Long-term alcoholism is the factor that increases the mac of inhaled anesthetics. Because the central nervous system has a high tolerance to inhalation anesthesia and intravenous drugs, that is to say, when such patients receive anesthesia, the dose mac will increase relatively. After alcohol enters the body, it will form a hypertonic environment, which will make the secretion of antidiuretic hormone increase the circulating blood volume, which will lead to the decrease of anesthetic concentration and the increase of anesthetic mac.