[A case of severe bradycardia and AV block during administration of propofol]

A 69-yr-old man underwent emergency laparotomy. He was in endotoxic shock. Preoperative evaluation including a full blood count, chest X-ray and ECG were normal. Body temperature was 37.4 degrees C. Preoperative arterial pressure was 140/80 mmHg and heart rate 65 bpm. Anesthesia was induced with ketamine 100 mg, propofol 20 mg, fentanyl 50 micrograms and vecuronium 4 mg and maintained with propofol 4 mg.kg-1.hr-1 and fentanyl. Soon after opening the abdominal peritoneum, severe bradycardia (< 20 bpm) occurred, but it was effectively treated by ephedrine 16 mg. After that, surgery was performed uneventfully. In the intensive care unit (ICU), the patient developed four episodes of severe atrioventricular (AV) block after stimulation of the trachea by suction drainage under sedation with propofol, although there was no AV block during sedation with ketamine and propofol. After stopping propofol, the AV block was no longer observed. He was discharged from the ICU on the 12th postoperative day. Postoperative Holter ECG and echocardiography showed no abnormalities. It is likely that stimulation of the trachea triggered vagovagal reflex and propofol prolonged AV conduction, causing the AV block.