Differential Diagnosis for 73 y.o Female Patient

Single Most Likely Diagnosis

• Severe Pneumonia or Acute Respiratory Distress Syndrome (ARDS): The patient's symptoms of dyspnea, cough, fever, and physical examination findings of rhonchi in both lungs, low O2 saturation, and high respiratory rate are highly suggestive of a severe respiratory infection. The sudden loss of consciousness could be due to hypoxia.

Other Likely Diagnoses

• Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycemic State (HHS): Given the patient's high blood glucose level (320), DKA or HHS should be considered, especially with symptoms like vomiting and dehydration. However, the primary presentation of respiratory distress and fever points more towards an infectious cause.
• Sepsis: The combination of fever, tachypnea, and altered mental status could indicate sepsis, potentially originating from a pulmonary source given the respiratory symptoms.
• Cardiac Causes (e.g., Myocardial Infarction, Pulmonary Embolism): Although less directly indicated by the symptoms provided, cardiac issues can lead to sudden loss of consciousness and should be considered, especially in an elderly patient with potential for underlying cardiovascular disease.

Do Not Miss Diagnoses

• Stroke: Although the patient's GCS is 11 and there's no lateralization, a stroke (ischemic or hemorrhagic) could cause sudden loss of consciousness and should always be considered in the differential diagnosis of altered mental status.
• Status Epilepticus: Post-ictal state from a seizure could present with altered mental status, and the history of vomiting and loss of consciousness could be consistent with a seizure, although other signs like lateralizing features are not mentioned.
• Pulmonary Embolism: This is a critical diagnosis to consider due to its high mortality rate if untreated. The symptoms of dyspnea and tachypnea could be indicative of a pulmonary embolism, especially if there's a background of immobility or other risk factors.

Rare Diagnoses

• Meningitis or Encephalitis: Although less likely given the primary respiratory symptoms, infections like meningitis or encephalitis can cause altered mental status, fever, and in severe cases, respiratory distress.
• Endocrine Emergencies (e.g., Adrenal Insufficiency): These could present with a variety of non-specific symptoms including altered mental status, but are less directly suggested by the information provided.