Lask Gary, Friedman David, Elman Monica, Fournier Nathalie, Shavit Raphi, Slatkine Michael
UCLA Medical School, Los Angeles, CA, USA, and LaseOhr Medical Centre, Jerusalem, Israel.
J Cosmet Laser Ther. 2006 Jun;8(2):76-81. doi: 10.1080/14764170600719775.
Intense pulsed light (IPL) aesthetic treatment, such as hair removal from large areas, is often very painful. The problems of pain and discomfort can be divided into two different phases: immediate acute pain and the long-term, milder, post-treatment discomfort also associated with erythema. The immediate acute pain is felt during each treatment pulse and can accumulate to an intolerable sensation after a few shots, resulting in the necessity of either using topical analgesic creams which have several limitations or else to considerably slow down the process and/or apply less efficient low-energy densities. The immediate pain is created by the stimulation of sensory nerves located near the basal layer of the epidermis and adjacent to the treated hair follicles. There is an interest in a technology which would significantly reduce acute pain and post-treatment erythema, without the necessity of lowering the energy density or speed of treatments.
To examine the advantages of pneumatic skin flattening (PSF) with negative pressure: (i) for the reduction or elimination of pain, without chilling the skin, during hair removal with high energy density IPLs and pulsed lasers; (ii) for the reduction of post-treatment erythema; and (iii) for the enhancement of hair removal.
We have removed hair from large areas such as legs and backs with a high-energy (42 J/cm2) pulsed diode laser and an IPL (15-20 J/cm2). Room temperature gel was applied to the skin before treatment. In all cases but one, skin was not chilled by external cooling devices. We utilized a vacuum chamber and a transparent sapphire window to generate deep negative pressure in the treatment site and flatten the skin against the window. The level of applied vacuum was in the 200-600 mmHg range. We have compared the level of pain (I-V according to a modified McGill Pain Questionnaire) and the efficacy of hair removal on a total of 40 treatment sites The results of the vacuum-assisted treatment sites were compared with the results on adjacent control areas, obtained without the application of vacuum. Post-treatment erythema was also compared.
PSF significantly reduces pain in all patients, even when higher (+30%) treatment energy levels are applied. Skin is well protected thermally by the conductive sapphire window. Post erythema and edema is considerably reduced, as well. Hair removal efficacy is preserved or enhanced. Treatment is faster and is uninterrupted by pain, without the necessity to apply topical anesthetic over a large area. Blood expulsion resulting from flattening the skin has also enabled the treatment of thin hair in light-skinned patients, using yellow and green wavelengths (540 nm cut-off filter) and short pulse durations with a higher efficacy than with the 650 nm cut-off filter.
强脉冲光（IPL）美容治疗，如大面积脱毛，通常非常疼痛。疼痛和不适问题可分为两个不同阶段：即时急性疼痛和长期较轻的治疗后不适，后者也与红斑有关。即时急性疼痛在每次治疗脉冲期间都会感觉到，几次照射后可能会累积到无法忍受的程度，这就导致要么使用有多种局限性的外用镇痛乳膏，要么大幅减慢治疗过程和/或采用效率较低的低能量密度。即时疼痛是由位于表皮基底层附近且与被治疗毛囊相邻的感觉神经受到刺激引起的。人们对一种能显著减轻急性疼痛和治疗后红斑，而无需降低能量密度或治疗速度的技术很感兴趣。
研究负压气动皮肤扁平化（PSF）的优势：（i）在使用高能量密度IPL和脉冲激光进行脱毛时减轻或消除疼痛，且不使皮肤冷却；（ii）减轻治疗后红斑；（iii）增强脱毛效果。
我们使用高能量（42 J/cm²）脉冲二极管激光和IPL（15 - 20 J/cm²）对腿部和背部等大面积部位进行脱毛。治疗前在皮肤上涂抹室温凝胶。除一例之外，在所有情况下皮肤均未通过外部冷却装置进行冷却。我们利用一个真空室和一个透明蓝宝石窗口在治疗部位产生深度负压，并使皮肤紧贴窗口扁平化。施加的真空度在200 - 600 mmHg范围内。我们比较了总共40个治疗部位的疼痛程度（根据改良的麦吉尔疼痛问卷分为I - V级）和脱毛效果。将真空辅助治疗部位的结果与未施加真空的相邻对照区域的结果进行比较。还比较了治疗后红斑情况。
PSF能显著减轻所有患者的疼痛，即使应用更高（+30%）的治疗能量水平时也是如此。导电蓝宝石窗口能很好地保护皮肤免受热损伤。治疗后红斑和水肿也明显减轻。脱毛效果得以保持或增强。治疗速度更快，且不会因疼痛而中断，无需大面积涂抹外用麻醉剂。皮肤扁平化导致的血液排出还使得能够使用黄色和绿色波长（540 nm截止滤光片）以及短脉冲持续时间对浅色皮肤患者的细毛进行治疗，其效果比使用650 nm截止滤光片时更高。
