Lasers in surgery

aditya kalyan

LASER

Light Amplification by Stimulated Emission of Radiation

History Maiman ,1960, Ruby 1962, Leon Goldman . Dr.Goldmans experiment was the first use of lasers in

the medical history Early 1980s, John Parrish and Rox Anderson -

Selective Photo Thermolysis - Risk of scarring & damage to normal tissue

Common Components of Lasers

Production of Laser

Laser output

2 Modes Continuous mode (Watts) Pulsed mode (Joules) Output depends upon the Medium

Properties Collimation

Monochromacity Coherence

Effect of Laser on tissues

When a laser beam projected to tissue

Biological activity of laser light is due to Absorption phenomenon by chromophores

Photons energy of laser light is transferred to blood, tissues or bone in the form of heat.

Laser can transfer photon energy to chemical bond energy of the molecules in human body, like DNA.

There are generally three interaction mechanisms involved.

1) Photocoagulation2) Photovaporization3) Photoablation Thermal effects depend on Energy density.

Photocoagulation A Laser heating of tissues above 50 oC & below

100oC induces disordering of proteins and other bio-molecules

Shrink in mass – water expelled Heated region loses its mechanical integrity Cells in the photocoagulated region die and a region

of dead tissue called photocoagulation burn develops

Applications Destroy tumors Treating Retinal disorders caused by diabetes Hemostatic laser surgery - bloodless incision,

excision: Blood vessel subjected to photocoagulation

develops a pinched point due to shrinkage of proteins in the vessel’s wall, helps seal off the flow.

Photovaporisation With very high power densities,lasers will quickly

heat the tissues to above 100o C water in tissues boils and evaporates. Since 70% of the body tissue is water, the boiling

change the tissue into a gas. Results in complete removal of the tissue. Hemostatic incision or excision, Skin

Rejuvenation, Resurfacing.

Photoablation When using high power lasers of ultraviolet

wavelength, chemical bonds are broken,without causing local heating.

Thermal component is relatively small and zone of thermal interaction is limited

Results in clean cut incision

Selective absorption A given color of light is strongly absorbed by one

type of tissue,while transmitted by another. Lasers’ pure color is responsible. Oxyhemoglobin in blood: Absorption of

UltraViolet, blue and green light Melanin a pigment in skin, hair, moles etc:

Absorption of visible and near Infrared light Water in tissues: Transparent to visible light

Selective absorption : Absorbing component being Melanin pigment in hair and follicle, it is best worked with a Red light ruby laser. White hair can not be treated with any laser due to the lack of absorbing component

Excimer Laser Excited Dimer Noble gas halide Photoablative effect-Cool Laser Ophthalmologic sugeries like LASIK, PRK.

Argon Laser Tissue depth penetration only 1mm-

Superficial coagulation Precise cutting with minimal damage to

adjacent tissue Absorbed best in Red,Black tissue Retinal photocoagulation Arterial Recanalisation

Dye Laser Pulsed Lasers Organic Dyes like Kiton Red,Rhodamine. Tunable Lasers Dye can be replaced-Different wavelengths

with same laser Port-wine stains,Pigmented lesions

Co2 Lasers Most effective Laser Scalpel 0.1mm zone of Histologic Necrosis Cutting & Vapourising Instrument Seals lymphatics as it cuts through,decreasing

spread of malignant cells Loss of tissues through Evaporisation Skin resufacing- Laser Facelifts

Nd:YAG Laser Most widely used in medical field High penetration capacity of >5mm Photocaogulation Endoscopic Laser To arrest bleeding GI varices Debulking GIT & Pulmonary tumours Coagulates Bladder tumour

Ho:YAG Treats tissue in a liquid-filled environment

(e.g., saline, blood) Endoscopic Laser Orthopaedic Laser used in Arthoscopy

Er:YAG Shallow penetration Extreme surgical precision

Diode Laser Semiconductor devices that emit Laser light as

electric current passes through them Tunable laser Fiberoptic delivery system Photocoagulation for general surgery Hair removal

