Acute Methaemoglobinemia-Early Indicators of Prognosis-An Emergency Department based Study

To study the clinical manifestations, laboratory findings, complications and outcome of acute methemoglobinemia secondary to nitrobenzene poisoning.

prospective observational study done in a tertiary care teaching hospital of central Karnataka for 3 years. All the cases were followed up till the discharge and results were formulated based on clinical features, duration of hospital stay and ventilator support, dose of methylene blue and outcome.

total of 16 cases were admitted over a period of 3 years from June 2014-june 2017. Out 16 cases 15 were due to nitrobenzene ingestion and 1 case was dapsone induced methemoglobinemia. Among 16 cases 13 had favourable outcome and among the 3 patients died, hemodynamic and respiratory parameters were deranged at the time of presentation to ED.

In our study it is been evident that predictors of poor outcome based on initial clinical features were presenting blood pressure, percentage saturation, ABG, Po2, sao2 and so2. Metabolic acidosis at presentation is a better predictor of outcome in a case of methemoglobinemia. The dose of methylene blue is completely dependent on clinical improvement of the patient, it does not have much of value in predicting mortality. As the duration of mechanical ventilation increases, the prognosis will be worsening.

Thus managing a case of methemoglobinemia in an emergency department needs high level of suspicion, with assessment of early clinical and vital parameters which could have a significant impact on outcome as mentioned above. Meticulous use of antidote along with correction of acidosis remains main stay of management. By using above mentioned clinical parameters ED physician can predict the mortality in case of methemoglobinemia.