Therapeutic Ultrasound #1
Deep Thermotherapy
(local or general use of energy (ie. sound, electromagnetic) in rehab with goal of increasing tissue temp; capable of heating to depths of 3-5cm) 1) ultrasound 2) diathermy
Thermal effects of ultrasound
*Acceleration of metabolic rate *Reduction of control of pain and muscle spasm *Alteration of nerve conduction velocity *Increased circulation *Increased soft tissue extensibility
Ultrasound transducer/sound head
A crystal that converts electrical energy into sound; also called head. This term also used to describe the part of an ultrasound unit that contains the crystal.
Acoustic
A term that is used when discussing sound, how its created, and how its measured, and the mechanical waves that can be produced in the liquid, gases, and the air.
Thermal Effects of Ultrasound
Acceleration of metabolic rate Reduction or control of pain and muscle spasm Alteration of nerve conduction velocity Increased circulation Increased soft tissue extensibility
Contraindications of Superficial Thermotherapy
Acute Mucshuloskeletal trauma Arterial Disease Bleeding or Hemorrhage OVer an area of compromised circulation Over an area of malignancy Peripeheral Vascular diease Thrombophlebitis
Frequency of Treatment
Acute conditions Require more treatment over a shorter period of time (2 X/day for 6-8 days) Consider pulsed ultrasound Can begin using within 48 hours Chronic conditions Require fewer treatments over a longer period (alternating days for 10-12 treatments) Treatment should continue as long as there is progress
Non-Thermal Effects of Ultrasound
Altering membrane permeability to accelerate tissue healing. Studies found it also facilitates the healing of dermal ulcers, surgical skin incistions, tendoninjuries, and bone fractures.
Documentation
Area treated Ultrasound frequency Ultrasound intensity Ultrasound duty cycle Treatment duration If underwater Response to intervention
Order of Attenuation of 1MHz Ultrasound
Blood Fat Nerve Muscle Bloodvessels Skin Tendon Cartilage Bone
Precautions
Bony prominences Decreased sensitivity Regenerating nerves Acute inflammation Epiphyseal plates- mixed data on this but it is recommended that high-dose ultrasound not be applied over growing epiphyseal plates. Fractures- low dose ultrasound has been shown to accelerate fracture healing but high intensity ultrasound may ca pain and possibly impair fracture healing Breast implants- heat may increase the pressure inside a breast implant and cause it to rupture
Adverse Effects
Burns (always move the sound head) Standing waves - avoid this by moving sound head. The reflected wave and incident wave entering the tissue are superimposed Cross-contamination/infection
Continuous Ultrasound
Continuous delivery of ultrasound throughout the treatment period
Absorption
Conversion of the mechanical energy of ultrasound into heat. The amount of absorption that occurs in a given tissue type at a specific frequency is expressed by its absorption coefficient.
Transducer or Applicator (care)
Crystal converts electrical energy to sound energy through mechanical deformation Treatment surface of the trasnducer is the metal plate called the interface between the crystat that is inside and the patient's tissue. Can be damaged by dropping the sound head or holding up in the air where there is no medium. The waves do not travel out of the transducer head through the air. Its gets reflection back upon itseld inside the head and that will damage the crystal.
Frequency and Intensity
Depth of penetration is frequency dependent not intensity dependent 1 MHz transmitted through superficial layer and absorbed at 3-5cm considered to be Deep 3 MHz absorbed Superficial (1-2 cm deep) tissues Intensity- rate at which energy is Delivered per unit area. Usually Expressed in watts per square centimeter (w/cm2). Most intensity in therapy ranges from .25 to 3.0w/cm2. With all other factors held constant, the greater the intensity, the greater the resulting temperature elevation.
