Types and applications of medical gases
1 Types of medical gas
Medical gas refers to the gas used in medical procedures. Some are used for treatment, some are used for anesthesia, and some are used to drive medical equipment and tools. There are 7 commonly used gases: oxygen, nitrogen, nitrous oxide, argon, helium, carbon dioxide and compressed air.
2 Nature and use of medical gas
The molecular formula of oxygen is O2. It is a strong oxidizer and combustion aid. When high-concentration oxygen encounters grease, it will have a strong oxidation reaction, produce high temperature, and even burn and explode. Therefore, it is listed as a Class B fire hazard substance in the "Code for Fire Protection Design of Buildings".
However, oxygen is also the most basic substance to sustain life, and is used medically to supplement oxygen for patients with hypoxia. 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 humidifying bottles; critically ill patients take oxygen through ventilator.
Oxygen is also used in high-pressure chambers to treat diving sickness, gas poisoning, and for drug atomization.
(2) Nitrous oxide
The molecular formula of nitrous oxide is N2O. It is a colorless, pleasant, and sweet gas. After a small amount of inhalation, facial muscles will spasm and the expression of laughter will appear, so it is commonly called laughing gas.
Nitrous oxide is inactive and non-corrosive at room temperature. Nitrous oxide will decompose into nitrogen and oxygen when the temperature exceeds 650℃, so it has a combustion-supporting effect. At high temperatures, pressures above 15 atmospheres will cause grease to burn.
After a small amount of nitrous oxide is inhaled, it has anesthesia and analgesic effect, but a large amount of inhalation can cause suffocation. Medically, a mixture of nitrous oxide and oxygen is used as anesthetic, and the patient is inhaled for anesthesia through a closed method or a ventilator.
Using nitrous oxide as anesthetic has the advantages of short induction period, good analgesic effect, quick recovery, and no adverse effects on breathing, liver and kidney functions. But it has a slight inhibitory effect on the myocardium, muscle relaxation is not complete, and general anesthesia is weak. Nitrous oxide alone as anesthetic is only suitable for minor dental and surgical operations such as tooth extraction, fracture restoration, abscess incision, and surgical suture. In major operations, it is often used in combination with barbiturates, succinylcholine, opiates, cyclopropane, and ether to enhance the effect.
(3) Carbon dioxide
The molecular formula of carbon dioxide is CO2, commonly known as carbon dioxide. Medically, carbon dioxide is used to inflate the abdominal cavity and colon for laparoscopy and fiber colonoscopy. In addition, it is also used to cultivate bacteria (anaerobic bacteria) in the laboratory.
Carbon dioxide can be made into dry ice by pressurizing (5.2 atmospheres) and cooling (below -56.6°C). Medically, dry ice is used in cryotherapy to treat cataracts and vascular diseases.
(4) Argon, helium
The molecular formula of argon is Ar and the molecular formula of helium is He. They are a colorless, odorless, and non-toxic inert gas. Medically used for surgical instruments such as argon knife and helium knife.
(5) Compressed air
Compressed air is used to transmit power for oral surgical instruments, orthopedic instruments, ventilators, etc.
The molecular formula of nitrogen is N2. It is a colorless, odorless, non-toxic, non-combustible gas. It is inactive at room temperature and does not chemically react with common metals. Medically used to drive medical equipment and tools