[New Aspects of Burn Management] #1. Diagnosis & Classification of Burns

This series delivers the latest knowledge of burn management by Professor Youngcheol Jang, a world-renowned authority on burn management at the Burn Center of Hallym University's Medical Center in Korea. Prof. Jang will introduce the diagnosis and classification of burns, management of acute burns, treatment of burns, advanced dressing materials and the use of cultured epithelial cells such as keratinocytes.

Extent of burns

The most important step in determining the direction and method of burn management is to pinpoint the extent and depth of the burns. For example, burns covering 20% or more in adults are presented as a systemic reaction and require fluid therapy. The area of the burn is indicated as a percentage (%) of the total body surface area (TBSA). 2nd and 3rd degree burns are included in the TBSA percentage while 1st degree burns are excluded.

① Rule of 9’s: The burned area can be calculated easily and quickly by dividing the body into upper and lower limbs on both sides, torso, head and genitalia. Being a rough calculation, this method is less accurate, though commonly used in emergency unit. The percentage of each body section of TBSA of infants and children is different from that of adults. Therefore, the following chart is used for more accurate estimation (Figure 1). In general, head and neck account for 19%, and each leg accounts for 13% in a 4-years-old or younger child, unlike 9% and 18%, respectively, in an adult (Figure 1).

② Lund and Browder chart: This method of measuring burns by age is more accurate but also more complex than the rule of 9’s, and is often used for permanent medical records.

[Figure 1. Rule of 9's]

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Classification of Burns

1. Classification by burn depth

① First degree burn: These burns are confined to the epidermis and are generally sun burns. Painful erythema and edema recover spontaneously without special treatment, and most of these burns do not scar.

② Second degree burn, or partial thickness burn: This type of burn affects both the epidermis and part of the dermis. Blisters (bullae) may develop, indicating partial damage of the dermis under the blister. Recently, 2^nd degree burns have been subdivided into superficial, mid, and deep 2^nd degree burn categories.

②-1 Superficial second degree burn (Figure 2): These burns affect the entire epidermis and upper third of the dermis, including the papillary layer of the dermis. Edemas and red areas are painful when disturbed. Most of the burns recover within two weeks and may leave slightly rough and weak scars accompanied by the appearance of wide pores, hyperpigmentation, or hypopigmentation.

[Figure 2. Superficial 2nd degree burn]

②-2 Mid second degree burn: These include the epidermis and the extend to about half of the dermis. Treatment requires 2-3 weeks, and the wound may extend to classification as a deep dermal burn if treated improperly. The scar is more severe than the weak scar observed in superficial second degree burns. Continuous prognoses should be made for more than 3 months in children or for injuries at joint areas with much momentum so that the burn does not develop a hypertrophic scar.

[Figure 3. Mid 2nd degree burn]

②-3 Deep dermal burn: This type of burn affects the most reticular layer of the dermis and extends down to about 3/4 of the dermis. It requires 3-4 weeks of treatment, sometimes including even escharotomy and skin grafting, and leaves severe scars, with high possibilities of developing into hypertrophic scars. Skin grafting should sometimes be considered for children, at the finger joints or other joint areas. Inappropriate treatments, including drying up of early burns, dressing which prevents circulation, or measures liable to infection, may worsen the burn to a third degree burn.

③ Third degree burn, or full-thickness burn (Figure 3): This type of burn affects more than 3/4 of the dermis and makes the skin look pale like beeswax, brown, or black, with a dry leathery texture and even the development of thrombi in some cases. External stimulus does not trigger pain or any sensation. Recovery takes from weeks to months since most of the pilosebaceous organs, which are essential for external wound recovery, are damaged, preventing epithelialization from the lower layers of the skin. The recovery time can be shortened by performing skin grafts. Narrow wounds and wound contractions can recover in some cases via slow epithelialization, but skin grafting or skin flaps are more beneficial in terms of both aesthetics and functionality.

[Figure 4. 3rd degree burn]

2. Classification by burn size

① Minor burn: A second degree burn accounting for up to 10% of TBSA in children and up to 15% in adults, or a third degree burn accounting for up to 2% of TBSA regardless of age.

② Moderate burn: A second degree burn accounting for 10-20% of TBSA in children and 15-25% in adults.

③ Major burn or critical burn: A second degree burn accounting for 20% or more of TBSA in children and 25% or more in adults, or a third degree burn accounting for 10% or more regardless of age. Not very extensive burns involving 1) critical body parts such as the face, hands and perineum; 2) injuries via inhalation; 3) severe injuries via electrical or chemical means; 4) fracture or other serious trauma; and 5) preexisting diseases, such as severe diabetes or cardiopulmonary diseases are all also termed as critical burns and included in the major burn category (Table 1).

[Table 1. Classification of burns by severity]

Management of acute burn wound management

The pathophysiology of burned tissues should be first understood to manage burns properly.

Pathophysiology of skin injuries by high temperatures

1. High temperature induces rapid denaturation of proteins as well as cell injury. The degree of tissue damage is proportional to the temperature and duration of exposure, and can also be determined by the medium of heat transfer. Hot water transfers heat more rapidly to tissues (scalding burns), whereas contact thermal burns cause deeper injuries. Burns may occur not only by a very high temperatures, but even at only 6℃ from core temperature (37℃) as low-temperature burns. Body cells may be damaged and thrombi may develop immediately from a body surface temperature of 60℃. People with thin skin, children or elderly people may suffer deeper burns more easily.

[Table 2. Water temperature and exposure time that can cause full-thickness burns]

2. Inflammation-mediated injuries (1-3 days after original infliction)

Tissues can be damaged not only by direct tissue damage via heat but also by toxic mediators, produced by generally or locally activated inflammatory responses. Inflammatory response is required in the process of would recovery, but excessively produced oxidants or proteases may aggravate capillary endothelia and damage skin cells. Protease, among other proteins, directly damages recovering tissues and neutralizes growth factors, while oxidants damage cells or denaturize proteins while furthering inflammation. Activities of these mediators need to be prevented in the early phases of recovery.

3. Ischemia-induced cell injury

Injured capillaries continue to develop thrombi and induce more severe ischemia and tissue necrosis. Systemic hypotension and local circulatory disorders also induce similar effects.

