Objective: To study the clinical profile and cholinesterase levels of
subjects of organophosphate and carbamate poisoning and to identify th
ose subjects who would require ventilatory support. Design: Prospectiv
e, observational study. Setting: Intensive care unit of a tertiary car
e urban hospital. Subjects: Fifty-two patients admitted with a diagnos
is of organophosphate or carbamate poisoning. Outcome Measures: Subjec
t survival and ventilator requirement. Intervention: Treatment with at
ropine and pralidoxime and mechanical ventilation for patients with re
spiratory failure. Clinical features were monitored at every stage, an
d blood for plasma and red blood cell cholinesterase levels was collec
ted on admission. Results: According to the ingested poison, subjects
were divided into four groups: organophosphates (13 subjects), mixed o
rganophosphate and carbamate (18), carbamates (13), and a fourth misce
llaneous group (8). Dyspnea and vomiting were the most common symptom
and miosis and cyanosis were the most frequently observed signs. Plasm
a and red cell cholinesterase levels were lowest in the mixed poison g
roup and highest in the carbamate group. Twenty-seven subjects develop
ed Type I respiratory failure and 7 had Type II respiratory failure. M
echanical ventilation was required in 31 subjects. Overall 33 subjects
survived. A scoring system, on a point scale of 16, was developed usi
ng 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 cho
linesterase level to be of greatest predictive value.