Continuous versus pulsed ultrasound?
This setting is indicated for subacute, chronic conditions with no active inflammation. Soundwaves are emitted continuously throughout the treatment. Because of the amount of friction created in the tissue, heat is created.
Pulsed ultrasound is beneficial in acute conditions, inflammatory responses, nerve entrapment and neuromas in scar tissue. Soundwave propagation is intermittent, retaining the mechanical effects of mild cavitation and micro massage without any thermal effects.
Methods of Soundwave Transmission?
Direct Contact- When using the direct technique, the ultrasound head is put against the skin with only a thin layer of couplant (gel or lotion) in between. Considerations when using this technique are the amount of soft tissue over the bone in that area (“bony” areas may be better suited to indirect treatment, described below) and the size of the soundhead (large soundheads may require the indirect technique when treating a small area.)
Treatment time: 5 – 10 minutes
Mode of heat transfer: Conversion
Penetration: 4 – 6 cm
Step 1: Apply a generous amount of coupling medium to clean dry skin
Step 2: Move transducer in either a circular or stroking pattern
Step 3: Turn intensity up to treatment level
Step 4: Each circle / stroke should overlap the previous by ½
Step 5: Treatment area limited to 2 times size of transducer
Step 6: Slow and deliberate (moving the soundhead approximately 4 cm per second)
Step 7: Transducer must stay in contact and in motion to avoid overheating of the transducer
and damage to the crystal
Immersion Application Procedure (Under Water Treatment)
Step 1: Submerge part fully in tub of water (plastic, ceramic, rubber, or fiberglass)
Step 2: Submerged ultrasound head and hold approximately 0.5 to 1 cm from the skin surface
(intensity should be increased possibly as much as 50% to ensure effectiveness)
Step 3: Move ultrasound head slowly over treatment area (if air bubbles accumulate on the
soundhead or treatment area, they may be wiped away quickly)
Step 4: Turn intensity up to treatment setting
NOTE: Most ultrasound machines are designed so the transducer can be safely placed underwater without risk of damage to the patient or machine. Check with the manufacturer if the machine capabilities are not known, particularly if the unit is old.
Preparing the patient?
It is important to remember that everyone’s tolerance to heat is different, and thus ultrasound intensity should always be adjusted to patient tolerance. The patient should not feel very warmth during the treatment. If the patient reports that the transducer feels very hot at the skin surface, it is likely that the coupling medium is inadequate. If the patient reports a deep aching sensation during the treatment, stop immediately. Periosteal burns may feel like a deep ache while the ultrasound is still on, and only later in the day will feel intensely painful.
Prentice, William E., Therapeutic Modalities for Allied Health Professionals, McGraw-Hill. 1998.
Jaskoviak, Paul A., Schafer, R.C., Applied Physiotherapy. The American Chiropractic Association. 1993.