The Rule of Nines is a quick method used by medical professionals to estimate the percentage of a person's body surface area (BSA) affected by burns. This estimation is crucial for determining the severity of the burn and guiding treatment decisions, such as fluid resuscitation and determining the need for specialized burn care. It's a simplified system, providing a reasonable approximation rather than a precise measurement.
How the Rule of Nines Works
The Rule of Nines divides the body into regions, each representing 9% or multiples of 9% of the total BSA. This system simplifies assessment in emergency situations where precise measurements aren't immediately possible.
Body Regions and their Percentage Allocation (Adult):
- Head and Neck: 9% (anterior and posterior combined)
- Each Upper Extremity (arm and hand): 9% (anterior and posterior combined) — totaling 18% for both arms.
- Each Lower Extremity (leg and foot): 18% (anterior and posterior combined) — totaling 36% for both legs.
- Anterior Trunk: 18%
- Posterior Trunk: 18%
- Perineum: 1%
Important Considerations:
- Children: The Rule of Nines is modified for children because their body proportions differ significantly from adults. Specific percentages for children's body parts are used.
- Partial vs. Full-Thickness Burns: The Rule of Nines considers both partial-thickness (affecting epidermis and dermis) and full-thickness (affecting all skin layers) burns in the BSA calculation.
- Accuracy: The Rule of Nines provides an estimate. More precise methods, like Lund and Browder charts, exist but require more time and may not be practical in all situations.
Example: If a patient has burns covering their entire right arm and the anterior surface of their trunk, the estimated BSA affected would be 9% (right arm) + 18% (anterior trunk) = 27%.
The Rule of Nines, also known as the Wallace Rule of Nines, is a valuable tool used by paramedics, emergency room physicians, and burn center staff for rapid assessment of burn severity in emergency situations. While not perfectly accurate, its speed and simplicity make it an essential part of initial burn management.
