Laser, cryosurgery and its application in veterinary practice

1. LASER AND CRYOSURGERY AND ITS APPLICATION
Prepared by:
Ganga Prasad Yadav

2. INTRODUCTION
 A laser is a device that emits light through a process
of optical amplification based on the stimulated
emission of electromagnetic radiation.
 The term "laser" originated as an acronym for "light
amplification by stimulated emission of radiation”.
 Laser produce electromagnetic radiation, requires no
medium for its transmission because it can travel
through the vacuum of space. It can also travel through
matter in the form of gases, liquids or solids. The
speed and direction of the propagation of radiation will
be changed upon the transition from one medium to
another in the form of heat. Red (660 & 635 nm), green (532 & 520 nm) and
blue-violet (445 & 405 nm) lasers

3. PRODUCTION OF LASER
 Functional laser Production requires 3 things,
optical resonant cavity that contains the lasing
medium and external energy source.
 Electron is pumped to a higher energy level by
supplying energy
 The electron in the meta stable state jumps to a
lower level releasing a photon
 The photon interacts with another electron in the
meta stable state. This interaction produces another
photon at the same wavelength and same phase.
 These photons are reflected by mirror and the laser
beam comes through the partially transparent
mirror.

4. PROPERTIES OF LASER
 MONOCHROMATIC : Single
color/ wavelength.
 COLLIMATED : Non-
divergent (single direction), tight
beam and parallel paths
 COHERENT : Parallel waves
of laser light moves in a phase,
reinforcing each other as they
travel through space

5. CLASSIFICATION OF LASER
 Broadly classified into 2 groups
 High power lasers or surgical lasers: indicated for surgery (cutting,
coagulation, cauterization) and ablation effects (cavity preparations,
prevention).
 Low power lasers or therapeutic lasers: widely used for therapeutic
and bio-stimulating purposes, which mainly act as accelerators of
healing processes.

6. PURPOSE OF LASER SURGERY
 Cut or destroy tissue that is abnormal or
diseased without harming healthy or
normal tissue.
 Shrink or destroy tumors & lesions.
 Close off nerve endings to reduce
postoperative pain.
 Cauterize blood vessels to reduce blood
loss.
 Seal lymph vessels to minimize
swelling & decrease spread of tumor
cells.

7. BENEFITS OF LASER SURGERY FOR PATIENTS
 Less Bleeding
 Less Pain
 Less Swelling
 Reduced risk of infection
 Quicker recovery time

8. BENEFITS OF LASER SURGERY FOR SURGEON
 Unique surgical capabilities.
 Enhanced visibility of the surgical field.
 Increased precision & control.
 Reduction of surgery time.

9. INTERACTION OF LASER WITH TISSUE
 A highly focused laser beam can
efficiently ablate the living tissue. At the
same time, it seals capillaries, small
blood vessels, lymphatic & nerve
endings
 Depends upon target tissue composition
and laser wavelength and time of its use.
 Four different basic interactions of laser
light at the surface it strikes i.e.,
reflection, scatter or transmission and
absorption.

10. PHOTOBIOLOGY
 Photobiologic effect consists of
1. Photochemical
2. Photothermal
3. Photomechanical
Photochemical effect
 Laser light is absorbed and converted into chemical energy, resulting in
tissue destruction.
 Directly breaks the complex organic biochemical bonds, resulting in
tissue destruction or alteration.

11. PHOTOTHERMAL EFFECT
 Laser light is absorbed & converted to heat within the tissues .
 Water, hemoglobin, melanin & some proteins – Absorb varying
wavelengths of laser light.
 At 40-60 degree Celsius – Hyperthermia occurs causing contract, constrict
or destroy blood vessels resulting in tissue hypoxia and cell death.
 At 60-100 degree Celsius – Coagulation occurs, collagen contracts and
proteins are denatured.
 Vaporization occurs as tissues are superheated (> 100 degree Celsius) and
solid tissue becomes gaseous vapor.
 Used for endoscopic control of bleeding. Examples : Bleeding ulcers

12. PHOTOMECHANICAL EEFECT
 Pulsed laser light can be converted into acoustical energy upon impact
create a shock wave that disrupts the target tissue.
 Short, high power laser energy pulses are directed at tissue through a
small core optical fibre.
 Maximum vaporization efficiency & minimum energy deposition into
the tissue .
 Reduces tissue carbonization & thermal necrosis at the edge of
incision.
 Example : Lithotripsy & Ophthalmic surgery.

