Differential Diagnosis for Hypoxia on Hospital Day 1

• Single most likely diagnosis

  • Acute Respiratory Distress Syndrome (ARDS): Given the patient's exposure to smoke and the potential for inhalation injury, ARDS is a common complication that can develop within the first 24-48 hours after the incident. The presence of second-degree burns and the initial findings of soot in the oropharynx increase the risk for developing ARDS, which is characterized by hypoxia, often requiring mechanical ventilation.

• Other Likely diagnoses

  • Carbon Monoxide Poisoning: Although the patient's oxygen saturation was initially 94% on room air, carbon monoxide poisoning can have a delayed presentation, and its effects might not be immediately apparent. Carbon monoxide binds to hemoglobin, reducing the oxygen-carrying capacity of the blood, which can lead to tissue hypoxia.
  • Pulmonary Edema: This can occur due to the systemic inflammatory response and fluid resuscitation efforts in burn patients. It may lead to hypoxia as fluid accumulates in the lungs, impairing gas exchange.

• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)

  • Upper Airway Obstruction and Asphyxia: Although the patient had unlabored breathing initially, the potential for airway compromise due to edema from thermal injury or other mechanisms cannot be overlooked. Upper airway obstruction can rapidly lead to severe hypoxia and death if not promptly addressed.
  • Bronchospasm: While less common in this context, bronchospasm could occur, especially if the patient has a pre-existing condition like asthma. It would lead to increased airway resistance and could cause hypoxia.

• Rare diagnoses

  • Other rare conditions such as pneumonia or thromboembolic events could also potentially cause hypoxia but are less directly related to the immediate effects of smoke inhalation and burns in this scenario. However, they should be considered if other explanations are ruled out and the patient's condition does not improve as expected.