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8/6/2019 Thapliyal CO2 Lasers
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CO2 Lasers in Biomedicine
Tanuj Thapliyal
5/11/2010
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Link to presentation
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presentation
The actual presentation can be found here:
http://prezi.com/njrss5m1oxjm/
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History & Basic Facts
One of earliest and most powerful lasers every made
Invented by C. Kumar Patel in 1964 @ Bell Labs
One of the first lasers ever invented, after Ruby laser and HeNe laser
Extremely efficient laser optical power out/electrical power in from 5 to 20%
Comparison: HeNe or Ar/Kr lasers have .1 % efficiency
IR laser diodes have higher efficiency, >50%
Highest power continuous wave laser
Operates at 9.4 and 10.6 micrometer wavelengths
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Theory of Operation
Traditional Laser Operation has direct electron
excitation
Laser consist of:
Active Medium (gas, crystal, semiconductor,
liquid)
Pump (Optical, Electrical)
Laser Cavity between 2 mirrors (100% reflective,
partially reflective mirrors)
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Theory of Operation
1) Excited active medium --> electrons at excitedenergy levels (POPULATION INVERSION)
2) When electrons relax back to ground state,
they release energy in form of a photon at aspecific wavelength and in phase (coherent)
3) Photons bounce back and forth in cavity bymirrors, allowing more stimulated emission of
excited electrons and amplification of laser light 4) Photons that pass through partially reflective
mirror is the "LASER" light
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Theory of Operation
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Theory of Operation
CO2 Lasers use molecularvibrations for laser action
Typical CO2 Laser ActiveMedium
10-20% Nitrogen 10-20% CO2
60-80% Helium
Trace % of Hydrogen and/orXenon
Methods of Excitation Radiofrequency
Pulse Width Modulation
DC
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Theory of Operation
1) Plasma, or heat vibrates Nitrogen in gas mixture
2) Nitrogen vibrations remain for long time because they'resymmetric
3) Nitrogen vibrational frequency couples nicely with
energy required to bring CO2 electrons up to 3rd energylevel
4) When CO2 electrons relax from 3rd to 2nd energy levels,photons are released
5) Helium accomplishes 2 functions a) Helps CO2 relax to ground state b) Improve thermal conductivity of active medium
Hot CO2 --> electrons stay in 2nd energy level, negating populationinversion
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General Advantages
The CO2 Laser's power makes it like a great but collaterally dangerous scalpel
10.6 micrometer wavelength energies nicely absorbed by water and organic tissue--> for soft tissue ablation
Narrow, focused area of energy delivery
Cauterizes wounds and seals off nerves and small blood vessels - a good but notgreat coagulator
Laser acts like a natural sterilizer as it functions, reducing secondary infectionoccurences
Less swelling (generally no crushing of tissue)
Precision
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Histology and Scalpel
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General Disadvantages
Slow recovery
can be painful post-operation
Surrounding tissue damage can be massive andmust be carefully controlled by not applying laser
for too long
Expensive procedures
ll fl ibl id
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Small, flexible waveguides
revolutionized CO2 lasers in minimally
invasive surgery CO2 lasers in minimallyinvasive surgery had limitedapplication due to large,bulky, and unwieldy energydelivery systems
Advent of flexible hollowwave guides in mid 2000'shas allowed for increasedapplications of CO2 lasersin surgery since hard toreach tissue can now beeasily accessed
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Otology
Two major types of ear surgeries
CLASS (CO2 laser Assisted StapesSurgery) CO2 laser is used in middle/inner ear
surgery where innermost bone of the ear(stapes) is removed and replaced withprosthesis to improve hearing by better
conducting sound to inner ear Surgery needed when stapes no longer
functioning properly, a result ofotosclerosis (spongy bone hardensaround base of stapes)
CLEAR (CO2 laser Enabled Ablationand Resection) Diseased tissue removal during other ear
surgery procedures Adhesion ablation
Scar tissue dissection
Debulking and coagulation of vasculartumors
Flexible CO2 laseradvantageous here because:
1) Flexible sheath means surgeoncan hold laser in hand allowing
extremely high precision indelicate, small space
2) There is increased visualizationin tight area so surgeon can bettersee the operation
3) Hemostasis of tinymicrovasculature occurs
http://www.youtube.com/watch?v=X_z3T1TPjjw
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Dentistry
