Medically Reviewed by Dr. Luis Alberto Vallejo
What is ultrasound?
It is a form of energy that comes from mechanical vibrations. This energy is propagated in the form of longitudinal compression waves and needs an elastic means to be transmitted.
Ultrasonic treatment is understood as the use of sound vibrations in the non-audible spectrum, for therapeutic purposes.
Their employment is documented from the thirties.
In the fifties its use is generalized as a new form of diathermy. From the sixties, the pulsating form is introduced. It is used as a selective, anti-inflammatory and analgesic diathermy agent.
Ultrasound as a therapy is also known as a boundary surface therapy.
This is because the effects of ultrasound will occur more sharply between tissue boundaries.
Therapeutic Ultrasound Frequency
- High Frequency: It is 3 MHz. It is little penetration. Indicated in surface treatments.
- Low frequency: It is 1 MHz. Greater penetration Used in deep treatments.
The piezoelectric effect of the Ultrasound
Piezoelectricity is the property that some bodies or materials have of presenting electric charges on their surface caused by mechanical compressions and dilations, when a pressure is applied.
It is a reversible effect since the crystal is compressed and dilated as often as the poles are inverted.
The effect occurs in bone tissue, collagen fibers and body proteins.
Types of Ultrasound
- Continuous ultrasound: It is used as deep and selective thermotherapy in tendon and periarticular structures.
Its dosage is controlled by the appearance of periodic pain if there is local thermal overload.
It can be applied in the presence of metallic osteosynthesis.
Contraindicated in acute inflammatory processes, recent trauma, ischemic areas or with sensitivity alterations.
- Pulsed Ultrasound: Pulsating emission is currently used for its positive effects on inflammation, pain and edema.
It is indicated in acute and inflammatory processes since with adequate parameters it lacks thermal effects.
As there is no periodic pain, the warning of overdose is lacking and it is necessary to be cautious at medium and high intensities.
Mechanical effect: Cellular hydromassage or cavitation: Mechanical effect on living tissues. It is a rapid formation and collapse of dissolved gas or vapor bubbles that can converge and increase in size cause the destruction of subcellular structures.
Biological effects: They are due to the absorption coefficient.
- Promotes muscle relaxation.
- Increase membrane permeability.
- Increases the regenerative capacity of tissues.
- Effect on peripheral nerves.
- Pain reduction
- Decrease or increase in spinal reflexes according to the dose applied.
Ultrasound application methods
- Direct Coupling: The head is applied to the skin by previously cleaning it with soap or 70% alcohol. A thin layer of contact gel should be applied to the area to be treated.
- Underwater Coupling: This modality is used for the treatment of irregular surfaces and painful areas. Use a large plastic cuvette because it produces few reflections on the wall. Never use it in metallic therapeutic tanks as they produce reflections, in addition to the risk of an electrical accident. Water must be previously degassed or boiled. The appropriate temperature is 36-37 ° C. The head is located 3 cm away from the area to be treated, keeping it moving. It works in the near field of the beam. The therapist should not put his hand in the water and if it is inevitable he should use a rubber glove to avoid the diffuse effect by dispersion. Doses similar to those of direct coupling are used.
- Mixed Coupling: For the treatment of concave regions or that cannot be treated by the underwater method. A latex or plastic balloon filled with degassed water is placed, which adapts to the area. Contact gel is placed between the head and the balloon and between it and the skin to complete the coupling. As energy is lost in the transmission, in this mode doses somewhat higher than normal are used.