A 32-year-old male utility worker is brought to the emergency department after sustaining … — USMLE Step 2 CK

A 32-year-old male utility worker is brought to the emergency department after sustaining a high-voltage electrical injury while repairing a power line. The incident occurred exactly 2 hours prior to his arrival. On presentation, he is awake, alert, and complains of severe pain in his extremities. His temperature is $36.8^\circ \text{C}$ ( $98.2^\circ \text{F}$ ), heart rate is $112/\text{min}$ , and blood pressure is $110/70 \text{ mm Hg}$ . Physical examination reveals deep, full-thickness burns involving his entire anterior trunk and his entire right lower extremity. There are also deep, charred entry and exit wounds on his right hand and left foot, though these cover a negligible surface area. His body weight is estimated at $75 \text{ kg}$ . A Foley catheter is inserted to monitor urine output, and large-bore intravenous access is obtained. According to the Advanced Trauma Life Support (ATLS) guidelines for high-voltage electrical injuries, what is the appropriate initial intravenous fluid infusion rate (in $\text{mL/hour}$ ) for this patient?

Answer: 900 mL/hour

Answer

900

The appropriate initial fluid infusion rate is 900 mL/hour because high-voltage electrical burns require 4 mL/kg/%TBSA for fluid resuscitation, totaling 10,800 mL for this 75 kg patient with 36% TBSA burns. Half of this total (5,400 mL) must be administered in the first 8 hours post-injury. Because 2 hours have already elapsed, the 5,400 mL must be infused over the remaining 6 hours, yielding a rate of 900 mL/hour.

Step-by-Step Solution

Calculate the Total Body Surface Area (TBSA) burned using the Rule of Nines.

TBSA = 36%

The entire anterior trunk accounts for 18% and the entire right lower extremity accounts for 18% (

18 + 18 = 36

Select the correct ATLS fluid resuscitation multiplier for the injury mechanism.

4 mL/kg/%TBSA

High-voltage electrical injuries require 4 mL/kg/%TBSA to ensure adequate diuresis and prevent acute kidney injury from rhabdomyolysis, unlike the 2 mL/kg/%TBSA used for standard thermal burns.

Calculate the total estimated fluid requirement for the first 24 hours.

10,800 mL

4 \text{ mL} \times 75 \text{ kg} \times 36\% = 10,800 \text{ mL}

Determine the fluid volume to be administered in the first 8 hours.

5,400 mL

Half of the total 24-hour calculated volume is given in the first 8 hours (

10,800 \div 2 = 5,400 \text{ mL}

Calculate the target hourly infusion rate, accounting for time elapsed since the injury.

900 mL/hour

The patient presented 2 hours post-injury, leaving 6 hours for the first 8-hour window (

8 - 2 = 6

). The rate is

5,400 \text{ mL} \div 6 \text{ hours} = 900 \text{ mL/hour}

Key Concept

High-voltage electrical burns require fluid resuscitation at 4 mL/kg/%TBSA, with half the volume administered over the first 8 hours starting from the time of injury, requiring rate adjustments for delayed presentations.

Estimated Time:2m 0s

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