Theophylline overdose Treatment with charcoal haemoperfusion

Six hours after ingesting approximately 50 slow release theophylline 200mg tablets a 38-year-old man, with a past history of mild chronic asthma, was admitted. He was agitated and tremulous with a pulse rate of 180 beats/min and BP of 110/70mm Hg. The patient's white blood cell count was 16.2 x 103jcm3 and serum creatinine and glucose levels were higher and potassium, calcium and bicarbonate levels lower than normal. The serum theophyJline concentration was 732 I'mol/L and sinus tachycardia appeared on the EeG. Despite gastriC lavage and activated charcoal administration his BP fell over 2 hours to 80/5Omm Hg, agitation increased and episodes of supraventricular tachycardia (up to 220 beats/min) occurred. Thus, charcoal haemoperfusion therapy was selected . However, belore its initiation his BP dropped to 40/30mm Hg, a generalised convulsion occurred and, after diazepam 10mg and suxamethonium 100mg IV, the patient was intubated. Two HIres of normal saline and dopamine (12 p.g/kg/ min) increased BP to BO/55mm Hg. Severe metabolic aCidosis was identified. Haemoperfusion was begun and the patient was given heparin 1O,OOOU IV immediately followed by an infusion of 1000 U/hour. Over the next hOllr 275m mol of sodium bicarbo'nate was infused which raised both arterial pH and bicarbonate concentration. Over 24 hours insulin 5 U/hour. potassium 109mmol and calcium gluconate 2g were infused and 140mmol of potassium was lost in urine .

Six hours alter initiation of haemoperfusion the patient's clinical condition had greatly improved. This improvement paralleled the fall in plasma theophylline concentration. The BP was now 160/60rnm Hg, pulse rate 130 beats/min and the patient was no longer agitated. An hour later haemoperfusion was discon~inued . Serum potassium, PC02 and bicarbonate had risen slightfy and creatinine and glucose fallen from admission values . Although the white blood cell and platelet counts and phosphate concentration fell during haemoperfusion other commonly reported side effects (a fall in calcium and blood glucose concentrations) did not occur.

When therapy for theophylline overdose is being considered the authors suggest that 'aggressive drug removal with enteral activated charcoal in all, and haemoperfusion in those likely to have high blood theophylline concentration, should lessen mortality'. Two fUrther recommendations are that haemoperfusion be continued until the patient is clinically stable with a plasma theophylline concentration < 150l'moi/L and that the procedure should be performed by experienced personnel . Kelly WJ. w. and Parkin. W.O . AuslraiJan and New Zealand Journal of Medicine 15. 75-77 (Feb 1985)