Passive Care - Exam 2

Ultrasound uses _____ at high frequencies (acoustical energy)

sound waves

Sound waves in an US are generated by

vibration of the crystal (quartz, lead zirconate, lead titanate, barium titanate)

What is the audible range that humans can hear

15-20,000Hz

The frequencies of US and their uses

1 MHz = deep

3.3 MHz = superficial

What are the two duty cycles used in US

continuous (100%) - tissue heating

pulsed (50% or 20%) - mechanical/non-thermal effects

Piezoelectric effect

mechanical deformation of a crystal causes an electrical current to form

Reverse Piezoelectric effect (indirect)

alternating current is passed through a crystal

results in very fast contraction and expansion of crystal

vibration produces high frequency sound waves

US uses what type of piezoelectric effect

Reverse Piezoelectric effect (indirect)

Ultrasound beam characteristics

near field = treatment area/ Fresnel zone

far field = Franhofer zone

Spatial peak intensity (Isp)

peak/maximum intensity

Watts per cm²

Spatial average intensity (Isa)

average intensity

Isp x duty cycle

Quality of US machines

ERA = effective radiating area

BNR = bean nonuniformity ratio

Effective radiating area (ERA)

area of sound head that produces sound energy

always smaller than the size of US head

Beam nonuniformity ratio (BNR)

US beams are not uniform across the head

BNR = amount of variability of the beam

ratio btw peak intensity of beam / average intensity of beam

Ideal BNR is 1, but within the range of 2:1-8:1 is acceptable, however, the _____ the BNR the more uniform the intensity of the sound wave

lower

Why is a lower BNR better

eliminated hot spots

allows for higher dosage without discomfort

allows for greatest comfort and safety

____ is a poor conductor of ultrasound

air

Conducting media for US

coupling medium (gel) = prevents reflection of sound waves by air

keep sound head flat against skin

Underwater US

indirect ultrasound

plastic bucket

0.5-3.0 cm

wipe bubbles from skin and sound head occasionally during tx

More watts means more heating NOT

greater penetration

Absorption in tissue (US) - protein and higher density

higher absorption

Bone, tendon, cartilage, ligaments, and joint capsules absorb the _____ US waves

MOST

Skin and fat absorb the _____ US waves

LEAST

Scattering of US

when US wave encounters a boundary btw tissues, energy will scatter by reflection or refraction

Reflection

reversal of the direction of propagation of the US wave

• low reflection in muscle, fat, water

• high reflection in soft tissue-bone interface (inc. heating/dose)

Refraction

change of US wave from a straight path when passing obliquely from one medium to another

• bending of US energy within tissue can lead to concentrations of US at point of refraction (where tendon joins bone!!)

Tissue heating via US benefits

increase in metabolic activity → increases oxygen demand → increase blood flow

1 deg C increase in temperature via US is associated with

an increase in metabolic activity

2-3 deg C increase in temperature via US is associated with

reduction in muscle spasm

increase blood flow

reduction of chronic inflammation

4 deg C increase in temperature via US alters

viscoelastic properties of collagen (stretchiness)

____ treatment times are needed when lower intensities are used

longer

Therapeutic effects of US

increase extensibility of collagen fibers of tendons and joint capsules

increase blood flow

increase cell metabolism

increase collagen synthesis

decrease joint stiffness

decrease muscle spasm

enhanced tendon, ligament, muscle healing

Thermal effect of US is only temporary, so any tissue manipulation or stretching should be performed

immediately after US treatment

Pulsed US effects (acoustical streaming/nano motions + stable cavitation)

stimulation of fibroblast activity

increase blood flow

increase protein associated w/injury repair

Acoustical streaming (nano motions)

movement of fluids along cell membranes due to mechanical pressure exerted by sound waves

• movement in direction of sound waves

  • facilitates fluid movement + increases cell membrane permeability

Cavitation

Stable - rhythmic expansion and contraction of bubbles during repeated pressure changes

