karboxyhemoglobinemia

Carboxyhemoglobinemia, sometimes spelled karboxyhemoglobinemia, is a medical condition characterized by elevated levels of carboxyhemoglobin in the blood due to exposure to carbon monoxide (CO). It impairs oxygen transport and can cause tissue hypoxia.

CO binds hemoglobin with high affinity to form carboxyhemoglobin, reducing oxygen-carrying capacity and shifting the dissociation curve to the left, which limits oxygen release to tissues. CO may also impair cellular respiration at the mitochondrial level, contributing to hypoxic injury in organs such as the brain and heart.

Common causes include inhalation of CO from fires, malfunctioning furnaces or heaters, car exhaust in enclosed spaces, and smoke inhalation.

Symptoms range with exposure: headache, dizziness, weakness, confusion, nausea, and shortness of breath early, progressing to chest pain, syncope, seizures, or coma in severe cases. Cherry-red skin is not a reliable sign.

Diagnosis relies on clinical suspicion and measurement of carboxyhemoglobin by co-oximetry. Smokers may have mildly elevated baseline COHb.

Treatment includes removing the patient from exposure and administering 100% oxygen. This accelerates COHb clearance. Hyperbaric oxygen therapy is considered for signs of neurocognitive impairment, loss of consciousness, very high COHb levels, or pregnancy.

Prognosis improves with rapid treatment, though severe exposures can cause persistent neurologic deficits. Prevention focuses on proper venting and maintenance of fuel-burning appliances, and the use of carbon monoxide detectors in homes and workplaces.