Treatment of Sodium Nitrite Poisoning
The immediate treatment for sodium nitrite poisoning is intravenous methylene blue, which must be administered as early as possible to reverse life-threatening methemoglobinemia and prevent death. 1, 2, 3
Immediate Recognition and Diagnosis
Sodium nitrite poisoning causes severe methemoglobinemia, presenting with:
- Profound cyanosis with chocolate-brown colored blood that does not change color even when oxygenated 4
- Rapid progression to altered mental status, coma, and cardiovascular collapse 2, 3
- Severe hypotension and metabolic acidosis 2
- Oxygen saturation readings that do not correlate with clinical appearance (pulse oximetry is unreliable) 3
Do not wait for confirmatory methemoglobin levels to initiate treatment—clinical suspicion alone warrants immediate therapy. 1, 3
Primary Antidote: Methylene Blue
Administer methylene blue 1-2 mg/kg IV over 5 minutes immediately upon suspicion of sodium nitrite poisoning. 2, 5
Dosing Considerations:
- Early administration is the single most important factor determining survival 1, 2, 3
- Repeat doses may be necessary every 30-60 minutes if methemoglobinemia persists or recurs 2
- Consider higher initial doses (up to 2 mg/kg) or more frequent redosing than standard methemoglobinemia protocols given the massive oxidative stress from sodium nitrite 2
- Maximum cumulative dose is typically 7 mg/kg, though higher doses may be required in severe cases 2
Critical Timing:
The two survivors in a case series of five patients both received methylene blue early in their clinical course, while all three fatalities had delayed or no methylene blue administration 2. One fatal case during ECPR went unrecognized because point-of-care testing failed to provide methemoglobin levels 4.
Supportive Care
Aggressive cardiovascular support is essential:
- Secure airway early—patients rapidly progress to respiratory failure 3
- Administer high-flow 100% oxygen (though this will not correct the methemoglobinemia, it maximizes oxygen delivery to tissues) 3
- Provide aggressive IV fluid resuscitation for hypotension 2
- Use vasopressors (norepinephrine preferred) if hypotension persists despite fluids 2
- Correct metabolic acidosis with sodium bicarbonate 3
Advanced Interventions
Consider extracorporeal membrane oxygenation (ECMO) early for refractory shock or cardiac arrest, but recognize that ECMO alone will not reverse methemoglobinemia—methylene blue remains essential 4. One case demonstrated failed ECPR when methemoglobinemia went untreated, with blood maintaining a brown color throughout the circuit 4.
Monitoring
- Serial methemoglobin levels every 1-2 hours until declining and patient stabilizing 2
- Continuous cardiac monitoring for dysrhythmias 2
- Arterial blood gas monitoring for metabolic acidosis 3
- Neurological assessment for hypoxic brain injury 3
Critical Pitfalls to Avoid
Do not delay methylene blue administration waiting for laboratory confirmation—methemoglobin levels above 70% have been documented, and death can occur within hours 2, 3. Point-of-care testing may fail to provide accurate readings in severe cases 4.
Do not rely on pulse oximetry—it becomes unreliable at methemoglobin levels above 15% and will not reflect true oxygen saturation 3.
Do not assume standard methylene blue dosing will suffice—sodium nitrite ingestions often require higher or more frequent doses than other causes of methemoglobinemia 2.
Recognize that sodium nitrite is increasingly accessible online and promoted on suicide forums, making this an emerging public health threat with rising incidence since 2017 1, 5. Estimated ingested doses in reported cases ranged from 15-113 grams, with survival possible even after 60-gram ingestions if treated promptly 2.
Prognosis
Symptoms typically resolve within 24 hours in survivors who receive early methylene blue 2. However, delayed treatment results in severe hypoxic brain injury and death 3. The mortality rate is extremely high without prompt antidote administration 1, 2, 3.