4. Delayed injury

Tissue damage may continue even beyond what is caused by the initial burns and mediators. More specifically, eschar on the burned area, bacterial colonization, mechanical trauma, and even topical antibacterial agents may be factors in developing complications later on. Excessive neutrophils and intense proteolytic activity at the site of injury can delays recovery.

5. Three zones of injury (Figure 5)

Another important concept of burn management is dividing the burned area to three zones. This more abstract concept attempts to use tissue reversibility to switch a zone of stasis to a zone of hyperemia, which can be recovered within days, by intensive treatment in the early phases of the burn.

① Zone of coagulation or zone of tissue necrosis: This irreversibly damaged zone requires escharectomies to prevent tissue necrosis.

② Zone of stasis or zone of tissue injury: This zone develops necrosis within 24-48 hours without special treatment. Continuous fibrin deposition, vasoconstriction and thrombosis leads to ischemia and cell damage. In order to prevent the burn from extending into a deeper layer, a proper environment should be made early on to gain an opportunity for tissue recovery. Flushing the wound with cold running water, administration of an anti-inflammatory drug, and providing a damp wound environment immediately after burn infliction may be helpful.

③ Zone of hyperemia: This zone has less cell damage and is reversible within days in the absence of dryness, circulatory disorder due to edema, infection or severe inflammatory response.

[Figure 5. Diagram showing zones of coagulation, stasis and hyperemia]

※ Zone of stasis: reversible when treated, but irreversible when not treated

※ Zone of hyperemia: becomes improved

6. Wound conversion: This refers to conversion of a deep second degree burn to a third degree burn and may occur when circulation at the affected area is reduced, treatment is delayed, and the presence of excessive inflammation or sever infection hinders the burn. This also refers to conversion from a zone of stasis to a zone of coagulation.

-To be continued-

▶ Next Artlcle : #2. Emergency Care of Burn

[Laser Resurfacing] #1. History of Laser Resurfacing

Laser resurfacing is safer and more effective than dermabrasion or chemical peeling and has wide applications. Laser resurfacing often brings drastic improvements in scar or facial wrinkle removal. Professor Park Seungha, the bestselling author or ‘Laser Plastic Surgery’ is an expert in laser resurfacing in Korea. Professor Park is working hard to promote positive image of laser treatments in patients through education on correct use of laser. With this article, Professor Park intends to share his extensive experience in laser resurfacing technology with our readers. This article will provide helpful tips to plastic surgeons who perform laser resurfacing procedures.

The first time I witnessed the procedure of facial laser resurfacing was when I visited Dr. Fitzpatrick’s clinic in La Jolla, California in 1995. The CO₂laser (Ultrapulse), which wasprohibitively expensive at the time was first introduced in the university hospital which opened the era of laser resurfacing in Korea. Before this I had only witnessed laser resurfacing on videos but watching the procedure in person witnessing the subsequent effect made me trust. Laser did not have a very positive public image in the past. The Argon laser that was introduced in Korea in the 80s was effective against nevus or mole removal but also caused depigmentation or scar and was not in high demand despite its novelty.



During my trainee days, my professor used dermabrasion with low conviction on patients with smallpox scars and often warned us that any dermatologist with a good track record could suffer a major career setback with one mistake with this procedure. Dermabrasion caused a lot of bleeding as it surgically removes the skin layer. The patient suffered a lot of pain as the blood clots and crusts remained after the procedure, not to mention the rather unappealing and sickly appearance of the face post-procedure.



Patients with flame burn in the face often visited the plastic surgery clinic. I could see that during the course of the treatment, their skin first developed blisters and redness, but in about a week, the recovered skin was cleaner, more elastic and free from blemishes than the pre-burn skin. This not only pleased the patient and his or her caretaker but many doctors would have thought if they could burn the skin just enough to cause this kind of recovery, they would bring back magically clean and rejuvenated skin.

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The introduction of CO₂ laser in dermatology

Laser resurfacing uses adjusted burning of the skin to give rejuvenating and clarifying effect. I have been performing laser resurfacing since the mid-90s and held several symposia on laser resurfacing at our hospital to educate Korean doctors the benefits of the procedure. I also performed live surgery to allow real time observation of the procedure in the operation room as they do in the US. However, a more than expected number of people signed up for the observation and we had to air part of the procedure on a screen in the auditorium. At the time, laser resurfacing was a new field and a lot of the professionals related with this field were greatly interested in the live surgery presentation which was a rare occasion in Korea.



A patient of mine who received the laser resurfacing on the entire face about 10 years ago came back recently for a repeat procedure. This patient received the same procedure from other clinics but the effect was not as good as 10 years ago and wanted to get the same procedure. She said she recommended the laser resurfacing procedure to those around her. Immediately after getting laser resurfacing and before the skin recovers, the face still has red splotches. This may give people a negative idea about laser. However, if you wait 2-3 months after the procedure you can see a dramatic improvement of the skin.



Chemical peeling was once popular as it was believed to rejuvenate and clarify the skin. Chemical peeling was actually performed centuries ago in Europe as a secret treatment and disappeared over time. Some had positive results, however, it was not a safe procedure at the time and resulted in horrible scars and serious sequelae in some cases.

[laser resurfacing before and after (left shows skin before laser resurfacing, right shows skin after laser resurfacing)]

Peeling involves removal of the outer layer of the skin to allow skin regeneration by skin appendages. Just like the onion, the skin resurfaces in the same way regardless of how many times the outer layer is removed. The most important principle in peeling is to maintain the appropriate depth of removal. If one fails to do so, skin regeneration is not obtained and irreversible scar may result.



I once watched a movie titled ‘Faceless.’ Most people would have found this movie rather unrealistic and farfetched but as a plastic surgeon, I could relate to the story and it left quite a lasting impression on me. The main character was a plastic surgeon who ran a famous rejuvenation clinic in Paris. He brought youthful energy back to elderly patients and applied secret substance on their faces to make them appear younger. He makes a mistake with one female patient and turns her face into a large lump of scar tissue. The aggravated female patient decides to take a revenge on him, and pours hydrochloric acid on his younger sister’s face making her horribly disfigured. In this story, the magical substance that the doctor applied on his patients’ faces, could be comparable to chemical peel. To treat his sister’s face, he kidnaps a young woman at night and transplants her healthy skin to his sister’s face. He performs total facial skin graft just as in the movie ‘Face Off’. However, the patient’s body keeps rejecting the graft and the doctor brings in a German doctor who’s an expert in in vivo experiments. He continues to try facial graft on his sister, however, his efforts keep failing. The plastic surgeon murders the young women whom he kidnaps and uses their blood to inject into elderly patients for rejuvenation effect. Finally, he gets arrested by the police who have been investigating a case of serial kidnapping and murder. This movie dealt with rejuvenation therapy, chemical peeling, sequalae of chemical peel, facial graft and graft rejection, which were all pertinent topics in plastic surgery. Whenever I hear of chemical peeling, I think of this movie.



