Low-Frequency Non-Contact Ultrasound and Pulsed Lavage Flashcards
What is the frequency range of high frequency US?
0.5-3.0 MHz
What is the frequency range of low frequency US?
20-50 kHz
What is the sound wave size of high frequency US?
Short–higher attenuation and absorption rates
What is the sound wave size of low frequency US?
Long–lower attenuation and absorption rates
What is the tissue penetration of high frequency US?
- 0 MHz – 1-2 cubed cm
3. 0 MHz – 5 cubed cm
What is the tissue penetration of low frequency US?
Noncontact 40 kHz – 3 cubed mm
Contact debridement devices depend on application technique
What are the modes for high frequency US?
Continuous – tissue heating, 100% duty cycle
Pulsed – tissue repair, 20% duty cycle
What are the modes for low frequency US?
Continuous and pulsed modes depending on the device
Heat dissipated by non-contact and by saline irrigation
What is the application of high frequency US?
Direct contact with coupling medium
What is the application of low frequency US?
Non-contact and contact devices depending on treatment goal
What are the therapeutic uses of high frequency US?
Tissue healing, tissue repair, pain reduction
What are the therapeutic uses of low frequency US?
Non-contact devices – tissue repair, wound cleansing, pain reduction
Contact devices – debridement
What are the features of low frequency non-contact US?
PRIMARY METHOD OF US DELIVERY FOR WOUND MANAGEMENT (TREATMENT MODALITY)
This mist of sterile saline as a coupling medium to transfer US energy to tissues
Continuous energy that does not result in heating of tissues
- Low intensity therapeutic range
- Heat dissipating saline mist
- Noncontact delivery method
Produces higher levels of cavitation compared to HFUS
- Allows low frequency devices to deliver greater amounts of US energy to tissues during comparable treatment times
How does low-frequency non-contact US work?
Uses low-frequency (40kHz) and low therapeutic intensities (0.1-0.5 W/squared cm
Tissue stimulation
Promotion of fibrinolysis
Removal of bacteria and exudate through cleansing
Active bacterial killing (damage to cell wall)
Proposed that LFUS may alter the genetic code of certain bacteria thus increasing antibiotic susceptibility and decreasing virulence
What is Pulsed Lavage with Suction (PLWS) and the theory behind it?
Debridement and cleansing modality
Theory:
- Delivery of pulsed irrigation at controlled psi with suction of contaminated irrigation fluid
- Both positive and negative pressure
What provides the POSITIVE PRESSURE with pulsed lavage with suction?
HYDROTHERAPY:
- With whirlpool, psi is not documented
- Psi too low—not effective for wound cleansing
- Psi too high—tissue can be damaged and bacteria pushed further into the wound
- Recommended psi between 4 and 15
What provides the NEGATIVE PRESSURE with pulsed lavage with suction?
Suction forces stimulated granulation tissue proliferation and epithelization
What are the BENEFITS of Pulsed Lavage with Suction?
Wound cleansing
Debridement of slough
Loosening of nonviable tissue
Reduction of surface bacteria
Increased local perfusion
Stimulation of granulation tissue through negative pressure
What are the INDICATIONS of Pulsed Lavage with Suction?
Critically colonized wounds with decreased or stalled granulation tissue
Infected or necrotic wounds
Thick or mucous-like exudate
Undermining, tunneling or sinus tracts
Open amputation sites
Traumatic wounds with foreign debris
Stage 3 and 4 pressure ulcers
What are the PRECAUTIONS associated with Pulsed Lavage with Suction?
Anticoagulants or active bleeding
Poorly visualized wound spaces
Near fistula or cavity linings
Near visible blood vessels
Over exposed tendon or bone
Near recent bypass grafts or recent surgical closures
Facial wounds
Near LVAD drives
Hypothermia with cool fluid irrigation
What are the irrigation force parameters associated with PLWS?
4-6 psi for sensitive areas
- For initial treatment to gauge response
- Situations of anticoagulation therapy, fragile hemostasis, exposed structures, intense pain
- For tracts and tunnels, as low as 2 psi
8-9 psi to decrease bacterial load
9-15 psi for removal of debris in non-infected wounds
What are the suction force parameters associated with PLWS?
60-80 mmHg for wounds that are painful or bleed easily
80-100 mmHg for removal of exudate and necrotic tissue
What should the temperature of irrigation fluid be for PLWS?
37-38 degrees Celsius facilitates vasodilation and prevents wound tissue hypothermia
What should the frequency and duration be for PLWS?
Wounds with infection, odor, or > 50% necrotic tissue
- 2x daily
For general cleansing and tissue stimulation
- Daily or scheduled every other or every third day
Should be discontinued after 1 week without improvement
