Differential Diagnosis for Post-Operative Hypotension

The patient presents with hypotension (90/60 mmHg), tachycardia (140 bpm), and an irregularly irregular heartbeat, following a varicose vein operation. Given the clinical presentation and laboratory results, the differential diagnoses can be categorized as follows:

• Single Most Likely Diagnosis

  • Arrhythmia (C): The patient's irregularly irregular heartbeat suggests atrial fibrillation, a common arrhythmia that can lead to hypotension due to reduced cardiac output. The patient's history of ischaemic heart disease increases the risk of arrhythmias.

• Other Likely Diagnoses

  • Acute Myocardial Infarction (A): Although the patient is afebrile and his bandages are not blood-stained, his history of ischaemic heart disease and the current presentation of hypotension and tachycardia could be indicative of an acute myocardial infarction, especially if the arrhythmia is a consequence of myocardial ischemia.
  • Haemorrhage (E): Despite the bandages not being blood-stained and the haemoglobin level being within the normal range, occult bleeding cannot be entirely ruled out, especially in a post-operative setting. However, the lack of obvious signs of bleeding makes this less likely.

• Do Not Miss Diagnoses

  • Septic Shock (H): Although the patient is afebrile, septic shock can present with hypotension, tachycardia, and an elevated white cell count, as seen in this patient (12.0 x 10^9/L). Early sepsis might not always present with fever, making it a critical diagnosis not to miss.
  • Anaphylaxis (B): This is a life-threatening condition that can cause hypotension, tachycardia, and can occur in response to medications or latex used in surgery. The absence of typical symptoms like rash or respiratory distress does not entirely rule out anaphylaxis, especially if it's an atypical presentation.

• Rare Diagnoses

  • Cardiomyopathy (D): While cardiomyopathy could lead to arrhythmias and hypotension, there's no direct indication in the provided history that would make this a primary consideration in the immediate post-operative period.
  • Medication Side Effects (F): The patient has only received analgesics and anti-emetics, which are less likely to cause hypotension and arrhythmia in the absence of other symptoms or known allergies.
  • Psychosomatic Illness (G): This would be an unlikely cause of the objective findings of hypotension, tachycardia, and arrhythmia in a post-operative patient.