The most important aspect of peeling is adjusting the depth of penetration as the facial skin has differing thickness depending on the area. The thinnest skin is the eyelids and the skin in the neck is also thinner than one might expect. The thickness of the skin is determined by the thickness of the dermis rather than epidermis. The thickness of epidermis varies from 0.11mm at the thinnest to 0.15mm in thicker regions. The thickness of dermis is about 0.2mm in the eyelid and neck and 1.0~1.5mm in the forehead and cheek. Including the hypodermis, thin skin is about 0.5mm and thick skin is around 2.0mm in depth.



Chemical peeling has serious side effects

The eyelid and neck where the dermis is thin and thus more susceptible to have problems after chemical peeling have less pilosebaseous units which are dermal appendanges that regenerate the skin. Deep peeling in these regions results in scars without achieving skin regeneration.



As the eyelid and neck have thin skin, dermabrasion is dangerous and can cause the skin to roll in. In these areas, chemical peeling is not suitable as it could create irreversible scar. On the contrary, laser resurfacing can adjust penetration depth with laser output and can perform peeling in weaker skins with optimal depth. In laser resurfacing, as the irradiation depth is maintained at 0.2mm~0.5mm, it is safe and can be performed with desired depth. As it is safe and unlikely to leave scars, it can be used to perform deep penetration peeling as well.  When irradiated on the skin, the laser coagulates the capillaries and lymph nodes minimizing bleeding and edema. It also blocks nerve endings thereby causing little pain after the procedure. There is also none of the bleeding or edema that often follow dermabrasion and the patient feels more comfortable during the procedure.



Chemical peel results in thick crusts on the skin and the penetration depth can be measured only when the thick crusts come off. The depth varies depending on the concentration of the peeling agent, number and force of rubbing and existence of additives. In general, chemical peeling is suitable as mild skin scaling or esthetic care of the skin, however, is riskier as a deeper form of peeling. Laser resurfacing allows a markedly safer and simpler procedure compared to chemical peeling and has excellent rejuvenating effect. Thus, it has a wide variety of applications in esthetic treatment of the skin. 



Laser resurfacing treats skin diseases through the principle of skin rejuvenation and brings marked improvement of wrinkle, elasticity, and scar removal, etc. With accurate understanding of the principle, indications and contraindications of laser resurfacing as well as pre- and post-procedural skin care methods, it can be used to bring satisfactory results for both patients and doctors.  



Reference: Laser Plastic Surgery, Koonja Publishing, 2008, Seoul

- To be continued-

[Case Series in Dermatologic Surgery] #1. Epidermal Cyst Surgery

Dermatology performs various surgical procedures. However, the number of surgical procedures is decreasing relative to the increased popularity of noninvasive procedures with recent introduction of lasers. The information on dermatological surgery seems lacking accordingly. This article is a dermatological case series by Professor Kim Il-Hwan at the Department of Dermatology in Korea University Ansan Hospital. Prof. Kim will present patients he had treated in the past, with detailed explanations on the diagnoses, examinations and the course of treatments as well as vivid clinical photographs. He will also present analyses about the diseases and treatments. This dermatological case study by Prof. Kim Il-Hwan will be of help for treatment of various diseases in the clinical setting.

Case #1

■ Patient: a 30-year-old male

■ Chief complaint: He visited the hospital for a cystic subcutaneous nodule palpated at the right nasolabial fold for 10 days before the visit.

■ Past medical history and family history: The lesion was resected at private clinics for the last 2 years but recurred 3 times. The symptom reappeared without any specific triggering factor.

■ Skin findings: Palpation of a skin-colored cystic subcutaneous nodule at the right nasolabial fold (Figure 1)

■ Surgical findings: Excisional biopsy was performed and the well-defined fibrous cyst was completely dissected (Figure 2).

■ Histology findings: The epidermal cyst had layered epithelial cells containing a granular layer and inside the cyst were keratin contents and some of fragmented remaining wall (Figure 3). 

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[Figure 1. A subcutaneous nodule is palpated at the right nasolabial fold.]

[Figure 2. Well-defined pocket-like cyst is dissected.]

[Figure 3. Histological image (x12.5)]

Analyses on the examination and diagnosis

1. Diagnosis: Commonly diagnosed by confirming an opening of the cyst or the characteristic odor and confirming mushy palpation. When the opening is hard to find or it is necessary to confirm whether it’s a cyst, the opening can be found by injecting normal saline with a syringe and the lesion can be diagnosed as a cyst when nucleated keratinocytes and wavy keratin materials are detected by Wright-Giemsa stain of the extracted and smeared content.



2. Necessity of examination: Generally unnecessary, although bacterial culture is needed in case of infection without response to antibiotics. Ultrasonography, CT or MRI can be performed for imaging when the lesion is large and deep. 



3. Histology findings: The wall of the epidermal cyst is consisted of layered epithelial cells containing a granular layer and inside the cyst are keratin contents. Older lesions become calcified, and ruptured lesion often presents foreign body granuloma reaction. 





Treatment and surgical methods for each epidermal cyst 

1. Excision: wide excision, mini-incision, punch excision

2. Removal by case and size

1)    Size ≥2㎝, past history of rupture or squeeze or recurrence after mini-incision technique – the lesion including the cyst wall is removed completely by wide excision.

2)    Size ≤1㎝ or lesion on the face – mini-incision technique is performed.

3)    In the presence of active inflammation – the inflammation is treated first.

Epidermal cyst surgery and surgical technique

1. Wide excision: As a standard treatment, the cyst is completely removed with the surrounding tissue after fusiform incision and subdermis dissection. This method is used mostly in areas other than the face as novices take much time for the dissection and leave a large scar from the incision.



