A 44-year-old man is brought to the emergency department after sustaining high-voltage electrical burns over his left upper limb. On examination, the tip of his left middle finger is charred, and there are 2nd-degree burns involving the whole of the left upper limb. Radial and ulnar pulses are strong, and there are no signs of compartment syndrome. An exit wound is present over the sole of his right foot. His temperature is 37.7°C (99.8°F), the blood pressure is 110/70 mm Hg, the pulse is 105/min, and the respiratory rate is 26/min. His urine is reddish-brown, and urine output is 0.3 mL/kg/h. Laboratory studies show: Hemoglobin 13.9 g/dL Hematocrit 33% Leukocyte count 11,111/mm3 Serum Creatinine 4.6 mg/dL Creatine phosphokinase 15,230 U/L K+ 7.7 mEq/L Na+ 143 mEq/L What is the most likely mechanism for this patient's renal failure?

Rhabdomyolysis, myoglobinuria, and renal injury

Septicemia leading to acute pyelonephritis

Direct visceral electrical injury to the kidneys

Fluid and electrolyte loss and hypovolemia

Volume overload because of excessive intravenous fluid resuscitation

A 28-year-old soldier is brought back to a military treatment facility 45 minutes after sustaining injuries in a building fire from a mortar attack. He was trapped inside the building for around 20 minutes. On arrival, he is confused and appears uncomfortable. He has a Glasgow Coma Score of 13. His pulse is 113/min, respirations are 18/min, and blood pressure is 108/70 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 96%. Examination shows multiple second-degree burns over the chest and bilateral upper extremities and third-degree burns over the face. There are black sediments seen within the nose and mouth. The lungs are clear to auscultation. Cardiac examination shows no abnormalities. The abdomen is soft and nontender. Intravenous fluid resuscitation is begun. Which of the following is the most appropriate next step in management?

Intubation and mechanical ventilation

Insertion of nasogastric tube and enteral nutrition

Intravenous corticosteroid therapy

A 35-year-old man is pulled out of a burning building. He is unconscious and severely injured. He is transported to the nearest emergency department. Upon arrival, he is stabilized and evaluated for burns and trauma. Approximately 40% of his body is covered in burns. The burned areas appear blackened and charred but the skin is mostly intact. It is noted that the patient has loss of pain sensation in the burnt areas with minimal blanching on palpation. The affected area is leathery when palpated. What category of burn did the patient most likely to suffer from?

Superficial-partial thickness (2nd degree)

Deep-partial thickness (deep 2nd degree)

Full-thickness with extension to underlying structures (4th degree)

A 35-year-old woman is brought to the emergency department 45 minutes after being rescued from a house fire. On arrival, she appears confused and has shortness of breath. The patient is 165 cm (5 ft 5 in) tall and weighs 55 kg (121 lb); BMI is 20 kg/m2. Her pulse is 125/min, respirations are 29/min, and blood pressure is 105/65 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 97%. Examination shows second and third-degree burns over the anterior surfaces of the chest and abdomen, and the anterior surface of the upper extremities. There is black debris in the mouth and nose. There are coarse breath sounds over the lung bases. Cardiac examination shows no murmurs, rubs, or gallop. Femoral and pedal pulses are palpable bilaterally. Which of the following is the most appropriate fluid regimen for this patient according to the Parkland formula?

Administer 6 liters of intravenous crystalloids over the next 24 hours

Administer 4 liters of intravenous colloids over the next 8 hours

Administer 5 liters of intravenous colloids over the next 6 hours

Administer 5 liters of intravenous crystalloids over the next 6 hours

Administer 8 liters of intravenous colloids over the next 12 hours

A 33-year-old man is brought to the emergency department because of trauma from a motor vehicle accident. His pulse is 122/min and rapid and thready, the blood pressure is 78/37 mm Hg, the respirations are 26/min, and the oxygen saturation is 90% on room air. On physical examination, the patient is drowsy, with cold and clammy skin. Abdominal examination shows ecchymoses in the right flank. The external genitalia are normal. No obvious external wounds are noted, and the rest of the systemic examination values are within normal limits. Blood is sent for laboratory testing and urinalysis shows 6 RBC/HPF. Hematocrit is 22% and serum creatinine is 1.1 mg/dL. Oxygen supplementation and IV fluid resuscitation are started immediately, but the hypotension persists. The focused assessment with sonography in trauma (FAST) examination shows a retroperitoneal fluid collection. What is the most appropriate next step in management?