Bone fractures
Early text did not recommend ultrasound because continuous high dose over an unhealed fracture caused pain. Much research is being done of this topic including nonunion fractures with good results. Current research supports the use of very lose-dose ultrasound for facilitation of fracture healing. The parameters found to be effective are 1.5 MHz frequency, .15 w/cm2 intensity, 20% duty cycle for 15 to 20 minutes One study using traditional ultrasound unit in clinic used 1 MHz frequency, .5 W/cm2 intensity, 20% duty cycle, 20 minutes a day. Study done on rats and at 40 days , treatment done 5 days per week, the fracture site resulted increased bone mineral content and a 81% greater mechanical strength than placebo treated fractures
Preparing the patient
Evaluate the patient and establish that no contraindications are present Determine the method and mode of ultrasound application to be used and safety *Inspect the skin Clean the area to be treated Select the sound head Determine the type of coupling method to be used Identify a treatment area that is 2 to 3 times the ERA For direct coupling: spread the gel over the area to be treated Select treatment parameters Turn on machine Move sound head Document
Frequency of Therapeutic Ultrasound
Frequency range of therapeutic ultrasound is 0.75 to 3.3 MHz Frequency is the number of oscillations a molecule undergoes in 1 second. Expressed in units of hertz (HZ), 1 HZ=1 cycle per second; 1 kHz=1000 cycles per second; 1MHz= 1 million cycles per second The human ear is sensitive only to sound frequencies between 16 Hz and 20,000 Hz. Sound with a frequency greater than 20,000 Hz is called ultrasound Most units produce either 1.0 or 3.0 MHz
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) Move the sound head s-l-o-w-l-y 4 cm/sec Moving the head faster decreases heating Heating of gel does not increase the effectiveness of the treatment If the patient describes discomfort, decrease the output intensity
Immersion Technique/indirect coupling
Good for treating irregular surfaces A plastic, ceramic, or rubber basin should be used Tap water is useful as a coupling medium, but may need to increase output intensity by about .5 w/cm2 Transducer should move parallel to the surface approximately .5 to 3 cm from body part Air bubbles should be wiped away- reduces the transmission of ultrasound Increase output secondary to bubbles
Bladder/ pad Method
Good for treating irregular surfaces when body part cannot be submerged in water Uses a balloon filled with water Both sides of the balloon should be liberally coated with gel Also have commercial gel pads that can be used
Conversion
Heating that occurs when nonthermal energy is abosorbed into tissue and trasformed into heat. Thransformed from one form to another. Ultrasound is a modality that uses this kind of heat tranfer.
Advantages of Phonophoresis
Higher initial drug concentraion at delivery site Avoids gastric irritation Bypass liver, lessening metabolic elimination Non-invasive VS injection Increases depth of delivery by up to 6 cm Effective with both continuous and pulsed techniques Both perscription and non-perscription meds may be used Meds must be specifically intended for this type of ultrasound and must have molecules of small size and weight to diffuse through the skin.
Termination of treatment
If the treatment is being terminated prematurely: Reduce the intensity before removing the transducer Clean the remaining gel from the patient's skin To ensure continuity of treatment sessions: Record the treatment parameters Output frequency Intensity Duration Duty cycle Running count of ultrasound treatments given for this condition Immediately initiate any post-treatment stretching Joint mobilization and stretching should be done immediately following ultrasound heating
Therapeutic Ultrasound- What is it?
Inaudible, acoustic vibrations of high frequency that can produce both non-thermal and non-thermal physiologic effects Classified as a deep heating agent with the ability to heat tissues to a greater degree in less time as compared to other superficial heating modalities. ( hot pack, fluidotherapy, paraffin) Ultrasound is used in medicine for diagnosis ( imaging of internal structures), physical therapy ( functional restoration and healing of soft tissue aliments), and tissue destruction ( in surgery and hyperthermia for tumor irradiation)
Ultrasound Parameters
Intensity - W/cm2 Frequency - MHz Duty cycle - % Effective radiating area (ERA) - cm2 Beam nonuniformity ration (BRN) Ultrasound is sound > 20,000 Hz
Standing wave
Intensity maxima and minima at fixed positions one-half wavelength apart. These occur when the ultrasound transducer and a reflecting surface are exact multiples of wavelength apart, allowing the reflected wave to superimpose on the incident wave entering the tissue. This can be avoided by moving the sound head throughout the treatment.