2. Mini-incision and punch excision: 2-3㎜ incision or a disposable biopsy punch is used to cut a hole, through which the content of a cyst is squeezed out with suction, dissected pocket is carefully removed. This method reduces hemorrhage, recovery time and scar formation but requires extensive hands-on experiences due to a higher risk of recurrence after incomplete removal. The author often uses a combination of both wide excision and mini-incision technique. More specifically, an incision is made minimally according to the size of a cyst so as to reduce scar formation, and an opening for removal of the content is made to reduce dissection.



3. Surgical techniques required for complete removal: In order to obtain visibility during the surgery, bleeding should be minimized and hemostasis should be applied at the right time. 1% dental lidocaine containing epinephrine should be used for local anesthesia before the surgery, and suction should be applied during the surgery to find accurate bleeding point. Hemostasis is available mostly by electrocautery. Blade No. 15 is used, instead of scissors, for precise dissection.



Frequent recurrence and measures to be taken

1. Treatment of inflammatory and infectious cysts: Inflammation or infection should be treated beforehand for easier rupture of the lesion, making the cyst wall more definite and enabling complete removal of the cyst. An inflammatory and swollen cyst with pain can rupture easily while attempting to remove it before treating the inflammation, and if only incision and drainage are performed, the remaining cyst wall may cause recurrence. In this case, 10-20㎎/㎖ of triamcinolone can be injected to the surrounding tissues, which can calm the inflammation within several days allowing easier removal. Infection is generally uncommon and is mostly a secondary inflammatory response to a foreign body when the cyst wall is damaged and the keratin content is leaked to the surrounding tissues.



2. Treatment of a ruptured cyst and cases of rupture during removal: A large cyst ruptures easily during a surgery if the incision line is small. Once ruptured, thicker dissection can be attempted again on the other side of the ruptured cyst wall for complete removal. In this case, a knife, rather than small scissors, is suitable for a precise procedure. If dissection is not available on the other side either, the remaining tissues and expected regions should be removed at once together with some of fat layer tissues, and suspected remnants can be removed with a curette. 



References

1. Mehrabi D, Leonhardt JM, Brodell RT. Removal of keratinous and pilar cysts with the punch incision technique: analysis of surgical outcomes. Dermatol Surg 2002;28:673-7.

2. Zuber TJ. Minimal excision technique for epidermoid(sebaceous) cysts. Am Fam Physician 2002;65:1409-12, 17-8, 20.

3. Diven DG, Dozier SE, Meyer DJ, et al. Bacteriology of inflamed and uninflamed epidermal inclusion cysts. Arch Dermatol 1998;134:49-51.

4. Lee HE, Yang CH, Chen CH, et al. Comparison of the surgical outcomes of punch incision and elliptical excision in treating epidermal inclusion cysts: a prospective, randomized study. Dermatol Surg 2006;32:520-5.

5. Marks J, Miller J, editors. Lookingbill and Marks’ Principles of Dermatology 3rd ed: Saunders; 2006.

- To be continued -

▶ Next Artlcle : #2. Pigmented Basal Cell Carcinoma on the Face Mimicking a Nevus

[The Principle and Application of Laser(with focus on medical lasers)] #1. The birth of laser and its characteristics

Laser procedures in the field of dermatology and plastic surgery will continue to grow in importance in the future. It requires medical as well as general knowledge in laser engineering to repeat the benefits shown in clinical trials on laser in actual patients. D&PS publishes series of articles on the extensive and detailed views of an engineer, developer and manufacturer of lasers to provide doctors who use medical lasers with insightful tips. Starting with this article, we will cover all topics on the principle and application of laser as well as types of laser used in dermatology and plastic surgery. The below article was contributed by Dr. Chu Hong, an authority of laser engineering in Korea. Dr. Chu served as a senior researcher from 1985 to 2002 at Korea Institute of Science and Technology and has been the CEO of LASEROPTEC co., ltd. since 2000.

1. History behind the birth of laser

1-1. What is laser?

The term ‘laser’ was coined from putting together the initials from ‘Light Amplification by Stimulated Emission of Radiation.’ The direction, frequency, and phase of the light created by stimulated emission, that is the photon, is completely identical with those of the incident photon stimulating emission of radiation. Therefore, laser has excellent collimation, focus, and coherence as well as very high brightness.



Laser is one of the most notable inventions in human history and since its creation in 1960s, diverse types of laser have been developed to be widely used in basic sciences, engineering and medicine, etc. To better understand the phenomenon of laser, it may help to imagine the acoustic system. The sound system consists of the microphone, amplifier and speaker. The microphone converts the sound input into electronic signals and the amplifier magnifies these signals so that the speaker can produce sound with adjustable volume. If you place the microphone right in front of the speaker, you will hear a sudden burst of a loud noise. This can be explained as the following. When a very low volume of sound is input through a microphone, this sound is amplified and output through a speaker. This amplified sound is re-input into the microphone to be repeated in a positive feedback, the end result of which is the ear-splitting noise. This process resembles that of a landslide and also the production of great laser output. The details of this process will be discussed in ‘Generation of Laser.’

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1-2. History of laser

a)Niels H. D. Bohr (1885-1962): Bohr was a Danish physicist who contributed greatly to the advancement of quantum mechanics. In 1913, Bohr was able to accurately demonstrate the spectrum of a hydrogen atom using the hypothesis on a new atomic orbital and emission of photons, on which the new theory of quantization of matter was founded. This achievement won him the Nobel Prize in Physics in 1922.



b)Einstein (1879-1955): Einstein was the most respected physicist and intellect of the 20th century. He proposed revolutionary theories such as special theory of relativity, photoelectric, Brownian movement, and general theory of relativity, etc. and won the Nobel Prize of Physics in 1923.



Einstein provided a more systematic analysis of the hypothesis involving Niels Bohr’s atomic model. The hypothesis posits that an electron can jump between quantized orbits by absorbing(induced absorption) or emitting(spontaneous emission) a photon. In Bohr’s frequency condition, atoms’ emission of light in high energy levels was not related to the existence of external light.



In 1917, Einstein suggested that a second possibility of light emission was needed considering the thermal equilibrium. This introduced the concept of stimulated emission, light emission from the influence of surrounding light. At the time, this was a groundbreaking idea. Along with this concept of stimulated emission, Einstein was able to establish a comprehensive theory on the light absorption and emission of the atom and this provided an essential step toward invention of laser 40 decades later. Einstein incorporated the new concept of stimulated emission to Bohr’s hypothesis of the interactions between light and the atom (stimulated absorption, spontaneous emission) and discovered an important basic principle of laser.



