Precipitous bradycardia induced by laryngoscopy in cardiac surgical patients.

We present three patients with severe ischaemic heart disease who developed profound bradycardia (heart rates of 15 beats.min-1, 10 beats.min-1 and asystole) at the time of laryngoscopy and spraying of the trachea with topical lidocaine. All patients had received fentanyl 20-30 micrograms.kg-1 and pancuronium 0.1-0.13 mg.kg-1 and in each case laryngoscopy was performed three minutes after the administration of these agents. We believe that in these cases the dosage of fentanyl was inadequate and since increasing the dosage of fentanyl to at least 50 micrograms.kg-1 and eliminating the manoeuvre of laryngeal spraying with topical anaesthesia, we have not encountered this problem.