Burn Injury Assessment

The most accurate way to estimate the amount of tissue injury following a burn is to measure the extent of the body surface burned. The "Rule of Nines" method is a simple and reasonably reliable guide in which the various parts of the body are divided into surface areas of 9% each (or multiples of 9%).

As the percent of the surface burned increases, morbidity and the probability of mortality increases sharply. Burns which cover 20% or more of the body surface can be fatal without treatment.

Even with treatment, mortality from extensive burns will be high, particularly in the very young or the aged. Young healthy casualties who have uncomplicated burns may survive even extensive involvement with proper care.

Determination of the percent of the body involved will aid in planning resuscitative treatment and estimating fluid requirements during the first 48 hours after the burn injury.

Casualties with severe burns will suffer quite extensive fluid and electrolyte losses, resulting in severe hypovolemic shock requiring aggressive fluid replacement therapy as early as possible.

Involvement of Critical Organs

When certain organ systems are involved, the clinical effects of burns can be quite serious in spite of the fact that only a small fraction of the body is involved.

1. Head and Neck Burns
   Burns of the face can be serious problems, even if the eyes are not involved. Burns of the head frequently are complicated by severe edema, which can result in respiratory obstruction. This can be quite serious when the inhalation of hot gases has occurred. It may be necessary to do tracheotomies on many of these casualties.
2. Burns of Hands and Feet
   These can be very disabling and may require long hospitalization for extensive surgical care even though they are not life threatening injuries. These casualties may not be able to care for themselves and, as a result, will require extensive nursing care.
3. Burns of the Respiratory Tract
   When hot gases are inhaled, this very serious type of injury may be sustained. These injuries have a high probability of mortality if the burns extend deep into the alveoli. These casualties are very fragile and may not tolerate early evacuation. Pulmonary edema may develop abruptly, without warning, requiring vigorous ventilator support. These injuries can be very diffi cult to manage.

Depth of Burn

Burns are classified on the basis of the depth of the injury.

• Superficial or Partial Skin Thickness Burns
  These are lesions in which the dermis is intact and only the epidermis is injured. When the injury is limited and only erythema occurs (such as in a sunburn), these are usually called first-degree burns. If blistering is seen, the injuries are called second-degree burns.
  
  Superficial burns are usually painful but will heal readily by epithelization unless infection occurs. Infection can convert a typical second-degree, superfi cial burn into a deep or full-thickness burn which will not heal by epithelization but rather by scarring.
  
  Second-degree burns will be very common in nuclear combat and may be the one most common injury seen.
• Deep or Full-Thickness Burns
  Injuries involving the full thickness of the skin which cannot heal by epithelization are called third-degree burns. Instead, these injuries heal by scarring, and as a result there may be contraction and loss of function, particularly if extremities are involved.
  
  Extensive plastic surgery may be required to prevent or limit loss of function. The areas of a burn which are third-degree are usually painless, and this helps differentiate areas of third from second-degree when both are present.