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Lasers in Medical Science |
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© Springer-Verlag London Ltd 2009 |
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10.1007/s10103-009-0710-3 |
Original Article
Comparison of the effects of short- and long-pulse durations when using a 585-nm pulsed dye laser in the treatment of new surgical scars
Keyvan Nouri1 , Mohamed L. Elsaie2, 3 , Voraphol Vejjabhinanta3, Mark Stevens5, Shalu S. Patel4, Caroline Caperton1 and George Elgart1
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(1) |
Department of Dermatology and Cutaneous Surgery, University of Miami Miller School of Medicine, 1475 NW 12th Ave, Suite 2175, Miami, FL 33136, USA |
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(3) |
laceType w:st="on">UniversitylaceType> of laceName w:st="on">Miami, Miami, USA |
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(4) |
University of Miami Miller School of Medicine, Miami, USA |
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(5) |
Department of Oral Maxillofacial Surgery, Medical College of Georgia, Augusta, GA, USA |
Received: 12 June 2009 Accepted: 29 June 2009 Published online: 7 August 2009
Abstract
More than 70 million surgical procedures are performed annually in the USA with the majority involving a skin lesion and almost all individuals in their lifetime will have one or more surgical procedures resulting in scars. Patients and physicians alike are thereby motivated to improve the cosmetic outcome of scars. Prior studies have shown that the pulsed dye laser (PDL) is effective in improving the quality and appearance of the scar when using the 585-nm PDL immediately after the removal of sutures. Most published studies used a pulse duration of 450 µs, which along with the other study parameters, has led to an overall improvement of the scars. However, a pulse duration of 1.5 ms is also available when using the pulsed dye laser and it should theoretically cause fewer side-effects. To our knowledge, there are no other studies comparing the effectiveness of different pulse durations in the treatment of surgical scars starting on the day of suture removal. The purpose of this study is to compare the effect of different pulse durations (450 µs vs. 1.5 ms) in the treatments of postsurgical linear scars immediately after suture removal when using the 585-nm pulsed dye laser (PDL). Twenty non-hospitalized male and female patients (older than 18 years of age) with skin types I?IV and with postoperative linear scars measuring at least 2.1 cm were enrolled in this prospective study. Scars were randomly divided into three equal sections. The different fields were randomly chosen to receive treatment (two out of three fields) or remain as control (one field). The two fields chosen to be treated received treatment with the 585-nm PDL using a 7-mm spot size at 4.0 J. One of the treated sections was randomly selected to receive a pulse duration of 450 µs, and the other section to receive a 1.5-ms pulse. The remaining scar section was designated as control (no treatment). The three sections were mapped and recorded. The patient received treatment immediately after the sutures were removed from the wound and then monthly for 3 months. Evaluations were performed before each treatment and 1 month after the last treatment. The short-pulse and long-pulse 585-nm PDL-treated sections demonstrated a statistically significant overall average improvement of the VSS of 92 and 89%, respectively, compared to 67% for the control site (Fig. 1). Further, for individual parameters of the Vancouver scar scale (VSS), there were significant (p < 0.05) differences between control and treatment groups for all parameters, but there were no differences between the short- and long-pulse treatment groups for any parameter. Both short-pulse and long-pulse PDL are safe and effective in improving the quality and cosmetic appearance of surgical scars in skin type’s I?IV starting on the day of suture removal with no significant difference between the two pulse durations.
Keywords Pulsed dye laser (PDL) - Surgical scars - Keloid
Introduction
More than 70 million surgical procedures are performed annually in the USA, with the majority involving a skin incision [1]. Almost all individuals in their lifetime will have one or more surgical procedures resulting in scars. Both patients and physicians seek ways to diminish the appearance of these scars, and laser treatment may provide an alternative to the current treatment options. These current methods for reducing surgical scars include surgery/grafting, dermabrasion, cryotherapy, pressure therapy, intralesional corticosteroids, interferon, imiquimod, and intralesional 5-fluorouracil. Lasers such as the CO2 laser, argon laser, Nd:YAG laser, non-ablative lasers, and the pulsed dye laser (PDL) have been proven effective in improving the cosmetic appearance of keloids and hypertrophic scars.
