Ultrasound therapy uses sound waves to heat muscles, increasing blood flow to the area and relieving pain.
Recent evidence from a comprehensive systematic review demonstrates that non-contact low frequency ultrasound therapy effectively debrided necrotic tissue in chronic wounds without using direct contact; the authors believe, however, that further clinical and basic science research of this technology was required for full success.
Improved Blood Circulation
Ultrasound waves can generate heat in the body using sound waves. Ultrasound can also have nonthermal biological effects, including sonoporation (increased cell permeability) that allow oxygen from blood cells more freely pass through their walls thereby improving circulation, which helps with wound healing, pain relief, and other conditions.
Physical therapists will typically place an ultrasound probe near or directly over the area being treated, applying gel on its head so sound waves penetrate evenly. Moving in a circular motion over this area for approximately 5-10 min while gradually increasing or decreasing intensity depending on what condition needs treating, an ultrasound therapist can adjust intensity as necessary for best results.
Research has demonstrated that low frequency ultrasound therapy can increase lung oxygen concentration due to its direct effect on gas exchange in the pulmonary vascular system. An experiment using anesthetized sheep revealed that after 7 minutes of sonication oxygen concentration had increased by 10% while pulse rate and pulmonary arterial pressure had both dropped by 13%.
As aggregated erythrocytes dissociate when exposed to low frequency ultrasound, their individual hemoglobin molecules become larger and their surface area considerably greater than in aggregated forms; increasing oxygen saturation levels.
Pulsed low-frequency ultrasound therapy has also proven successful at decreasing vascular permeability by stimulating production of nitric oxide, which relaxes arterial walls. This feature of ultrasound therapy may make it particularly suitable for treating pulmonary hypertension.
Nitric oxide acts as a vasodilator and improves oxygen supply to the lungs while simultaneously preventing formation of edema and interstitial fibrosis. Low-frequency ultrasound may also aid blood circulation by stimulating nitric oxide release; this may help relieve symptoms like shortness of breath and fatigue as well as facilitate formation of new vascular tissue.
Reduced Inflammation
Ultrasound therapy in wound care has been associated with decreased exudate and slough, reduced wound closure time, increased tissue elasticity and less pain. This noninvasive form of treatment should not be underestimated when treating wounds.
Low frequency ultrasound works because sound waves cause mechanical vibration in cells and tissues. While the vibrations do not penetrate deeply into the body, they have an impactful on nearby structures like blood vessels, muscles, and tissue – this phenomenon is known as micro impact phenomenon. Furthermore, vibrations may help break down scar tissue to increase movement in affected areas and decrease pain levels.
Low frequency ultrasound therapy for wound healing also uses ultrasound waves to form new collagen and increase protein synthesis, two important elements in supporting healthy tissues. Furthermore, ultrasound waves also have antiseptic properties due to disrupting biofilms forming on bacteria’s surfaces – helping speed the healing process overall.
Diagnostic and therapeutic ultrasound machines exist. Diagnostic devices utilize high-frequency ultrasound waves to image organs more clearly; while therapeutic machines utilize lower frequency waves to treat specific medical conditions.
US is known to play an essential role in wound healing’s inflammatory phase by stimulating cell proliferation of endothelial cells and myofibroblasts as well as stimulating production of cytokines and other inflammatory mediators, and increasing cellular proliferation and protein synthesis.
Increased Collagen Synthesis
Therapeutic ultrasound works by inducing mechanical acoustic vibration that increases concentrations of pro-growth factors such as fibroblast growth factor (FGF) and matrix metalloproteinases in tissue, stimulating collagen synthesis which in turn expedites normal repair processes while improving scar tissue quality (scar remodelling).
Frequency of US waves plays an integral part in achieving therapeutic effects: lower frequencies penetrate deeper tissues; however, as depth of penetration increases energy is absorbed and its therapeutic impact diminishes – this phenomenon known as half value depth is determined by frequency of US machine, tissue characteristics and size of target area.
Therapeutic ultrasound can modulate pro-inflammatory cytokines and cell signalling pathways, as well as influence gene and molecular expression involved in nerve regeneration, including Krox20 which acts as an inducer of neurotrophic factors. Furthermore, ultrasound may change collagen fibre polarity from typical Type III construction towards more favorable Type I structures to increase tensile strength and facilitate scar mobility.
Low frequency ultrasound therapy offers an easy, painless solution to debridement. By significantly decreasing wound bioburden and speeding healing time, this approach can promote quicker healing rates and contribute towards faster healing times.
Ultrasound technology has been utilized clinically since the 1970s for both diagnostic and therapeutic purposes, typically to create mechanical vibrations with thermal or therapeutic effects. Acoustic waves used to generate ultrasound waves create mechanical vibrations with thermal or therapeutic benefits. Mechanical vibration has been shown to increase blood flow in targeted tissue areas, decreasing viscosity of fluid and increasing metabolic rate and capillary permeability. Furthermore, vibration has been proven to decrease inflammation as well as promote cell division – including in fibroblast cells. Fibroblasts then produce high levels of collagen, leading to improved tissue integrity and reduced permeability. Thermal effects of US waves come from their absorption by tissue tissues; this causes localised heating of these areas, decreasing pain and discomfort while improving overall tissue elasticity.
Decreased Pain
Ultrasound therapy can relax muscle tissue and increase circulation, helping cells receive healing fluids for faster wound healing and less discomfort and inflammation. Furthermore, ultrasound therapy may debride wounds more effectively as well as decrease slough and odor levels in wounds that require chronic healing.
Ultrasound debridement can accelerate the healing process by relieving pain and swelling, increasing granulation and decreasing bioburden of wounds. Ultrasound debridement has proven more effective than mechanical debridement as a treatment approach, as it’s more well tolerated among patients.
An ultrasound session begins by applying a layer of hypoallergenic gel to the area being treated, which allows sound waves to travel into and disperse more evenly through skin layers. A probe is then placed over this target area for 5-10 minutes while you feel a slight pulsing sensation as treatment occurs.
Ultrasound waves penetrate tissue layers and break apart protein fibers in an area, liberating their toxic components to be processed by the body and decreasing inflammation caused by these toxins. They also increase blood circulation to aid cellular metabolism while alleviating any associated inflammation.
Studies conducted using low frequency ultrasound therapy demonstrated its efficacy at relieving pain intensity from chronic leg ulcers among those living with diabetic foot disease, significantly lessening pain intensity compared to patients in sham-treated groups after only one month of therapy. While this positive result suggests promise, more high-quality research needs to be completed in order to fully ascertain the impact of ultrasound on chronic wounds such as this one.
Another study determined that continuous-wave low-frequency ultrasound was superior in stimulating microcirculation in human venous leg ulcers than sham-ultrasound or tetanus antitoxin alone in stimulating microcirculation stimulation, potentially improving oxygenation of ulcer beds and aiding granulation processes.
The American College of Rheumatology recommends noncontact ultrasound as an adjunctive treatment option in wound care for the following conditions: