A 30-year-old male electrician is brought to the emergency department after sustaining a h… — USMLE Step 2 CK

A 30-year-old male electrician is brought to the emergency department after sustaining a high-voltage electrical injury at a construction site. The accident occurred exactly 2 hours prior to his arrival. On physical examination, the patient is awake and alert. Vital signs show a heart rate of 115/min and blood pressure of 105/65 mm Hg. He has deep partial-thickness and full-thickness burns involving his entire right arm and his entire anterior trunk (chest and abdomen). No other areas of the body are burned. His body weight is 75 kg. Two large-bore peripheral intravenous lines are established, and a Foley catheter is placed.

Based on current Advanced Trauma Life Support (ATLS) guidelines for high-voltage electrical burns, what should be the continuous intravenous fluid infusion rate (in mL/hr) of lactated Ringer solution for this patient over the next 6 hours?

Answer: 675 mL/hr

Answer

675

The correct infusion rate is 675 mL/hr. Electrical burns require aggressive resuscitation at

4 \text{ mL/kg/\%TBSA}

. For a 75 kg patient with a 27% TBSA burn (9% right arm + 18% anterior trunk), the 24-hour requirement is

4 \times 75 \times 27 = 8100 \text{ mL}

. Half of this volume (4050 mL) must be infused within the first 8 hours of injury. Because 2 hours have already passed, the 4050 mL must be infused over the remaining 6 hours (

4050 \div 6 = 675

Step-by-Step Solution

Determine the Total Body Surface Area (TBSA) burned.

27%

Using the Rule of Nines, the entire right arm is 9% and the entire anterior trunk (chest and abdomen) is 18%.

9\% + 18\% = 27\%

Calculate the total 24-hour fluid volume requirement.

8100 mL

Current ATLS guidelines mandate

4 \text{ mL/kg/\%TBSA}

for electrical burns to prevent rhabdomyolysis-induced renal failure. Total volume =

4 \times 75 \text{ kg} \times 27\% = 8100 \text{ mL}

Calculate the fluid volume to be given in the first 8 hours post-injury.

4050 mL

Half (50%) of the total 24-hour calculated volume must be administered during the first 8 hours following the time of injury.

8100 \text{ mL} \div 2 = 4050 \text{ mL}

Calculate the hourly infusion rate for the remaining time in the first 8-hour window.

675 mL/hr

The patient arrived 2 hours after the injury, leaving 6 hours to infuse the first half of the fluid.

4050 \text{ mL} \div 6 \text{ hours} = 675 \text{ mL/hr}

Key Concept

ATLS electrical burn fluid resuscitation (4 mL/kg/%TBSA) and accounting for pre-hospital time delay.

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