PRINCIPLES OF CRYOSURGERY Cryosurgery (cryotherapy) is the application of extreme cold to destroy abnormal or diseased tissue. The term comes from the Greek words cryo ("icy cold") and surgery meaning "hand work" or "handiwork". Cryosurgery has been historically used to treat several diseases and disorders, especially variety of benign and malignant skin conditions. Mechanism of cryosurgery o The destructive effect of freezing tissue has been categorized into two major mechanisms-  Immediate cell destruction.  Delayed cell destruction. Application techniques  Probe freezing: It is done by direct application of a probe tip to the lesion. The cryogen circulates through the probe tip and super cools it, when allowed to contact the target tissue. Probe freezing can be accomplished by one of the two mechanisms: contact freezing and penetration freezing.  In contact freezing, firm contact is made between the cryoprobe and the target tissue.  While in penetration freezing probe penetrates the target tissue, providing a large area of direct contact.  Spray freezing: It is done by direct application of the liquid nitrogen to the tissue and is the most destructive method. Liquid nitrogen is delivered to the target tissue at such a volume and velocity that it evaporates at the edge of the lesion. The spray orifice allows deeper and faster tissue penetration than the probe tip but the probe method is safer and more precise. Benefits of Cryosurgery in Veterinary Medicine  Painless.  No Preparation.  No post op care.  No open wounds – No Bleeding.  No suturing.  No general anaesthesia – safe for older animals.  Rapid treatment time – only seconds.  Cost Effective.  Pressure to treat lesion.  Pinpoint Accuracy. CryoProbe’s different micro applicators tips allow pinpoint accuracy to treat skin lesions from 1mm to 8mm in size.  Blue dot applicator Applications 1-3 mm.  White dot applicator Applications 2-4 mm.  Green dot applicator Applications 3-6 mm.  Yellow dot applicator Applications 4-10 mm. Lesions With the CryoProbe you will be able to treat (but not limited) to the following lesions successfully:  Perianal Adenomas.  Epuli.  Papilloma.  Lick Granulomas.  Warts.  Small Sarcoids.  Eye Lid Tumors. You will be able to quickly and easily treat skin lesions that you could not treat before without undesired side effects. Disadvantages of Cryosurgery As with the advantages of cryosurgery, the disadvantages can also be categorized into those for the clinician and those for the patient. Disadvantages for the clinician include the following:  Liquid nitrogen needs to be delivered and stored. A liquid nitrogen generator may be purchased. If that is not done, nitrous oxide tanks or other supplies will need to be replenished as needed.

1. Submitted to:
Dr.B.R.Balappanavar
Dept. of Veterinary Surgery
and Radiology
Submitted by:
Kanteshkumar M J
Jr. MVSc
PRINCIPLES OF
CRYOSURGERY

2. Cryosurgery
 Application of extreme cold to destroy
abnormal or diseased tissue.
 The term comes from the Greek words cryo
("icy cold") and surgery meaning "hand work"
or "handiwork".
 Cryosurgery has been historically used to
treat a number of diseases and disorders,
especially variety of benign and malignant
skin conditions.

3. HISTORY OF CRYOSURGERY
 James Arnott, in 19th century, stated that a
very low temperature will arrest every
inflammation which is near enough to the
surface.
 The first cryogens were liquid air and
compressed carbon dioxide snow.
 In 1961, Cooper and Lee developed the first
cryotherapy probe system, involving the
circulation of liquid nitrogen through a
closed metal tube placed in direct contact
with the target tissue.

4. Cryogens
 Liquid nitrogen (most commonly used) : -196°C
 Nitrous oxide : - 89°C
 Solidified CO2 (dry ice, CO2 snow) : -78°C
 Chlorodifluoromethane : -41°C
 Dimethyl ether and propane : -24°C
 Argon

5. Liquid nitrogen
 Cryogun used to spray liquid nitrogen
 A common method of freezing lesions is using
liquid nitrogen as the cooling solution. The
super-cooled 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
 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.

6. Argon
 Recent advances in technology have allowed for the
use of argon gas to drive ice formation using a
principle known as the Joule-Thomson effect. This
gives physicians 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 in
some preparations such as Dr. Scholl's Freeze Away.
The mixture is stored in an aerosol spray type
container at room temperature and drops to −41 °C
when dispensed. The mixture is often dispensed into
a straw with a cotton- tipped swab.

7. Mechanism of cryosurgery
The destructive effect of freezing tissue has
been categorized into two major mechanisms
 Immediate cell destruction
 Delayed cell destruction

9. Application techniques
 Probe freezing: It is done by direct application of
a probe tip to the lesion. The cryogen circulates
through the probe tip and super cools it, when
allowed to contact the target tissue. Probe
freezing can be accomplished by one of the two
mechanisms: contact freezing and penetration
freezing.
 In contact freezing, firm contact is made
between the cryoprobe and the target tissue.

