What are the three levels of carbon monoxide poisoning?

Under normal circumstances, gas poisoning usually refers to carbon monoxide poisoning, which can be classified into mild, moderate, and severe degrees. Mild and moderate cases generally do not pose a life-threatening risk, while severe poisoning may endanger life. The details are as follows:

1. Mild Poisoning

In mild poisoning, the concentration of carboxyhemoglobin in the patient's blood ranges from 10% to 20%. Due to oxygen deprivation in the brain and gastrointestinal tract, patients may experience symptoms such as dizziness and vomiting. Once removed from the contaminated environment and breathing fresh air or receiving oxygen therapy, symptoms usually resolve quickly, and there is generally no threat to life.

2. Moderate Poisoning

In moderate poisoning, the carboxyhemoglobin level in the blood reaches 30%–40%. Patients often sweat excessively, have rapid heart rate, feel agitated, and may become drowsy, frequently experiencing unconsciousness and collapse. If treated promptly—by removing the patient from the toxic environment and providing fresh air or oxygen—they can regain consciousness and recover within several days, typically without complications or long-term sequelae.

3. Severe Poisoning

In severe poisoning, the carboxyhemoglobin concentration rises to 40%–60%. Patients may fall into a coma and develop pulmonary edema, breathing difficulties, and arrhythmias; some may even suffer heart failure. In such cases, the patient must be immediately moved out of the contaminated environment and given fresh air. Prompt hospitalization is essential. Under medical guidance, hyperbaric oxygen therapy should be administered. If breathing becomes extremely weak or cardiac arrest occurs, cardiopulmonary resuscitation (CPR) must be initiated immediately.

Patients with carbon monoxide poisoning should seek immediate medical attention and receive treatment under the supervision of qualified healthcare professionals.