Modalities for Wounds PT 632

What are the proposed benefits of using e-stim for wound healing?

1. bioelectrical current replication

2. galvanotaxis

3. cell proliferation (granulation tissue formation)

4. augmentation of angiogenesis

5. increase blood flow (increased tissue oxygenation)

6. bactericidal (effect of cathode)

7. decreased edema (decreased microvascular permeability)

8. debridement

In a healthy epidermis, what is the bioelectrical current mV?

-23.4 mV (e-stim replicates this current)

Explain galvanotaxis and the cells that is effects.

guided cell movement by the electrical current created by e-stim.

effects macrophages, neutrophils, fibroblasts, endothelial cells

With e-stim, what type of debridement is performed and what electrode helps with it?

autolytic debridement using the cathode

Explain the "Current of Injury" theory.

normal skin maintains its own bioelectricity called transepithelial potential (30-100 mV).

when a wound occurs, the mV drops and an endogenous electrical field forms and drives healing. but as a wound closes or becomes chronic it declines

e-stim provides an exogenous field to an endogenous current** (but it is not known whether or not the current of injury actually contributes to healing)

E-stim can be used to assist or accelerate wound healing for wounds that are...

- stage ii-iv pressure ulcers

- other wounds >30 days of care and are not progressing with standard care

What is the indication for use of e-stim for a wound?

it has been >30 days and the wound is not progressing with standard care

Can e-stim be used as a stand-alone treatment?

no, it should be used in conjunction with standard wound care (adjunctive therapy)

What are the two primary types of current used for e-stim with wound healing?

HVPC monophasic (has best evidence!)

low-voltage biphasic (symmetric/asymmetric)

Explain the waveform, pulse duration, voltage, and direction of current flow?

WAVEFORM: monophasic twin-peaked

PULSE DURATION: ~154 microsec

VOLTAGE: >100 V (can be up to 150-500 V)

CURRENT FLOW: unidirectional flow (cathode or anode can set polarity)

For biphasic pulsed current, where are the electrodes typically placed?

both electrodes are placed on the wound edge

What is the most effective modality for diabetic ulcers?**

asymmetrical biphasic square-wave pulse (it enhances diabetic wound healing by 60%!)

asymm. is SUPERIOR to symmetric biphasic

Explain the effect of the anode (+) on a wound bed

- ACIDS form under the electrode (Cl + H2O = HCl)

- coagulation of proteins

- HARDENS TISSUE!

- CAPILLARY CONSTRICTION

- decreased nerve irritability

- promotes granulation and epithelialization or reactivation of inflammatory phase

Explain the effect of the cathode (-) on a wound bed

- bases form under the electrode (Na + H2O = NaOH-)

- liquifies proteins

- SOFTENS TISSUE!

- CAPILLARY DILATION

- repels "-" edema (reduce swelling)

- bactericidal effects/decreased bioburden

- promotes galvanotaxis of fibroblasts

What has the best evidence as a modality used for wound healing?

e-stim!!

What are the parameters for monophasic HVPC?

- intensity: strong tingling sensation

- choose polarity (cathode or anode)

- 80-125 pps (higher = galvanic effects)

- high frequency 80-120 Hz

- 45-60 mins/day, 5-7 days/week, 4-8 weeks

Explain the monopolar set up for e-stim wound healing.

- one electrode over/on wound with saline-soaked gauze underneath

- the other electrode distance to wound (15-20 cm)

this is called the DIRECT technique

Explain the bipolar set up for e-stim wound healing.

two electrodes on intact skin adjacent to/on opposite sides of the wound (both are RX)

this is called the INDIRECT/PERIWOUND technique

What polarity for wounds would you likely begin with? How effective is this polarity?

cathodal polarity

has been shown to reduce wound area by 82% in 6 weeks (cathodal+anodal switching produced similar results with a 71% reduction)

If you are routinely using e-stim on a wound and the healing plateaus, what factors could you change to help promote healing?

change the POLARITY or the PARAMETERS

For direct placement, the RX electrode and the dispersive electrode go where?