Pulsed Ultrasound
Intermittent delivery of ultrasound during the treatment period. This minimizes its thermal effects
Contraindications for Ultrasound
Malignancy Pregnancy- CNS tissue- cns tissue is usually covered by bone in the spinal cord and brain so it is rarely a problem. If had a laminectomy above l2, the spinal cord may be exposed and should not be applied over this area Joint cement and plastics- although very little ultrasound can reach the depth of prosthetic joints, we should err on the side of caution because these materials are rapidly heated by US Pacemaker- right over pacemaker it may heat it up or interfere with electric circuitry Thrombophlebitis- may dislodge thrombus Eyes and reproductive organs
abbreviation
Millisecond - ms Hertz - Hz Megahertz - MHz
FDA Labeling Requirements
Output frequency Effective Radiating Area (ERA)- the Portion of the transducer that actually produces sound waves Should be only slightly smaller than transducer surface Beam Nonuniformity Ratio (BNR) Defines the maximal point intensity ( spatial peak intensity) on the transducer to the average intensity value ( spatial average intensity) across the transducer surface. Should be as low as possible between 2 and 6- less risk of damage to tissue from areas of concentrated ultrasound energy Date of last service/ calibration should also be posted on the unit
Duty Cycle
Percentage of time that ultrasound is being generated ( pulse duration) over one pulse period Duty cycle may be set to 20% 0r 50% Total amount of energy delivered would be only 20% or 50% of the energy delivered if a continuous ultrasound wave was being used Determine the proportion of thermal and nonthermal effects High duty cycle: Predominantly thermal effects Low duty cycle: Predominantly nonthermal effects Thermal effect used in subacute and chronic conditions Nonthermal effects may be beneficial in acute stages
Answer; 1 to 2 cm
Questin A PTA uses 3MHz ultrasound bean to treat a patient diagnosed with carpel tunel, the majority of ultrasound energy with be absorbed within a depth of?
Answer; 20% non-thermal
Question A patient is treated using pulse wave ultrasound for seven min the specific parameters of the pulse wave are 2ms on time and 8ms off for one pulse period the duty cycle should be recorded on the SOAP note as?
No
Question Can ultrasound waves travel throught the air?
False becasue its 1 sec per hurtz
Question In sound waves the definition of frequency is the number of compression-rarefaction cycles per unit of time, its expressed in cycles of 5 sec per hurtz. T or F
False these are Thermal effects
Question Non thermal effects of ultra sound include modulation of pain exceration of metabolic rate reduction of muscle spasm decressed joint stiffness and increase nerve conduction velosity? True or false
Answer; Frequency
Question What is the primary deteminite in the depth of ultrasound penatration?
False its 1 MHz
Question Three MHz is related to a low pitch and treats deeper tissue up to 5 cm in depth. True or False
Treatment
Reduce the INTENSITY to zero before turning on the POWER. Select the appropriate mode for the output (CONTINUOUS or PULSED) Set the WATT METER to displays the appropriate output for the type of treatment Set the TIMER to the appropriate treatment duration Begin slowly moving the sound head over the medium Press the START button to begin the treatment session Units having low BNR may be moved at a slower rate than those with a higher BNR Slowly increase the INTENSITY Keep the sound head moving Move the head at a moderate pace (4 cm per second or slower) Use firm, yet not strong, overlapping strokes If pain is experienced: Move the sound head at a faster rate Use a lower duty cycle Use a lower intensity If the gel begins to wear away or if the sound head begins sticking on the skin, depress the PAUSE button and apply more gel
Duration of Treatment
Size of the area to be treated What exactly are you trying to accomplish Thermal vs. non-thermal effects Intensity of treatment What is the desired effect? Usually 5-10 minutes If you want to go deep to gastroc muscle need to use the 1 MHz frequency
Clinical Applications
Soft tissue shortening Pain control Dermal ulcers Surgical skin incisions Tendon and ligament injuries Bone fractures Carpal tunnel syndrome Phonophoresis
Dermal ulcers
Studies published so far show pulsed ultrasound may facilitate wound healing. Treatment parameters- are 20% duty cycle, .8 to 1.0w/cm2, 3 MHz frequency for 5 to 10 minutes Can be applied to intact skin around the wound with gel or treated directly by covering with an ultrasound coupling sheet or by placing it and the ultrasound transducer in water.
Effective Radiating Area (ERA)
The area of the transducer from which the ultrasound energy radiates. Because the crystal does not vibrate uniformly, the ERA is always smaller than the area of the treatment head.
Unstable Cavitation
The bubbles formed by the ultrasound grow over a number of cycles and then suddenly implode. The implosion produces large, brief local pressure and temperature increases and caused free radical formation.
Stable caviation
The bubbles formed by the ultrasound oscillate in size throughtount many cycles but do not burst. This has been proposed as a mechanism for the nonthermal therapeutic effects of ultrasound.
Attenuation
The decrease in ultrasound intensity as ultrasound travels through tissue
Cavitation-
The formation, growth, and pulsation of gas-filled bubbles caused by ultrasound. It may be stable or unstable. Stable cavitation the bubbles do not burst but in unstable cavitation the bubbles burst which produce large local pressure and temperature increases and cause free radical formation. In non thermal ultrasound we have stable cavitation.