KTP Laser Fiberoptic delivery system Cholecystectomy

Applications Vascular Malformations of GIT Diffuse gastric antral vascular ectasia Colonic vascular malformation Argon & Nd:YAG lasers Photocoagulation therapy 80% success rate in contolling recurrent

blood loss & subsequent transfusions

Upper GIT Carcinoma Early Gastric cancer Endoscopic laser therapy (Nd:YAG) can

eliminate cancers completely 3 Requirments:Lesion <4cm with no

lymphnode metastasis,Followup,operator Advanced carcinoma it is a palliative

procedure to relieve obstruction,dysphagia or bleeding

Destroy neoplastic tissues & recanalise lumen

Relief of dysphagia 92%,perforation 10% Outpatient basis

Colorectal Cancer Laser therapy with Nd:YAG indicated in Patients with Metastatic or unresectable

local disease In Obstruction,Haemorrhage for Palliative

therapy

Liver Fibrotic Liver Resection Controlled resection of liver without

bloodloss possible Nd:YAG Laser with tissue contact tip Insitu ablation of Intrahepatic

malignancies (metastases) Palliation in HCC

Bile duct stones Laser Lithotripsy Coumarin pulsed dye laser For Bileduct stones that can’t be extracted

easily Break stones into small fragments which

pass spontaneously Light energy to Acoustic energy

Haemorrhoidectomy CO2 or Nd:YAG Laser with contact tip Like scalpel precisely cut through pile mass, melt them & subsequent sloughing

Neurosurgery-Nd:YAG AV malformations Highly Vascular Meningiomas Lesions at inoperable sites like Base of

skull,midbrain,floor of fourth ventricle

Laparoscopic Surgery

CO2 Laser Argon laser & Nd:YAG with contact tips Endometriosis Cholecystectomy (KTP/Nd:YAG) Lymphadenectomy (KTP) Posterior trunca vagotomy in peptic ulcer disease

Vascular Applications Laser Endarterectomy – Argon laser Smart Laser- Reflective Fluorescent spectral data Combination of Helium laser for fluorescence

excitation & Holmium laser for plaque ablation are tried

Laser Angioplasty – Co2,Argon,Nd:YAG

Laser angioplasty.avi

Laser assisted balloon angioplasty done in localised lesions of common iliac & superficial femoral artery

Prosthetic graft stenosis – Argon laser Angioplasty

Urology Renal stones - Laser lithotripsy Coumarin-based pulsed dye laser Light energy is delivered through Flexible quartz

fibers, directed Endoscopically onto a calculus Mechanism of action occurs via plasma

formation between the fiber tip and the calculus, which develops an acoustic shockwave that disrupts the stone along fracture lines

Endoscopic extraction

BPH Photovaporisation - Tissue water is vaporized

resulting in an instantaneous debulking of prostatic tissue.

KTP or Greenlight is commonly used for its vaporization effects on prostate tissue.

Less bleeding and fluid absorption than standard TURP

Lack of tissue obtained for postoperative pathological analysis 

 Urothelial stricture Disease

Nd:YAG, KTP, and Ho:YAG lasers have all been used experimentally to vaporize fibrous strictures

Urothelial malignancies Transitional cell carcinoma of bladder, ureter, and renal pelvis

Skin lesions CO2 Lasers - Condyloma acuminata, Haemangioma

of external genetalia,early penile carcinoma.

Advantages Bloodless field Excellent Haemostasis Excellent Healing Allow precise Microsurgery Less postoperative pain & oedema Lower infection rate Outpatient procedure

Precautions

Laser Plume High Filtration surgical masks Smoke Evacuation units

Drapes, Towels – Wet Fire Extinguisher, Water/Saline Water/Saline saturated fire retardant materials Laser safety officer- Hazard zone, Minimal access

Disadvantages Atmospheric contamination: Laser Plume Mutagenic,Teratogenic or vector for viral infection. Interstitial pneumonia Bronchiolitis Reduced mucociliary clearance, inflammation

Misdirection of laser energy perforation of viscous or large blood vessels Eye damage Skin damage Fire and explosion: Gas embolism: laparoscopic or Hysteroscopic laser surgery

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