Rule of Nines

Excerpt

The Rule of Nines, also known as the Wallace Rule of Nines, is a tool utilized by medical providers to assess the total body surface area (TBSA) involved in burn patients. The measurement of the initial burn surface area is important in estimating fluid resuscitation requirements, as patients with severe burns will have insensible fluid losses due to loss of the skin barrier. Moreover, an accurate assessment provides data that will assist in determining the patient's eventual outcomes. Both inadequate estimates and overestimation have their own shortcomings, as under-resuscitation can lead to progressive shock and, ultimately, end-organ damage, and excessive resuscitation places the patient at risk for developing acute respiratory distress syndrome and abdominal compartment syndrome.

The Rule of Nines was first discussed by Pulaski and Tennison in 1949 and later presented at the National Burns Research Council at a symposium; in 1951, A.B. Wallace published an article in the Lancet in describing the Rule of Nines. The Rule of Nines estimation of body surface area burned is based on assigning percentage estimates to different body areas.

1. The entire head: 9% (4.5% for anterior and posterior)

2. The entire trunk: 36% (can be further broken down into 18% for the anterior torso and 18% for the posterior torso)

3. The anterior aspect of the trunk: Can further be divided into the chest and abdomen, each representing 9%

4. The upper extremities: 18% (includes 9% for each upper extremity)

5. Each upper extremity: Can be further divided into its respective anterior and posterior portions (4.5% each).

6. The lower extremities: 36% (18% for each); can be further divided into 9% for the anterior and 9% for the posterior aspect

7. The groin: 1%

Only second- and third-degree burns, more commonly referred to as partial- and full-thickness burns, respectively, are included in the determination of the TBSA. This method aids hospital and prehospital providers in making a quick assessment to determine the severity, indications for intravenous fluid resuscitation, and the need for transfer to a certified burn center. Age and body mass index (BMI) are several factors that may affect changes to the Rule of Nines.