Diathermy Flashcards
what is electromagnetic radiation
radiation composed of (you’ll never guess it) electric and magnetic fields that vary over time and are oriented perpendicular to one another
what are the physical agents that use electromagnetic radiation (EMR)
infrared light
ultraviolet lights
cold laser
diathermy
explain wavelength and tissue penetration
longer waves = deeper penetration
how are frequency and wavelength related
inversely
greater frequency = shorter wavelengths
wavelength definition
length of wave from peak to peak
inverse square law
intensity at the target is equal to the inverse of the distance from the source
ie = longer distance means less energy delivered
cosine law
angle of incidence of the beam with the tissue
- perpendicular = most energy delivered, less if not
what is the effect of EMR mostly determined by
frequency and wavelength
arnold schultz law
a minimal amount of stimulus is needed to initiate biological processes
as the stimulus grows, there will be a point in which it no longer is beneficial and will become detrimental
physiological effects of EMR
thermal/nonthermal mechanisms
thermal effects are seen via EMR on superficial / deep tissue by which modalities
superficial tissue = Infrared radiation
deep tissue = continuous shortwave and microwave diathermy
non thermal effects of EMR are seen in superficial/deep tissue via which modalities
superficial = UV radiation
deeper = pulsed shortwave diathermy
explain dipole rotation
ions with a positive and negative charge will spin when placed between positive and negatively charged plates
–> will cause for more energy to be produced
– ionic will only go from positive to negative and vice versa
physiological thermal effects of diathermy
vasodilation
increased:
nerve conduction velocity
pain tolerance
tissue extensibility
metabolic activity
decreased:
muscle spindle activity
muscle spasms
muscle strenght
nonthermal effects of diathermy
alter membrane permeability/function
attraction of fibroblasts, macrophages, lymphocytes, collagen
–> promote healing process
repolarization of damaged cells
how does diathermy work
waves of radiofrequent radiation absorbed by the body are converted to heat
shortwave diathermy specifics
27 MHz (3-200m wavelength)
continuously or pulsed
microwave diathermy specifics
2450 MHz (1mm to 1 m wavelength)
continuous short wave diathermy effects
thermal effect
≥ 80-120 Watts
pulsed shortwave diathermy effects
vasodilation (≥ 38 Watts)
pulsed shortwave diathermy for vasodilation in relation to
pulse duration
frequency
peak pulse power
duration = 0.25 ms
frequency = 250 pps
power = 750 watts
pulse period related to pulsed shortwave diathermy
4 miliseconds
what are the two main subtypes of shortwave diathermy
capacitive
inductive (via magnetic)
what are the types of capacitive shortwave diathermy treatments
series - contraplanar
parallel - coplanar
formula for heat
(I²) x Resistance x Time
what type of resistors are in series for capacitive diathermy
contraplanar
what type of resistors are in parallel for capacitive diathermy
co-planar
in a series circuit, how is total resistance calculated
resistance of current flow is equal to the added total of all components together
in a parallel circuit, the current flow is _______ to the resistance of the pathway
inversely proportional
how is the total voltage calculated in a parallel circuit
sum of voltages at each resistance component
explain tissues most heated in contraplanar vs co-planar capacitive diathermy
contra = tissue with greatest resistance (fat/skin)
co = tissue with least resistance
(cutaneous skin)
how many plates are in capacitive diathermy
2
explain how capacitive plates work
high frequency alternating electric current flows from one plate to another through body tissue
how is heat generated in the body via capacitive plates
current flow through tissue will cause charged particles to oscillate and generate heat
what is the down-side of capacitive plates?
fat and skin heat the most rather than muscle
explain how distance between capacitive series in parallel can affect tissue heating
closer that the capacitive heads are, the more superficial the heating
further = deeper heating
how does magnetic field change affect electrical fields
one changes, the other changes as well
explain tissue penetration of inductive diathermy
tissue of least resistance
2-3 cm penetration if fat at treatment site is <2cm
types of electrodes used in inductive diathermy
cable or inductive coil
mono or dipole drums
explain the process of inductive diathermy
alternating current flowing through coil
produces perpendicular magnetic field that induces electrical eddy currents in the tissue
when particles oscillate in the body, what occurs
increased friction and heating
what determines the amount of heat generated in inductive therapy
intensity of magnetic field via distance of applicator from body
strength of eddy currents via body tissue type
explain heating depth of inductive vs capacitive plates
inductive = deeper
physiological effects of diathermy
vasodilation
improve wound healing
increase collagen elasticity
decrease pain
time period associated with thermal effects of diathermy
20 min
indications for diathermy
non-acute MSK injury
OA
non-acute RA
improvement of blood flow
soft tissue healing
increased metabolism
decreased
muscle spasm/guarding
joint stiffness/contractures
trigger points/neuralgia pain
advantages of diathermy
heats deeper tissues than other superficial heating agents
cover a larger area than US
Shortwave does not reflect from bone
do not have to maintain direct contact with patient for treatment
diathermy application steps
clean area
apply toweling to treatment area
align plates close to skin w/o touching
turn heat intensity to proper level
duration of 15-20 for lasting effect of 20-30 min
contraindications for diathermy
epiphysis of growing bones
metal in area
implanted neural stimulators
pacemakers
sensory disturbances at area
infection / malignancy or neoplasia / fever / active bleeding
therapist or patient pregnancy
precautions of diathermy
external electronic devices
epileptic seizures
sensory disturbances
obesity
documentation of diathermy
area treated
type of diathermy
position
intensity
duration
pre and post assessment
