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Ultrasound, phonophoresis, physiotherapy

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  1. 1. Sreeraj S R ULTRASOUND 1
  2. 2. Sreeraj S R SOUND & ULTRASOUND Periodic mechanical disturbance of an elastic medium such as air. Ultrasound refers to mechanical vibrations of a higher frequency, beyond the range of human hearing Frequency - Typically 1 or 3 MHz Wavelength - @ 1MHz would be 1.5mm and @ 3 MHz would be 0.5 mm. velocity of ultrasound - Sound waves can travel more rapidly in a more dense medium. The velocity varies from 331 m/sec in air 1450 m/sec in fat, 1570 m/sec in blood 2
  3. 3. Sreeraj S R 3 Transducer (sound head): A crystal that converts electrical energy into sound Power: The amount of acoustic energy per unit time. This is usually expressed in Watts. Intensity: The power per unit area of the sound head. This is usually expressed in Watts/centimeter2.
  4. 4. Sreeraj S R 4 Spatial Peak Intensity: The peak intensity of the ultrasound output over the area of the transducer. The intensity is usually greatest in the centre of the beam and lowest at the edges of the beam. Spatial Average Intensity: The average intensity of the ultrasound output over the area of the transducer. Beam Nonuniformity Ratio (BNR) : The ratio of the spatial peak intensity to the spatial average intensity . For most units this is usually between 5:1 and 6:1,
  5. 5. Sreeraj S R 5 Continuous Ultrasound: Pulsed Ultrasound: Pulsing the ultrasound minimizes its thermal effect. Duty Cycle: The proportion of the total treatment time that the ultrasound is on. This can be expressed either as a percentage or a ratio.
  6. 6. Sreeraj S R 6 Spatial Average Temporal Peak (SATP) Intensity: The spatial average intensity of the ultrasound during the on time of the pulse. Spatial Average Temporal Average (SATA) Intensity: The spatial average intensity of the Ultrasound averaged over both the on time and the off time of the pulse. SATP x duty cycle = SATA
  7. 7. Sreeraj S R Effective Radiating Area (ERA)Effective Radiating Area (ERA)Effective Radiating Area (ERA)Effective Radiating Area (ERA) area of the sound head that produces ultrasonic waves; expressed in square centimeters (cm2) Always lesser area than actual size of sound head Large diameter heads – column beam Small diameter heads – more divergent beam Low frequency (1 MHz) – diverge more than 3 MHz 7
  8. 8. Sreeraj S R Near Field/Far Field: The near field, also known as the Fresnel zone is the convergent region and the far field, also known as the Fraunhofer zone, is the divergent region Length of near field = Radius of transduce2 / Wavelength of ultrasound (r2 /λ) 8
  9. 9. Sreeraj S R Acoustic Impedance It is a measure of the resistance of particles of medium to mechanical vibrations This resistance increases in proportion to the density of medium and velocity of ultrasound in the medium 9
  10. 10. Sreeraj S R Reflection most reflection occurring where there is the greatest difference between the acoustic impedance of adjacent tissues. In the body, most reflection i.e. 1% in soft tissue / fat interface about 35%, occurs at soft tissue-bone interfaces there is 100% reflection of ultrasound at the air skin interface and only 0.1% reflection at the transmission medium-skin interface 10
  11. 11. Sreeraj S R Standing Wave When reflected ultrasound meets further waves being transmitted, a standing wave (hot spot) may be created, which has potential adverse effects upon tissue. Such effects can be minimized by ensuring that the apparatus delivers a uniform wave, using pulsed waves and moving the transducer during treatment 11
  12. 12. Sreeraj S R Standing Wave 12
  13. 13. Sreeraj S R Absorption Absorption coefficients are tissue and frequency specific. They are highest for Tissues with highest collagen content and Increase in proportion to the ultrasound frequency 13
