PAMS II (Exam 4) Flashcards
Ultrasound
Method: conversion
- An acoustic (sound wave) energy greater than 20 kHz
used to create thermal or mechanical effects to underlying
tissue from 1-5 cm deep- normal audible frequency 50 Hz-20 kHz
- ultrasound > 20 kHz
- clinical use 1 MHz - 3 MHz
- Equipment must be used with a coupling agent (gel) to
seal the surface of delivery and protect deep-lying tissue
from burning
Indications:
- pain reduction
- increased rate of recovery
- speed up healing process
Piezoelectric Properties (Ultrasound)
- Properties of certain crystals develops a voltage when
compressed/distorted
- squeeze certain crystals (such as quartz) and you can
make electricity flow through them = piezoelectricity
(also called the piezoelectric effect) is the appearance
of an electrical potential (a voltage) across the sides of
a crystal when you subject it to mechanical stress
(squeeze it) - Reverse Piezoelectric Effect
- when voltage applied crystal distorts
- used to produce therapeutic ultrasound - There are crystals in the device that create the sound wave (the applied voltage causes vibration into the sound waves)
Ultrasound Frequencies Used
2 Primary frequencies used:
- 1 MHz - used to target deeper tissues (5-6 cm)
- 3 MHz - used for more superficial structures (1-2 cm)
Intensity (W/cm2): usually less than 2.0 W/cm2
* the greater intensity, the higher tissue temp
* hot spots - build-up of heat (keep sound head moving)
* greater 3 W/cm2 is potentially damaging to tissues
b/c it causes cavitation (gas bubbles and pockets)
2 Cycles used to produce diff effects depending upon
desired outcome: continuous or pulsed
1 - deep
3 - shallow, superficial
LE (lateral epicondyle use 3 MHz not 1)
Intensity - 1.5 W/cm2 for pain reduction or decrease swell
2.0 W/cm2 on fibrotic scar tissue
Don’t use sound head too big for hand, use smaller one and keep it moving, the bigger the unit is you have to move faster
Greater than 3 W/cm2 will burn
Pulsed Ultrasound for Mechanical Effect
Pulsed Ultrasound (20%, 10% or 50% refers to on-time
during US cycle)
* non-thermal or mechanical ultrasound
* facilitates wound healing process through destabilization
of cellular membrane through ion diffusion and
subsequent increase in phagocytic activity and
eventually enhanced protein synthesis
* can be used to decrease inflammation in both acute and
chronic inflammatory conditions with low intensity
* increased membrane permeability
- ionic streaming
- mechanical disruption
* increased plasticity of scar and connective tissue
- disrupts collagen bonds
- stimulates fibroblasts
- alters pattern of collagen formation
* accelerated healing: skin, wounds, ulcers
* increased protein synthesis
* mast cell degranulation
* histamine release
Low intensity - changes cell membrane
lymphatic stimulation
swelling, tissue healing, and wound healing
help prevent laying down of bone
tendon rupture use pulse early - progress to
thermal effect continuous
Thermotherapy: Continuous Ultrasound
Continuous ultrasound: used for thermal (heating) effect
* used for 5-8 or more minutes
* can be used for healing scar tissue (fibrotic)
* heating joint capsules, ligaments, and tendons to
loosen adhesions
* increased ROM, decreased muscle spasms, decreased
edema if it is a vascular issue
* increased tissue length and facilitate function
* therapeutic interventions should be initiated during or
immediately following application of thermal US
Physiological Effects of Ultrasound/Thermal
- Heat
- Increased metabolism
- Increased circulation
- Softening of collagen
- Pain modulation
- Increased nerve conduction velocity
- Thick fibrotic scar will soften
- Sub-acute
Contraindications of Ultrasound
- Vascular thrombosis
- Malignant tumor
- Pregnancy-lumbar or abdomen
- Plastic joint or cement
- Metal implant
- Spinal cord
- Eyes
- Cardiac pacemaker
- Central nervous system stimulator - like an indwelling
TENS - Nn sensitive to vibration - continuous can make nerve
mad and will last for several days - Must know if anyone near you has a pacemaker b/c
that can interfere
Precautions for Ultrasound
- Altered thermal sensibility
- Area of acute inflammation
- Fracture (non-healed_
- Growth plate
- Breast implants - rupture
- If really swollen may not have sensory perception to
give you feedback so don’t use continuous, but use
pulsed
Clinical Application of Ultrasound
- Determine purpose for US
- If thermal, check for sensibility
- Select appropriate equipment
- Apply coupling agent-Gel or lotion (can be performed
under distilled water) - Apply sound head and start timer
- Move slowly over area 1-3 diameter of sound head
per second - Raise intensity to desired level
Ex: really stiff and can not get PIP to move
deep US (1) into a shallow area is bad, use (3)
How intense how deep what size sound head conti or pulse start
Cavitation
The formation of vapor cavities in a liquid, small liquid-free zones, that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities in the liquid where the pressure is relatively low.
- This can create hot spots
- Water straight from a faucet can have air bubbles in it
and could lead to burns
What is the Desired Effect?
Thermal - continuous (100%) requires normal sensibility
Non-thermal - pulsed (usually 20%) heal and reduce
swelling and low intensity
Healing - low intensity (.3-.5 W/cm2) pulsed at 10-20%
Target Tissues
Ultrasound energy is absorbed mostly in tissues with high collagen content: bone periosteum cartilage ligaments capsules tendon fascia scar tissue tissue interface (i.e. bursa and synovium)
- Bone reflects
- Fat impedes - so have to increase intensity
- If you have a long way to go, need to crank up volume to
get to target site (>1.0) - If target area is 1cm - shallow, should never go over 1.0
you will burn and keep it below .9 otherwise it will cause
an inflammatory response - 3.3 gets hotter faster b/c it does not go as deep, shallow
- Hand therapy using 3.3 b/c superficial so don’t do 1.5 but
do continuous or below .9 - Mechanical effects use 3.3 MHz use at 1.5
Target Areas
- How deep is the area I want to treat?
- Shallow structure use - 3 MHz sound head
0. 8 - 1.6cm deep - Deeper structures use - 1 MHz sound head
2. 3 - 5cm deep
Treatment Time
- Size of Area
- treatment time
- 3-5 mins per 1-3 times the ERA of sound head
ERA - effective radiating area
1cm sound head can treat 2-3cm in 5 mins
5cm sound head can treat 5 to 15cm (4-5 inches) in 3-5min
General Rule: Treatment area should not be any larger than 2 times the sound head
If choosing the right size sound head 5 mins should be
sufficient
- 3cm sound head can treat an area 3-9
Thermotherapy
- Phonophoresis (continuous US only)
- coupling agent is a topically applied drug
- ultrasound is used to drive topical agent to targeted
tissue transdermally - MUST have a prescription from the physician
- hydrocortisone
- dexamethozone mixed in ultrasound gel
- lidocaine mixed in ultrasound gel
