Critical Cases - Methemoglobinemia!


Case progression

  • ACLS measures are implemented with a presenting rhythm of asystole
  • Pts POC glucose is 230 
  • Pt's blood is noted to be very dark, almost chocolate colored
  • After 30 minutes, resuscitation is terminated and patient pronounced dead

Additional history from family

  • Discussion with family reveals the discovery of a large tub of soidum nitrite in the pts room
  • Her computer browser is open to a page titled "how to commit suicide with sodium nitrite"
  • Sodium Nitrite is readily available for order via the internet
  • The patient therefore likely died from methemoglobinemia


  • The mechanism of action of sodium nitrite is to oxidize the iron within hemoglobin from the ferrous Fe+2 state to the Ferric Fe+3 state
  • Fe+3 cannot bind oxygen, and the remaining subunits of hemoglobin bind o2 more tightly, preventing delivery to tissues
  • The tissues are essentially starved of oxygen even with normally functioning lungs
  • Clinical presentation: headache, confusion, dyspnea, seizure/coma/death
  • O2 sats will hover around 85% as there is still ample oxygen bound to hemoglobin which will be detected as oxyhemoglobin
  • Pt appearance is classically cyanotic, but this pt's extremely pale appearance is also described
  • Common causes: nitrites, nitrates, benzocaine, silo gas fumes
  • Treatment: methylne blue, reduces Fe+3 --> Fe+2



BMJ Case Report: A non-fatal intoxication with a high-dose sodium nitrate Authors: Dorien Joosen, Leo Stolk, Ronald Henry