Prolonged apnea after ECT in organophosphorus poisoning – the need to redefine norms

BACKGROUND: Poisoning and deaths by organo-phosphorous (OP) compounds are one of the major causes of death in developing and poor countries, and a common admission in the emergency ward and the ICU. OP compounds act by irreversibly binding to pseudocholinesterase enzyme and hence prolong the apnea in patients being given suxamethonium. We present a unusual case of OP poisoning (OPP) in which prolonged apnea ensued in a patient of severe depression following MECT (modified electroconvulsive therapy) in which suxamethonium was used as muscle relaxant, in whom we were cautious of the side-effect of prior organophosphorus poisoning. Since the cases of OPP are very high worldwide, a thorough knowledge of the interaction of the action of the drug and the receptors on which it acts takes pride of place. This article highlights the nuances in the field of psychiatry and anaesthesia in diagnosis and management of prolonged apnea after ECT. CASE PRESENTATION: A 53/F patient consumed OP 38 days prior to MECT. Since existing literature recommend a delay of 4 weeks and a subminimal dose of suxamethonium to prevent prolonged apnea, both these points were taken into consideration. Despite 38 days post exposure to OP, and a dose of succinylcholine of < 0.3 mg/kg, the patient remained apneic for 3 h. Suxamethionum apnea was managed with elective ventilation. After recovery, patient had no residual effect. Subsequently her pseudocholinesterase levels were done which were found to be very low. CONCLUSION: This case is being presented to emphasize that behaviour of post synaptic receptors cannot be relied upon after OP poisoning and pseudocholinesterase levels needs to be mandatorily checked, irrespective of duration post-exposure. In strong suspects dibucaine number and fluoride number also needs to be estimated.