10. Application techniques
 While in penetration freezing probe penetrates
the target tissue, providing a large area of direct
contact.
 Spray freezing: It is done by direct application of
the liquid nitrogen to the tissue and is the most
destructive method. Liquid nitrogen is delivered
to the target tissue at such a volume and velocity
that it evaporates at the edge of the lesion. The
spray orifice allows deeper and faster tissue
penetration than the probe tip but the probe
method is safer and more precise.

11. Controlling parameters during cryosurgery
Cooling rate
Temperature
Thawing rate
Freeze duration
Repetitive freeze- thaw cycle

12. COOLING RATE
 In cryosurgery, rapid cooling rate i.e. more than
50ºC/min produces intracellular ice- crystals which
is more destructive.
 Such higher rates of cooling can only be achieved
close to the cryoprobe
TEMPERATURE
 Mazur stated that the lethal temperature range is
between - 5ºC to -50ºC.
 The treatment of tumor requires a tissue
temperature at which all the abnormal cells are
certainly dead.

13. From the review of all experimental studies the end
point temperature below -40 0C has been
considered prime factor for tissue destruction

14. Thawing rate
 Thawing rate should be slow and continued for
longer time period; rapid thaw rates allow cell
survival.
Repetitive freeze- thaw cycle
 Rapid freezing and slow thawing do not guarantee
effective cell destruction.
 Use of repeated freeze-thaw cycle is also beneficial
in treatment of cancerous tumor

16. Bio-heat Equation
 Several heat transfer mechanisms occur during
cryosurgery, including conduction, convection,
metabolism and phase change.
 Heat transfer by conduction has been assumed to be
the primary heat transfer process during cryosurgery
since the cryoprobe operates at an extremely low
temperature.
 Bio-heat transfer is the study of heat transfer in
biological system.
 The fundamental heat transfer equation in biological
tissue was firstly suggested by Pennes.

17. Pennes suggested that the rate of heat transfer
between blood and tissue is proportional to the product
of the volumetric perfusion rate and the difference
between the arterial blood temperature and the local
tissue temperature.
He expressed that relationship as follows
Where,
hb is the rate of heat transfer per unit volume of tissue,
V is the perfusion rate per unit volume of tissue,
ρb is the density of blood,
cb is the specific heat of blood,
K is a factor that accounts for incomplete thermal
equilibrium between blood and tissue (0<K<1, for some
cases K = 0)
Ta is the temperature of arterial blood, and
T is the local tissue temperature

18. Procedure
 Warts, moles, skin tags, solar keratoses, and small
skin cancers are candidates for cryosurgical
treatment.
 Several internal disorders are also treated with
cryosurgery, including liver cancer, prostate cancer,
cervical disorders and, more commonly in the past,
hemorrhoids.
 Cryosurgery works by taking advantage of the
destructive force of freezing temperatures on cells. At
low temperatures, ice crystals form inside the cells,
which can tear them apart. More damage occurs when
blood vessels supplying the diseased tissue freeze

19.  The application of liquefied N₂0 sprayed directly
on the skin will bring temperature fully under
control (nitrous oxide always evaporates at -127⁰)
 Sophisticated micro-applicator technology
enables an unprecedented level of accuracy of
treatment from 1mm. The prevention of trauma to
surrounding tissue will assure patient’s comfort
 The pressure of the spray at 721 psi will give
maximum control over depth of freezing and will
guarantee the results of the treatment.

20. Why Pressure
 The penetration of the ice crystal into the
lesion as a result of cryosurgery with the
CryoProbe will go faster and deeper with
minimal surface trauma.
 The freezing rate of CryoProbe is 1mm per 5
seconds .
 Depth of treatment: the CryoProbe freezes up
to a maximum 5 mm cell structure

21.  In this approach, several hollow probes
(needles) are placed in direct contact with
target tissue.
 The doctor guides them into the gland(tumor)
using Trans-Rectal Ultra-Sound (TRUS).
 This type of procedure requires spinal or
epidural anesthesia (where the lower half of
your body is numbed) or general anesthesia.

22. Very cold gases are then passed through the
needles, creating ice balls that destroy the
gland(tumor).

23.  After the procedure, there will be some
bruising and soreness in the area where the
probes were inserted. Patients might need to
stay in the hospital overnight, but many
patients leave the same day.
 The most common method of freezing lesions
is using liquid nitrogen as the cooling
solution. The super-cooled liquid may be
sprayed on the diseased tissue, circulated
through a tube called a cryoprobe.

28. Benefits of Cryosurgery in Veterinary
 Painless
 No Preparation
 No post operative care
 No open wounds – No Bleeding
 No suturing
 No general anaesthesia – safe for older animals
 Rapid treatment time – only seconds
 Cost Effective
 Pressure to treat lesion
 Pinpoint Accuracy

29. Accurate Pinpoint Precision, Freezing Power
and Pressure with the touch of your Fingertip

30.  Cryogun used to spray liquid
nitrogen
 Manufacturers have devised
various metal attachments to
serve as heat-conducting probes
for cryotherapy. Copper, because
of its high conductivity, is
typically used

31. CryoProbe’s different micro applicators tips allow
pinpoint accuracy to treat skin lesions from 1mm to
8mm in size!
 Blue dot applicator Applications 1-3 mm
 White dot applicator Applications 2-4 mm
 Green dot applicator Applications 3-6 mm
 Yellow dot applicator Applications 4-10 mm

32. Lesions
With the CryoProbe you will be able to treat (but not
limited) to the following lesions successfully:
 Perianal Adenomas
 Epuli
 Pappilomas
 Lick Granulomas
 Warts
 Small Sarcoids
 Eye Lid Tumors
You will be able to quickly and easily treat skin
lesions that you could not treat before without
undesired side effects!

