Relationship Between the Methemoglobin Level and Oxygen Saturation on a Pulse Oximeter in Cases of Acute Methemoglobinemia

Shim, Jae Cheol; Ryu, Hyun Ho; Lee, Yu Jin; Kim, Yong San; Youm, Kyung In; Moon, Jeong Mi; Chun, Byeong Jo; Min, Yong Il; Koh, Yang Seok

Abstract

PURPOSE
Methemoglobinemia is a disorder caused by over accumulation of methemoglobin in the red blood cells of circulating blood, prohibiting adequate supply of oxygen to organs. The seriousness of its clinical symptoms and its treatment methods are determined by the blood methemoglobin level. Therefore, we revealed the clinical relation between the blood methemoglobin level and oxygen saturation on a pulse oximeter. Then we tried to indirectly measure the blood methemoglobin level by using their relation, instead of checking its level through blood sampling.
METHODS
The medical records of 39 patients who were admitted to the Chonnam University Hospital Emergency Medical Center due to acute methemoglobinemia between January 1, 2001, and June 30, 2005, underwent a prospective analysis.
RESULTS
Among the total of 39 cases, there were 25 males (64.1%) and 14 females (35.9%). There were 15 cases (38.5%) of dapsone overdosage, 18 cases (46.1%) of aniline- type pesticide intoxication, and 6 cases (15.4%) of aniline gas inhalation. As for the main symptoms for admission to the emergency center, there were 8 cases involving on altered mental state, 7 involving dizziness, 3 involving cyanosis, 7 involving dyspnea; and 14 cases were nonsymptomatic. Relational analyses of arterial blood gas analysis results, pulse oximetry saturation levels, and blood methemoglobin levels of the admitted patients revealed that only the pulse oximetry saturation level was related to the blood methemoglobin level (p<0.001).
CONCLUSION
When in doubt about the possibility of acute methemoglobinemia, differences in the oxygen saturation level on the pulse oximeter level can be used instead of repeated co-oximetry examinations, can be used to judge treatment responses.