The nature and use of medical gases

(1) Oxygen

The molecular formula of oxygen is O2. It is a strong oxidant and combustion improver. When high-concentration oxygen encounters oil, it will undergo a strong oxidation reaction, generate high temperature, and even burn and explode. Therefore, it is listed as a Class B fire hazardous substance in the "Code for Fire Protection of Building Design".

However, oxygen is also the most basic substance to sustain life, and it is used medically to supplement oxygen in hypoxic patients. Direct inhalation of high purity oxygen is harmful to the human body, and the oxygen concentration for long-term use generally does not exceed 30-40%. Ordinary patients take oxygen through a humidified bottle; critically ill patients take oxygen through a ventilator.

Oxygen is also used in high-pressure warehouses for the treatment of diving diseases, gas poisoning, and for drug atomization.

(2) Nitrous oxide

The nitrous oxide formula is N2O. It is a colorless, good-smelling, sweet-smelling gas. After a small amount of inhalation, the facial muscles will be paralyzed and a smiley expression will appear.

Nitrous oxide is not active at normal temperature and is non-corrosive. Nitrous oxide decomposes into nitrogen and oxygen at temperatures above 650 ° C, so it has a combustion-supporting effect. At high temperatures, pressures above 15 atmospheres can cause oil to burn.

After a small amount of inhalation of laughter, there is anesthesia and analgesic effect, but a large amount of inhalation can cause suffocation. Medically, a mixture of laughing gas and oxygen is used as an anesthetic, and the patient is inhaled by a closed method or a ventilator for anesthesia.

The use of nitrous oxide as an anesthetic has the advantages of short induction period, good analgesic effect, quick recovery, and no adverse effects on respiration and liver and kidney function. However, it has a slight inhibitory effect on the myocardium, incomplete muscle relaxation, and weak general anesthesia. It is only used as an anesthetic for laughing gas. It is only suitable for dental and surgical minor operations such as extraction, fracture reconstruction, abscess incision, surgical suture. Major surgery is often used in combination with barbiturates, succinylcholine, opiates, cyclopropane, and diethyl ether to enhance the effect.

(3) Carbon dioxide

The molecular formula of carbon dioxide is CO2, commonly known as carbonic acid gas. Medically, carbon dioxide is used to inflate the abdominal cavity and colon for laparoscopy and fiberoptic colonoscopy. In addition, it is also used in laboratory culture of bacteria (anaerobic bacteria).

The carbon dioxide can be made into dry ice by pressurization (5.2 atmospheres) and cooling (below -56.6 °C). Medically, dry ice is used in cryotherapy for the treatment of cataracts, vascular diseases, and the like.

(4) Argon and helium

The argon gas has the formula Ar and the helium gas formula is He. They are a colorless, odorless, non-toxic, inert gas. Medically used for surgical instruments such as argon knives and hernia knives.

(5) compressed air

Compressed air is used to transmit power to oral surgical instruments, orthopedic devices, ventilators, and the like.

(6) Nitrogen

The molecular formula of nitrogen is N2. It is a colorless, odorless, non-toxic, non-combustible gas. It is inactive at normal temperature and does not react chemically with ordinary metals. Medically used to drive medical equipment and tools.