Carbon Monoxide Poisoning

About Carbon Monoxide Poisoning

Carbon monoxide CO is a colorless, odorless gas produced by incomplete combustion of carbon based fuels. It is one of the most common causes of fatal poisoning in many countries. Sources include malfunctioning furnaces, gas water heaters, car exhaust in enclosed spaces, generators, charcoal grills, and fire. CO binds to hemoglobin with approximately 200 to 250 times the affinity of oxygen, forming carboxyhemoglobin COHb and reducing oxygen delivery to tissues. Symptoms correlate loosely with COHb levels: below 10 percent often asymptomatic, 10 to 20 percent headache and dyspnea on exertion, 20 to 30 percent throbbing headache and irritability, 30 to 40 percent severe headache, nausea, confusion, 40 to 50 percent syncope and tachycardia, above 50 percent coma and seizures. The classic cherry red skin is rarely seen in living patients. Diagnosis requires measuring COHb levels with co oximetry. Pulse CO oximeters can measure noninvasively. Suspected carbon monoxide poisoning is a medical emergency: moving to fresh air and calling the local emergency number are the key first steps. Hospital treatment involves high flow oxygen through a non rebreather mask, which reduces the half life of COHb from approximately 320 minutes to approximately 80 minutes. Hyperbaric oxygen therapy is considered in selected severe cases, for example with loss of consciousness, neurological symptoms, or pregnancy, though evidence for benefit is mixed. Delayed neurologic sequelae including cognitive impairment and parkinsonism can occur 2 to 40 days post exposure. CO detectors in homes prevent fatal exposure.