  14. 14. Sreeraj S R Refraction 14
  15. 15. Sreeraj S R Attenuation Attenuation is the result of absorption, reflection, and refraction, with absorption accounting for about one- half of attenuation. Attenuation coefficients are tissue and Frequency specific. They are higher for tissues with a higher collagen content and increase in proportion to the frequency of the ultrasound 15
  16. 16. Sreeraj S R Half value depth this is the tissue depth at which 50% of the ultrasound delivered at the surface has been absorbed. The average 1/2 value depth of 3MHz ultrasound is at 2.5 cm and 1MHz ultrasound as 4.0 cm 16 1 MHz 3 MHz Muscle 9.0 mm 3.0 mm Fat 50.0 mm 16.5 mm Tendon 6.2 mm 2.0 mm
  17. 17. Sreeraj S R Quantity of Ultrasound (fraction of beam being further propagated) 1.0 .5 .25 .125 1st Half Value 2nd Half Value 3rd Half Value 4th Half Value Tissue depth The quantity of the ultrasound beam decreases as the depth of the medium (tissue) increases. 17
  18. 18. Sreeraj S R Generation of Ultrasound Pizoelectric effect - generated by pizoelectric crystals occurs when an electric current is passed through the crystal crystal expands & contracts at frequencies that produce ultrasound pizoelectric crystal in transducer head Wavelength ultrasound transducer 18
  19. 19. Sreeraj S R Production 19
  20. 20. Sreeraj S R Ultrasound Machine & Coupling Agent 20
  21. 21. Sreeraj S R Types of Ultrasound Beams Continuous Wave - no interruption of beam: best for maximum heat buildup Pulsed Wave - intermittent “on-off” beam modulation builds up less heat in tissues used for post acute injuries 21
  22. 22. Sreeraj S R Pulsed Wave Mark Space ratio 22
  23. 23. Sreeraj S R Physiological Effects of Ultrasound Thermal effects (minimum 10 min - 2.0 watts - 1 MHz) ▲ blood flow ▼ inflammation and ▼ hematoma (remains controversial?) ▲enzyme activity ▲sensory and motor nerve conduction velocity ▲extensibility of connective tissue & possibly scar tissue ▼ joint stiffness ▼ muscle spasm ▼pain 23
  24. 24. Sreeraj S R Non-thermal effects cavitations alternating expansion & compression of small gas bubbles may cause ▲ cell membrane & vascular wall permeability (▲ nutrient and oxygen delivery) unstable cavitations may cause tissue damage unstable cavitations – large, violent changes in bubble volume Micro streaming bubble rotation of fluid movement along cell membrane boundaries (▲ nutrient and oxygen delivery) changes in cell permeability & ion flux reduces healing time gas buble expansion gas buble compression bubble rotation & associated fluid movement along cell membranes Cavitation Microstreaming Non-thermal Effects of Ultrasound 24
  25. 25. Sreeraj S R NonNonNonNon----thermal effectsthermal effectsthermal effectsthermal effects Possible therapeutic benefits of non- thermal effects difficult to make distinction from thermal benefits ▲ capillary density & ▲ cell permeability ▲ fibroblastic activity and associated collagen production ▲ cortisol production around nerve bundles reduce inflammation 25
  26. 26. Output Frequency Duration Duty Cycle Output Intensity 26
  27. 27. Sreeraj S R Output Frequency Determines the treatment depth 1 MHz Output Deep (5 to 7 cm) tissues ○ Rotator cuff, vastus intermedius, gastroc 3 MHz Output Superficial (up to 3cm deep) tissues ○ Patellar tendon, MCL, brachialis 27
  28. 28. Sreeraj S R Treatment Duration Depends on: Size of the treatment area Output intensity Therapeutic goals Vigorous heating 1 MHz output ○ 8 to 10 minutes 3 MHz output ○ 3 to 4 minutes 28
  29. 29. Direct Coupling Immersion Method Pad/Bladder Method 29
  30. 30. Sreeraj S R Coupling Methods Ultrasonic energy cannot pass through the air A coupling medium is required Medium should be water-based Coupling method should confirm to the body area The body area should be clean and relatively hair-free 30
