optimised ipl photocoagulation by methaemoglobin generation from whole blood - laser europe

7/28/2019 Optimised IPL Photocoagulation by Methaemoglobin Generation From Whole Blood - Laser Europe

1/14

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


2/14

Statement of Disclosure

The following potential conflict of interest relationshipsare germane to our presentation:

Salary and test equipment loan: CyDen Ltd., Wales


3/14

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


4/14

Background

Passive Target

(Hair Follicle)

Dynamic Target

(Blood vessels)

20-40ms TRT

Output parameters depend on many

variables eg, vessel diameter, depth,

density, pigmentation


5/14

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


6/14

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


7/14

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


8/14

Fluen

ce

Time

Tungsten Lamp used to

illuminate bloodSpectral of whole blood

Results: Spectral Absorption


9/14

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



10/14


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


11/14

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


12/14

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?


13/14

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


14/14

Email: [email protected]

Thank You

optimised ipl photocoagulation by methaemoglobin generation from whole blood - laser europe

Documents