Ultrasound Diathermy And Laser Flashcards
Ultrasound
form of acoustic (sound) energy with frequencies greater than 20,000 Hz
US waves travel by mechanically deforming/vibrating molecules
Vibrating tissue molecule “bumps” into adjacent molecule, transfers energy, sets adjacent molecule in motion
Requires medium
US Wave Velocity
Velocity: how quickly US waves travel through medium
Higher density: travel faster
Lower density: travel slower
US Machine
Generator: sends high-frequency AC to applicator
Transducer: piezoelectric crystal and sound head
Sound Wave Generation
Sound waves generated by oscillations of the piezoelectric crystal
Applying voltage to crystal induces it to compress or expand
Repeated compression/expansion = US pressure waves
Acoustic Impedance
Higher density: high impedance = low transmission (increased attenuation)
Lower density: lower impedance = high transmission (decreased attenuation)
Hot Spots
Reflected waves can interact with US waves traveling away from energy source
If in phase = additive effect, creates “standing waves”
Must move transducer during treatment
Frequencies for tissues
Old thinking -
3 MHz: tissue depth of 1–2 cm
Used for more superficial structures
1 MHz: tissue depth of 2–5 cm
Used for deeper structures
New thinking -
Higher frequency heats tissue faster
Continuous Mode
Uninterrupted stream of acoustic energy, thermal properties
Power emitted not uniform = “Hot spots”
Thermal Effects
Conversion: heating that occurs when nonthermal energy (i.e., mechanical, electrical) is absorbed into tissue and transformed into heat
US: mechanical energy = thermal energy
Deep heating modality
Physiologic changes with increased tissue temp
Increase metabolic rate
Decrease pain
Decreased muscle spasm
Increased blood flow
Increased CT extensibility
Decreased sympathetic activity
Nonthermal Effects
Microstreaming: ions, intra-/extracellular fluids in tissue undergo small- magnitude movements
Cavitation: pulsation of gas bubbles from condensations (compression) and rarefactions (expansion) of US wave
Both produce nonthermal effects:
Increase cell membrane permeability
Increased cellular activity
Facilitates tissue repair
Phonophoresis
Use of US for transdermal delivery of medication
Provides high concentration of drug directly to treatment site
Musculoskeletal inflammatory conditions: Anti-inflammatory agents and analgesics
Fracture Healing
Effective for facilitation of fracture healing
38% reduction in healing time
Low-intensity pulsed ultrasound
Sonic accelerated fracture healing system (SAFHS)
Indications:
Deep-heating modality (continuous)
Joint contracture, scar tissue
Pain
Muscle spasm
To increase blood flow in subacute/chronic inflammation
Facilitation of healing (pulsed)
Acute injury or inflammation of soft tissue
Wounds
Fracture
Contraindications and Precautions
Cardiac pacemaker
Sensory deficits
Peripheral vascular disease
Pregnancy (pelvic, lumbar, abdominal areas)
Eyes and testes
Region of active bleeding, infection
Region of malignancy/tumor
Region of DVT, thrombophlebitis
Over heart, stellate, or cervical ganglia
Over epiphyseal plates of growing bones
Precautions:
Patient’s ability to communicate
Over plastic/metal implant
Diathermy
Converts electromagnetic energy into therapeutic heat
Can heat surfaces up to 25 times the size of a typical US transducer
Continuous: thermal effects
Pulsed: nonthermal effects