Hollow wave guide allows flexible control to hard to reach places in the mouth
Co2 lasers coagulate and seal the sensory nerve endings, reducing need foranasthesia and postoperative pain
Treats: benign oral lesions:
fibromas
papillomas Hemangiomas
gingival hyperpasias
aphthous ulcers
ankyloglossias
premalignant lesions: lichen planus
oral leuokoplakia
CO2 laser doesn't enhance ability to cure oral disease compared to scalpel,electrosurgery, or cryotherapy
Scalpel and electrosturgery still method of choice
Ad d di l di
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Advanced cardiovascular disease
produces intense discomfort in
afflicted patients After a heart attack, tissue is dead and unableto conduct action potentials and beat theheart; blocked arteries prevent blood flow to
heart tissue
leads to condition called angina, chest pain or
discomfort that occurs when heart muscleisn't getting enough oxygen via blood toperform its functions
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The Solution - Trans-Myocardial
Revascularization (TMR)
Heart tissue is deliberately punctured with a
laser to stimulate growth factors and induce
blood vessel formation to provide tissue with
oxygen
This process is also combined with manually
introduced growth factors and gene therapy
to further induce vascularization
http://www.youtube.com/watch?v=sxwWeQNUa04
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Modes of Treatment
Controversy over efficacy of therapy as many claim it tobe a placebo effect, despite this, it's obtained FDA 510kpremarket approval in 2 laser treatment methods
Including CO2, 3 Laser treatments pursued
CO2 PLC Medical Systems, CO2 Heart Laser 2
Early pioneering work used CO2 using 80 watts of power Since it took long time to make holes in heart tissue at that low energy,
heart had to be non beating
New lasers pulse with heartbeat (on order of several millisecond
pulses) so it can work on a beating heart, but will only ablate whenthe heart is still (1000 watts)
Excimer (PhotoMedex, didnt work, approach abandoned)
Holmium:YAG (Cardiogenesis, market leader)
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Note on Prezi
Can be obtained for free at
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Educational license available for $60/year
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References 1 of 2
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Agarwal, Ravi, Ajit, Mullasari, Kurian, Valikapathalil M., Rajan, Sethuratnam, Arumugam, Sarasa B., Cherian, Kottoorathu M.Transmyocardial laser revascularization: early results and 1-year follow-upAnn Thorac Surg 1999 67: 432-436
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http://www.umm.edu/heart/tmr.htm
Patel, C. K.N. (1964). "Continuous-Wave Laser Action on Vibrational-Rotational Transitions of CO2". Physical Review136 (5A): A1187A1193. doi:10.1103/PhysRev.136.A1187.
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OH Frazier, RJ March and KA Horvath, Transmyocardial revascularization with a carbon dioxide laser in patients with end-stage coronary arterydisease, N Engl J Med341 (1999), pp. 10211028
Keith A. Horvath, Chia Yang J. Lu, Emmanuel Robert, Glenn F. Pierce, Rodney Greene, Barbara A. Sosnowski, and John DoukasImprovement of myocardial contractility in a porcine model of chronic ischemia using a combined transmyocardial revascularization and genetherapy approachJ. Thorac. Cardiovasc. Surg., May 2005; 129: 1071 - 1077.
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References 2 of 2
SARAH C CLARKE and PETER M SCHOFIELDPercutaneous myocardial laser revascularisationHeart, Mar 2000; 83: 253 - 254.
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M Mirhoseini, J C Fisher, and M Cayton
Lasers Surg Med. 1983; 3(3): 241245.
M Mirhoseini, S Shelgikar, and MM CaytonNew concepts in revascularization of the myocardiumAnn. Thorac. Surg., Jul 1988; 45: 415 - 420.
Aaberge, Lars, Nordstrand, Kenneth, Dragsund, Morten, Saatvedt, Kjell, Endresen, Knut, Golf, Svein, Geiran, Odd, Abdelnoor, Michel, Forfang,KolbjornTransmyocardial revascularization with CO2 laser in patients with refractory angina pectoris: Clinical results from The Norwegian RandomizedTrialJ Am Coll Cardiol 2000 35: 1170-1177
Horvath K Ai , Zhou Y i . Transmyocardial Laser Revascularization and Extravascular Angiogenetic Techniques to Increase Myocardial Blood Flow.Cohn Lh, ed. Cardiac Surgery in the Adult. New York: McGraw-Hill, 2008:733-752.
http://www.plcmed.com/Products-CO2-Technology.asp
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http://www.nhlbi.nih.gov/health/dci/Diseases/Angina/Angina_WhatIs.html
G. Chad Hughes, Alan P. Kypson, Brian H. Annex, Bangliang Yin, James D. St. Louis, Shankha S. Biswas, R. Edward Coleman, Timothy R. DeGrado,Carolyn L. Donovan, Kevin P. Landolfo, and James E. LoweInduction of angiogenesis after TMR: a comparison of holmium:YAG, CO2, and excimer lasersAnn. Thorac. Surg., Aug 2000; 70: 504 - 509.
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