Low Saturation Readings in a Patient with Congenital Methemoglobinemia Exposed to Patent Blue Dye: A Case Report

Abstract

Pulse oximetry is widely used perioperatively to detect respiratory events. Abnormal haemoglobins such as methemoglobin can result in inaccurate readings. Here we present the clinical challenges of managing a patient with congenital methemoglobinemia who went for surgery involving injection of patent blue dye and subsequently had a prolonged duration of poor saturation readings post-operatively. Differentials include desaturation due to respiratory causes, worsening of methemoglobinemia and delayed excretion of patent blue dye.