Gas poisoning in general refers to the poisoning caused by carbon monoxide produced by incomplete combustion of gas, which may cause dizziness, weakness of limbs, nausea and other symptoms, serious coma, or even death, requiring timely treatment. 1. Mild poisoning: patients have different degrees of headache, dizziness, nausea, vomiting, panic and limb weakness. Patients who originally suffered from coronary heart disease may have angina pectoris. Symptoms will disappear soon after inhaling fresh air or oxygen therapy away from the poisoned environment. 2. Moderate poisoning: patients may have chest tightness, shortness of breath, dyspnea, hallucinations, blurred vision, reduced judgment, dyskinesia, drowsiness, blurred consciousness or shallow coma. The mucous membrane of mouth and lips may be cherry red. After oxygen therapy, the patient can return to normal without obvious complications. 3. Severe poisoning: the patient may rapidly develop coma, respiratory depression, pulmonary edema, arrhythmia or heart failure. The patient may be in the state of decorticate syndrome. Some patients combine with aspiration pneumonia. Redness, swelling and blisters may appear on the skin of the pressurized area. Funduscopic examination may reveal optic disc edema. When carbon monoxide poisoning occurs, the first thing to do is to move the patient to a place where the air is more circulated, try to inhale fresh air, and promptly call 120 for help.