LASER

Prof.Dr.Gehan Mosaad

At the end of the lecture the student should be able to

• Define laser and know its physical properties• Discuss the mechanism of LASER production• Identify different classification of LASER• Understand the therapeutic effects of LASER• Know indications and contraindication of

LASER.• Identify the techniques of applications

Therapeutic effects of LASER

Laser has three main effects:I- Effect on tissue healing (wound and bone healing): a- wound healing: 1. Enhance collagen synthesis.2. Increase mitochondrial activity: which leads to increased ATP

production.3. Increase macrophage activity: which leads to increased immunity.4. Increase fibroblast activity: which leads to increased cell

production.5. Enhance protein synthesis (DNA, RNA synthesis)6. Accelerate inflammatory phase of healing by changing the level of

prostaglandin.7. Enhance the metabolism.

Therapeutic effects of LASER(cont.)

a- Bone healing :1. increase the rate of hematoma absorption2. enhance bone remodeling,3. increase blood vessel formation,4. increase calcium deposition 5. as well as increase macrophages, fibroblast,

and condrocyte activity.

Therapeutic effects of LASER(cont.)

II- Analgesic effect :• Laser accelerate the conversion of prostaglandin

into prostacycline i.e. decrease the amount of prostaglandin in the blood which leads to the reduction of pain. (Prostaglandin released after tissue damage decrease the threshold in pain receptors).

• Increase secretion of β-endorphin (which has an analgesic effect)

• Decrease in conduction velocity of sensory nerves.

Therapeutic effects of LASER(cont.)

III- Effect on tissue inflammation:It was reported that laser irradiation leads to:-1. It stimulates mitotic activity, increases metabolism

and influences the immune process in the tissues.2. Accelerate the inflammatory phase of healing

process by altering the level of prostaglandin that influences the process.

3. Enhance protein synthesis through DNA and RNA synthesis.

4. Micro-circulating effect: Laser light produces a reduction in exudates production through the lymphatic and venous system

Therapeutic uses of laser [Indications]

1 -Non infected and infected skin wound and ulcers Such as, open wounds, decubitus ulcer (Bed sores), diabetic ulcer,

lacerations, incisions, burns .2 -Acute and chronic inflammation of musculoskeletal system as

- Osteoarthritis and rheumatoid arthritis - Acute and chronic soft tissues injuries(tendon, ligament, muscle) - Acute and chronic sprain and strain.

3 -Pain management: -Acute and chronic pain of different cases: Spondylosis, arthritis, tennis elbow, epicondylitis, tendinitis, sprain,

supraspinatus tendinitis). - Neurogenic pain such as, carpal tunnel syndrome, trigeminal neuralgia, post-

herpetic neuralgia. 4 -Non-united fracture.

5 -Trigger point and acupuncture point stimulation.

Contraindications

1- Direct irradiation of the eye Laser may damage the retina, Thus, care must be taken when treating the head

area. The patient & therapist should wear protective glasses.

2- Pregnant uterus Laser may have a mobilizing effects on steroids in the human system. 3- Patients who are naturally photosensitive4- Malignancy5- Pacemaker6- Treatment of the thyroid gland and other sensitive organs.7- Hemorrhaging regions8- Within 4 to 6 months after radiotherapy

Calculation of the laser dose The intensity of the laser alters its clinical effects. High-intensity "hot" lasers heat and destroy tissue, while low intensity

“cold” laser is used in rehabilitation. Laser intensity or incident dose can b e expressed in terms of power

density or energy density

Power density is measured in watts per centimeter squared (W/(cm²).

Power density (W/cm2)= mean power (W)

Surface area(cm²)

Energy density is measured in Joules per centimeter squared (J /cm2) Energy density (J/cm2) = mean power (W) X time(min)

Surface area(cm²)

Therapeutic doses of LASER Low-intensity "cold lasers which output laser light with less than

500 mW power has generally at around 50 mW/(cm²) power density and with an energy density of less than 35 J/ (cm²), is recommended for using in rehabilitation.

In general lower-energy density between 0.05 and 1 J / (cm²) have been for the treatment of acute conditions, whereas higher dosage up to 40 J/(cm²) have been recommended the for treatment of chronic conditions.

There is wide variation in the recommendations for the optimal energy for different conditions the usual ranges are from 1 to 10 J/ (cm²) but doses as low as 0.5 J/ (cm²) and up to 32 J/ (cm²) have been suggested.

Higher doses are usually recommended for subcutaneous tissues. The most commonly used range for the dose is from 0.5 : 4 J/(cm²).

TYPES OF LASER

A variety of therapeutic laser devices currently available for clinical applications in the field of physical therapy

1- Helium neon laser was the first laser system to be used in clinical and research applications.

• Helium neon laser give radiation in the red visible region at 632.8 nm.

• The output is highly collimated laser beam about 1 mm to less than 1cm.

• Helium neon laser pose a greater ocular hazard, so the eyes must be protected during application.

• Helium neon laser penetrates 0.5 - 1mm before losing 37% of its intensity

TYPES OF LASER(cont.)

2-Semiconductor diode lasers (Infrared LASER) based upon the gallium arsenide (Ga-As) or gallium aluminum arsenide (Ga-Al-As).

• Due to the small size semiconductor lasers can be applied directly to the tissues in a hand held applicator.

