In the burn victim, an understanding of the anatomy and pathophysiology of burns is critical to patient management. Burns are characterized by the depth of injury into four categories (Table 1; Young 2006).

A first-degree burn is a superficial injury. The skin appears red and may be painful. The dermis is unaffected in these injuries. A sunburn is an example of a first-degree burn. These injuries require supportive care and will heal without scarring within 5–7 days (Fig. 1).

Second-degree burns can be superficial or deep (Fig. 2). Superficial second-degree burns are injuries to, but not through, the dermis. The skin is red, blistered, and swollen. Pain is prominent with a superficial second-degree burn. A superficial second-degree burn should heal spontaneously in 7–14 days. A deep second-degree burn is one that does not heal within 7–14 days. The dermis is injured in its full thickness and scarring will likely occur as a sequela.

Third-degree burns may appear whitish, charred, or translucent. Pinprick sensation is absent in the burned tissue because the nerve endings have been damaged by this injury, which traverses the dermis in its entirety. Because there are no dermal appendages to support wound healing, scar formation is inevitable and reconstruction using flaps or grafts is essential if the quantity of tissue loss is considerable.

Fourth-degree burns include full-thickness tissue loss to and including bone. Electrical injuries often cause fourth-degree burns. In these injuries, all overlying structures are dead and should be debrided.

As a general rule, all burns that are deep second degree, third degree, and fourth degree will require early excision and reconstruction. The nature of the reconstruction will depend on the location of the anatomic defect along with the functional deficit.

This section is concerned with the intersection of burn pathophysiology and hand function. To that end, the anatomy pertinent to caring for hand burns will be reviewed. Hand anatomy entails some unique features that will impact the manner in which burns are treated.

The volar, palmar skin of the hand provides padding for hand function with thick glabrous skin. However, there is relatively little room for swelling and expansion. This increases the risk for compartment syndromes.

The nail and nail bed are an often overlooked component of hand injuries, especially the burned hand. The nail and nail bed are specialized structures, which require both the matrices to make the nail and the proper support and surrounding tissues, which comprise the nail folds and distal phalanx.

The dorsal structures are more at risk due to the thin skin coverage and relatively little subcutaneous tissue. Specifically at risk is the PIP joint (Germann and Weigel 2011) due to its thin skin surface and the associated ligaments that arise from the extensor mechanism. Disruption of these structures can have devastating effect on function of the entire finger, even if the distal joint is uninvolved with the injury.

A burn is divided into three areas of injury called zones. These three zones are described as:

Irreversible tissue damage occurs in the zone of coagulation , while the zone of hyperemia will return to normal. The zone of stasis, however, is an area of tissue around the central coagulation zone, where the outcome can be modulated based on treatment. Proper resuscitation and care can salvage tissue in this zone, whereas inadequate resuscitation and treatment can lead to a worsening and loss of this tissue.

Heat injuries occur from the outside in and from superficial to deep. Injury is caused by flame or heat contact. The actual injury creates direct cellular destruction due to the thermal energy.

Cold injuries also occur from the outside in and from superficial to deep. However, at the cellular level there is cellular dehydration and crystal formation. Moreover, there is also the risk of cell damage that can occur during the rewarming phase as the crystals thaw and fluid shifts result in substantial edema.

Chemical burns can occur from acid, alkali, or specific chemicals common to hand burns. Knowledge of the causative agent is extremely valuable in treatment planning. The treatment for most chemical burns begins with copious irrigation. There are some exceptions to that. Hydrofluoric acid (HF) is one example. Exposure to HF often causes pronounced pain in the hands. This chemical is common in products used in auto detailing. Treatment may require either topical application or direct injection of calcium until the pain abates.

For management of several other specific chemical exposures, see Table 2.

With regard to electrical injuries, the mechanism of damage continues to be debated. However, as would be expected, the majority of the damage is often the consequence of high-voltage energy passing through the tissues, especially the deeper structures. Whether it is due to the fact that the bone heats the surrounding tissue due to its resistance or that the electrical current flows through the deep muscle and nerves more easily, severe deep tissue injury can occur in the presence of seemingly innocuous superficial wounds.

Nutritio n plays a major role in patients’ ability to heal and fight infection. Nutritional support is critical in management of the burn patient. Most calorie estimations of oral intake alone are grossly inadequate. Moreover, the formulas used for nutritional support are often insufficient in the face of burn and multiple trauma victims. It remains generally accepted that the patient’s own intestinal tract is the best route for nourishment whenever possible. Albumin and prealbumin are lab markers that can help guide nutritional support. The condition known as refeeding syndrome is exceedingly rare and many of the current-day fears about this process are unfounded. Nevertheless, all patients who can eat are encouraged to do so. The patient’s albumin and prealbumin are used to drive their nutritional support. A blood albumin level less than 2.7 g/dL is a reason to delay elective reconstructive surgery. For patients that are below 2.7d/dL and unable to take enough by mouth, a nasogastric feeding tube is routinely placed with around-the-clock feeds until the lab markers begin to correct and there are signs of healing. Patients who can eat are still encouraged to do so around the tube. The process is employed even for patients who must remain supine. Although these patients are monitored for aspiration, a properly placed and monitored feeding tube is a safe means to restore the nutritional balance.

