Ideal Parameters for the Treatment of Port Wine Stains with Lasers by babbian

VIEWS: 44 PAGES: 3

									                                                                           Aesthetic Dermatology              PHOTOTHERAPY




       Ideal Parameters for the Treatment of Por t Wine Stains with Lasers

       a report by
       Jean-Michel Mazer

       Former Vice-president, Laser Group, French Society of Dermatology




Vascular lasers have been used for more than 20 years       recently proposed. The theoretical relevance is that
to treat port wine stains (PWS). Two questions are          Nd:YAG optimises the penetration, and the effect on
still remaining: how can the rate of resistant port         vessels is optimised due to a preliminary change from
wine stains be improved, and what are the ideal             oxyhaemoglobin into deoxyhaemoglobin, another
parameters of treatment?                                    chromophor. In future it will be possible to define
                                                            the practical relevance (on this occasion, theorically
A lot of improvements have been made in                     synergetic), in which every laser beam, Nd:YAG and
understanding laser treatments within the field of          PDL is used with less fluence.
laser–piece interactions, but a definition of ideal                                                                        Dr Jean-Michel Mazer is the
parameters is still debatable with regard to                Ideal Pulse Duration                                           founding member and former vice-
                                                                                                                           president of the Laser Group at
wavelength, pulse durations or fluence.                                                                                    the French Society of Dermatology.
                                                            The main progress in PWS treatment was certainly
Ideal Wavelength                                            achieved when Rox Anderson et al. developed the
                                                            concept of selective photothermolysis. It is based on
Two wavelengths are essential, corresponding to the         the use of a very short pulse duration in order to
peak absorptions of oxyhaemoglobin: 532nm                   increase the selectivity on blood vessels, so as to
(potassium-titanyl-phosphate (KTP) lasers) and              optimise tolerance. It also allows use of very high
585–595nm (pulsed-dye lasers, PDL).                         fluences, a source of efficiency improvement.

Nevertheless, an excessive absorption can reveal itself     Thanks to this concept, it is possible to treat the
to be negative, as the laser beam penetration will          condition in the very early days, which minimises
decrease and the laser action will be too superficial.      possible psychological repercussions. For several years
For this reason, PDL have progressively developed           pulse durations between 0.5 and 10 milliseconds have
firstly from 577nm to 585nm and now 595nm, the              generally been used, rather between 5 and 10
wavelength being paradoxically much less absorbed           milliseconds, whereas those of the first PDL were
than 57nm.                                                  between 0.45 and 1.5 milliseconds. What is best? 0.5,
                                                            3, 6 or 10 milliseconds? The discussion is still open:
In the case of hypertrophic PWS, this notion of             short pulse durations are theorically more effective for
depth penetration gains importance. This explains           small vessels treatment. Between 6 and 10 millisecond
why longer wavelengths can be used: 755nm                   pulse durations are better for larger vessels, so it is hard
(alexandrite lasers), 810nm or 900nm (diode lasers)         to determine which is the best.
and 1,064nm (neodymium-doped yttrium-
aluminium-garnet (Nd:YAG) lasers).                          As demonstrated by a study the author introduced to
                                                            the Congress of the American Society for Laser
Many studies have demonstrated the relevance of             Medicine and Surgery (ASLMS) in Orlando (April
these lasers in treating PWS, with the sole exception       2005), it would probably be ideal to vary pulse
of hypertrophic lesions. On flat PWS, KTP and PDL           dimensions systematically from one session to the next:
applied on adults are still considered as references. In    for instance 5–6 milliseconds, then 10 milliseconds and,
children, and especially newborn and young children,        three months later, 1.5 or 3 milliseconds, and so on.
PDL must be preferred, whereas Nd:YAG and
alexandrite lasers should actually be avoided: lesions      Indeed, inside the PWS, the diameter of the vessels is
are flat, and the tolerance of these lasers is debatable    not always the same; some are very thin, others are
due to their lack of specificity on blood vessels.          larger. And this diameter will vary with time and
                                                            treatment repetition. Theorically, with time and
The combination of two wavelengths (595nm and               treatments, vessels become thinner and thinner. For
1,064nm) delivered in a single pulse has been               each vessel, according to its diameter and depth,


EUROPEAN DERMATOLOGY REVIEW 2006                                                                                                                          39
     Aesthetic Dermatology           PHOTOTHERAPY




           there is an ideal pulse duration. So, it is not possible      Ideal Parameters
           to determine an ideal pulse duration for the whole
           PWS at any time.                                              Consequently, the following are my proposals for
                                                                         ideal PWS treatment, which are certainly open for
           Fluence                                                       discussion.