• facilitates fluid movement and membrane transport

Unstable - collapse of gas bubbles which may cause tissue damage

• associated w/low frequency high intensity US

Contraindications to US

malignancy, hemorrhage, ischemia, thrombus, infection

gonads, eye, pregnant women’s abdomen

spinal cord after laminectomy

plastic, cemented, electronic implants

unknown etiology

Risks of US

bony prominences

epiphyseal plate

Treatment time of US

generally 5-8 minutes

can be as little as 1-2 minutes

NEVER more than 15 minutes

Phonophoresis/Sonophoresis

uses sound energy to drive medication into tissue

medication does not need to have a charge

US combo

used for - trigger points, epicondylitis, superficial pain areas, decrease adhesions

US head = treating electrode

Low intensity pulsed US (LIPUS)

stimulation of fracture healing

home units (self-adhesive applicators)

Diathermy

high frequency electromagnetic energy

• generate heat in body tissues

shortwave and microwave generators

FCC regulated

What is the MC type of unit in diathermy

shortwave (27.12 MHz, 11 meter)

Microwave diathermy

2450 MHz

not as safe as shortwave

Thermal effects of diathermy

dipole rotation (water molecules rotate)

ionic oscillation (ions (Na, K, Cl) in solution oscillate)

kinetic energy of rotation produces thermal energy

Types of electrodes in diathermy

capacitor electrodes produce electrical field

induction electrodes produce magnetic field

Capacitive/Capacitance technique (plates, pads)

tissues are placed in an electric field

greatest absorption in tissues w/low electrolyte and water content (adipose)

knee, foot, hand, shoulder (low subquanteous fat areas)

thin patients

Inductive/Inductance technique (drum, cables, garment)

tissues are placed in an oscillating magnetic field

great absorption in high electrolyte, high dipole (water) tissue (muscle, tendon, joint)

patients with more subcutaneous fat/ obese patients

Arndt-Schultz law (dose vs response)

low dose (<500Hz) = stimulates

hIgh dose (>500Hz) = Inhibits

Grotthuss-Draper Law (absorption vs therapeutic effect)

distortion occurs the deeper the tissue (has to be absorbed to have an effect)

Inverse Square Law (dose vs divergence)

the further away the diathermy lamp is to the pt, the lower the dose (vice versa)

intensity vs distance

Cosine Law/ Lambert’s Cosine Law (angle of application)

reduced energy if angle is increased

(cosine of angle will tell how much get into tissue)

Interactions diathermy can have within tissues

transmission, refraction (tissue interface), absorption (effect tissue), reflection, scattering

Pulsed shortwave diathermy

common

heat vs no heat

• heat = pain relief, wound management, joint contracture

Indications of shortwave diathermy

osteoarthritis

neck/back pain

ankle pain

dermal wounds

MSK pain

Contraindications of shortwave diathermy

loss of sensation

electronic or metal implants

jewelry, copper IUDs

over cancerous areas, hemorrhagic areas, ischemic areas

pregnant pts

testes, eyes, open growth plates in children

Risks for diathermy

operator should not be exposed for long periods

other pts near device (10ft distance)

other EPA devices (10ft distance)

mentally confused pts

Application of diathermy

test cold/warm sensation first

2-3cm layer of towels for spacing

advise pt to remain still

Visible light wavelengths

400-700nm

Principles of laser generation

adding energy to electrons causes them to move to a higher energy orbit (atom is in excited state)

if electron gives up energy it moves to a lower energy orbit (atom is in ground state)

Giving up energy (excited atoms release photon of light) and return to ground state is called

spontaneous emission

Production of a laser

1) pumping of active medium

2) population inversion

3) spontaneous emission

4) stimulated emission

5) amplification

Pumping of active medium

application of an external source of power to the lasing medium

causes population inversion

Population inversion

number of excited atoms outweighs the number at ground state

Stimulated emission

photon interacts with another excited atom releasing another photon

• these have identical frequency, direction, phase

both photons continue to cause release as long as excited atoms are present

Amplification

photons travel back and forth in resonance chamber

reflect btw the reflective/semi-reflective mirrors at the ends of chamber

amplifies stimulated emissions triggering more and more identical photons

resonance chamber reaches max capacity to store photons

beam of laser light is emitted when amplification process is max

Photons escape the chamber of the laser through the

semi-reflective mirror

Coherence

same wavelength and all in phase

light is emitted in an organized fashion

Monochromatic

single color (same wavelength)