Treatment with the PDL is non-invasive, painless, and requires no anesthesia. The PDL works via selective photothermolysis that targets blood vessels with minimal collateral damage. The energy from the PDL is preferentially absorbed by hemoglobin to cause local thermal injury, which is limited by the short pulse duration. Thrombosis, vasculitis, and gradual repair follow. Although the exact mechanism by which the PDL affects scarring is unknown, it is thought that microvascular destruction leads to ischemia, which may affect collagen or collagenase release, or which may deprive a scar of nutrients to prevent scar hypertrophy. Additionally, the increase in mast cells observed after PDL treatment provides histamine that stimulates normal and keloid fibroblast growth and has both positive and negative effects on collagen synthesis.
Various prior studies have evaluated the PDL and have shown that it is effective in improving the vascularity, color, height, texture, and pliability of scars [2?4]. Manuskiatti et al. treated ten keloidal or hypertrophic median sternotomy scars with the 585-nm PDL (450 µs [5]. The scars were divided into three segments and randomly treated with fluences of 3, 5, or 7 J/cm2. After PDL treatment, they found evident improvement in the factors listed above, but did not find a significant difference in the outcome of the different fluences. However, they did not find a trend of better results with the lower fluence, and suggested that multiple sessions may be needed for a greater response. McGraw et al. showed the benefit of early PDL use on surgical scars in an uncontrolled study [6]. They demonstrated improved quality of the scars (especially color), and a decreased rate of hypertrophic scarring when treated with the 585-nm PDL within the first 2 weeks after surgery. A previous study by Nouri et al. treated 12 postoperative linear scars with the PDL immediately following suture removal [7]. The scars were divided into two equal sections, one for the 585-nm PDL treatment (10-mm spot size and 3.5 J/cm2) and the other for control (no treatment). The treated halves scored better in cosmetic appearance using the cosmetic visual analog scale (CVAS) and in all scar parameters using the Vancouver scar scale (VSS). A final scar analysis by a blinded examiner revealed a significant difference between treated and untreated sites. In a subsequent study, Nouri et al. also compared the effectiveness of the 585-nm PDL vs. the 595-nm PDL for the treatment of new surgical scars [8]. A total of 19 scars were randomly divided into three equal sections. The first and third sections were randomized into treatment with either 585-nm or 595-nm PDL, and the middle section of each scar was designated as the control. After evaluating the scars using the VSS and the CVAS, it was found that the 585-nm and 595-nm treated sections demonstrated an overall average improvement of 67- and 55%, respectively, compared to 32% for the control side. There was a statistically significant difference between the treated sites and the control site, but there was no significant difference between the two treated sites (p > 0.05).
To our knowledge, there are no other studies comparing the effectiveness of different pulse durations in the treatment of surgical scars starting on suture removal day. Most published studies use a short-pulse duration of 450 µs, which along with the other study parameters, have led to an overall improvement of the scars. However, a long-pulse duration of 1.5 ms is also available when using the PDL, and it should theoretically cause less side-effects. The objective of this study is to document the effect of short- and long-pulse durations when using the 585-nm PDL and to see if one is better or both are equally effective in improving scarring conditions and outcomes.
The 585-nm pulsed dye laser has been shown to clinically improve erythematous and hypertrophic scars by 57?83% after one to two treatments in patients with a 2-year scar history. Also, this laser improved >1-year-old non-erythematous, minimally hypertrophic scars when used in combination with a CO2 laser [2].
Material and methods
Twenty non-hospitalized male and female patients (older than 18 years of age) with skin types I?IV and with postoperative linear scars measuring at least 2.1 cm were enrolled in this prospective study. Exclusion criteria were that the patient should not be receiving any additional systemic, topical, or intralesional treatment of the scars during the study.