Compartment syndrome is a clinical condition in which swelling within an anatomic compartment creates ischemia by first reducing blood inflow and later outflow from the compartment. Ultimately, the contents of the compartment will suffer irreversible ischemic damage if the pressure is not released through compartment fasciotomy.

Diagnosis of compartment syndrome is typically a clinical one, but there are some tests that can be of aid to the clinician. Compartment pressure can be measured using commercial devices or a standard arterial catheter. The pressure gradient is calculated as the difference between diastolic blood pressure (DBP) and the compartment pressure (CP). When the difference between these numbers (DBP-CP) is less than 30 mmHg, there is further evidence for compartment syndrome.

Management of compartment syndrome requires an understanding that escharotomy and fasciotomy are not the same thing. Escharotomy is typically used in circumferential chest wounds to allow chest expansion for breathing. Severe burns can create a leathery inelastic eschar that must be released when it involves a structure circumferentially. Depending on the severity of the burn and the condition of the patient, escharotomy can be done at the bedside with minimal sedation as the area is often insensate. However, should escharotomy be needed around the arm, hand or finger, fascial release (fasciotomy) may still be required to alleviate the compartment pressure.

A fasciotomy in a burn patient is most commonly performed for electrical injuries and in those patients who develop compartment syndrome due to over-resuscitation. Typically an escharotomy may precede fasciotomy (if deep external burn is involved) but fasciotomy seeks to release the deep fascial compartments to allow the muscle room to swell. Escharotomy will not accomplish this task. Failure to perform complete and timely fasciotomies will lead to loss of function and even loss of limb.

It is critical to understand that children express ischemic pain differently from adults. Adults in ischemic pain follow a pattern known as the 5 P’s, which represent pain, paresthesia, paralysis, pallor, and pulselessness. Loss of pulses is the last sign and often the harbinger that damage has already occurred. In contrast, the typical presentation in children involves what is known as the 3 A’s, which represent agitation, anxiety, and analgesia. A warning to the physician would be a worsening in agitation, a worsening in the child’s anxiety, and an increasing need for analgesia.

While there are many skin substitutes , none serves the same function as Integra® in terms of mimicking the natural epidermis and dermis. The product has a silicone layer that serves as a vapor barrier for the wound as well as protection for the underlying neodermis during incorporation. Integra® is expensive but in a clean wound and the appropriate patient, it can fundamentally change the approach to burn wound. Experience has clearly demonstrated that the indications for Integra® application go well beyond its initial indications (Armour and Billmire 2009, Tenenhaus and Rennekampff 2007, Chalmer et al. 2010). Our practice has been to use this “off the shelf product” to stabilize the wound bed and apply a graft only when the bed is ready and mature. For wounds that need flap coverage, Integra® is not routinely used. However, in a patient who is not ready for flap coverage, either due to polytrauma or severe malnutrition, Integra® can provide temporary wound coverage – especially for critical structures like tendon, nerve, and/or bone (Armour and Billmire 2009, Tenenhaus and Rennekampff 2007, Chalmer et al. 2010).

Allograft dermal grafts can be used as a temporary cover following removal of eschar. They can be used to stabilize wounds as a bridge to further grafting. While costly, they can be less expensive than Integra® and may be valuable in temporary coverage of wounds (Stanton and Billmire 2002).

Skin grafts are a useful tool in upper extremity burn reconstruction. Both full-thickness and split-thickness grafts can be utilized. Split-thickness skin grafts can be used after staged management with skin substitutes as well as for final repair of defects over surfaces where contracture is not a concern. For example, meshed grafts can be used following forearm fasciotomy to manage a wound that won’t close. Full-thickness grafts are useful in the hand and fingers. Splints are a useful adjunct to skin grafts in order to protect the grafts while healing and protect the joints at the same time. Table 3 reviews the distinctions between full- and split-thickness grafting.

The entire complement of flaps can be used in upper extremity burn reconstruction. Finger and hand flaps, both random and axial pattern, can play a role in management of burn injuries. Fasciocutaneous, muscle, and myocutaneous flaps play important roles in providing coverage and maximizing joint action at the same time. Classification of flaps is based on their vascular supply as described by Mathes and Nahai (Table 9). The use of flaps is generally delayed in burn reconstruction patients unless the injury is isolated and there is no reason to delay the final stage of reconstruction. Flaps derived from tissue expansion are useful in late repairs where increased amounts of tissue are needed. (Mathes and Nahai 1997; Dotan et al. 2009; McCraw and Arnold 1986).