Collimation

photons move in parallel fashion and do NOT diverge

Wavelength - Longer (lower frequency) =

deeper penetration

Types of lasers

gas, solid, liquid, semiconductor (two layers of material in silicon matrix)

The layer interface in a semiconductor is

reflective

Laser is absorbed by

water, hemoglobin, melanin

As the concentration of melanin or hemoglobin increases, the depth of penetration of the light

decreases

The _______ of the light will determine the overall depth of penetration the photons will attain

wavelength

Types of lasers

Helium-Neon (HeNe) - semiconductor, short wavelength (superficial penetration)

Indium-Gallium-Aluminum-Phosphide (InGaAIP) - semiconductor

Gallium-Aluminum-Arsenide (GaAIAs) - semiconductor

Gallium-Arsenide (GaAs) - semiconductor, long wavelength (deeper penetration)

Gridding technique of laser application

cover each square cm of the treatment area

Scanning technique (non-contact) of laser application

hold laser 5-10mm from skin

energy level decreases w/distance (have to alter intensity)

Scanning technique (contact) of laser application

move laser emitter while in contact (like US)

Photobiomodulation (photochemical effects)

effect is from absorption of photons of light by cells

• pain management, tendinopathy management, wound management

Photobiostimulation

lower doses of laser

Photoinhibition

higher doses of laser

Chromophores

molecules which accept energy from photons

Cytochromes (respiratory chain enzymes)

in mitochondria

sensitive to light photons

absorption of photons trigger biochemical reactions

1*, 2*, and 3* effects of photobiostimulation

1* - due to direct interaction of photons w/cytochromes

2* - in same cell in which photons produced primary effects (cell proliferation, protein synthesis)

3* - indirect responses of distant cells to changes in other cells that have interacted directly w/photons (least predictable)

Primary, secondary, and tertiary events of photostimulation summate to produce

phototherapeutic activity

Indications of low level laser therapy

AID HEALING

inflammatory phase = decrease pain and inflammation

proliferation phase = enhance angiogenesis, formation of granular tissue, collagen synthesis

FDA classifications of low level lasers

Class 1 - exempt invisible lasers

Class 1M - wavelengths btw 302.5nm-4000nm

Class 2 - low power visible lasers

Class 3 - mod risk to retina (operator and pt must wear PPE for eyes)

Class 4 - high power cause damage to eyes, skin burns, fire hazard

Protective eyewear is recommended when using which lasers

ALL

Contraindications to low level lasers

cancer, over areas of active hemorrhage, over thyroid

pregnancy

direct exposure to eyes, open wounds

epileptic pts

Precautions for lasers

infection, testicles

sympathetic ganglia, vagus N, cardiac region (heart disease pt)

open growth plates, bruises, photosensitive skin

Laser dose (Joules²) depends on

output of laser in mWatts

number of diodes

time of exposure in seconds

beam surface of laser in cm²

Super pulsed laser

the frequency pulses (not wavelength)

pulses/bursts of energy w/higher peak power and less thermal effects

• more directed energy delivered to target tissue

• greater safety and enhanced clinical outcomes

Frequency is defined as the number of

impulses per second

Lower frequencies/Bio-stimulatory (smaller energy dose) benefits

repair and regeneration of tissue

immune response

anti-inflammatory effects

Acute injuries (first 48hrs)

stimulate healing (low dose) vs inhibit pain (high dose)

smaller and more frequent doses are better

tx time 3 min

Chronic injuries

stimulate healing (low dose) ONLY

larger doses are better

tx time 5-10 min

Ultraviolet therapy

treatment of dermatoses