• Infrared radiation will penetrate > 2mm before losing 37% of its intensity.

• Lasers with wavelength is the near infrared such as 904 nm are chosen to treat subcutaneous structures.

• Whereas skin lesions or superficial wounds surfaces are appropriately treated by one of the He Ne lasers which will be absorbed largely in the skin .

Adverse effect of LASER

The primary hazards of laser irradiation are the adverse effects that can occur with irradiation of the eyes.

Exposure o f the eyes can cause retinal damage.

Clinical application of LASER

Techniques of applicationThere are two main techniques:• Contact technique• Non – contact technique

Techniques of applicationI- Contact technique• This technique using diode system hand held probe.• The tip of probe is held perpendicular with the tip pressed into the skin.• The amount of pressure used by the therapist depends on the depth of target

tissue and the tenderness of the area of tissue.• Its advantages: it allows deeper penetration and maximizes power density on the

target tissues as reflection is minimized.• The only exception for this technique is the open wounds treatment.

Methods of application of contact technique:l- Spot methods where only isolated points are irradiated. 2- Lineal methods where laser is irradiated linearly along the neural route related to

the painful area.3- Combined methods (Spot and Lineal), where laser irradiation started by lineal

methods and shifted to spot one.

Techniques of application(cont.)

2- Non – contact technique• This technique is used in treatment of open wound• The distance between the probe and wound should be 0.5 – 1 cm• The probe is held perpendicular to the site of radiation.• It produces greater reflection and lower irradiation.Methods of application of non contact technique:1- Scanning application:• It is used for treatment of large area specially open wound• It allows automatic and uniform easy application over large area

instead of using manual scanning.

II- Non – contact technique (cont.)

2- Manual scanning :• It is used in case of wound healing when the laser

machine is not offered with automatic scanners• It is applied using hand held probe (non- contact) by

moving the operator's hand. .

II- Non – contact technique (cont.)

3- Gridding:• It is alternative to manual scanning for treating wounds • A more practical and less time consuming alternative to manual scanning• For the area of wound is seen as covered with a grid work of square measuring 1 x 1 cm (1 cm2).• Treatment is applied systematically to each square using a single diode applicator from a distance of no more than 0.5-1 cm.• An energy density of 1.5-2.5 J/ cm2 in each irradiated grid square is

recommended as a minimum for the early stages of wound management.

• • A 30 mW unit is used for such treatment. The treatment probe can be used to irradiate each square for a total of 50 sec and to deliver 1.5 J /cm2 in non contact mode.

Point application of Laser

It is used to irradiate localized painful spotUsing hand held probe either with contact or non- contact techniqueIt is commonly used in treatment of localized painful site, trigger and acupuncture points.

Point application

Contact technique linear application on scar tissue

Non -contact technique wound bed application

LASER Treatment for WoundsI- The techniques used in treatment of wounds

1-Contact technique • It is used to treat a series of points around the whole

wound margin about 1cm from the edge of wound at dose of 4 J/cm² or 0.5 J/point .

• Laser treatment is applied 2 cm interval around the edge of wound with alteration of the position of the points between the treatment sessions.

• This technique is aimed to accelerate wound closure in addition increase blood flow to wound.

LASER Treatment for Wound2-Non- contact technique:

Scanning and gridding techniques are used to treat open wound with a dose of 1- 2 J/cm² and for 5 minutes.

The scanning may be automatic or manual according to the laser unit available.

II- Laser type:

Both types of laser (He Ne & IR Laser) are effective. III- Duration and frequency of treatment:

The duration of treatment is detected according to the power of laser unit.Laser treatment is given once daily or at alternate days.

 

LASER Treatment for Wound

Laser treatment for pain control

Point application:• Directly over the site of lesion or pain.• Trigger points• Nerve roots and superficial nerve trunks• Acupuncture pointsDose:• Higher doses are used because the target treated

tissue is deeply located • The dose is usually 1-3 J/ point or 8-12 J/cm² for about 1

minute for each point.

Laser treatment for pain control(cont.)

The technique of application:

Selection of the technique is according to the patient tolerance so, contact and non contact techniques are used.

In case of acute conditions, the non- contact one is used especially over the painful and trigger points.

The point application is used with hand held probe. Combined scanning and point application is used when treating a large

inflamed area in addition to trigger points within the treated zone. This method is used if the laser unit has a scanning .The treated area is scanned first then the trigger points are treated with the probe using point application .

Laser type:• Infrared laser is preferred for its deeper penetration than helium neon laser.

 

Cases study

Case study: A case of ligament strain.• Relevant joint is appropriately positioned.• Laser applied using a single probe with firm

but comfortable pressure. • Energy densities of at least 1 J/point or 8

J/cm².• In the early stage, daily treatment is

recommended.• In the latter stages, the frequency of treatment

should be decreased.

Cases study

Case study: Tendnitis /tenosynovitis• Laser irradiation should usually be applied to the

most sensitive areas of the tendon on palpation as well as to the area of tendon immediately above and below the site of tenderness or pain.

• Single diode probe and energy densities of at least 0.5 J/point or 4 J/cm² is used.

• During treatment, the tendon must be placed on a slight stretch but with pain free, and all aspects of the tendon are irradiated by directing the laser at a range of angles for treatment.

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