Imipramine overdose

Fatal cardiac arrest prevente4 by external cardiac massace Two cases of deliberate imipramine overdose are reported. A 28·year-old man had a sinus tachycardia of I 201 min and BP 100/80mm Hg on admission, I hour after ingesting an unknown quantity of imipramine. He had a grand mal seizure, and although urea and electrolytes were normal, and IV 8.496 sodium bicarbonate was used to normalise a moderate acidosis, ventricular tachycardia (150/ min) developed, with no. discernible cardiac output. Isoprenaline (isoproterenol), calcium chloride and adrenaline (epinephrine) failed to produce any response, and external cardiac massage and assisted ventilation were abandoned 40 minutes later When cardiac output could not be restored. A non-fatal outcome was achieved in a 19. year-old girl who was admitted 4() mins after taking I 000-1 25Vmg imipramine. Although her initial pulse was ISO/min and BP 17Q/lOOmm Hg, and she had suffered 2 grand mal convulsions and circulatory arrest, her cardiac output was maintained with assisted ventilation and external cardia\: massage. Once again, urea and electrolyte concentrations were normal, th.e slight metalxliic acidosis was corrected with sodium bicarbonate, and adrenaline, isoprenaline and calcium chloride were not beneficial. Continuous external cardiac massage was performed for 90 mins, during wh.ich time the patient remained asystolic. Lignocaine (lidocaine), disopyramide, and prostigmine did not control the intermittent supraventricular and ventricular tachycardias. External cardiac massage was maintained for a further 90 mins, during Which time the patient's cardiac rhythm stabilised. Assisted ventilation was continued for a further 36 hours. Although sinus tachycardia (> 1101 min) persisted for 8 days, and widespread ST depression lasted for more than 2 weeks, after 4 weeks her ECG had returned to normal. It should be realised that most patients taking drug overdoses have a healthy myocardium, Which is capable of returning to normal function. This is often not the case in patients with asystole caused by acute myocardial infarction. Prolonged external cardiac massage and assisted ventilation will allow time for drug metabolism and redistribution, thus reducing the toxic effects. On, D.A. and Bramble, M.G., British Medical Journal

283, 1107(24 Oct 19S1l

6 Reactions 13 Nov 1981 0157,7271/81/1113-0006/0$00.50/0 © AOISPress