When Einstein theoretically demonstrated the existence of stimulated emission as part of the interaction between light and matter in 1917, he laid the conceptual foundation for introduction of laser. However, there were no practical methods to empirically prove this idea and only 40 years later, in 1953, C.Townes and A.Schalow of the Bell Lab in USA empirically demonstrated for the first time that stimulation emission from ammonia gas (NH3) to microwave (24GHz) was possible.



In 1958, Townes and Schalow went on to show that light amplification through stimulated emission was possible in the visible light range. In 1960, T. Maiman at Hughes Research Laboratories brought into existence red ruby laser in the visible light range of 694.3nm. He inserted a synthetic ruby crystal created from dopping a small amount of chromium in aluminum oxide crystal( sapphire) in the center of a spiral-shaped flashlamp. By supplying high electric voltage and creating a spark across the electrodes in the flashlamp tube, he could input strong light into the ruby and succeeded in laser oscillation. This achievement led Townes to be jointly awarded the Nobel Prize in Physics in 1964 with Russian scientists Basov and Prokhorov. In 1961,immediately after ruby laser oscillation, oscillation of the world’s first gas laser, helium-neon laser (He-Ne Laser) was achieved by Javan, etc. Following this, research on laser saw explosive growth and by 1960s, most of the important lasers used today were developed. In the 70s and 80s, applied research on laser flourished and laser now took on a more important status in various areas and applications.



2. Characteristics of laser

Laser beams have three unique characteristics that set it apart from the natural light or lamp light; monochromatic, coherence, and collimation. Due to these characteristics, laser is being used extensively in various fields of medicine and industry. Therefore, accurate understanding of each of these properties of laser is necessary to find appropriate use of the laser. As laser is a tool, without the knowledge of the tool, predicting the results of using this tool becomes difficult. The following passage explains the unique characteristics of laser that are not found in general sources of light.



2-1. Monochromatic

The laser beam is single-wavelength, unlike other types of light and progresses straight forward without dispersing. Light from a burning material or light from fluorescent lamps are emitted from heated atoms or naturally created from individual atoms. This type of light, although originating from the same type of atoms or molecules, contains lights of widely different wavelengths. The light emitted from individual atoms or molecules is a collection of different lights that are not correlated to each other. However, the laser beam is monochromatic with a single wavelength and is continuous light with an even phase. Observing the spectrum of this light through a dispersing prism shows a very thin line spectrum on the screen. In other words, the laser beam is monochromatic with identical phase and it is also called coherent light or light with high coherence. Using a lens, the laser beam can be focused into a light beam of very small area (small enough to be measured by the wavelength).



Using this monochromatic characteristic, the laser can be selectively absorbed, reflected and transmitted on a material. For example, a medical laser, especially Q-switched Nd:YAG laser used in dermatology is easily absorbed in black and dark brown in the wavelength of 1064nm but is not readily absorbed in and penetrates other colors. That is, this laser does not respond to other pigments. Thus, the 1064nm wavelength is used to remove tattoos or pigmentary lesions such as melasma. In addition, the wavelength of 532nm is readily absorbed in yellow, red, dark brown, and blue, etc. making it ideal for treatment of Ota’s nevus and Becker’s nevus, etc. In order to treat pigmentary lesions, the knowledge of the pigment and the type of laser that is absorbed into that pigment is crucial for optimal treatment effect.



2-2. Coherence

Coherence refers to the degree of the wave phases that are in constant relative phase spatially and temporally. This is the most important property when it comes to application of light’s interference. In general, interference patterns are not visible with the light seen in everyday life, that is the sunlight or light from bulbs, as it has very low coherence. Coherence can be largely categorized as spatial and temporal as below.



1) Temporal coherence: the correlation of a light wave’s phase at different points along the direction of propagation of light. This is a measure of how close the light source is to single-wavelength(monochromatic).



2) Spatial coherence: the correlation of a light wave’s phase at different points transverse to the direction of propagation of light. This is a measure of how uniform the phase of the wavefront is.



Laser is in essence coherent, though in differing degree depending on the structure of a resonator. If the output of the laser is single mode, spatial coherence can be secured and the degree of temporal coherence depends on the wavelength bandwidth (△λ) of the laser. The degree of temporal coherence is also known as coherence length (Lc= λ2/△λ). This is related to the fact that temporal coherence is often used to create interference and interference is not observed in structures with larger optical path difference than this coherence length. Using this coherent property, measuring devices such OCT (Optical Coherence Tomography) can be operated for precise measurement of skin tissues.



2-3. Collimation

As only the light beam going parallel to the optical axis determined by the opposing mirrors (full reflection and partial reflection mirrors of the laser resonator) is amplified, it is collimated, or has linear progression in one direction. This property differs from thermal-radiated light that travels in all directions. Due to collimation, the laser beam can be used for precise alignment and it is possible to irradiate the laser beam accurately on the desired area using the reflection mirror. However, laser beam has the characteristics of a wave and can be affected by diffraction which results in some degree of divergence angle. The divergence angle differs depending on the structure of a resonator. In case of a gas laser (CO2 laser, He-Ne laser, etc.) the divergence angle generally does not exceed 1 mrad (0.05o).



Using a lens, a laser beam with strong collimation can be focused into a very narrow light (narrow enough to be measured by the wavelength), which allows maximal energy per unit area (Joule/ cm2) or power per unit area (Watt/ cm2) on the focal plane. On the contrary, the normal light travels in many different directions from the light source, creates light source image near the focus and cannot be condensed into a narrow beam using a lens. To minimize the light source image appearing near the focus, the lens should be placed infinitely far from the light source or the light source should be reduced to as small as a dot. However, this greatly weakens the light intensity. Therefore, it is very difficult to collect large light intensity into a small point using the normal light. As this is possible with the laser beam, it can be used to focus energy within only a few um of diameter for precision cutting of the skin or bone.

