- Hemoglobin changed to met-hgb form, which cant bind O2
- Often from meds like dapsone, benzocaine spray, rasburicase (in particular if G6PD deficient)
- Acidosis and target organ dysfunction→ more severe w/higher levels met-hgb
- Sometimes hemolysis
- Tachypnea
- Tachycardia
- O2 sat 85%
- PO2 and O2 saturation on ABG higher than expected compared with non-invasive O2 saturation
- Measured methhemoglobin level high
- Can have lactic acidosis, other end organ dysfunction from low O2 delivery
- Sometimes evidence hemolysis (drop in HgB, elevated T Bili, LDH, retics; low haptoglobin)