Ultrasound/ Ionto Flashcards
What is ultrasound?
is the application of high frequency sound waves beyond human audibility
arguably most effective deep heating tissue modality
Why is ultrasound effective?
provides heat to soft tissues with minimal increase in superficial temperature
How is ultrasound wave produced?
an alternating current passes through the crystal which causes crystal to vibrate which then creates high frequency sound waves
What is this process called?
reverse piezoelectric effect, expanding and compression of crystal produces heat
What does ERA stand for?
effective radiating area, area of US head that actually produces soundwaves, smaller than US head
described in cm2
What is the intensity formula for US?
watts/ERA= x w/cm2
What is size of treatment area in relation to ERA?
2-3 times the size of ERA
What is the beam profile?
describes the idea that multiple waves emerge from the head and the spatial peak intensity is farthest away from head
What is BNR?
beam non-uniformity ratio, measures consistency and quality of the crystal
Is a 6:1 or 4:1 ratio better for BNR?
4:1 as it will produce less high intensity areas and reduce risk of burn
What are two types of modes of application for ultrasound?
continuous and pulsed
What is continuous ultrasound?
outflow is 100%, can produce thermal effects based on intensity and tx duration
How deep can continuous go?
3-6 cm maybe deeper
What is pulsed?
produces non thermal effects
What is duty cycle equation?
pulse length/ (pulse length+ pulse interval) x 100
What are the two output frequencies most commonly used with US?
1 and 3 MHz
Which frequency goes deeper?
1mHz- goes 3-6 cm deep, thermal effects last longer
3 mhZ- 1-2 cm, heats 3 times faster than 1 mhZ
What are biophysical effects of US?
non thermal- changes within tissue resulting from mechanical energy
thermal- changes in tissue direct result of US elevation of tissue
Why would we want non thermal effects?
acute injury, wound healing
times when we don’t need inflammation
What are two ways non thermal can be achieved?
1) using pulsed output, duty cycle at 20–50%
2) continuous output with very low intensity (less than0.3 w/cm2
What are thermal effects of US?
1 degree- increase metabolism
2-3- decrease pain/spasm, increase blood flow, reduces chronic inflammation
4- increase collagen elasticity and extensibility
How does US directly reduce pain?
- increased nerve cell sodium permeability
- alters nerve function
- increases pain thresholds
How does US indirectly reduce pain?
- increase blood flow
- increase capillary permeability
- increase oxygen delivery
- decreased muscle spasm
How does US reduce muscle spasm?
- decreased pain
- altered nerve conduction velocity
- increased temp.
- muscle relaxation
How does US effect tissue elasticity?
by heating collagen rich tissues (tendon, fascia, scar tissue)
How long is stretching window after US?
3 minutes!!
What type of wounds can be helped by US?
skin ulcers- 3 mhZ, low intensity output
surgical wounds- may increase granulation
cover with hydrogel or transparent film
How can US help fracture healing?
mechnaical sound energy strikes bone, microvibration of bone triggers growth (osteogenesis) and osteoblastic activty
What type of fractures can be helped with US?
acute, nonunion, stress
What is phonophoresis?
use of US to assist with diffusion of medicine through the skin
How does phono work?
increases diameter of skin portals to allow the meds to pass through hair follicles, pores and sweat glands
What part of skin must meds diffuse from?
enzymatic barrier of epidermis, stratum corneum
meds stored in subcutaneous tissues for some time before going deeper
What helps medicine uptake?
hydrated skin, high density of skin portals, highly vascularized, thin skin, younger aged pts
What speed should the sound head be moved at?
4 cm/sec, faster movements decrease effectiveness
What is example of direct coupling methods and why is it used?
gels or creams, b/c loss of consistent skin contact can damage the crystal
What is example of indirect coupling agent?
water or gel filled bladder used for small or irregular areas, should be 1/2 -1 inch from skin and still kept moving
increase dosage
What are US indications?
pain control, increase collagen extensibility, tissue and bone healing
US contraindications?
cancer, pregnancy (avoid area of fetus), CNS tissue, joint cement, plastic or metal, pacemaker, thrombophlebitis (blood clot), hemophilia, decreased sensation or circulation
What are possible contraindications?
over spinal cord s/p laminectomy, epiphyseal plates, fx site, breast implants, acute inflammation
What is iontophoresis?
electrical repulsion of ions using direct current used for pain, inflammation and many other disorders
What is theory behind ionto?
charges from meds can drive meds into tissue, meds must have an electrical charge
What is the intensity of ionto machine?
3-5 mA
What is typical treatment time?
10-20 minutes checking every3-5 minutes for skin
What is dosage expressed in?
milliampere-minutes (mA-min)
total dosage delivered= current x treatment time
what is typical ionto drug dose?
40 mA-min
Contraindications of ionto?
same as US plus:
uncontrolled HTN, PVD, hx of seizures, confused pt, obesity
acute inflammation stage
What is charge of anode and cathode?
anode= positive
cathode = negative
remember opposites attract, same charge repulses
What is charge of acetic acid and use?
negative so place meds on cathode
myositis ossificans, calcific deposits
Calcium chloride?
pos.
scar tissue, keloids
copper sulfate?
pos. so place on anode
fungal infections
Dexamethasone?
inflammation, negative
Lidocaine?
pain control, pos.
magnesium sulfate?
ms spasms, ischemia
pos.
zinc oxide?
skin ulcers, wounds
pos.
