Laughing gas, angel or devil?

This is the 4244th article of Da Yi Xiao Hu

Recently, the news of a 14-year-old girl’s death after inhaling laughing gas has attracted widespread attention from the society. The name of laughing gas is still unfamiliar to many people. As an anesthesiologist, I have long known that laughing gas is an anesthetic drug, but because of its weak anesthetic effect and the possibility of hypoxia and other reasons, it is rarely used in the operating room.

The scientific name of laughing gas is nitrous oxide, a colorless and sweet gas. It was first discovered by British chemist Joseph Priestley in 1772. In 1799, another British chemist Humphry Davy discovered that inhaling nitrous oxide would produce euphoria, so he named it "laughing gas". People found that after inhaling laughing gas, they lost their sense of pain, but their consciousness remained clear. In 1845, Horace Wells demonstrated the pain relief of inhaling laughing gas during tooth extraction surgery at Massachusetts General Hospital in Boston, and he was therefore called the discoverer of modern anesthesia. In dental surgery, for children who refuse to cooperate and patients with mental tension, laughing gas has analgesic and sedative effects, making it very suitable for use as an inhaled anesthetic. The analgesic effect of laughing gas comes from its ability to stimulate the pituitary gland to release endogenous opioids-endorphins, thereby blocking the transmission of pain signals. Endorphins can cause euphoria and are known as "happy hormones". This is also one of the important reasons why laughing gas is abused.

Laughing gas is absorbed and excreted very quickly. It is not metabolized in the liver and kidneys, but is physically dissolved in the blood and does not bind to hemoglobin. However, laughing gas has strong diffusion properties, and inhalation may cause a decrease in blood oxygen content, resulting in brain hypoxia, suffocation, coma, and even death. Therefore, when used as an anesthetic, it is always inhaled with oxygen.

Laughing gas can destroy vitamin B12 in the body. Vitamin B12 is essential for maintaining healthy nervous system function. When it is deficient, it can cause neurological disorders, spinal cord degeneration, peripheral neuritis, and even serious mental symptoms. Some people who have been taking laughing gas for a long time have numbness and weakness in their hands and feet, unsteady walking, and even paralysis and disability in severe cases. Severe addicts will have hallucinations, mania, and violent aggressive behavior. Vitamin B12 deficiency can also lead to pernicious anemia, inflammation and ulcers of the tongue and oral mucosa, and other physical damage. Most people who take laughing gas lack medical knowledge and often wait until the symptoms of nerve damage are more serious before seeking medical treatment. According to literature reports, only 1/4 of patients can fully recover, and patients' initial treatment requires intramuscular injection of B12 supplements.

Laughing gas has so many hazards that my country listed it in the "Catalogue of Dangerous Chemicals" as early as 2015, and sentenced the first case of illegal operation of laughing gas in April 2018. However, the abuse of laughing gas is becoming more and more common, especially among young people, drug users, service industries, and entertainment venues. Although the addictiveness, harmfulness, and abuse characteristics of laughing gas are quite similar to those of drugs, it is not currently a legal drug in my country and cannot be strictly regulated and punished like drugs. Because in addition to being used as an anesthetic in medicine, laughing gas also has important uses in industry, and overly strict supervision may affect many production activities.

In the aerospace field, nitrous oxide is an excellent rocket propellant; in the automotive industry, nitrous oxide can be used as a combustion aid and to increase vehicle speed; high-purity nitrous oxide is an indispensable key raw material for the electronics industry and is widely used in the production of electronic products; in the food industry, nitrous oxide is used to beat cream to save time and effort, and it is also a good food preservative; nitrous oxide is also suitable as a refrigerant, a chemical raw material for producing phenol, used in atomic absorption spectroscopy analysis to meet scientific research needs, and can also be used to make pesticides.

Laughing gas also has a huge impact on the global environment. Its content in the atmosphere continues to rise, and it has become the second largest non-CO2 greenhouse gas and the largest ozone depleting substance. More than half of the laughing gas produced by human production activities is related to the use of nitrogen fertilizers in agricultural production.

Laughing gas has brought great help to mankind and has deeply affected every aspect of our lives. We must publicize the harmfulness of abusing laughing gas, strictly regulate its rational use, and reduce its large-scale emission, which are all serious issues facing us.

Author: Songjiang Hospital Affiliated to Shanghai Jiaotong University School of Medicine

Emergency Critical Care Department

Wang Xuemin