Each scar was divided into three equal sections and randomly assigned to receive treatment (two out of three sections) or remain as control (one section). One treatment section received the short-pulse (450-µs) 585-nm PDL using a 7-mm spot size at 4.0 J/cm2. The other treated section received the long-pulse (1.5-ms) 585-nm PDL using the same settings. The remaining scar section was designated as control (no treatment). The three sections were mapped and recorded.
Each patient received treatment immediately after the sutures were removed from the wound, and then monthly for three total sessions. Evaluations were performed before each treatment, at 1 month after the last treatment, and 6 months after the first treatment. Each scar was measured and recorded. Measurements and photographs were taken at each visit.
A blinded examiner then performed the final analysis by comparing pictures as well as evaluating the patient’s scar. The scars were evaluated using the VSS and CVAS. In order to compare histological changes achieved with treatment, biopsies of each third of the scar were performed in five randomly chosen patients. The VSS is a tool used to evaluate scars based on pigmentation, vascularity, pliability, and height (Table 1). The CVAS is a tool used by both a blinded observer and the patient to evaluate the cosmetic appearance of all three sections of the scar from a range of zero to ten. Statistical analysis of the data was achieved using McNemar’s test to determine the improvements based on the VSS (pigmentation, vascularity, pliability, and height) score of the scars in each of the three groups. Analysis of variance (ANOVA) was also used to assess the effect of treatment for the CVAS.
Table 1 Vancouver scar scale
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Pigmentation |
0 |
Normal color (close to normal skin) |
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1 |
Hypopigmentation |
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2 |
Hyperpigmentation |
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Vascularity |
0 |
Normal color (close to normal skin) |
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1 |
Pink (slight increase in local blood supply) |
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2 |
Red (significant increase in local blood supply) |
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3 |
Purple (excessive increase in local blood supply) |
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Pliability |
0 |
Normal (normal pliability) |
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1 |
Supple, flexible with minimal resistance) |
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2 |
Yielding (giving way to pressure, offering moderate resistance but does not behave as a solid mass of scar) |
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3 |
Firm (solid, inflexible unit, not easily moved, resistant to manual pressure) |
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4 |
Banding (rope-like tissue that blanches with extension of scar, does not limit ROM) |
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5 |
Contracture (permanent shortening of the scar producing deformity or distortion, limits ROM) |
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Height |
0 |
Normal (flat) |
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1 |
<2 mm |
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2 |
<5 mm |
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3 |
>5 mm |
Results
One month after the last treatment, final scar analysis revealed a significant difference between treated and untreated sites favoring the treated sites. The short-pulse and long-pulse 585-nm PDL-treated sections demonstrated a statistically significant overall average improvement of the VSS of 92 and 89%, respectively, compared to 67% for the control site (Fig. 1). Further, for individual parameters of the VSS, there were significant (p < 0.05) differences between control and treatment groups for all parameters, but there were no statistically significant differences between the short- and long-pulse treatment groups for any parameter (Fig. 2).
Fig. 1 Average percent improvement as measured by the Vancouver scar scale (VSS)
Fig. 2 Average percent improvement of individual VSS parameters
For overall cosmetic appearance, there were no baseline differences at visit #1 in between groups. At visits #2?4, both short- and long-pulse treatment groups showed a significant difference from the control. There were no significant differences between the two treatment groups (Figs. 3 and 4). Photographs taken at the first and last visit are compared in Figs. 5 and 6.
Fig. 3 Mean cosmetic visual analog scale (CVAS) results
Fig. 4 Post-treatment cosmetic visual analog scale (CVAS)
Fig. 5 Photographs from the first and last visit of five random patients
Fig. 6 Photographs from the first and last visit of five random patients
Discussion
Keloids and hypertrophic scars are sequelae of abnormal wound-healing process. They are a common reason for dermatologic consultation. A multitude of signaling molecules, including growth factors [TGF-β, PDGF, vascular endothelial growth factor (VEGF)], mitogen-activated protein (MAP) kinases, matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs), regulate this complex process of scar development on the molecular level [9]. The effector molecules that link these regulatory signals and the various phases of wound healing are incompletely understood, although it is known that a derailment in this complex wound-healing process contributes to hypertrophic scars and keloid formation [10].