Take the patient to the OR for an exploratory laparotomy

Perform an MRI scan of the abdomen and pelvis

CT of the abdomen and pelvis with contrast

Obtain a retrograde urethrogram

Perform a diagnostic peritoneal lavage

A 67-year-old man comes to the physician for a follow-up examination. He has had lower back pain for several months. The pain radiates down the right leg to the foot. He has no history of any serious illness and takes no medications. His pain increases after activity. The straight leg test is positive on the right. The results of the laboratory studies show: Laboratory test Hemoglobin 14 g/d Leukocyte count 5,500/mm3 with a normal differential Platelet count 350,000/mm3 Serum Calcium 9.0 mg/dL Albumin 3.8 g/dL Urea nitrogen 14 mg/dL Creatinine 0.9 mg/dL Serum immunoelectrophoresis shows an immunoglobulin G (IgG) type monoclonal component of 40 g/L. Bone marrow plasma cells return at 20%. Skeletal survey shows no bone lesions. Magnetic resonance imaging (MRI) shows a herniated disc at the L5. Which of the following is the most appropriate next step?

Autologous stem cell transplantation

A 35-year-old man is brought to the emergency department from a kitchen fire. The patient was cooking when boiling oil splashed on his exposed skin. His temperature is 99.7°F (37.6°C), blood pressure is 127/82 mmHg, pulse is 120/min, respirations are 12/min, and oxygen saturation is 98% on room air. He has dry, nontender, and circumferential burns over his arms bilaterally, burns over the anterior portion of his chest and abdomen, and tender spot burns with blisters on his shins. A 1L bolus of normal saline is administered and the patient is given morphine and his pulse is subsequently 80/min. A Foley catheter is placed which drains 10 mL of urine. What is the best next step in management?

Additional fluids and escharotomy

Additional fluids and admission to the ICU

Burns assessment and management for USMLE Step 2 CK: High-Yield Surgery Lessons

Burn Classification - Degrees of Damage

Degree	Layers Involved	Appearance	Sensation	Healing
1st	Epidermis	Red, dry, blanches	Painful	3-6 days
2nd (Partial)	Epidermis + Dermis	Blisters, moist, red/pink, blanches	Very painful	7-21 days
3rd (Full)	Through Dermis	Waxy, white, leathery, charred	Painless	Months, requires graft
4th	Into fat, muscle, bone	Black, charred, dry	Painless	Requires excision

TBSA Estimation - The Rule of Nines

A rapid method for estimating Total Body Surface Area (TBSA) for 2nd & 3rd-degree burns in adults. Not used for 1st-degree burns (e.g., sunburn).

Head & Neck: 9%
Anterior Torso: 18%
Posterior Torso: 18%
Each Arm: 9%
Each Leg: 18%
Genitalia/Perineum: 1%

Rule of Nines for TBSA estimation in adults

⭐ The TBSA estimate is a critical variable used in the Parkland formula to calculate IV fluid resuscitation volume for the first 24 hours.

For children, the Lund-Browder chart is more accurate due to different body proportions.

Fluid Resuscitation - The Parkland Plan

Purpose: Guides IV fluid resuscitation for 2nd/3rd-degree burns, typically for TBSA >20%.
Formula: Total fluid in 24h = $4 \text{ mL LR} \times % \text{TBSA} \times \text{Body Wt (kg)}$
Administration Schedule:
- First 8 hours: Infuse 1/2 of the total calculated volume.
- Next 16 hours: Infuse the remaining 1/2 of the volume.
Fluid of Choice: Lactated Ringer's (LR) is preferred over normal saline to prevent hyperchloremic metabolic acidosis.

⭐ The "first 8 hours" starts from the time of the burn injury, not from the time of hospital arrival.

Complications & Special Burns - Beyond the Basics

Systemic Complications:
- Infection: Pseudomonas (most common), S. aureus. High risk of sepsis.
- Metabolic: Hypermetabolic state (↑cortisol, ↑catecholamines) leading to hyperglycemia & muscle wasting.
- GI: Curling's ulcer (stress-related gastric ulcer).
- MSK: Joint contractures, heterotopic ossification.
Special Burn Types:
- Electrical: Deep tissue injury often hidden. Risk of rhabdomyolysis (check CK), arrhythmias (monitor ECG for 24h), and posterior shoulder dislocation.
- Chemical: Irrigate copiously. Alkali is worse (liquefaction necrosis) than acid. Brush off dry powders first.
- Inhalation: Suspect with facial burns/singed nares. Treat with 100% O₂; early intubation is key. Diagnose with bronchoscopy.

⭐ Marjolin's Ulcer: An aggressive squamous cell carcinoma that arises in chronic wounds or old burn scars, often years later.

High‑Yield Points - ⚡ Biggest Takeaways

The Parkland formula (4 mL/kg/%TBSA) is paramount for guiding IV fluid resuscitation over the first 24 hours.

Suspect inhalation injury with facial burns, soot, or hoarseness; prioritize early intubation to secure the airway.

Circumferential burns of limbs or the chest may require urgent escharotomy to prevent compartment syndrome.

Use the Rule of Nines for rapid estimation of Total Body Surface Area (TBSA) in adults.

Prevent infection, especially from Pseudomonas, with topical antibiotics.

Burns induce a hypermetabolic state, necessitating aggressive nutritional support.

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