Optimised IPL Photocoagulation by Methaemoglobin Generation From Whole Blood - Laser Europe
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Transcript of Optimised IPL Photocoagulation by Methaemoglobin Generation From Whole Blood - Laser Europe
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Optimised IPL Photocoagulation
by Methaemoglobin Generationfrom whole blood
Caerwyn Ash PhD1, Peter Bjerring MD PhD2,
Sean Lanigan MD3, Marc Clement PhD1, Godfrey Town4
Sam Webster PhD1
1. School of Medicine, Swansea University, UK, SA2 8PP2. Molholm Hospital, Vejle, Denmark
3. Sk:n Clinics, Birmingham, UK
4. University of Wales, Cardiff, CF10 3NS
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Statement of Disclosure
The following potential conflict of interest relationshipsare germane to our presentation:
Salary and test equipment loan: CyDen Ltd., Wales
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Background: Methaemoglobin
Measurement of transient cyanosis during non ablative dye laser wrinkle reduction and its
correlation to enhanced collagen production, P Bjerring, L Heickendorff, M Clement, M Kiernan,
ASLMS conference 2002In-Vivo Measurements of Stimulated Transient Cyanosis using RGB Histogram and a Spectrometer
Irradiated with Intense Broadband Light, C Ash, M Clement
Chemical and Structural Changes in Blood Undergoing Laser Photocoagulation. J Black and J
Barton. Photochemistry and Photobiology, 2004, 80: 8997
Cooperative phenomena in two-pulse, two-colour laser photocoagulation of cutaneous blood
vessels. J Barton, G Frangineas, H Plummer, JF Black. Photochem Photobiol 2001;73:642650.
Using a Non Uniform Pulse Sequence can Improve Selective Coagulation With a Nd:YAG Laser
(1.06 mm) Thanks to Met-Haemoglobin Absorption: A Clinical Study on Blue Leg Veins. S Mordon,
D Brisot, N Fournier. Lasers in Surgery and Medicine 32:160170 (2003)
Optical properties of human blood as a function of temperature. LL Randeberg, AJ Daae Hagen, LO
Svaasand. Proceedings of SPIE 2002;4609:2029.
MRI of thermally denaturated blood: Methaemoglobin formation and relaxation effects. K Farahani,
RE Saxton, HC Yoon, AAF de Salles, et al. Magn Reson Imaging 1999;17:1489149
Methaemoglobin Formation During Laser Induced Photothermolysis of Vascular Skin Lesions. L.L.
Randeberg, J.H. Bonesrnning, M. Dalaker, J.S. Nelson, L.O. Svaasand. Lasers in Surgery and Medicine34:414419 (2004)
Other authors have shown that laser-induced
changes in the optical properties of Hb can be
due to conversion to the Methaemoglobin
derivative.
Transient effect in skin
Lasts for 1-2 seconds
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Background
Passive Target
(Hair Follicle)
Dynamic Target
(Blood vessels)
20-40ms TRT
Output parameters depend on many
variables eg, vessel diameter, depth,
density, pigmentation
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Absorption of Haemoglobin
Methaemoglobin has greater absorption with respect to oxyhaemoglobin especially in
the longer wavelengths. Maximum absorption of methaemoglobin is at 632nm, at this
wavelength the relative absorbance is approximately four times higher than that of
deoxyhaemoglobin and thirteen times higher than the original haemoglobin species
oxyhaemoglobin
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The Concept
Efficient method of photocoagulation using asymmetrical pulse
to create methaemoglobin, then to coagulate the blood vessel
with lower energy pulses.
In-vivo study confirmed IPL suitability for Transient Cyanosis**
Fluen
ce
Time
Sustained heating of
vessel to 60-65C
Low fluence pulse
causes spectral shift into
longer wavelengths*
Methaemoglobin created
13 times increase in absorption
coefficient at 630nm
Secondary pulse
requires less energy to
coagulate vessel
*Ash C, Town G, Clement M, (2010), Confirmation of Spectral Jitter: A Measured Shift in the Spectral Distribution of Intense Pulsed Light Systems using a Time-Resolved Spectrometer during
Exposure and Increased Fluence, Journal of Bioengineering and Technology, Vol. 34, No. 1, January 2010, 111
**C Ash, In-Vivo Measurements of Stimulated Transient Cyanosis using RGB Histogram and a Spectrometer Irradiated with Intense Broadband Light, Private communication
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The Experiment
Author was inoculated in accordance with university guidelines for handling blood
Blood taken by a phlebotomist into tubes with EDTA anticoagulant
Blood was kept oxygenated by 100% oxygen bubbled through blood
iPulse i300 (17J/cm2, 15ms single pulse used for time resolved measurements)
Ocean Optics HR2000+ spectrometer
Tungsten illumination lamp
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Fluen
ce
Time
Tungsten Lamp used to
illuminate bloodSpectral of whole blood
Results: Spectral Absorption
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Fluen
ce
Time
Sustained heating of
vessel to 60-65C
Methaemoglobin created
increase in absorptioncoefficient at 630nm
Increase in absorption of wavelengths for
circa 7ms period
Spectral of blood 20ms after pulse
Results: Spectral Absorption
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Results: Spectral Absorption
Absorption spectra was measured using an Ocean Optics spectrometer with a time integral
of 1ms and recorded before, during, and after a single emission from an IPL.
For circa 7ms after IPL exposure an increase in absorption was seen around 600-660nm
with a maximum effect and beyond till 1000nm
We believe this to be due to temporary methaemoglobin generation
Optimum fluence was 17J/cm2 as over this threshold Coagula was seen against capillary
tube wall and shields blood below
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Why IPL is more beneficial than a laser for
Methaemoglobin Generation
IPL systems can generate abstract pulse structures of various energies,
pulse duration and dosimetry shape. IPL systems can also intentionally
shift the spectrum of the emission.
This mechanism also implies a reduction in the total radiant fluence
required for treatment when the target chromophore changes from oxy to
methaemoglobin, thus a reduction in potential adverse side effects andpain associated with the procedure, a great benefit especially in paediatric
cases.
Such a shift in absorption properties of blood can be taken advantage of
by a light source which produces a range of wavelengths that incorparatesthe absorption range of oxy, deoxy and methaemoglobin.
IPL Systems with large treatment areas provide deeper and more
uniformed heating of a tissue matrix
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Discussion
A real time detector built into handpiece could measure a
threshold of Methaemoglobin conversion, then deliver
secondary pulse of quantified energy to coagulate vesselsefficiently
Ongoing improvements to study design
Use of Cryo-electron-microscopy (School of Nanoheath,
Swansea) for studying coagula.
Initiated PWS study using new pulse arrangements against
a PDL and a traditional IPL
Algorithms to compensate for the effects of smoking on
capillaries?
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Transient formation of Methaemoglobin following IPL
application can be measured in real-time using spectrometer
optical detector.
Useful tool in clinical environment to optimise treatment
outcome and reduce the percentage of sub-clinical responses
By intentionally generating an amount of methaemoglobin in
blood with a pre-treatment pulse, then specifically targeting the
methaemoglobin, deeper target structures can be destroyed
due to the longer wavelengths used by the IPL system with
respect to a 585nm laser.
Typical IPL emission spectral encompasses absorption
spectra of all haemoglobin species
Conclusions
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Email: [email protected]
Thank You