ABSTRACT
A 71-year-old inpatient with pneumonia developed central cyanosis and decreased saturated oxygen pressure (84%) shortly after bronchoscopy and endotracheal intubation. During the procedure two doses of 20% benzocaine were sprayed over one second and were separated by approximately two hours. An arterial blood gas sample revealed a pHa of 7.43, PaC02 of 40 mmHg, PaO2 of 201 mmHg, and an arterial percent oxygen saturation gap of 9%. The methernoglobin level was 22.5% indicating methemoglobinemia. Treatment included intravenous methylene blue 1 YO (1 mg/kg) for five minutes with reversal within one hour. A repeated arterial blood gas sample revealed a pHa of 7.40, PaC02 of 41 mmHg, PaO2 of 129 mmHg, SaOz of 99% and Sp02 of 96%. At this time the methemoglobinemia level was 2.4%. Approximately 2.75 hours post methylene blue dose, the SaO2 and the Sp02 were 98%. Antimicrobial treatment for pneumonia was continued without event and no recurrences of methemoglobinemia recurred.
