L13: Laser Therapy Flashcards
What is the safety precaution with Laser?
Possible damage to the eyes
What does LASER stand for?
Light
Amplification by the
Stimulated
Emission of
Radiation
A laser generates a beam of ______ waves within the _____, ____ or ____range of the electromagnetic spectrum (wavelengths 100nm‐1mm)
electromagnetic; infrared (IR), visible or UV
What are 3 main characteristics of how laser radiation differs from ordinary lights?
- Monochromaticity
- Coherence
- Collimation
What are 2 characteristics of monochromaticity in laser radiation?
- Single specific frequency
- Defined wavelength eg ruby lasers give a red light at 694.3nm
What are 2 characteristics of coherence in laser radiation?
- Temporal – in phases, peaks and troughs all at same time
- Spatial – all travelling in same direction
What are 3 characteristics of collimation in laser radiation ?
- Remain in a parallel beam (Can focus it very well)
- Does not diverge from point source
- Can be used for measurement over long distances
What are the 3 types of light?
- White light
- Laser light
- LED light
What are 2 characteristics of white light?
- Multiple wavelengths
- Non coherent
What are 2 characteristics of laser light?
- Single wavelength
- Coherent
What are 2 characteristics of LED light?
- Monochromatic
- Non‐coherent
What are 3 properties of laser?
- Reflection (Eg. don’t want to shine in the mirror)
- Refraction ‐ Focussed or Scattered
- Absorption
- Penetration Depth of red light = 1‐2 mm
- Penetration Depth of infrared = 2‐4 mm
Does laser get absorbed deeply or more superficial?
Not very deeply absorbed
There are ____ and ____ effects in medicine (Class ____ lasers)
Photothermal; photoablative; 4
What lasers are used for physiotherapy?
non‐thermal –> low level laser therapy (LLLT)
Physiotherapists use Class 2, 3A or 3B lasers
What 3 classes of laser that physiotherapists use?
Class 2, 3A or 3B lasers
What is the advantage of using LLLT (Low level laser therapy)?
Fairly small devices that is able to be moved around
What are the 4 types of laser?
Laser production is most commonly mains supply “_____” the lasing medium
pumps
What are 2 lasing medium?
- Gas
- Semi‐conductor (diode lasers)
For lasing mediums, these media when “pumped” by the power source emit a ____ of _____ due to a stimulated quantum jump from higher to lower energy state of the electrons
large number; identical photons
What are 5 characteristics of resonating cavity?
- Cavity of chamber containing lasing medium
- Pair of parallel reflecting mirrors
- Photons of light reflected back and forth
- One of the mirrors is not “pure”
- Allows some of the light to emit out
What do laser probes look like?
What is energy density?
Amount of energy falling on a surface measured in J/cm‐2
What is rate at which energy is produced by laser measured in?
joules/cm‐2 per second ie Watts
1 Watt = 1 J/cm2
What is power density?
the amount of energy they produce per second per unit area
How are lasers classified?
Power density- the amount of energy they produce per second per unit area
Therapeutic lasers used by physios usually in ____
mW
What are the 2 types of pulsed laser?
temporal peak power or temporal average power
How long should you use a therapeutic laser for?
20-30 secs for each point (similar to ERAs in ultrasound)
What are the 4 classification of laser?
What is the power in a class 1 laser?
Low
What is the power in a class 2 laser?
Low up to 1mW
What is the power in a class 13Alaser?
Low-medium up to 5mW
What is the power in a class 3B laser?
Medium up to 500mW
What is the power in a class 4 & 5 laser?
High over 500 mW
What are the effects in a class 1 laser?
None on eyes or skin
What are the effects in a class 2 laser?
Safe on skin. Eyes protected by aversion response
What are the effects in a class 3A laser?
Viewing with optical aids may be hazardous
What are the effects in a class 3B laser?
Viewing may be hazardous
What are the effects in a class 4&5 laser?
Hazardous to skin and eyes
What is the usage of a class 1 laser?
- Laser pointer
- Barcode reader
What is the usage of a class 2 laser?
Therapeutic lasers
What is the usage of a class 3A laser?
- Laser pointer
- Therapeutic lasers
What is the usage of a class 3B laser?
- Laser pointer
- Therapeutic lasers
What is the usage of a class 4 &5 laser?
Destructive-surgical
What are the 3 characteristics of absorption into tissue for laser radiation?
- Passes easily through air so no coupling medium required
- Readily absorbed by biological tissues, particularly haemoglobin, melanin and water molecules
- Penetration depth small
- 3‐4mm for GaAlAs
- 1‐2mm He‐Ne
Laser radiation passes easily through _____ so ___ (a/no) coupling medium required
air; no
Laser radiation is readily absorbed by ______, particularly haemoglobin, melanin and water molecules
biological tissues
The penetration of laser radiation is _____ superficial/deep.
superficial
What are the 2 biological physiological effects of laser (while being poorly understood)?
- Bio‐stimulation‐ soft tissue healing (Try to enhance healing)
- Bio‐inhibition‐ pain relief (Inhibition of nerves) eg. gate mechanisms
What are 4 bio-effects of laser?
- Photochemical effects
- Potential to effect cytochromes in mitochondria
- short term activation of electron transport chain
- increased ATP synthesis
- reduction in cellular pH
- leads to accelerated healing process
- Vasodilation
- Nerve conduction and regeneration
- Pain control
What are 5 photochemical effects of laser?
