[Medical Q&A] If you have carbon monoxide poisoning, why do you need hyperbaric oxygen therapy?

Planner: Chinese Medical Association

Reviewer: Yu Qiuhong, Chief Physician, Beijing Tiantan Hospital, Capital Medical University

In carbon monoxide poisoning, the affinity of carbon monoxide to hemoglobin is 200 to 300 times higher than that of oxygen to hemoglobin. Therefore, carbon monoxide can easily bind to hemoglobin to form carboxyhemoglobin (COHb). The dissociation rate of carboxyhemoglobin is 3,600 times slower than that of oxyhemoglobin, causing hemoglobin to lose its oxygen-carrying capacity and function, resulting in blood hypoxia. Carbon monoxide also inhibits the activity of cytochrome oxidase in mitochondria, affects the respiration and oxidation process of cells, and further hinders the use of oxygen, leading to hypoxia in various organs and tissues of the body. In severe cases, this hypoxia may cause coma, organ failure, and even endanger life. As a treatment method, hyperbaric oxygen therapy plays an important role in the first aid of carbon monoxide poisoning.

During hyperbaric oxygen therapy, the air pressure is 2 to 3 times the normal atmospheric pressure, which can significantly increase the amount of oxygen dissolved in the blood. When a large amount of oxygen dissolves into the blood, it will replace the carbon monoxide molecules on the hemoglobin, shorten the half-life of carboxyhemoglobin, and accelerate the discharge of carbon monoxide, thereby restoring normal oxygen supply. After carbon monoxide poisoning, the oxygen content in the patient's blood drops sharply, resulting in insufficient oxygen supply to the organs. Hyperbaric oxygen can quickly provide enough oxygen, improve cell respiration, help restore the oxygen supply to important organs (such as the brain and heart), and reduce organ damage caused by hypoxia.

In addition, hyperbaric oxygen can also reduce sequelae. Carbon monoxide poisoning not only causes acute hypoxia, but may also cause delayed damage to the nervous system and other organs. Hyperbaric oxygen can effectively reduce long-term sequelae and accelerate the patient's recovery by promoting the repair and regeneration of cells or myelin.