- To be continued -

▶ Next Artlcle : #2. Development Process and Types of Lasers

[Regenerative Surgery] #1. Introduction of Regenerative Surgery and Regenerative Medicine

Recently, there is growing interest in regenerative surgery, one of the newer fields in plastic surgery. Currently, many types of regenerative surgery involving stem cell, PRP (platelet-rich plasma), and cell therapy, etc. are being performed. Laser along with other devices are also being used in clinical practice. Regenerative surgery or regenerative medicine is still a rather obscure field as it was recently developed. It also covers a wide range of applications which requires publication of more organized and coherent data. In this light, Professor Park Eunsoo of Plastic Surgery, Bucheon Soon Chun Hyuang University Hospital, who is an expert in regenerative surgery in Korea, contributes a series of articles on regenerative surgery. In this series, Professor Park will systematically discuss many different fields of regenerative surgery including stem cell, PRP, cell therapy, tissue engineering, and laser, etc.

Significance of stem cell and PRP in regenerative surgery

Recently, the Mainichi Shimbun of Japan reported “Shinjuku Clinic Hakatawon, a dermatologist clinic located in Hakata, Fukuoka, has been receiving patient referrals from a Korean bioventure since May 2012 and been injecting the stem cell the Korean company has cultured. Over 500 Korean patients are being treated at this clinic every month”.

Another Japanese newspaper controversially reported “A clinic in Fukuoka, Japan is performing stem cell surgery in Korean patients without safety verification.” Another report’s headline read ‘Cha Hospital of Korea improves cerebral palsy with a donor’s cord blood stem cell’. This procedure took place from May to October, 2010 involving 31 patients with cerebral palsy. Cha Hospital used the stored donor cord blood approved for clinical trial. Through immune compatibility test, they injected the cord blood that was compatible with the patient into the periphery veins. Follow-up of 6 months after injection of the cord blood showed improvement in normal body posture and motor activity as well as cognition. Magnetic resonance imaging (MRI) results also showed that the cell density in the areas on brain overseeing motor system and sensory nerves increased. Moreover, positron emission tomography-computed tomography (PET CT) that evaluates the cerebral glucose metabolism confirmed activation of the basal ganglia and thalamus which play an important role in motor ability and cognition.

Typing in the term ‘stem cell’ into an internet search engine retrieves related search words such as ‘stem cell cosmetics’, ‘stem cell breast enlargement’, ‘stem cell treatment of baldness’, ‘stem cell fat transplant’, and ‘stem cell diet’, etc. In addition, numerous clinics and hospitals are actively advertising on the internet cell-assisted fat transplantation, stem cell fat transplantation, stem cell breast augmentation, PRP (platelet-rich plasma) autologous cellular skin regeneration, PRP injection, PRP treatment of alopecia, and PRP facial autologous fat transplantation, etc.

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Stem cell and PRP technologies are expected to provide new solutions to difficult diseases and open up a new chapter of advanced medicine. However, physical, chemical and biological modification of stem cells including ex vivo culture and proliferation, etc. may cause genetic change and other side effects during processing and administration, which calls for safety verification. In other words, for clinical application of these procedures, efficacy and safety must be secured. Up to now, three stem cell therapy products have been approved and commercialized in Korea.

The first product is a treatment of acute myocardial infarction called Hearticellgram-AMI (PHARMICELL). Introduction of this product earned Korea the title of “the first country in the world to develop commercialized stem cell therapy’. Hearticellgram-AMI is a treatment that extracts mesenchymal stem cells (MSCs) from the patient’s bone marrow and after four-week isolation culture in the laboratory, it is formulated into an injection and administered in the heart.

The second product was Cartistem (MEDIPOST) which was used in the world’s first stem cell surgery conducted at Sun Orthpedics Clinic in Korea. Cartistem is the world’s first allogenic cord blood derived MSC treatment that was approved for treatment of knee cartilage defects in patients with degenerative osteoarthritis or osteoarthritis due to repeated trauma.

The third stem cell product was Cupistem (ANTEROGEN). Cupistem is an autologous adipose derived MSC treatment. It earned conditional approval for treatment of fistula in Crohn’s disease. This also was the first in the world for autologous adipose derived MSC treatment. It is well known that the commercialized stem cell therapy uses stem cells that can differentiate into a variety of body tissues, or undifferentiated cells. As they can differentiate into many types of tissue cells under the right conditions, they can be applied to regeneration of damaged tissues.

The stem cell or PRP procedures can be categorized as regenerative surgery. These two types of procedures may be the most well-known and widely performed of regenerative surgery. What are other areas of regenerative surgery besides stem cell and PRP procedures? Before we can answer that question, we should first understand the definition of regenerative surgery.

Definition of regenerative surgery

‘Regeneration’ will be the key word that plays an important role in the medicine of the near future. The dictionary definition of regeneration is ‘1. Revival from death. 2. A depraved or hopeless person rediscovering a correct way of life. 3. Reprocessing an old or broken object for use again’. The three tools for tissue regeneration in my field, plastic surgery, may be fat (adipose cell), adipose-derived stem cells, or PRP. However, AlloDerm, also known as regenerative tissue matrix, and many other artificial dermal substitutes have entered the market. Various products are introduced and being developed including commercialized growth factors (EGF, FGF), nucleic acid preparations including PDRN (polydeoxyribonucleotide) that are advertised as a tissue regeneration activator, and autologous fibroblast culture, etc.

The word ‘plastic’ in plastic surgery originates form the Greek word ‘plastikos’. This word has the meaning ‘to mold or give form’. Modern-day plastic surgery has its roots in this meaning. Plastic surgery is often understood from the perspective aesthetic enhancement, however, a more correct recognition of it may be that it corrects physical or structural defect or deformity for restoring normal function. Plastic surgery is a specialized surgical field that deals with this type of correction. In other words, plastic surgery is a type of surgery that corrects congenital or acquired physical deformity or defect to restore the normal function and form. Plastic surgery deals with all parts of the external body from head to toe. Moreover, plastic surgery includes cosmetic surgery and reconstructive surgery. Aesthetic surgery is also used to replace the term plastic surgery, however, this may be limited to the efforts to correct non-defective appearance for enhanced aesthetic effect.

On the other hand, reconstruction refers to correction and restoration of deformity or defects to normal. All types of congenital deformity including the cleft lip and cleft palate, facial deformation as well as burn scar and physical trauma from accidents, can be subjects of reconstruction which is part of plastic surgery. Moreover, reconstructive plastic surgery can be performed in combination with tumor removal. The most representative example of this is breast reconstruction performed after mastectomy.