           In cases of PWS, the highest fluence is probably              Regarding laser and wavelength on newborn and
           the most effective. But increasing the fluence can            young children, PDL are the best. Concerning
           also increase side effects and risks, mainly achromia         adults, KTP lasers can be added, particularly when
           and scars. For this reason, there has been significant        they are fitted out with large diameter spots and a
           progress made with epidermal protection devices (air          cooling device. Nd:YAG lasers, possibly with diode
           cooling and the ‘dynamic cooling device’, probably            or alexandrite, are recommended in cases of
           the most sophisticated). Epidermal protection allows          hypertrophic lesions. However, they must be used
           the use, without risk, of higher fluences. This has           very carefully because there is a risk of scaring. Flash-
           really been the most important development of the             lamps have sometimes been suggested for adults.
           last few years, not only in terms of comfort for the
           patient but also in terms of tolerance and efficiency.        Regarding pulse duration, on flat PWS, the pulse
                                                                         duration must be short, between 0.45 and 10
           Spot Size                                                     milliseconds. On hypertrophic PWS, pulse durations
                                                                         can be longer by using KTP and PDL lasers. It is also
           Of course, the greater the spot size, the faster the          possible to use Nd:YAG lasers, diode or alexandrite.
           treatment; a larger spot size also gives the ability to       This is why pulse durations are longer with regard to
           treat large areas, especially on the limbs and trunk. But     spot size.
           theorically, laser penetration depends on the diameter
           and increases with it. A bad choice can be easily made:       Regarding spot size and fluence, the largest spots will
           favouring a larger spot size at the risk of using a fluence   be chosen on condition that they do not oblige the use
           that is too weak. Acting deeply matters little as long as     of weak fluences. Some lasers, especially PDL,
           it is weakly. Nevertheless, the latest vascular lasers        currently allow the choice of up to 10mm pulses. In
           (PDL and KTP) allow the use of high fluences with             case of Nd:YAG lasers, it is certainly better to decrease
           pulses of a sizeable diameter, for instance 1cm.              the spot size. Fluence will be as high as possible
                                                                         considering tolerance. The relevance of a cooling
           We noticed, following Geronemus and Bernstein                 device must be emphasised; indeed, it improves
           (Congress of ASLMS in Orlando), that a new type of            tolerance and treatment comfort for the patient.
           PDL, using fluences in the order of 8–9/cm2 with              Furthermore, it makes it possible to increase fluence in
           spots of 10mm and a pulse duration of 1.5                     complete security.
           milliseconds, resulted in some PWS showing very
           clear improvements. Some did not show lightening              Age of treatment – as soon as possible! If treatment
           at the time of the final session when fluences from           can be started in the first weeks after birth,
           12–13.5/cm2 were used with the same pulse                     treatment will be easier; it is a question of a smaller
           duration but some spots of 7mm diameter. So,                  angioma suffered by a newborn, who is not yet
           concerning that point, it can be observed that there          distressed by consulting hours compared to a child
           is no absolutely unbreakable rule: some PWS                   at the age of 4. However, it is possible to undergo
           especially need very high fluences, others are perhaps        treatment at any age. It must be emphasised that in
           less sensitive to this parameter and respond better to        order to ‘have a good conscience’, some parents
           less important fluences providing that higher spot            prefer waiting for their child to need treatment; this
           sizes are chosen.                                             also means they are waiting for the child to have
                                                                         complexes and, as the treatment will last several
           Conclusion                                                    years, this is not reasonable behaviour and will be
                                                                         distressing for the teenager.
           Faced with an untreated PWS, it is still impossible, at
           the end of 2006, to be able to claim a complete               In conclusion, many improvements have been
           regression. In many cases, progress will be                   made during the last 20 years. There are still many
           considerable with a satisfactory, but not complete,           questions. It is absolutely certain that there is
           cosmetic result. It can be considered that about 20%          neither an ideal parameter nor a ‘miracle cure’
           of PWS prove to be resistant – that is to say there is        suitable for all patients. At any session, every patient
           no significant improvement after a great number of            will benefit from variable parameters; it all depends
           treatments. It can be remarked that there is no               on the individual case. The right choice just has to
           consensus on the definition of resistance.                    be made, which is precisely the challenge. ■


40                                                                                   EUROPEAN DERMATOLOGY REVIEW 2006

								
To top