Relevance of Plasma Cholinesterase to Clinical Findings in Acute Organophosphorous Poisoning

Background: Organophosphorus (OP) poisoning is a major public health problem in developing world. OP pesticides inhibit carboxylic esterase enzymes including plasma cholinesterase (PChE). Clinical manifestations following OP poisoning can be associated with the extent of decrease of PChE. This study was designed to investigate the relevance of PChE level to clinical manifestations in OP poisoning and to evaluate usefulness of PChE in predicting clinical outcomes. Methods: This was a cross-sectional study which was conducted at Jawaharlal Nehru Medical College, Karnataka from 1st October 2009 to 30th September 2010. Seventy-six OP poisoned patients were enrolled and their clinical manifestations were recorded. 5-ml samples of intravenous blood were collected from each patient (on first day and fifth day of treatment) under strict aseptic precaution and the PChE level was measured. Results: In total, mean age of patients were 25.5 (range: 21-30) years. Majority of patients were males (65.7 %), from rural areas (86.84 %) and agricultural workers (25%). Main clinical findings at the time of admission were congested conjunctiva (87%), pin point pupil (83%), lacrimation (80%), vomiting (78%), non-reactive pupil (75%), respiratory distress (60%) and abdominal pain (37%). Mean (SD) PChE at 6 hours post-exposure was 3672.4 (4200.1) IU/L. At presentation, cyanosis, muscle weakness, convulsion, respiratory distress and fasciculation were related to cases with >75%reduction of PChE, while,  constricted and non-reactive pupil, lacrimation and congested conjunctivae were related to cases with 50-75% reduction and abdominal pain, dryness of conjunctiva, vomiting and diarrhea were related to