Functional and aesthetic effects are considered in reconstructive surgery as well and the distinction between aesthetic plastic surgery and reconstructive surgery does not carry much meaning other than categorization of the patient undergoing surgery as having normal function or not. Based on this information, the regenerative surgery can be defined. First, in regenerative medicine, replacing, restoring or improving the function of congenital defect or accidental tissue or organ damage is carried out. Organ transplantation, reconstructive surgery, artificial organ transplantation, tissue engineering and cell therapy are among the methods of treatment available in regenerative medicine.

Therefore, regenerative surgery could be defined as use of the above methods or tools for tissue regeneration or application of techniques based on regenerative medicine for surgical treatment. The definition of regenerative surgery proposed in published literature differs slightly but the a study by Scala et al., published in 2012, defines regenerative surgery as ‘a new medical field in which stem cells are induced to migrate to the damaged tissue with the use of biological products (PRP, gel, etc.) or stem cells to encourage tissue proliferation and eventual tissue recovery’. In addition, the definition of regenerative surgery offered by ISPRES (International Society of Plastic Regenerative Surgery) at its website discusses reconstructive surgery using adipose-derived MSCs. The website also goes into three advantages of this new field.

First, regenerative surgery allows the possibility of minimally invasive autologous transplants. Adipose-derived MSCs are isolated through centrifugation and lipoaspiration or can be extracted and directly transplanted during surgery.

Second, with regenerative surgery, cell expansion is not necessary.

Third, regenerative surgery has made age no longer a barrier. Adipose-derived stem cells are abundant in elderly patients and have excellent regenerative effect.

Regenerative surgery and tissue engineering

In April 2012, Moral et al. published a paper in the field of orthopedics and sports medicine which discussed the link between science and surgery in regenerative surgery. This paper argued that a surgeon can repeat the benefits of regenerative medicine proven in laboratory in real patients in sports medicine.

In fact, the term ‘tissue engineering’ was first used by Joseph Vacanti of Harvard Medical School and Robert Langer of MIT, pioneers of the field in the late 1980s. The definition of tissue engineering is ‘the science that aims to restore, preserve or improve the function of an organ or tissue through developing and transplanting a biological tissue by combining basic concepts of bioengineering and engineering’. Therefore, the ultimate purpose of tissue engineering is to provide patients a healthy, disease-free life through clinical application of technology. Recent advances in related fields such as material engineering, drug and gene carrier studies, stem cell studies, and nanotechnology, etc. have expanded the application of tissue engineering and increased its use in the clinical setting. This has allowed it to evolve into a high-tech medicine that befits the name regenerative medicine.

In the case of organ transplantation, transplanting the donated organ to a recipient can bring optimal treatment effects, however, the number of donated organs falls far short of needed organs and an alternative treatment is urgently needed to tackle this problem. Reconstructive surgery uses a variety of materials to create an organ similar to the damaged organ for transplantation. It is mainly applied as part of plastic surgery and the function of transplanted material is limited.

Artificial organ transplantation refers to transplantation of metal or ceramic organs to replace the mechanical function of the damaged organ. Prosthetic hip joints, cardiac valves, and intraocular lens, etc. are currently the most widely used artificial organs. However, this method is limited to organs with little biological functions and deterioration of the material in the long-run may cause problems. Therefore, use of live tissues for tissue regeneration or function enhancement may solve the fundamental problems. Cell therapy is part of such endeavor. With cell therapy, cells or pluripotent stem cells are injected in the desired organ for regeneration. Some argue that this is the start of regenerative medicine. Moreover, tissue engineering combines the use of materials to supplement the limitations of the cell therapy.

In tissue engineering, cells that compose the organ or tissue or stem cells that may differentiate into such cells are placed into a three-dimensional scaffold (artificial substrate). Then an environment conducive to graft survival is provided through allowing blood flow into the transplant for regeneration of a damaged organ or tissue.

Three essential conditions for tissue regeneration are cells, scaffold (substrate), and blood flow and may also include growth factors or cytokines. According to a study by Smith et al. published in 2011, the three essential elements for tissue regeneration are cells, protein, and scaffold. Unlike artificial organ transplantation, after a period of time, the transplanted artificial substrate is dissolved and replaced by a new organ or tissue with natural cells and extracellular matrix. Therefore, the regenerated tissue grows as the body matures and may last semi-permanently going through the same aging process as the rest of the body.

Degradable scaffolds used in tissue regeneration can be categorized into porous and hydrogel types. Especially, minimally invasive procedure is possible using injectable hydrogel where large amounts of cells can be delivered through a needle.

The next article will take a closer look at the essential elements of tissue regeneration.

References

❶ Regenerative Surgery 3rd e). compiled by Ji Yu, Ilwoo Lee, Koonja Publishing, Copyright. June 10, 2010.

❷ Regenerative surgery for the definitive surgical repair of enterocutaneous fistula. Scala M, Spagnolo F, Strada P, Santi P. Plast Reconstr Surg. 2012 Feb;129 (2):391e-392e.

❸ Advancing regenerative surgery in orthopaedic sports medicine: the critical role of the surgeon. Moran CJ, Barry FP, Maher SA, Shannon FJ, Rodeo SA. Am J Sports Med. 2012 Apr;40 (4):934-44.

❹ Regenerative surgery in cranioplasty revisited: the role of adipose-derived stem cells and BMP-2 Smith DM, Cooper GM, Afifi AM, Mooney MP, Cray J, Rubin JP, Marra KG, Losee JE. Plast Reconst r Surg. 2011 Nov;128 (5):1053-60.

-To be continued-

▶ Next Artlcle : #2. Elements of Tissue Regeneration

[History and Development of Cutaneous Lasers ] #1. Naissance of Cutaneous Laser

This series is intended to investigate the history, theory and indications of medical lasers from the user’s perspective. An explanation about lasers from a clinician who uses lasers in clinical settings will be a practical help to readers. The author of this series is Director of JMO Dermatology, Wooseok Koh. As a an authority on hair removal treatment in Korea, Director Wooseok Koh is well known for having profound knowledge in medical lasers to such an extent as to have obtained patents in laser devices. He also participated in a collaborative research with Dr. R. Rox Anderson, a pioneer in skin laser device, while working as a fellow in The Wellman Center for Photomedicine in Harvard Medical School in the department of Dermatology. Director Koh will vividly deliver his knowledge and experiences in lasers to the readers.

