**13. Conclusion**

*Clinical Management of Shock - The Science and Art of Physiological Restoration*

thermal damage of the abnormally dilated blood vessels with minimal to no collateral damage of surrounding cutaneous structures. Eventually, 585 and 595 nm wavelength PDL devices were developed to allow slightly deeper penetration through the skin (to a depth of around 1.2 mm) while still maintaining precise absorption. The development of surface cooling devices has, subsequently, afforded the use of higher energy fluences with larger spot sizes and improved treatment in darker skin surfaces. When applied to hypertrophic burn scars, PDL causes selective photothermolysis that induces coagulation necrosis of capillaries within the scar itself [236]. Because hypertrophic burn scars are characterized by pathologic neovascularization, PDL devices help to mitigate inflammation and collagen production and reduce the overall hypervascular response. From a patient perspective, PDL is also useful for helping to improve overall burn scar texture, pruritus, pain, and pliability [237]. Laser resurfacing has long been used for cosmetic indications such as treatment of fine rhytids of the eyelids and mouth, treatment of photoaging, and management of dyspigmentation. Original "fully ablative" devices, such as the carbon dioxide laser, target intracellular water as the main chromophore. Because of the abundance of water in human tissue, this process leads to non-selective and near-immediate vaporization of treated skin and a denaturation of surrounding extracellular proteins. In contrast to ablative devices, nonablative approaches induce coagulation as their primary mechanism of action without directly destroying tissue or exposing dermis to the external environment. The concept of "fractional photothermolysis" was fairly recently introduced and describes treatment of the target tissue with the generation of a precise array of evenly spaced areas of injury known as microscopic treatment zones (MTZ) [238]. Clinically, this technique results in untreated areas between the MTZs, containing significant amounts of intact epidermis and dermis available as a reservoir for a more rapid micro-healing response. With ablative fractional resurfacing (AFR) technologies, such as the fractional carbon dioxide (CO2) and Erbium-YAG lasers, the operating surgeon may change device parameters to adjust for desired depth of treatment (to a maximum of about 3.5–4.0 mm with current devices) and accurately control the total ablated surface area within a treated area. The general rule for AFR is to decrease density (i.e., total ablated surface area) while increasing fluence (i.e., energy). How repeated pixelated thermal injuries to a burn scar could result in subjective and objective improvements is not entirely understood; however, the technique has consistently demonstrated the ability to facilitate rapid reepithelialization and a vigorous scar remodeling process while maintaining excellent safety margins [239–243]. Perhaps most notably, long-term, persistent gains in pliability, resulting in improved function and quality of life, most likely occur from a gradual process of diffuse dermal remodeling and a relative rehabilitation of dysfunctional

The varied nature of individual burn scars, the heterogeneity of burn patients, small sample sizes, a lack of treatment controls, and the cost of the devices themselves have been major limitations to research surrounding the use of lasers in the treatment of burn scars. Thankfully, several large, prospective studies are currently underway to

investigate the utility of these devices, including in the pediatric population.

The notion that certain medications or agents could be delivered topically through burn scar tissue has three potential advantages over oral administration of the same agent: directed therapy to the targeted tissue, limited systemic toxicity and side effects, and avoidance of first-pass metabolism. To this end, various chemical, biochemical, and physical strategies have attempted to enhance topical drug delivery into burn scar tissue. It is only relatively recently that AFR devices

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scar tissue [244].

**12.5 Laser-assisted drug delivery**

The primary goal of clinical management of burns is to prevent the development of "burn shock." Early classification of burns by depth and size is critical to goal-directed treatment strategies, with subsequent approaches guided by the post-injury physiological and metabolic demands. Appropriate anticipation and proactive, multimodality support of the patient, through fluid resuscitation, nutritional supplementation, and pharmacologic therapy is required for optimizing patient outcomes. Additionally, clinicians should closely monitor the patient for the development of secondary adverse events, such as infections and under- or over-resuscitation. Management of burns is complex and requires specialized facilities, teams of experienced burn surgeons, dedicated burn nurses, social workers, nutritionists, physical therapists, occupational therapists, pharmacists, respiratory interventionists, pain specialists, dermatologists, and psychologists [246, 247].


#### **Table 4.**

*Summary of burn center referral criteria; Legend: TBSA = Total body surface area.*

*Patient 2006, Committee on Trauma, American College of Surgeons.*

The tremendous amount of progress in treatment of thermal injuries over the past several decades was possible because of the continuous evolution of trauma systems and burn centers, along with the development of state-of-the-art resuscitative and procedural approaches.

The critical timeline for thermal injury management occurs in the first 48 h from time of initial burn. Early burn classification should determine need for referral to a designated burn center (**Table 4**). The American Burn Association (ABA) list criteria for burn injuries that warrant referral to a designated burn center including: partial thickness burns of greater than 10% TBSA, burns involving the face, hands, feet, genitalia, or major joints, any third degree burns, electrical burns, chemical burns, inhalation injuries, burn injury to patients with significant pre-existing medical conditions, burns with additional traumatic injury, burns in children, or any burn injury to patients who may require special social, emotional, or rehabilitative assistance.
