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Rule of Nines for Burn Estimation

Sep 16, 2025

Overview

This lecture covers the Rule of Nines, a tool for estimating the percentage of body surface area burned in adult patients and its importance for treatment planning.

Purpose of the Rule of Nines

  • The Rule of Nines estimates the percentage of total body surface area (TBSA) affected by burns in adults.
  • Knowing burn percentage helps determine the need for a burn unit and guides fluid replacement.
  • Severe burns increase capillary permeability, risking hypovolemic shock due to fluid loss.
  • TBSA is used in the Parkland burn formula to calculate fluid needs in the first 24 hours.
  • Lactated Ringer’s solution is commonly used for fluid replacement in burn victims.

Breakdown of Body Areas (Rule of Nines)

  • Head and neck: anterior (front) is 4.5%, posterior (back) is 4.5%, total is 9%.
  • Trunk: anterior is 18%, posterior is 18%, total is 36%.
  • Each arm: anterior is 4.5%, posterior is 4.5%, total per arm is 9%; both arms together total 18%.
  • Perineum: 1%.
  • Each leg: anterior is 9%, posterior is 9%, total per leg is 18%; both legs together total 36%.
  • Always consider both sides (anterior and posterior) and both limbs.

Example Calculation

  • Problem: Burns on front and back of both arms (18%), anterior trunk (18%), back of left leg (9%), anterior and posterior right leg (18%), posterior head and neck (4.5%), perineum (1%).
  • Adding up these areas: 18 + 18 + 9 + 18 + 4.5 + 1 = 68.5% TBSA burned.

Key Terms & Definitions

  • Rule of Nines — A method to estimate the TBSA (%) burned by dividing the body into sections, each representing approximately 9% or multiples thereof.
  • Total Body Surface Area (TBSA) — The percentage of the body affected by burns.
  • Hypovolemic Shock — A condition where severe fluid loss makes the heart unable to pump enough blood to the body.
  • Parkland Burn Formula — A formula to calculate fluid requirements for burn patients in the first 24 hours.
  • Lactated Ringer’s — A common intravenous solution used for burn fluid resuscitation.
  • Anterior — The front side of the body.
  • Posterior — The back side of the body.

Action Items / Next Steps

  • Take the free quiz on calculating the Rule of Nines.
  • Watch the next video on the Parkland burn formula.

Full transcript