Therapeutic Ultrasound #2 Flashcards
Acute Effects of Therapeutic Ultrasound Delivered at Varying Parameters on the Blood Flow Velocity in a Muscular Distribution Artery
Conclusion: 1.0 MHz ultrasound delivered at 1.0 and 1.5 w/cm2 to the triceps surae musculature as described in the present study can increase the blood flow velocity in the popliteal artery.
A Comparison of Human Muscle Temperature Increases During 3-MHz Continuous and Pulsed US With Equivalent Temporal Average Intensities
Pulsed US produces similar increases in intramuscular temperature as continuous US given equivalent SATA intensities
1.8°F(1°C) mild heat temp increase effects
Increase metabolism
Reduces mild swelling
3.6-5.4°F(2-3°C) Moderate heat temp increase effects
Reduces pain and muscle spasm
Increases blood flow
7.2°F(4°C) Vigorous heat temp increase effects
Increases ROM and tissue extensibility
Factors that influence tissue temperature rise from US
- Rate at which energy is applied
- Intensity and mode of application
- Length of time energy is applied
- The thermal conductivity of the tissue
- Bone has high absorption coefficient and high thermal conductivity.
- Heat is dissipated to cooler, nonsonated areas
- Rate of perfusion of blood to the tissue
Nonthermal effects of US
- Increased histamine release
- Influx of calcium ions
- Increased phagocytosis of macrophages
- Increased protein synthesis
- Increased capillary density of ischemic tissues
- Tissue regeneration
- Wound healing
- Cell membrane alteration
- Attraction of immune cells to the injured tissues
- Increased fibroblast activity
- Vascular regeneration
Physiological effects: nonthermal effects
-Originate at cell membrane
-Membrane deforms slightly due to pressure against cell wall
-Due to micromassage, microstreaming, and cavitation
-Frequency response theory
*Specific frequency will cause specific tissue resonance
-Attraction of Immune Cells to Injured Area
Alters Cell Membrane Properties
*Cellular adhesion
*Membrane permeability
*Calcium influx
*Cellular proliferation
*Activation of signal-transduction pathway
US in inflammatory phase
Aid immune response: -Inducing vasodilation -Activation of adhesion molecules How? -Modulating signal transduction pathway *Series of enzymatic proteins *US alters protein structure (phosphate moderation
US in Repair phase
Immune response:
-Induce tissue debris clearance
-Stimulate tissue remodeling
How?
-Anti-inflammatory cytokines down-regulate T-cells
-Redirect cellular activity toward proliferation
Frequency response hypothesis: central premise
- US mechanical energy is absorbed by proteins
- Alters structural conformation of protein
- Modulates protein function
Incisional Wound Healing: A Controlled Study of Low and High Dose Ultrasound
Conclusion: Both low and high dose US increased the wound breaking strength and collagen deposition in incisional wounds
Frequency response hypothesis: Frequency resoonance
Each frequency of US may have a unique resonant or shearing force. This may effect proteins differently. Looking at targeted effect of frequency on proteins.
Efficacy studies
Positive benefit AND no benefit -Ankle sprains - elbow epicondylitis -carpal tunnel snydrome - calcific tendonitis of shoulder Just positive benefit - myofascial pain
Why discrepancy in efficacy studies?
- TUS provides effect at impairment level.
- Studies often do not report impairment being studied.
- Studies often do not report stage of healing.
Therapeutic US clinical uses
- Aiding the inflammatory response to injury
- Connective tissue healing
- Superficial wound healing
- Bone healing
- Pitting edema
- Reducing muscle spasm
- Reducing pain
- Restoring ROM due to scar/contracture
- Stretching connective tissue
US aiding inflammatory response
- Stimulates collagen synthesis
- Stimulates cell proliferation
- Stimulates release of histamine
Parameters
- Pulsed 20% duty cycle,0.5 W/cm2, 5 minutes
- Continuous, 0.1 W/cm2, 5 minutes
US for CT healing
Many animal studies demonstrated positive effects to stimulate cartilage growth, tendon repair, nerve repair
US for superficial wound healing
- Increased fibroblast production of collagen
- Increased blood vessel development
- Increased smooth muscle activity
US for bone healing
- Nolte et al, J Trauma, 2001;51:693-702
- Pulsed, low intensity US assisted in healing non union fractures
- Parameters:
- Duty cycle:20%
- Frequency: 1.5MHz
- Intensity: 30mW/cm2
- Time: 20 min
US for pitting edema
- Draper et al.