  31. 31. Sreeraj S R Direct Coupling Gel or Creams Only use approved coupling agents Apply liberally to area Remove air bubbles by passing sound head over area (before power is increased) 31
  32. 32. Sreeraj S R Direct Coupling Move the sound head s-l-o-w-l-y 4 cm/sec Moving the head faster decreases heating If the patient describes discomfort, decrease the output intensity 32
  33. 33. Sreeraj S R Coupling Ability of Various Media Substance Transmission Saran Wrap 98 Lidex ge, fluocinonide (.05%) 97 Thera-Gesic 97 Mineral oil 97 US Transmission gel 96 US Transmission lotion 90 Chempad-L 68 Hydrocortisone powder (1%) 29 Hydrocortisone powder (10%) 7 Eucerin cream 0 Myoflex 0 White petrolatum gel 0 33
  34. 34. Sreeraj S R Immersion Technique Used to treat irregularly shaped areas The limb is immersed in a tub of degassed water If tap water is used, increase the output intensity by 0.5 w/cm2 Transducer is held appx. 1” from the body part Avoid the formation of air bubbles 34
  35. 35. Sreeraj S R Pad (Bladder) Method A mass of conductive gel Commercial pads Self-made bladders Conforms to the treatment area Commercial pads help limit the size of the treatment area 35
  36. 36. Sreeraj S R Contraindications Acute injuries (100% duty cycle) Ischemic areas Areas of impaired circulation including arterial disease Over areas of deep vein thrombosis Anesthetic areas Over cancerous tumors Over sites of active infection or sepsis Over the spinal cord or large nerve plexus in high doses Exposed metal that penetrates the skin (e.g., external fixation devices) Areas around the eyes, heart, skull, or genitals Over the thorax in the presence of an implanted pacemaker Pregnancy when used over the pelvic or lumbar areas Over a fracture site before healing is complete Stress fracture sites or sites of osteoporosis Over the pelvic or lumbar area in menstruating female patients 36
  37. 37. Sreeraj S R Precautions Symptoms may increase after the initial treatments. Use caution when applying ultrasound around the spinal cord, especially after laminectomy. The use of ultrasound over metal implants is not contraindicated Keep the sound head moving Use caution when applying ultrasound over epiphyseal plates of growing bone 37
  38. 38. Sreeraj S R PHONOPHORESIS 38
  39. 39. Sreeraj S R PHONOPHORESIS It is the movement of drugs through skin into the subcutaneous tissues under the influence of ultrasound Also known as sonophoresis or ultrasonophoresis 39
  40. 40. Sreeraj S R 40
  41. 41. Sreeraj S R Pathways of drug penetrationPathways of drug penetrationPathways of drug penetrationPathways of drug penetration 1.Through stratum corneum 2.Transfollicular 3.Through sweat gland 41
  42. 42. Sreeraj S R Advantages Avoid risk and inconvenience of IV therapy Bypass liver in terms of elimination Less chance of overdose or underdose Allow easy termination Permit both local and systemic treatment effects 42
  43. 43. Sreeraj S R Effectiveness Depends upon Anatomical area treated Hydration of the skin Health or pathological condition of the skin State of cutaneous and systemic metabolism Patient’s age 43
  44. 44. Sreeraj S R Methods of application Adequate quantity of drug rubbed into the skin over the target area Same gel mixed with standard ultrasound gel placed over transducer head as coupling medium US is then applied as a direct contact method Standard intensity is 1 to 2 w/cm² Standard duration is 5 to 10 minutes Lower ultrasonic frequencies and pulsing lead to deeper penetration 44
  45. 45. Sreeraj S R Phonophoretic agents Drug Indication Reactions/ contraindications Hydrocortison Anti inflammatory Skin rashes Lidocaine/xyclocaine Acute pain Methyle salicylate Chronic painfull MS disorders Sensitivity to aspirin Zinc oxide/siloderm Open wounds Allergy to metals Iodine Adhesion,calcification ,adhessive capsulitis Allergic to sea food 45