Hypertrophic scars are typically raised, red or pink, and sometimes pruritic, but do not exceed the margins of the original wound, whereas keloids infiltrate into surrounding normal tissue and rarely regress. Hypertrophic scars usually subside with time, whereas keloids continue to evolve over time, without a quiescent or regressive phase. The choice of an appropriate laser for treatment is influenced by a number of factors such as the fluence, spot size, scar location and duration [11].
The pulsed dye laser has become the popular treatment for remodeling post-operative scars. Both types of scars are abnormal wound responses in predisposed individuals and represent a connective tissue response to trauma, inflammation, surgery, or burns [12]. The first challenge to scar therapy begins with the simple identification and diagnosis of the problematic abnormal wound healing [13].
During the mid-1980s, the introduction of the theory of Selective Photothermolysis by Anderson and Parrish, led to the birth of the pulsed dye laser. Pulsed dye lasers are unique in that they can deliver very high peak powers of energy over short periods of time. These high peak power pulses cause a selective thermal injury to targeted structures in the skin with minimal collateral injury to surrounding tissue. The first commercialized pulsed dye laser was designed to deliver 450-µs pulses at a wavelength of 585 nm. This parameter set was the closest technical specification to the ideal parameters per Anderson and Parrish’s description of Selective Photothermolysis. The trend for scar treatment had always been towards the 585-nm wavelength and the short duration at 450 µs.
The PDL is considered to be the standard treatment of vascular lesions, such as port wine stains, initial hemangiomas, and facial telangiectasias. Additionally, this laser type is often successfully used for non-vascular indications, such as keloids or hypertrophic scars [14]. Currently, the PDL wavelengths of 585 and 595 nm are most frequently used for therapeutic purposes. Alster reported an average improvement of 57% after the first treatment and 83% after the second treatment with PDL for hypertrophic surgical and traumatic scars. In addition to a reduction in erythema, flattening, a clear reduction in itching and pain, and optimization of the skin texture have been observed [15]. The entire scar in each patient was exposed to PDL at a wavelength of 585 nm, a pulse duration of 0.45 ms, and a fluence of 6.5 to 7.25 J/cm2. Recent biochemical studies suggest that 585-nm PDL treatment alters signaling pathways to favor collagen degradation and fibroblast apoptosis [16]. In contrast to the above-cited results, Chan and colleagues failed to show any clinical improvement using PDL for hypertrophic scars. In 27 hypertrophic scars, one side of each of which was treated (585 nm, 7?8 J/cm2, 2.5 ms, 5 mm), the authors documented no superiority of the treated half after three to six treatments regarding thickness and elasticity, although pain and touch sensitivity were far better on the treated side [17]. Currently, there is no consensus on the mechanism by which the PDL achieves such clinical outcome. Hypotheses have included selective destruction of microvasculature and regulation cellular activity, such as inhibition of growth factors TGF- β and PDGF, and stimulation of MMP and IL-6 for matrix degradation. The short duration at 450 μs may more selectively eliminate the small vascular supply of the scar. The long duration at 1.5 ms may generate heat more slowly and results in less side-effects. Both short-pulse and long-pulse 585-nm PDL resulted in scar improvement, but there was no difference between the two pulse durations.
Conclusions
The PDL is safe and effective in improving the quality and cosmetic appearance of surgical scars in skin types I?IV starting on the day of suture removal. Both short- and long-pulse 585-nm PDL resulted in scar improvement, but there was no difference between the two pulse durations. Laser therapy for improvement in the parameters of postoperative scarring continues to merit further studies to refine the laser settings that will lead to the best cosmetic outcome in patients. Both short-pulse and long-pulse PDL are safe and effective in improving the quality and cosmetic appearance of surgical scars in skin types I?IV starting on the day of suture removal with no significant difference between the two pulse durations
Acknowledgments We would like to thank the Hugoton Foundation for their grant and support of this project.
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