Failure of Pulse Oximetry and Cooximetry as Monitors in a Patient With Hemoglobin MIwate: A Case Report.

We present the perioperative details of a 2-year-old child scheduled for cleft palate repair. Low pulse oximetry readings after induction of anesthesia and before surgery led to the diagnosis of HbMIwate, a rare congenital methemoglobinemia due to mutation in the α-globin gene. We explored the utility of noninvasive cooximetry to monitor methemoglobin and oxygenation during anesthesia and found that noninvasive cooximetry is not useful to monitor oxygenation or to detect the percentage of methemoglobin arising from congenital variants like HbMIwate.