Question 3#

A 40-year-old woman is admitted to the burn unit after an industrial fire at a plastics manufacturing plant with burns to the face and arms. Her electrocardiogram (ECG) shows S-T elevation, and initial chemistry panel and arterial blood gas reveal an anion gap metabolic acidosis with normal arterial carboxyhemoglobin.

What is the most appropriate next step?

a. Correction of acidosis by adding sodium bicarbonate to IV fluids
b. Administration of 100% oxygen and hydroxocobalamin
c. Transthoracic echocardiogram
d. Blood culture with IV antibiotics

Correct Answer is B


Hydrogen cyanide toxicity may also be a component of smoke inhalation injury. Afflicted patients may have a persistent lactic acidosis or S-T elevation on ECG. Cyanide inhibits cytochrome oxidase, which is required for oxidative phosphorylation. Treatment consists of sodium thiosulfate, hydroxocobalamin, and 100% oxygen. Sodium thiosulfate works by transforming cyanide into a nontoxic thiocyanate derivative, but it works slowly and is not effective for acute therapy. Hydroxocobalamin quickly complexes with cyanide and is excreted by the kidney, and is recommended for immediate therapy. In the majority of patients, the lactic acidosis will resolve with ventilation and sodium thiosulfate treatment becomes unnecessary.