Submitted by Dr TAM Oi Yan Jackie (Resident Trainee); Department of Intensive Care, PYNEH on 9 March 2009
A 62-year-old lady with history of bipolar affective disorder was brought to the AED for abnormal behaviour and confused speech at home. She had coarse tremor and unsteady gait. Her usual medications included Lithium, Risperidone and Benzhexol.
Further history taking reviewed an accidental overdose of twenty-three 400mg tablets of Lithium over the previous 5 days, though the dosage was meant to be only 600mg daily. She had no loss of consciousness, convulsion, palpitation, nor any gastrointestinal symptoms. On physical examination, her GCS was E4M6V4 with stable haemodynamics. She had severe tremor, ataxia, muscle fasciculations, and hyperreflexia. She was diagnosed lithium toxicity clinically and was admitted to the Intensive Care Unit. The serum lithium level was 3.61. Her renal function test was unremarkable.
She was given a session of haemdialysis (SLED) with the following prescription:
Machine: AK200US
Dialyser: Polyflux 8L
Blood flow: 150-200ml/min
Dialysate: Na 140, HCO3 28, flow 300-400ml/min, Temp 37C
Duration: 7hrs
UF: 2L
Replacement: 2L NS + 40mmol KCl/L
Anticoagulation: Tinzaparin 2000 units at start and 1000 units at 3rd hr
The serial Lithium levels were plotted as above.
SLED was completed uneventfully within the prescribed time. The patient was orientated and less disturbed after a session of haemodialysis. She was kept close monitoring for any rebound in lithium level, which was unremarkable.
Discussion
1. A similar case here in Medscape.
2. A powerpoint presentation on “Lithium poisoning: To dialyse or not to dialyse …” Dr Sophie Gosselin, MD, FRCP, in September 2003 is here.