A 32-year-old male farmer suffers a flame burn injury to both lower limbs and the anterior trunk while working near agricultural machinery. Using the Rule of Nines to estimate burn surface area, all of the following statements regarding his BSA involvement are true EXCEPT:

Question

Accepted Answer

A. The posterior trunk would account for 9% of total BSA if burned. ## Rule of Nines Application in Clinical Scenario

**Key Point:** Accurate BSA estimation is critical for determining burn severity, fluid resuscitation requirements, and prognosis. The Rule of Nines provides a rapid, reproducible method in emergency settings.

### Analysis of the Clinical Case

| Burned Region | BSA % |
| --- | --- |
| Anterior trunk | 18% |
| Both lower limbs (each 18%) | 36% |
| **Total in this case** | **54%** |

### Evaluation of Each Statement

**Statement 0 (Correct):** Anterior trunk = 18% — matches Rule of Nines.

**Statement 1 (Correct):** Both lower limbs = 18% + 18% = 36% — each limb is 18%.

**Statement 2 (Correct):** Anterior trunk (18%) + both lower limbs (36%) = 54% total BSA.

**Statement 3 (INCORRECT):** The posterior trunk = 18%, NOT 9%. The trunk is divided into anterior (18%) and posterior (18%), totaling 36% for the entire trunk.

**High-Yield:** The trunk (front + back) = 36% total. Many students mistakenly think the posterior trunk = 9% because they confuse it with the head or arm percentages.

### Clinical Implications for This Patient

**Clinical Pearl:** A 54% BSA burn is a **major burn** (>20% in adults) requiring:
1. Immediate fluid resuscitation (Parkland formula: 4 mL × 32 kg × 54% = ~6,912 mL over 24 hours)
2. Transfer to a specialized burn center
3. Monitoring for burn shock, infection, and systemic complications

**Mnemonic: TBSA Rule of Nines (Adult) — "9-18-36-1"**
- **9:** Head, each arm
- **18:** Anterior trunk, each leg
- **36:** Posterior trunk + anterior trunk (whole trunk)
- **1:** Genitalia

### Burn Severity Classification

| Severity | BSA Involvement | Management |
| --- | --- | --- |
| Minor | <10% | Outpatient |
| Moderate | 10–20% | Hospital admission |
| Major | >20% | Burn center referral |
| Critical | >40% or inhalation injury | ICU + specialized care |

This patient with 54% BSA qualifies as **critical** and requires burn center admission.

[cite:Park 26e Ch 24]

Answer

B. The total BSA burned in this patient would be approximately 54% if all three regions are completely involved

Answer

C. Both lower limbs together would represent 36% of total BSA if completely burned

Answer

D. The anterior trunk burn alone represents 18% of total BSA

A 32-year-old male farmer suffers a flame burn injury to both lower limbs and the anterior trunk while working near agricultural machinery. Using the Rule of Nines to estimate burn surface area, all of the following statements regarding his BSA involvement are true EXCEPT:

Explanation

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