Intermittent haemodialysis and sustained low-efficiency dialysis (SLED) for acute theophylline toxicity

Theophylline overdose can result in significant cardiovascular and neurologic toxicity and is potentially fatal. Clearance of theophylline can be enhanced by the administration of multiple-dose activated charcoal (MDAC) and extracorporeal elimination techniques. We report a case of severe theophylline toxicity initially treated with MDAC and intermittent haemodialysis. Subsequent to this, sustained low-efficiency dialysis (SLED) was undertaken. This is a prolonged renal replacement therapy that uses blood and dialysate flow rates between those of intermittent haemodialysis and continuous renal replacement therapy.

A 61-year-old man presented following ingestion of 24 g of theophylline SR (300 mg/kg), 240 mg of diazepam and 2 g of gabapentin. He required intubation and developed a supraventricular tachycardia treated with esmolol, but suffered no seizures. Serum theophylline concentration peaked at 636 μmol/L (55-110) at 9.5 h post-ingestion. Intermittent haemodialysis was performed for 4 h and resulted in a theophylline extraction ratio of 0.57 with elimination half-life of 2.3 h. SLED was subsequently performed on two occasions for 7 h. Theophylline extraction ratio ranged from 0.46 (half-life 5.3 h during the first cycle) to 0.61 (half-life 10.6 h during the second cycle). After cessation of SLED, elimination half-life was 26 h. The patient made an uneventful recovery.

Intermittent haemodialysis is the current recommended extracorporeal technique for enhancing theophylline elimination in the absence of charcoal haemoperfusion. However, SLED produced similar apparent extraction ratios with longer associated elimination half-life for theophylline than for intermittent haemodialysis. SLED is undertaken by intensive care unit (ICU) staff and may be a useful extracorporeal elimination technique in cases where access to intermittent haemodialysis, requiring specialist dialysis nursing staff, is limited or may be delayed.