13. SELECTION OF LASER
 Depends on:
Tissue characteristics.
Whether procedure requires cutting, ablation or coagulation.
 Carbon dioxide laser & Erbium: YAG laser
Good cutters but poor coagulators.
Wavelengths greater than 2,500nm.
Extinction depth – less than 1mm.
 Diode laser & Nd : YAG laser.
Good coagulators but poor cutters.
Wavelength between 600nm to 1,400nm.
Area affected – 5mm to 10mm.
Thermal damage.

14. DIFFERENT TYPES OF LASER
 Carbon dioxide laser (10,600 nm ) : highly absorbed by
water and rapidly absorbed within the first 0.1 to 0.3
mm of tissue. Good ‘cutter’ but poor cauterizer.
 Argon laser (524 nm) : Penetrates 2-3mm . Highly
absorbed by haemoglobin.
 Tunable dye laser (400 -1000 nm)
 Nd : YAG laser (1064 nm ) - Penetrates 4-5 mm of
tissue. Highly absorbed by water & haemoglobin. Good
cauterization.
 Potassium titanyl phosphate laser (KTP : 532 nm )
 Diode lasers (635-675nm): used for photodynamic
therapy

15. POWER DENSITY
 Intensity of laser beam.
 Directly proportional to the power that a laser can
deliver.
 Inversely proportional to the surface area that the beam
strikes.
 Units: W/cm2
 For optimal ablation & incision of tissue :
High power density and
Small focal spot size.
 For coagulation : Low power density and Large focal
spot size.

16. EQUIPMENTS AND PREPARATION
 Specially trained veterinarians.
 Laser hazards & safety.
 Laser delivery system
Flexible fiber. Eg., Nd:YAG laser, Argon laser
Articulated arm. Eg., CO2 laser
 Smoke evacuation system.
 Protective goggles and face mask.
 Hand piece – Straight & angled.
 Focusing tips – To focus laser beam emerging
from the fiber.
1.4mm , 0.8mm, 0.4mm & 0.3mm.

17.  Sterile surgical pack – Additional
hand piece, instruments, gauze,
sterile saline.
 Moistened gauze – barrier to absorb
any stray beams of laser energy.
 Octylated cyanoacrylate – clear
tissue adhesive, most useful in feline
declaw procedures, routine spay and
neuter procedures.
EQUIPMENTS AND PREPARATION

18. SURGICAL TECHNIQUE
 Laser surgery done either by contact or non-
contact mode.
 Tension is applied across the planned incision site
using digital manipulation .
 The hand piece is held perpendicular to the target,
and the incision is made with hand speed
appropriate for tissue separation under tension.
 Using a pulsed pattern allows the tissue to cool
between laser energy bursts, thus minimizing
char.
 Once completed, the edges are wiped free of
excessive char using sterile, saline-soaked gauze.

19. APPLICATIONS OF LASER SURGERY
 GENERAL SURGERY PROCEDURES: Traumatic
wound debridement, Everted saccule resection,
Hepatic lobectomy, Thyroidectomy, Cystotomy, Mast
cell tumors, fibrosarcoma, Enterotomy, Perianal tumors,
Urethral prolapse removal, Granulation tissue shaving,
Tail amputation etc.
 OPHTHALMOLOGY SURGERY PROCEDURES:
Cherry eye , Entropian , Distichia , Eyelid tumor
removal, Ectopic cilia etc.

20. APPLICATIONS OF LASER SURGERY
 ENT AND ORAL SURGERY PROCEDURES:
Oral mass excision, Ear cropping, Aural
hematoma, Ear canal polyps, Stenotic nares repair,
Gingival hyperplasia, Ranulas, Salivary gland
removal etc.
 DERMATOLOGY SURGERY PROCEDURES:
Cutaneous masses ,Hyperkeratosis of digital pads,
Papillomas, Acral lick granuloma ablation etc.
 ELECTIVE PROCEDURES: Castration,
Ovariohysterectomy etc.