- Heating effect from US will liquefy gel-like cellular debris in pitting edema
- Will aide in allowing fluid to be removed by massage, elevation, etc.
US for reducing muscle spasm
- Increases blood in area
- Removed irritants
- Reduces pain cycle
- Increases 02 delivery to tissues
US for Reducing pain
- Altering transmission or perception of pain
- Modifying underlying condition causing pain
US for reducing pain: altering transmissionor perception of pain
- Selectively heats peripheral nerve
- May alter or block impulse conduction
- parallel relationship between increased tissue temp and increased sensory nerve conduction velocity
- speed of conduction increase as tissue temp inc
- Increase nerve cell membrane permeability
- Increase tissue metabolism
US contraindications
- Near a malignant or benign tumor
- Near the uterus of a pregnant female
- Central nervous system tissue
- Over cemented joint replacement
- Near a pacemaker
- Near a suspected thrombophlebitis
- Over the eyes, ears, and genitalia
- Near an area with infection
- Over areas that have recently been exposed to radiation and radioactive isotopes
- Over areas with active bleeding or susceptible to hemorrhage
US precautions
- Acute Inflammation
- Epiphyseal Plates
- Fractures
- Breast Implants
US dosimetry
- Typically 0.5 – 2.0 w/cm2 for 5-10 minutes
- However, need to know:
- Stage of healing
- Treatment area size
US dosimetry: Therapeutic dose
- The amount of acoustic energy delivered to the tissue per square centimeter
- Measured in J/cm2
- Takes into consideration relationship between total treated area (S) and the sound head ERA
Therapeutic dose: calculate total energy (E)
E=P(power) X T(time) (1J = 1W/sec.)
Therapeutic dose: Calculate total energy delivered per sound head square cm
Es (Energy/cm2 of sound head) = E/ERA
Therapeutic dose: Calculate therapeutic dose
D = Es/(S (treated area) /ERA)
Therapeutic dose: TX area
2-3 times ERA
Therapeutic dose: frequency to tx
Depends upon level of US being used
Depends upon the stage of healing
*Thermal – sub acute to chronic stage
*Non-thermal – acute stage
Therapeutic dose: duration of intervention
- Depends upon desired effect of treatment
- No definitive, objective standard exists
- Acute conditions may be treated for shorter periods than chronic conditions
- Smaller areas require less time than larger areas
Duration of intervention : subactute
- Tx. Area = 30 cm2
- ERA = 10 cm2
- Time = 30cm2/(.67 X 10cm2) = 4.5 minutes
Duration of intervention: chronic
- Tx. Area = 30 cm2
- ERA = 10 cm2
- Time = 30 cm2/(.5 X 10cm2) = 6 minutes
Duration of intervention: Max thermal
- Tx. Area = 30 cm2
- ERA = 10 cm2
- Time = 30 cm2/(.4 X 10cm2) = 7.5 minutes
- Tx. Area = 2xERA = 5 min
- Tx. Area = 3xERA = 7.5 min
- Tx. Area = 4xERA = 10 min
Therapeutic dose: intensity
- Acute conditions (non thermal effects)
- 0.1-0.5 W/cm2
- Pt should feel NO warmth
- Sub acute conditions (non thermal effects)
- 0.5-1.0 W/cm2
- Pt should feel none to minimal warmth
- Chronic conditions (thermal effects)
- 1.0-2.0 W/cm2
Coupling Medium
- Sound waves do not travel well through air.
- They reflect off most structures
- Need a mechanism to connect US to tissue
- Conductive (aqueous) coupling gel, glycerol contact coupling, Hydrogel sterile wound dressing, & water (degassed) coupling
Couplant
– any agent that allow for smooth transmission of US from sound head to tissue (skin)
* water > min oil> US gel (ultraphonic) > US lotion (polysonic)