RX: over the wound

dispersive: elsewhere (15-20cm away)

monophasic pulsed current is most commonly used**

Can you choose polarity with indirect placement?

no, the pulsed current is biphasic

What type of mode is used for HVPC?

continuous mode to deliver the "ionic effects"

What are the biphasic current parameters?

phase duration: 100µs - 1 sec

pulse rate: 0.5 - 100 Hz

amplitude: below contraction to contraction

location: periwound

frequency/duration: 1-3x daily

can be used for VIUs, PUs, and mixed wound to improve healing rates and time to closure + decreased size

What are important contraindications for e-stim?

- malignancy (can be in a remote area if metastases have been ruled out)

- untreated osteomyelitis

- over a pacemaker/defib. (REGARDLESS OF AREA)

- close to developing fetus (not over low back or abdominal area)

- over areas of active bleeding

- transcerebral

Explain the parameters for LFUS and the evidence.

20-100 kHz with direct application to wound bed

most promising evidence: 40 kHz (non-contact)

LF-contact US debridement can be used to remove necrotic tissue and biofilm

Explain the parameters for HFUS and the evidence.

1-3 MHz applied to peri-wound

evidence is weak and inconsistent and some guidelines recommend against for neuropathic ulcers

non-contact LFUS evidence found that..

there is a suggested dose-response relationship as a study found that performing it x3/week provided better outcomes than x1/week

What are the suggested mechanisms of US?

- ion transport

- enhances all 3 phases of wound healing

- affects scar tissue formation

What are the affects on ion transport by US?

- stimulation of FIBROBLAST synthesis

- increased release of growth factors from MAST CELLS

- degranulation of macrophages and mast cells that release chemical mediators that ACTIVATE THE HEALING PROCESS

How does US affect scar tissue formation?

- collagen deposition and organization

- scar flexibility/pliability

can be used on a mature scar

What are the 2 ways that LFUS works?

1. cavitation --> micron sized bubbles go into the wound and "implode" to destroy bacteria to liquify necrotic tissue

2. acoustic streaming --> movement of fluid across acoustic boundary and chemical mediators follow and improve cellular activity

What are some general contraindications of US?

- over growth plates

- over breast implants

- malignant tumor

- over joint cement or plastics used for prosthetics

- pace maker

- acute inflammation

- pain of fx site

- untreated osteomyelitis

- DVT

- thrombophlebitis

For VAC/NPWT, what is the pressure typically set to? What things are used in the wound bed?

-75/125 mmHg

use sterile foam in wound sealed with an occlusive film, and use a portable vacuum to provide continuous or negative pressure (facilitates autolytic debridement)

Explain the evidence behind VAC/NPWT.

overall strong evidence - associated with decreased wound size and a shorter time to healing

is especially useful in wound preparation for skin grafts/flaps and closure of deep, large wounds

What does VAC/NPWT help promote?

- increased blood flow, granulation tissue, angiogenesis, epithelialization, cell proliferation

- decreased wound edema

- maintains a warm/moist environment

helps in ALL stages of healing

What are the important contraindications for NAC/NPWT?

- untreated osteomyelitis

- untreated arterial insufficiency

- malignancy

- exposed nerves, vessels, organs w/o adequate protection of impregnaed gauze

- >20% slough/eschar w/o planned debridement**

CANNOT be ontop of any necrotic material

What are 3 other types of wound modalities that could be used besides US or e-stim?

1. low level laser therapy

2. topical oxygen therapy

3. hyperbaric oxygen therapy

not very strong evidence for any but did report cell proliferation, increased collagen and protein synthesis, ANGIOGENESIS, granulation tissue, and improved tensile strength

When providing modalities in conjunction with excellent wound care, what is important to remember?

traditional/typical interventions are still important!!

you need to consider adjunctive therapies when wounds become CHRONIC and are failing to heal (your best bets are e-stim, MIST, and VAC/NPWT)