US Flashcards
what is acoustic impedence
a material’s ability to transmit sound related to density
what happens when sound waves are absorbed?
sound is transmitted to thermal energy
what happens when sound is refracted?
the wave is bent in a different direction
what happens when sound is reflected?
they interact with other waves to enhance or diminish intensity
in order of high attenuation to least, where do you put bone, muscle, tendons, and skin?
bone > tendon > skin > muscle
what frequencies are most often on US machines?
1 and 3 MHz
what does wave frequency determine?
treatment depth
how do you determine intensity of US?
no consensus on intensity, you want the pt to feel the heat
what is the main difference between continuous and pulsed US?
pulsed is nonthermal
what is the BNR?
the crystal is imperfect and can thus create areas of high intensity
what is the clinical relevance of BNR?
can cause hotspots
treatment area should be how many times the size of the ERA?
2x
how much does a tissue have to heat up to cause extensibility?
inc 7degF or 4degC
which frequency of US targets deeper tissue?
1Hz up to 6cm
3Hz up to 2.5cm
which frequency heats up tissue faster?
3Hz
describe tissue cooling after tx
tissue, regardless of type, takes 5 minutes to cool
why do applicator heads need to be kept 90 deg?
reduces reflection
what has high transmission rate for US?
water and US gel
what has okay/bad transmission rate for US?
creams and ointments
what has poor transmission rate for US?
air
is there evidence for US for trigger point pain?
yes, but adding it to manual shows no additional benefit
is there evidence for US for cervical pain?
no
is there evidence for US for subacromial shoulder pain?
evidence against use
is there evidence for US for frozen shoulder?
no
there is evidence for US for inflammation in which two locations? (4)
tennis elbow, acute carpal tunnel, calcific tendinitis, and arthritis
is there evidence for US for tissue healing?
no
is there evidence for US for tissue extensibility?
no
what are the 13 contraindications for US?
- eyes
- impaired congnition
- impared sensation
- pacemaker
- cancer
- TB
- hemorrhage
- impaired circulation
- anterior neck
- skin disease
- area of radiation
- bone growth at epiphysis
- pregnancy
what are the 2 precautions for US?
- plastic or cemented implants
2. SC or superficial regenerating nerves
when would you use low intensity pulse US?
bone healing, not good evidence