Internsity
The power per unit area of the sound head, expressed in watts per centimeter squared (W/cm2). The World Health Organization limits the average intensity output by the therapeutic ultrasound units to 3 W/cm2
Piezoelectric
The property of being able to generate electricity in response to an electric current (as in an ultrasound transducer)
Beam Non-Uniformity (BNR)
The ratio of the spatial peak intensity to the spatial average intensity. (the spatial peak is the peak output coming out of the sound head)
Reflection
The redirection of a wave at an interface. When refraction occurs, the ultrasound wave enters the tissue at one angle and continues throught the tissue at a different angle.
Sound
The vibration of a medium
Thermal versus Non-thermal Effects
Thermal effects Tissue heating: affected by absorption coefficient/tissue type ; intensity; frequancy (Duty cycle of more than 50% because it is starting to be a more constanct heat to the area) Non-Thermal effects (effects of the result of the mechanicat events produced by ultrasound) Tissue repair at the cellular level/promotes cell funtion cavitation, microstreaming, acoustic streaming Thermal effects occur whenever the spatial average intensity is > 0.2 W/cm2 Whenever there is a thermal effect there will always be a non-thermal effect
Treatment Area
US has a limited area and 1 ½ to 4 times the size of the irradiating crystal or the ERA should be used Treatment for larger area should be divided into smaller zones
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 3 methods 1) direct coupling 2) immersion method 3) Bladder method
Tendon and ligament injuries
Ultrasound can help in the healing of tendons and ligaments after surgical incision and repair and help with tendonitis It is recommended that ultrasound be applied in a pulsed mode at low intensity (.5 to 1.0 w/cm2) during the acute phase of tendon inflammation to reduce aggravating the condition and accelerate healing, and continuous US at high enough intensity to increase tissue temperature be applied in combination with stretching to help with chronic tendonitis.
Soft tissue shortening
Ultrasound can increase soft tissue extensibility by increasing tissue temperature which can increase joint ROM when applied with stretching Treatment parameters most likely to be effective are: 1 or 3 MHZ frequency depending on tissue depth .5 to 1.0 w/cm2 intensity with 3 MHz for 5-10 minutes 1.5 to 2.5 w/cm2 with 1 MHz for 5-10 minutes It is recommended that stretching be applied during heating by ultrasound and maintained for 5-10 minutes after ultrasound while tissue cools
Pain control
Ultrasound may control pain by altering its transmission or perception or by modifying the underlying condition causing the pain. Possible reasons why: Stimulation of cutaneous thermal receptors Increased soft tissue extensibility by increased tissue temperature (continuous) Changes in nerve conduction caused by increased tissue temperature Modulation of inflammation caused by nonthermal effects Treatment parameters effective to help reduce pain are 1 to 3 MHz frequency, continuous, .5 to 3.0 W/cm2 for 3 to 10 minutes
Phonophoresis
Use only approved ultrasound transmission media. The direct coupling method is recommended Efficacy of phonophoresis using the bladder method has not been established Ensure that the skin is well moistened; avoid areas of dry skin Position the extremity to encourage circulation. Use a continuous output to maximize the effect of phonophoresis Unless the thermal effects of ultrasound are contraindicated After treatment, cover the remaining medication with an occlusive dressing. Types of drugs used Corticosteroids- hydrocortisone Lidocaine-pain relief Salicylates- reduce inflammation and pain
Carpal Tunnel Syndrome
Use pulse ultrasound not continuous. Continuous may impact the nerve conduction velocity by overheating. Proposed mechanism for benefit of ultrasound for patients with carpal tunnel syndrome include anti-inflammatory and tissue stimulating effects. 2010 systematic review of ultrasound for carpal tunnel syndrome showed moderate evidence that it is more effective than placebo after 7 weeks of treatment and at 6 months follow up, but no evidence of benefit if only done for 2 weeks
Answer; Foam
What has the highest acoustic absortption and is a good absorber of ultrasound?
1 MHz
What vibrates molicules more slowly, thus extenting energy more slowly and has a greater capasity to travel distance?
When not to use Thermal Ultrasound
When there are contraindications of superficial thermotherapy EX: when somone has acute inflammation (72 hour window) if they show outward signs or symptoms of inflammation we cannot heat their tissue up. It will make them maintain the inflammartory stage longer and they will not progress.
Microstreaming-
occurs around the gas bubbles set into oscillation by cavitation. Microscale eddying that occurs near small, vibrating objects.
Answer; Dropping and holding it in the air?
question What two things can damage a ultrasound head?
Acoustic streaming-
steady circular flow of cellular fluid induced by ultrasound- the flow is larger than with microstreaming and alters cellular activity by transporting material.
