone layer)
–Used for bacterial control in wounds
- Effective in in vitro studies of artificially inoculated animal wounds
- Results not as strong for heavily infected wounds or deep wounds
what does the research say for UV light wound healing?
For healing of pressure ulcers
–Two studies, both with VERY small sample sizes
- One reported that UVC may help to reduce ulcer area (used with low-level laser therapy)
- One showed that UVA and UVB treatment could reduce the time to healing
how is UV light applied?
Contraindications of UVC
- Dermatological conditions (eczema)
- Photosensitivity
- Fever
- Erythema
- TB
- Skin cancer (Hx or active)
- HIV (activated by UVC)
Safety Precautions for UVC
- Eyes (wear protection)
- Cancer
–Minimize exposure
–Avoid UVA/UVB wavelengths
•Burn
what is infrared light used for? how is it applied? what does research say?
what is the therapeutic effect of Low-Level Laser (LLL) Therapy
Low radiation intensities, no thermal effect
–a.k.a. cold lasers
–energy typically about 10 J/cm2, using lasers operating at powers of 50 mW or less
–Any biological effects are therefore likely due to the direct effect of radiation.
Might favour wound healing by promoting:
–fibroblast proliferation
–collagen production
–epithelialization
May also:
–improve metabolism, increase of cell metabolism
–alter prostaglandin levels at the cellular level
–Modulate blood circulation
–increase ATP production
–Have anti-inflammatory & anti-edematous effects
–Alter nerve conduction velocity (stimulates nerve activity)
–Aid in degranulation
**Some evidence suggests that LLL kills bacteria, while other evidence suggests a stimulation of bacterial growth
***Therefore … NOT used if infection is present
what does research show for Low-Level Laser (LLL) Therapy?
Some evidence that LLL may be effective for wound healing
–most beneficial parameters for laser therapy are not known
–positive results have been demonstrated with different forms of laser
- helium neon (632.8 nm - largest body of evidence)
- gallium arsenide (904 nm)
what is Negative-pressure wound therapy (NPWT)?
what are the indications for Negative-pressure wound therapy (NPWT)?
what does the research say about Negative-pressure wound therapy (NPWT)
Current evidence has demonstrated positive clinical outcomes in acute / postsurgical wounds
–improved healing times
–shorter hospital stays
–reduced infection rates
–increased survival of flaps and grafts
Effectiveness compared to other therapies in chronic wounds is unclear
–used as a method to prepare the wound bed for definitive closure
–not typically continued until complete wound closure
Pressure Ulcers
–Evidence is mixed, with many studies having fundamental methodological flaws