33. Treat a lesion with Pinpoint accuracy

37. Skin Tumor before treatment

47. Cryotherapy was chosen as the treatment
because it causes little discomfort
requires no preparation and no follow up care.
Since the CryoProbe has a penetration rate of
freezing into the tissue @ 1mm per 5 seconds,
a 20-30 second treatment is was performed on
the lesion that is estimated to be 3 to 4mm
deep.
An ulcerous skin lesion on the top of the head

51. After second freeze

52. AFTER
5 WEEKS

53. Disadvantages of Cryosurgery
As with the advantages of cryosurgery, the
disadvantages can also be categorized into those for
the clinician and those for the patient.
Disadvantages for the clinician include the following:
 Liquid nitrogen needs to be delivered and stored. A
liquid nitrogen generator may be purchased. If that
is not done, nitrous oxide tanks or other supplies will
need to be replenished as needed.
 The clinician must be certain of the diagnosis
because no tissue will be sent for pathology.
 Cryosurgery is not as accurate as a scalpel or laser
in cosmetic work.

54. Disadvantages of Cryosurgery
Disadvantages for the patient include:
 Erythema and swelling are the normal. Blistering is
common.
 Pain, especially throbbing pain around the nail folds.
 Pain with walking if plantar warts are treated.
 May require multiple visits.
 Hypopigmentation.
 Damage to adjacent structures such as joints and
bones may lead to lameness and fracture.
 Risk of uncontrolled freezing - resulting in
destruction of normal tissue.

55. RECENT ADVANCES
 While cryosurgery is not a new modality, the tools used to deliver
the required temperature change are evolving, making the target
areas very precise. This enhanced precision reduces collateral
tissue damage, leading to faster healing and less scarring. The
capacity to achieve this precision is also what makes the biggest
difference in treating smaller lesions. The specific unit I use in my
practice is the CryoProbe X+, which runs at about -127°F. This
specific model includes five separate tip sizes that can be used to
match the lesion being treated, and can be operated with available
8g and 16g cartridges. (While treatment is often done without
sedation or general anesthesia, the locations of some lesions will
still require chemical immobilization to achieve desired results).
Thanks to the precision of the micro-applicator tips, there is no
collateral damage to healthy tissue, resulting in no discomfort to
the patient. As such, treatments are very controlled and can be
longer in duration if necessary. There is no required post-operative
care; there is no bleeding, and sutures and cones are unnecessary,
a wonderful benefit for both patients and caregivers. The following
discussion identifies common lesions the author has treated with
cryotherapy, but the modality’s use is certainly not limited to these.
Zielinska et al., 2017

56.  Sebaceous adenomas
 Cutaneous histiocytomas
 Mast cell tumors:
 Acral lick granulomas
 Epidermal and follicular inclusion cysts:
 Meibomian gland adenomas:
 Eosinophilic granuloma complex, ulcerative paradental stomatitis and
oral neoplasia:
 Prior to cryosurgery implementation, it is imperative that current
standards of care be followed, with appropriate cytological and
histopathological diagnostic steps performed as indicated. If a mass is
deemed malignant with metastatic potential, addressing the mass with
aggressive surgical intervention, radiation and chemotherapy would be
indicated based on oncologist recommendations should the patient’s
owner elect to pursue that line of treatment. Once a mass has been
diagnosed, the use of cryosurgery can be employed for nearly any
lesion on the skin, as well as some mucus membrane tissues.
 cryosurgical unit to my treatment toolbox, I have been able to offer
another option for commonly-seen dermatological lesions that is quick,
effective, less invasive, and requires little to no anesthesia.
Cryosurgery has been readily accepted by my clientele and well
tolerated by my patients, making it a great fit for my practice.

57. References
Korpan, N.N. (2001). Cryosurgery in the 21st Century. In:
Korpan, N.N. (eds) Basics of Cryosurgery. Springer,
Vienna. https://doi.org/10.1007/978-3-7091-6225-
5_1
Baxter, J.S. and Meek, R., 1988. Cryosurgery in the
treatment of skin disorders in reptiles. Herpetological
journal, 1(6), pp.227-229.
De Queiroz, G.F., Matera, J.M. and Zaidan Dagli, M.L.,
2008. Clinical study of cryosurgery efficacy in the
treatment of skin and subcutaneous tumors in dogs and
cats. Veterinary Surgery, 37(5), pp.438-443.