Objective: To study the clinical profile and cholinesterase levels of subjects of organophosphate and carbamate poisoning and to identify those subjects who would require ventilatory support.
Design: Prospective, observational study.
Setting: Intensive care unit of a tertiary care urban hospital.
Subjects: Fifty-two patients admitted with a diagnosis of organophosphate or carbamate poisoning.
Outcome measures: Subject survival and ventilator requirement.
Intervention: Treatment with atropine and pralidoxime and mechanical ventilation for patients with respiratory failure. Clinical features were monitored at every stage, and blood for plasma and red blood cell cholinesterase levels was collected on admission.
Results: According to the ingested poison, subjects were divided into four groups: organophosphates (13 subjects), mixed organophosphate and carbamate (18), carbamates (13), and a fourth miscellaneous group (8). Dyspnea and vomiting were the most common symptom and miosis and cyanosis were the most frequently observed signs. Plasma and red cell cholinesterase levels were lowest in the mixed poison group and highest in the carbamate group. Twenty-seven subjects developed Type I respiratory failure and 7 had Type II respiratory failure. Mechanical ventilation was required in 31 subjects. Overall 33 subjects survived. A scoring system, on a point scale of 16, was developed using miosis, unconsciousness, fasciculations, and plasma cholinesterase levels to predict ventilator requirement.
Conclusion: This study helps to identify at an early stage those patients with organophosphate or carbamate poisoning who would ultimately require ventilatory support. We found miosis, unconsciousness, fasciculations, and a low plasma cholinesterase level to be of greatest predictive value.