Therapeutic Ultrasound (2) PDF

Therapeutic Ultrasound (2)  Objectives of the lectures: At the end of the lecture the students will be able to: - Define sound and ultrasound wave energy. - Explain the production of ultrasound. - distinguish between different physical phenomena of ultrasound. - describe the physiologic...

Therapeutic Ultrasound (2)  Objectives of the lectures: At the end of the lecture the students will be able to: - Define sound and ultrasound wave energy. - Explain the production of ultrasound. - distinguish between different physical phenomena of ultrasound. - describe the physiological effect of ultrasound. - identify the therapeutic effect of ultrasound. - list the indication and contraindication of ultrasound.  Physiological Effects of US Non thermal Thermal effect effect  1- Thermal effects The energy within the sound waves is passed and absorbed by the tissues, it will cause oscillation of the molecules of that tissues about their mean position, clearly any increase in the molecular vibration will result in heat generation. Significant thermal effect is achieved, if the temperature of the tissue is raised to between 40-45° for at least 5 minutes. If the temperature is raised above 45, tissue destruction occurs.  2- Non-Thermal Effects (mechanical effects) Non thermal means: without producing significant temperature changes Acoustic Cavitation Micro massage Streaming Stable Unstable  1- Cavitation DF: The formation of gas bubble within the tissues and body fluids during the phase of relaxation or rarefaction of an ultrasound wave. -There are 2 types of cavitation (Stable and Unstable ).  A- Stable cavitation - Is not dangerous to the tissues as bubbles remain intact and oscillate harmlessly in the U.S field. - The stable cavitation lead to changes in cell permeability to various ions such as calcium can have a profound effect upon the activity of the cell. - This cavitations has been proposed as a mechanism for the non-thermal therapeutic effect of US.  B- Un Stable cavitation ( transient- inertial) Is dangerous to the tissues as the bubbles ground collapses rapidly in U.S causing increase in temperature and causes free radical formation  How to minimize the danger of cavitation : 1- Using of low intensities. 2- Using a pulsed U.S. 3- Moving the treatment head during treatment.  2- Acoustic Streaming Df: is the unidirectional movement of a fluid in US field. - This is a steady circular flow of cellular fluid.  The acoustic streaming phenomenon is known to affect on: 1. Diffusion rates and membrane permeability, with a result that protein synthesis is enhanced. 2. Sodium ion permeability is altered resulting in changes in the cell membrane potential. 3. Calcium ion transport is modified which leads to an alteration in the enzyme control mechanisms of various metabolic processes, especially concerning protein synthesis.  3- Micro massage The sound wave travelling through the medium will cause the molecules to vibrate. Possibly it is enhancing tissue fluid interchange and affecting tissue mobility which is used to reduce oedema. Combined with thermal effect, lead to easier stretch of scar and adhesion and reducing pain.  Therapeutic Effects of Ultrasound Two schools of thought have developed concerning the therapeutic mechanisms of US. A. Considers the heating to be the only effect (ultrasonic Diatheramy). B. More concerned with the possibility of low intensities causing important mechanical and biological effects with pulsed treatments.  Therapeutic Effects of Ultrasound 1. Recent injuries and inflammation pulsed mode, at low intensity in resolution of acute inflammation. The mechanical and biological effects bring about removal of traumatic exudates and promotion of tissue repair. 2. Chronic edema The acoustic streaming force of US helps in the removal of chronic odeama, thereby helping breaking of adhesions formed between adjacent layers. 3. Adhesion and scar tissues Collagen has high absorption ability and it canbe heated with US.The thermal effect of US lead to increasing extensibility of collagen rich tissues, thus US could be used prior to ROM and stretching exercises. 4. Pain control: Ultrasound can produce pain relief through direct and indirect mechanism. Direct effect: US directly influence the cell membrane permeability of the nervous tissue resulting in; Increase pain threshold Decrease transmission of pain impulse (gate theory for pain inhibition) Indirect effect: Result from the other effect of US which could lead to removing the source of pain as: increase capillary permeability and removing waste products and oedema reduction improving tissues healing. decrease muscle spasm and breaking down adhesion. 5. Effect on wound healing Pulsed US at low intensities was effectively enhance healing of wound by: - stimulating collagen production by fibroblasts. - Increases the intracellular calcium ion levels. - improve the local blood supply. - Encourage the growth of new capillaries. - Stimulates the myofiboblasts to contract, giving rapid initial wound strength. 6. Fracture healing The use of US could accelerate the rate of fracture repair. US delivered a low intensity (0.03 W/cm2) at 1.5 MHz pulsed at a ratio of 1:4. for 20 minutes. N:B: Using higher ultrasound doses (1- 2 W/cm2) could have an adverse effect on the fracture healing process. 1. Acute and chronic soft tissues injuries. 2. Acute and chronic inflammation. 3. Wound and ulcers healing. 4. Fracture healing. 5. Neurogenic pain. 6. Muscle spasm. 7. Trigger areas. 8. Scar tissue. 9. Joint contractures.  CONTRAINDICATIONS 1. Pregnancy when used over the pelvic or lumbar area. 2. Over areas of acute infection. 3. Areas of severely impaired circulation. 4. Over malignant tumours. 5. Over growing epiphyseal plates and bony prominence. 6. Areas around the eyes, heart, and genitals. 8. venous thrombosis. 9. Metallic implants or surgical fixation materials. 8. 10. Hemophilia. 11. Special care to patient with sensory loss. 12. Patient having deep x-ray therapy. - Introduction of the molecules of drugs through the intact skin by the mechanical effect of US. - It depends on the molecular weight of the drug, skin pores, frequency, intensity of insonation. - Examples (Hydrocortisone, Nonsteriodal anti inflammatory drugs, Lidcocain, Salicylate) Advantages of phonophoresis: - Localized effect on the area of problem. - Safe. - painless ( non invasive)  Parameters of ultrasound when used as a phonophoresis - Introduction of the molecules of drugs through the intact skin by the mechanical effect of US. - It depends on the molecular weight of the drug, skin Low frequency pores, frequency, intensity of ( 1 MHZ) Pulsed mode insonation. High intensity ( 1-1.5 W/cm2) - Examples (Hydrocortisone, Nonsteriodal anti inflammatory drugs, Lidcocain, Salicylate)