Differential Diagnosis

The patient's clinical presentation suggests a respiratory complication, likely related to the ventilator use and recent septic shock from perforated diverticulitis. Here's a categorized differential diagnosis:

• Single most likely diagnosis
  • Ventilator-associated pneumonia (VAP): The patient has been on a ventilator for the last 3 days, which increases the risk of developing VAP. The increased ventilator requirements, thick white secretions, fever (101.2°F), and new LLL infiltrate on the chest x-ray are all consistent with VAP.
• Other Likely diagnoses
  • Hospital-acquired pneumonia (HAP): Although HAP is a broader category that includes VAP, the patient's specific scenario (ventilator use and recent septic shock) makes VAP more specific. However, HAP remains a consideration due to the hospital setting and the patient's compromised state.
  • Pneumonia: This is a more general term and could encompass both HAP and VAP. The presence of pneumonia is likely, given the clinical findings, but specifying it as VAP or HAP provides more detail about the context and potential causative factors.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Aspiration pneumonia: Given the patient's recent history of septic shock and ventilator use, there's a risk of aspiration, especially if the patient has been fed enterally or has had episodes of vomiting. Aspiration pneumonia can present similarly to VAP and requires prompt diagnosis and treatment.
  • Pulmonary embolism: Although less directly related to the ventilator and infection, pulmonary embolism is a critical diagnosis to consider in any hospitalized patient, especially those with recent immobilization or sepsis, due to its high mortality rate if untreated.
• Rare diagnoses
  • Lung abscess: This could be a complication of pneumonia but would typically present with more localized and severe symptoms, including significant fever, cough, and possibly hemoptysis, along with a distinct cavity on imaging.
  • Empyema: An infection of the pleural space, which could occur as a complication of pneumonia. It would typically present with fever, chest pain, and possibly a pleural effusion on imaging.