Methemoglobin Pearls — Nitric Oxide, Inhaled, for Newborns with Persistent Pulmonary Hypertension — Clinical Pathway: ICU

Inhaled Nitric Oxide for Persistent Pulmonary Hypertension Clinical Pathway — N/IICU

Methemoglobin Pearls

  • In blood circulation, NO binds to the ion of the hemeprotein to produce nitrosyl hemoglobin.
  • Nitrosyl hemoglobin is oxidized to methemoglobin with the release of nitrates.
  • Premature infants have reduced levels of methemoglobin reductase and therefore are at a higher risk of methemoglobin toxicity. However, at iNO doses of < 20 ppm, methemoglobin levels were not found to be elevated.
  • When using iNO for a prolonged time or at doses > 20 ppm, consider checking methemoglobin levels (to be kept < 2.5%).
  • In the Neonatal Inhaled Nitric Oxide Study Group (NiNOS) trial, the peak level of methemoglobin was 2.4%±1.85%.
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