Metahemoglobinemia Detected during General Anesthesia - A Case Report

Abstract

Methaemoglobinaemia can cause significant tissue hypoxia, leading to severe, potentially life-threatening clinical features and/or death. We describe the anesthetic care of a patient with acquired methemoglobinemia related to recreational drug use. As was the case in this patient, the diagnosis may first be made intraoperatively. A 38-year-old man who had to have emergency surgery due to traumatic colonic perforation. At the physical examination presented a blue skin colour, cyanosis, normal blood pressure and heart rate, respiratory rate of 18/min. Pulse oximetry revealed an oxygen saturation (SpO 2 ) of 85% with a 36% FIO 2 , normal chest x-ray. The first arterial blood sample had a chocolate brown colour and the co-oximeter showed a methemoglobin level of 31%. Methylene blue was administrated. Pulse oximetry revealed an increase in saturation to 100%. One day after the surgery, we asked the patient for the causative agent of his Metahemoglobinemia and we found out that he had taken amyl nitrite (poppers).