21. LASER SAFETY
 A sign indicating a laser is in use should be kept at the entryway of the laser treatment
area
 Aseptic technique should be maintained .
 Eye shields/goggles, protective face mask must be worn at all times by all personnel.
 Safety shields on the patient’s eyes must be used.
 Safety orientation for laser use should be required of all surgeons, anesthesia personnel
and operating room staff.
 If cloth drapes are required, it is recommended that heavily moistened sterile towels be
used in the immediate area of the surgical field; the towels become flammable if they
are dry.
 Paper drapes should not be used because they can be easily burned; laser resistant
drapes are available.
 If general anesthesia is used, it is recommended that oxygen supplementation be
minimized during laser surgery.
 Avoid use of alcohol or any flammable material in the surgical field preparation.
 Use a smoke evacuation system while the laser is at work.

22. CRYOSURGERY
 Cryosurgery (cryotherapy) is the use of extreme cold
in surgery to destroy abnormal or diseased tissue.
 Used to treat a number of diseases and disorders,
especially a variety of benign and malignant skin
conditions.
 Cryosurgery works by taking advantage of the
destructive force of freezing temperatures on cells.
When their temperature sinks beyond a certain level ice
crystals begin forming inside the cells and, because of
their lower density, eventually tear apart those cells.
Further harm to malignant growth will result once
the blood vessels supplying the affected tissue begin to
freeze.

23. DIFFERENT METHODS OF CRYOSURGERY
 Liquid nitrogen
Cryogun used to spray liquid nitrogen
A common method of freezing lesions is using liquid nitrogen as the cooling solution. This −196 °C
(−321 °F) cold liquid may be sprayed on the diseased tissue, circulated through a tube called a
cryoprobe, or simply dabbed on with a cotton or foam swab.
 Carbon dioxide
Carbon dioxide is also available as a spray and is used to treat a variety of benign spots. Less
frequently, doctors use carbon dioxide "snow" formed into a cylinder or mixed with acetone to form a
slush that is applied directly to the treated tissue.
 Argon
Recent advances in technology have allowed for the use of argon gas to drive ice formation.
This gives excellent control of the ice, and minimizing complications using ultra-thin 17 gauge
cryoneedles.
 Dimethyl ether – propane
A mixture of dimethyl ether and propane is used. The mixture is stored in an aerosol spray type
container at room temperature and drops to −41 °C (−42 °F) when dispensed. The mixture is often
dispensed into a straw with a cotton-tipped swab.

24. TYPES OF CRYOSURGERY DEVICES
1. Cryoprobe:
 Accurate Pinpoint Precision
 Penetration of lesion is faster and deeper
with minimal surface truma
 Freezing Power and Pressure with the touch
of your Fingertip
 Freezing rate of cryoprobe is 1mm per 5
seconds
 Depth of treatment: the cryoprobe freezes
up to a maximum 5 mm cell structure
2. Cryo spray by using straight spray aperture
having different aperture sizes.
Used for lesion on outside of the body.
3. Cryo swab: less preferred

25. BENEFITS OF CYROSURGERY IN VETERINARY MEDICINE
Painless
No Preparation
No post operative care
No open wounds – No Bleeding
No suturing
No general anthesia – safe for older animals
Rapid treatment time
Cost Effective
Pressure to treat lesion
Pinpoint Accuracy

26. USED TO TREAT
• Perianal Adenomas
• Epulis
• Pappilomas
• Lick Granulomas
• Warts
• Small Sarcoids
• Eye Lid Tumors
Skin Tumor before treatment

27. REFERENCES
 Veterinary Laser Surgery A Practical Guide by Noel Berger and Peter
H. Eeg
 http://support.cpdpro.org.uk/article/171-photobiology-and-safety
 https://en.wikipedia.org/wiki/Cryosurgery

28. Thank you