- Potential to effect cytochromes in mitochondria
- short term activation of electron transport chain
- increased ATP synthesis
- reduction in cellular pH
- leads to accelerated healing process
What are 12 other theories for the effects of laser?
- Altered cell motility
- Activation of phagocytes
- Stimulation of immune responses
- Increased cellular metabolism
- Stimulation of macrophages
- Stimulation of mast cell degranulation
- Activation & proliferation of fibroblasts
- Alteration of cell membrane potentials
- Stimulation of angiogenesis
- Alteration of action potentials
- Altered prostaglandin production
- Altered endogenous opoid production
What are 4 clinical uses of laser?
- Wound healing
- Inflammatory arthropathies
- Soft tissue injury
- Pain relief
What are 9 specific clinical uses of laser radiation?
- Soft tissue injuries
- more successful than placebo
- Tennis elbow, supraspinatus tendinitis
- Joint conditions and chronic pain
- RA, cervical OA, back pain, Neck pain
- Non healing wounds and ulcers Heat –> speeding up recovery
- In mice ‐ surgical wound ‐ greater wound contraction, greater cellularity and better organised fibroblasts
- Limited clinical evidence
- Post‐operative pain
- Acupuncture/acupressure – trigger points
- Carpal tunnel
- Increases nerve conduction velocities
- Improved clinical symptoms
- Oedema following ankle sprain
- Lymphodema post mastectomy
- Parkinson’s Disease
- Early research suggesting slowing neurodegeneration
Application of laser in vet applications for post‐surgical _____ healing and _____.
wound; tendinopathies
Moderate quality evidence in favour of LLLT (laser) for chronic _____ pain
neck
SR LLT in management of neck pain, pain relief in acute and chronic ____ pain
neck
_____ is no better than sham for osteoarthritis of the hand
LLLT
Despite the presence of some contradiction in the short term effects of LLLT, there is no evidence of effect of laser over placebo, in short or long term for _______
lateral epicondylalgia
What are 8 procedures in the principles of application for laser?
- Explanation to patient
- Clean skin
- Protective goggles
- Usually need a key or key code to turn on machine
- Hold laser perpendicular to skin
- In contact preferably
- Apply with even pressure
- Patient and therapist position of comfort
Nb. No sensation testing required
Is sensation testing required in laser?
No
Why is laser used?
Speed up healing
Why must you hold the laser perpendicular to the skin?
Effect will be considerably less if not perpendicular
What are the 3 methods of the application technique of laser?
- Single point or spotting
- Gridding
- Scanning
- For larger areas
- Not really recommended
Are you able to pick up and put down laser?
Yes- unlike ultrasound
What do you do with laser with open wounds?
cover laser with sterile transparent film (Op‐site) and hold just above surface
What are 3 dosage consideration?
- Power output
- mostly fixed can range from 30 to 200mW/cm2
- some have selection/ pulsed eg 50%, 20%, but currently no evidence for use You are able to use on continuous
- Consider area treated
- Power/ area of beam x time
What is power density?
power per unit area
If power output = 10mW
Area of beam = 0.125cm2,
What is power density?
Power density = 10 / 0.125 = 80mW/cm2
How does energy density relate to dosage consideration?
treatment dose
If power output = 10mW
Area of beam = 0.125cm2,
Density = 80mW/cm2
What is the treatment dose?
power density(power/ area) x time
= 80mW/cm2 x 60 secs
= 4800mJ/cm2 or 4.8J/cm2
What is the equation for treatment dose for laser?
power density(power/ area) x time
What is pulsed parameters for laser in acute conditions?
Low pulse frequency, long pulse duration rate
What is pulsed parameters for laser in chronic conditions?
High pulse frequency, short pulse duration More stimulating
What is the recommended dosage for initial treatment ?
~ 4K/cm2
What is the recommended dosage for initial treatment for acute conditions?
>4J/cm
What is the recommended dosage for initial treatment for chronic conditions?
4-50J/cm2
What is the progression of treatment if laser is improving?
maintain dose
What is the progression of treatment if laser is worse?
reduce dose or maintain
What is the progression of treatment if laser is no change?
Increase dose
What are the Walt 2010 guidelines for laser dosage ?
In laser, number of points to treat depends on ______(similar to ERA)
area
What are the 6 dangers of laser?
- Damage to eyes
- Remove reflecting surfaces eg mirrors
- Must switch on only when in contact
- Well lit area for treatment
- Infected wounds ‐ universal precautions
- Photosensitivity
- If they burn easily in the sun –> can be very sensitive with laser
What are 2 contra-indications of laser?
- Pregnancy / in area of uterus
- Direct treatment of eyes
What are 5 precautions of laser?
- Inbuilt pacemaker
- Risk of dissemination
- Exacerbation of existing conditions
- Unable to communicate
- Circulatory insufficiency (May cause vasodilation)
What are 4 warning of laser?
- You should feel nothing apart from applicator on skin
- If you feel any discomfort inform me immediately
- Side effects common such as dizziness, nausea or an initial increase in pain
- Short term effect (particularly in the higher doses)
- Only short term and usually only if the dose is too high
What is the safety feature of class 3B laser?
Pin -1111
Key
What does the default screen for laser look? Where setting per point?
What is essential for laser application?
Eye protection for patient and therapist
How do you deliver the dose for laser application?
Press button to deliver each dose (trigger button)
Laser is more likely used for small joints and small areas. Why?
Beam is so small (no practical)