When I was asked to write a series about lasers, I couldn’t help worrying where to start and what to write. As anyone would do before writing, I was not certain if I was qualified for this. But I decided to write this series in the hope that this would be a good opportunity to look back my own thoughts on cutaneous lasers and that a chronological description on the development of cutaneous laser would be of help for clinicians. Nothing happens in one day, but what happened in the past looks as if they occurred individually, in the eyes of people who did not live in that period, due to the limited memory of humans. As an old saying that ‘Rome wasn’t built in one day’, we might say that ‘cutaneous laser was not made in one day’. There might be some parts in this series where I put in a wrong date for my personal experiences in the past due to a slip of memory, but I will try my best not to make such errors affect the overall flow of this series.

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Birth of Selective Photothermolysis

Before laser (Light Amplified by Stimulated Emission of Radiation) was first realized as a ruby laser in 1960 by Maiman, it had gone through physical development not easily understandable for physicians. It is well known that Einstein played a critical role in the process.

Maiman did not develop the whole concepts of laser alone, but he is the one who practically realized the first laser. R. Rox Anderson would be the one who did a similar role for cutaneous laser. The concept of ‘Selective Photothermolysis’, also the title of an article published by R. Rox Anderson and John Parrish in the Science in 1983, was a concept developed through various stages, not an original idea that suddenly came into the world. More specifically, Dr. Anderson created the concept in 1983 by organizing existing ideas, with a little added creativity, and giving it a proper name like the icing on the cake. Since then, the concept of Selective Phototermolysis (SP) has become the foundation for the development and description of almost every cutaneous laser.

Back in the day, research papers on medical lasers can be found from 1960s, but systematic studies starts to be found from 1970, possibly because lasers were studied mainly for military purposes in 1960s. All efforts were focused on developing a laser weapon or lauching apparatus at that time but such studies were at a standstill without a tangible result. In the late 1960s, a lot of scientists turned to the medical world when it became difficult to receive any more research funds for military purposes.

For this reason, studies or textbooks on medical lasers have started to be published from 1970s, although sporadic. Leon Goldman was interested in lasers so much as to publish a textbook titled ‘Lasers in Medicine’ in 1971. He was the first executive director of American Society for Laser Medicine and Surgery and his name is on the award presented by this society. Various but sporadic studies on medical laser over the course of 10 years were focused on the skin and eyes in the early 1980, because laser pulse can be easily delivered to the skin and eyes, although it is difficult to be delivered to targets inside the body. In 1981, R. Rox Anderson and J. Parrish published two important studies on laser titled ‘The optics of human skin (J Invest Dermatol.)’ and ‘Microvasculature can be selectively damaged using dye lasers: a basic theory and experimental evidence in human skin (Lasers Surg Med)’.

In 1999, at the entrance of The Wellman Center for Photomedicine: R. Rox Anderson (far left of the front row), Thomas B. Fitzpatrick (third from the left in the front row), and the author (right side of the third row)

At that time, Dr. Parrish was a professor of Dermatology at Harvard School of Medicine, and Dr. Anderson graduated from MIT and, after working as a science teacher at a secondary school, had been working with Dr. Parrish as a researcher for several years at the Wellman Center for Photomedicine, an affiliated organization of Harvard Medical School. Dr. Anderson entered Harvard Medical School in the mid 80s and completed his dermatology residency at Harvard. He is now Harvard Medical School Professor in dermatology, but it is interesting to think that he was not a physician or a professor but just a researcher in 1983.

The above two studies introduced two important concepts in cutaneous lasers. One of them is ‘therapeutic window’, and the other is ‘selective damage’. The former refers to the possibility of delivering light energy to even deep and widely distributed chromophore at the wavelength range that can minimize scattering by collagen, and the latter refers to the possibility of selecting a proper laser light for destructing blood vessels inside the skin while minimizing injuries to the surrounding tissues and epidermis. These two concepts become the basis of the study ‘Selective photothermolysis: precise microsurgery by selective absorption of pulsed radiation (AndersonRR, Parrish JA.)’ published 2 years later in the Science.

The study ‘Selective Photothermolysis’ provides basic concepts which are important for the understanding of cutaneous lasers; however, misunderstanding these concepts as absolute may work as a barrier in understanding clinical effects and side effects. Therefore, it would be helpful for overall understanding of this study if this term was switched to ‘relatively selective photothermolysis’ on the assumption that this is not an absolute theory to cover every case. This is an excellent study which is helpful for any clinicians utilizing lasers for skin therapy, and can be obtained easily on the internet. Below is the abstract of this study:

'Suitably brief pulses of selectively absorbed optical radiation can cause selective damage to pigmented structures, cells, and organelles in vivo. Precise aiming is unnecessary in this unique form of radiation injury because inherent optical and thermal properties provide target selectivity. A simple, predictive model is presented. Selective damage to cutaneous microvessels and to melanosomes within melanocytes is shown after 577-nanometer (3 x 10(-7) second) and 351-nanometer (2 x 10(-8) second) pulses, respectively.'

In summary, this is a simple theory that radiation of a relatively better absorbable pulse to a target within a short period of time provides selective damage to the target while preventing injuries to the surrounding tissues. The relationship among selective damage, radiation time and wavelength is well documented in this study. This theory itself is not sufficient to be applied for a procedure since the study does not highlight the fact that the condition of surrounding tissues differs between people and races and that even the same target may have different size and depth in each individual. Nevertheless, there is no question that understanding this theory well is the basis of understanding cutaneous laser. This theory triggered the development of vascular lasers from argon laser, which would leave scars a lot, to dye laser (Flashlamp Pumped Pulsed Dye Laser). This theory was also the basis applied for the development of lasers for pigmentation disorders, as well as lasers for skin resurfacing and hair removal.

Early lasers for vascular diseases have been developed to target mainly nevus flammeus in children due to the difficulty of selecting a radiation time and wavelength, because the radiation time of a dye laser is too short to damage thick vessels.

The development of lasers for vascular lesions since 1980s will be presented in the next article.

- To be continued -

▶ Next Artlcle : #2. Development of Vascular Laser I