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

INTRODUCTION

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.

CASE REPORT

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.

DISCUSSION

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.

Severe theophylline poisoning: charcoal haemoperfusion or haemodialysis?

Theophylline poisoning with a blood level of 183 mg/l in a 38-year-old man was treated with activated charcoal by mouth, but despite this the blood level of theophylline rose and there was circulatory collapse with rhabdomyolysis, acute renal failure and hyperthermia. Treatment with charcoal haemoperfusion and simultaneous haemodialysis was given, followed by continuous arteriovenous haemodialysis (CAVHD). Mean extraction rates of theophylline were 26% during CAVHD, and 86% during combined dialysis and charcoal haemoperfusion. During combined treatment, the mean extraction rate of haemodialysis was 62%, compared with 48% for charcoal haemoperfusion. In summary, activated charcoal given by mouth may be unable to prevent a rise in blood levels and the development of complications after substantial theophylline overdose. If theophylline is to be removed from the blood, a combination of charcoal haemoperfusion and haemodialysis will give the best clearance, but haemodialysis alone may be effective.