Deep coma and hypokalaemia of unknown aetiology following Bungarus caeruleus bites: Exploration of pathophysiological...

Bungarotoxin present in Bungarus caeruleus (BC) causes life threatening respiratory muscle paralysis. Deep coma and hypokalaemia have been observed in a significant proportion of patients, but the cause is unknown. We postulate the likely mechanism behind these two phenomena. We studied clinical details of two patients admitted with deep coma and performed electroencephalograms (EEG) and brain stem auditory and visual evoked potentials (BAEP and VEP). Daily serum potassium was measured along with urinary potassium excretion as a marker of total extracellular body potassium. Both patients had no brain stem reflexes on admission and the EEG revealed absent alpha and delta activity and presence of dominant theta activity. Alpha rhythm returned on the 3(rd) day in one patient, while in the other it did not, and the latter patient died on the 13(th) day due to disseminated intravascular coagulation. BAEP were delayed and VEP were absent in the deceased patient. Both had low serum potassium and low urinary potassium excretion. Replacement of potassium (up to 1.5mmol/kg/day) did not improve serum potassium and urinary potassium excretion. Absent alpha and delta activity in EEG and delayed BAEP and absent VEP are suggestive of a central action of the venom on both the cortical and brain stem neurones. Persistently low serum potassium and reduced urinary potassium excretion are suggestive of intracellular shift as the causative mechanism of hypokalaemia.