Differential Diagnosis for Fluctuations in Blood Pressure

The patient's complex medical history and current presentation of fluctuating blood pressure from 70/40 to 130/90 require a thorough differential diagnosis. The following categories organize potential causes:

• Single Most Likely Diagnosis
  • Dehydration and Autonomic Dysfunction: Given the patient's history of recurrent UTIs and the presence of a cystostomy, dehydration could be a significant factor. Additionally, autonomic dysfunction, which can occur in patients with a history of myocardial infarction and diabetes (though not explicitly mentioned, it's a common comorbidity), could contribute to blood pressure fluctuations.
• Other Likely Diagnoses
  • Sepsis: Recurrent UTIs increase the risk of sepsis, which can cause significant fluctuations in blood pressure due to the body's inflammatory response.
  • Cardiac Arrhythmias: Although the recent ECG was normal, arrhythmias can be intermittent. Given the patient's history of CABG and myocardial infarction, arrhythmias could lead to fluctuations in cardiac output and blood pressure.
  • Medication Side Effects: The patient is likely on multiple medications for his various conditions, and some of these could contribute to hypotension or hypertension, especially if there are interactions or if doses are not appropriately adjusted for renal function or other factors.
• Do Not Miss Diagnoses
  • Cardiac Tamponade: Although less likely given the recent normal ECG and troponin, cardiac tamponade can present with hypotension and should be considered, especially in a patient with a history of myocardial infarction and CABG.
  • Pulmonary Embolism: This is another critical diagnosis that could present with hypotension and should not be missed, given the patient's history of cancer and potential for immobility.
  • Adrenal Insufficiency: This condition can cause hypotension and should be considered, especially if the patient is on steroids for any condition, as abrupt withdrawal can lead to adrenal insufficiency.
• Rare Diagnoses
  • Pheochromocytoma: Although rare, this condition can cause significant fluctuations in blood pressure. It might be considered if other diagnoses are ruled out, especially given the patient's history of stage 4 prostate cancer, which, although in remission, prompts a thorough evaluation for other potential malignancies.
  • Multiple System Atrophy (MSA): This is a rare neurodegenerative disorder that can cause autonomic dysfunction leading to significant blood pressure fluctuations. It would be considered if other diagnoses are excluded and there are other suggestive symptoms such as parkinsonism or cerebellar ataxia.