A 62-year-old man is evaluated in the burn unit due to progressive confusion, lethargy, and reduced urine output. Five days ago, the patient was hospitalized for a 20% body surface area burn and mild inhalation injury after his house caught fire. He is receiving analgesics, enteral feedings, and intravenous fluids. Temperature is 35.5 C (96 F), blood pressure is 100/60 mm Hg, pulse is 120/min, and respirations are 26/min. Physical examination shows third-degree burns on sections of the bilateral legs and a second-degree burn on the torso. Some areas of partial-thickness injury appear to have progressed to full-thickness necrosis. Laboratory results are as follows: Which of the following is the most likely cause of this patient's current condition?

Question

A 62-year-old man is evaluated in the burn unit due to progressive confusion, lethargy, and reduced urine output.  Five days ago, the patient was hospitalized for a 20% body surface area burn and mild inhalation injury after his house caught fire.  He is receiving analgesics, enteral feedings, and intravenous fluids.  Temperature is 35.5 C (96 F), blood pressure is 100/60 mm Hg, pulse is 120/min, and respirations are 26/min.  Physical examination shows third-degree burns on sections of the bilateral legs and a second-degree burn on the torso.  Some areas of partial-thickness injury appear to have progressed to full-thickness necrosis.  Laboratory results are as follows:  Which of the following is the most likely cause of this patient's current condition?

Quizplus · Accepted Answer

Explanation: Severe burns disrupt the skin barrier and create an avascular, immunologically poor, protein-rich substrate for the growth and proliferation of bacteria and fungi. Immediately after a severe burn, gram-positive organisms (eg, Staphylococcus aureus) from hair follicles and sweat glands dominate; after more than 5 days, most infections are due to gram-negative organisms (eg, Pseudomonas aeruginosa) or fungi (eg, Candida). Wound infections are common, and patients with large surface area (>20%) burns are at highest risk. The earliest sign is usually a change in appearance (partial-thickness injury turns into a full-thickness injury) of the wound or the loss of a viable skin graft. Burn wound sepsis can develop rapidly and is associated with some or all of the following systemic findings: Temperature <36.5 C (97.7 F, as in this patient) or >39 C (102.2 F) Progressive tachycardia (>90/min) Progressive tachypnea (>30/min) Refractory hypotension (systolic blood pressure <90 mm Hg) These criteria for burn wound sepsis differ slightly from those for the systemic inflammatory response syndrome (SIRS), which also include hypothermia (defined as <36 C [96.8 F]) as a concerning finding. Oliguria, unexplained hyperglycemia (from infection), thrombocytopenia, and mental status changes are also common. Diagnosis requires quantitative wound culture (>10⁵ bacteria/g of tissue) and biopsy for histopathology (to determine tissue invasion depth). Treatment involves empiric, broad-spectrum intravenous antibiotics (eg, piperacillin/tazobactam, carbapenem) with the addition of potential coverage for methicillin-resistant Staphylococcus aureus (eg, vancomycin) or multidrug-resistant Pseudomonas aeruginosa (eg, an aminoglycoside). Local wound care and debridement are usually necessary. systemic inflammatory response syndrome (SIRS) ⁵ (Choice A) Carbon monoxide poisoning due to fire exposure can sometimes cause a delayed neuropsychiatric syndrome (eg, altered mental status) but would not explain the hypothermia, laboratory abnormalities, or change in wound appearance seen in this patient. (Choice C) The metabolic rate drastically increases after a large surface area burn due to the release of inflammatory mediators; this may cause increased basal temperature (to 38.5 C [101.3 F]), tachycardia, tachypnea, and hyperglycemia. However, this patient has hypothermia, a change in wound appearance, reduced urine output, and confusion, making sepsis more likely. (Choices D and E) Myocardial infarction can complicate burn injuries, and this patient may be at risk for renal tubular injury due to sepsis or hypotension. However, change in wound appearance, thrombocytopenia, and hypothermia are more consistent with sepsis. Educational objective: Severe burns are often complicated by wound infections and sepsis. Risk is increased with large burns (>20% body surface area). Gram-positive organisms are common soon after injury; gram-negative organisms and fungi are more common after 5 days. A change in burn wound appearance or the loss of skin graft is often the first sign of a burn wound infection.

A 62-Year-Old Man Is Evaluated in the Burn Unit Due