Ultrasound. Ultrasound What is Ultrasound What is Ultrasound Defined as sound w/ frequency > 20,000 cycles per sec Defined as sound w/ frequency > 20,000.

Ultrasound

Ultrasound

What is Ultrasound Defined as sound

w/ frequency > 20,000 cycles per sec

Ultrasound travels thru materials

Thermal & non-thermal properties

Ultrasound

Terminology Transducer (sound head) – converts

electrical energy into sound energy Power (W) – amount of sound energy

per unit of time Intensity (W/cm2) – amount of power

per unit time

Ultrasound

Terminology Continuous US Pulsed US

Ultrasound Terminology

Pulsed US Duty cycles

20% duty cycle – 20% on : 80% off

50% duty cycle – 50% on : 50% off

Ultrasound

Terminology Frequency – number of cycles per

sec (Hz)1.0 MHz penetrates deeper tissues3.0 MHz or 3.3 MHz penetrates more

superficial tissuesPhonophoresis – application of US

with a topical drug

Generation of Ultrasound

Crystals in the sound head expand & contract in response to electrical current resulting in resonating ultrasound

Effects of Ultrasound

Thermal Effects Tissues Affected

Effects of Ultrasound Thermal Effects

Factors Affecting the Amount of Temperature Increase

Areas of increased collagen content achieve higher temps

Areas of greater circulation cooler faster

Thicker tissues heat slower

Effects of Ultrasound

Thermal Effects Applying Other Physical Agents in

Conjunction With Ultrasound Hot pack prior to US US & electrical stimulation US & cryotherapy – used to limit/control

thermal effects of US

Effects of Ultrasound

Nonthermal Effects Increase intracellular Ca Increase skin & membrane

permeability (phonophoresis) Increase macrophage response Increase protein synthesis by

fibroblasts

Clinical Applications of Ultrasound

Soft Tissue Shortening Thermal effects

Pain Control Thermal effects

Clinical Applications of Ultrasound

Dermal Ulcers Thermal effects Increased

macrophage activity

Increased protein synthesis by fibroblasts

Clinical Applications of Ultrasound

Surgical Skin Incisions Thermal effects Increase

macrophage response

Increase protein synthesis by fibroblasts

Clinical Applications of Ultrasound

Tendon Injuries Thermal effects Increase

macrophage response

Increase protein synthesis by fibroblasts

Clinical Applications of Ultrasound

Clinical Applications of Ultrasound

Bone Fractures Promotes healing Simulates

osteoblast activity Increase

intracellular Ca Reabsorption of

Calcium Deposits Unknown how this

occurs

Clinical Applications of Ultrasound

Carpal Tunnel Syndrome Phonophoresis

Unit on phonophoresis in your book is required reading

Contraindications for the Use of Ultrasound

Malignant Tumor Pregnancy Central Nervous System Tissue Joint Cement

Contraindications for the Use of Ultrasound

Plastic Components Pacemaker Thrombus Eyes Reproductive Organs

Precautions for the Applications of

Ultrasound Acute Inflammation Epiphyseal Plates Fractures (high frequency US) Breast Implants

Adverse Effects of Ultrasound

Adverse effects are “rare” Burn is the most common adverse

effect

Ultrasound

Autosound video

Torn Peroneal Tendon After Lateral Ankle Sprain

Use of Ultrasound Debate http://ptjournal.apta.org/site/misc/podca

sts.xhtml#discussions