CRYOSURGERY

PRESENTED BY- $UCHITRA B. SURYAVANSHIPATIL

(Dept.of vety surgery & radiology,AKOLA)

Subbmited to- DR.FAHREEN FANI

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 a

number of diseases and disorders, especially

variety of benign and malignant skin conditions.

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.

Cryogens -

Liquid nitrogen (most commonly used) : -196°C

Nitrous oxide : - 89°C

Solidified CO 2 (dry ice, CO 2 snow) : -78°C

Chlorodifluoromethane : -41°C

Dimethyl ether and propane : -24°C (42°f)

Argon

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.

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.

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.

Controlling parameters during cryosurgery

o cooling rate

o Temperature

o Thawing rate

o Freeze duration

o Repetitive freeze- thaw cycle

Cooling rate

• In cryosurgery, rapid cooling rate i.e. more than 500C/minproduces intracellular ice- crystals which is more destructive

• Such higher rates of cooling can only be achieved close tothe cryoprobe

Temperature

• Mazur stated that the lethal temperature range is between -50C to -500C.

• The treatment of tumor requires a tissue temperature at which all the abnormal cells are certainly dead.

From the review of all experimental studies the end pointtemperature below -40 0C has been considered prime factorfor tissue destruction

Thawing rate

• Thawing rate should be slow and continued for longer timeperiod; 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

Bio-heat Equation

o Several heat transfer mechanisms occur during cryosurgery, including conduction, convection, metabolism and phase change.

o 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.

o Bio-heat transfer is the study of heat transfer in biological system.

o The fundamental heat transfer equation in biological tissue was firstly suggested by Pennes.

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

Procedure

o Warts, moles, skin tags, solar keratoses, and small skin cancers are candidates for cryosurgical treatment.

o Several internal disorders are also treated with cryosurgery, including liver cancer, prostate cancer, cervical disorders and, more commonly in the past, hemorrhoids.

o 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

• 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.

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

o In this approach, several hollow probes (needles) are placed in direct contact with target tissue.

o The doctor guides them into the gland(tumor) using Trans-Rectal Ultra-Sound (TRUS).

o This type of procedure requires spinal or epidural anesthesia (where the lower half of your body is numbed) or general anesthesia.

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

o After the procedure, there will be some bruising and sorenessin the area where the probes were inserted. Patients might need to stay in the hospital overnight, but many patients leave the same day.

o 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.

Benefits of Cyrosurgery in Veterinary Medicine

Painless

No Preparation

No post op care

No open wounds – No Bleeding

No suturing

No general anthesia – safe for older animals

Rapid treatment time – only seconds

Cost Effective

Pressure to treat lesion

Pinpoint Accuracy

Accurate Pinpoint Precision, Freezing Power

and Pressure with the touch of your Fingertip!

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

CryoProbe’s different micro applicators tips allow pinpoint accuracy to treat skin lesions from 1mm to 8mm in size!

Blue dot applicatorApplications 1-3 mm

White dot applicatorApplications 2-4 mm

Green dot applicatorApplications 3-6 mm

Yellow dot applicatorApplications 4-10 mm

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!

Treat a lesion with pinpoint accuracy

Skin Tumor before treatment

Total recovery after 6 weeks.

Plantar-WartPapilloma situated at the

posterior face of the carpus

Papilloma in frozen condition

Frozen condition before 2nd freeze

Partial necrose at control visit

Fall of the papilloma with total recovery after 4 weeks

an ulcerousskin lesion on the top of the head.

Cryotherapy was chosen as the treatment for Nat because it causes little discomfortrequires 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 performed on the lesion that is estimated to be 3 to 4mm deep.

After second freeze

Although not required Nat came back after treatment for a check up at 5 weeks. A very nice result was achieved with the easy and practical CryoProbe treatment modality

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.

Disadvantages for the patient include:

Erythema and swelling are the norm. 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.