First, the types of medical gases

Medical gases refer to gases used in medical procedures. Some are used for therapy, some for anesthesia, and some to drive medical devices and tools. Seven gases are commonly used: oxygen, nitrogen, nitrous oxide, argon, helium, carbon dioxide, and compressed air.

The medical gas system also includes negative pressure suction system and anesthesia exhaust gas discharge system.

The nature and use of medical gases

(1) Oxygen

The molecular formula for oxygen is O2. It is a strong oxidant and an accelerant. High concentration of oxygen will have a strong oxidation reaction when it meets grease, resulting in high temperature and even combustion and explosion, so it is listed as class B fire danger substance in the Code for Building Fire Design. However, oxygen is also the most basic substance for life, and is used medically to replenish oxygen for patients who lack oxygen. Temmao gas suggests that direct inhalation of high purity oxygen is harmful to human health, and the oxygen concentration for long-term use generally does not exceed 30 ~ 40%. Ordinary patients receive oxygen through humidifying bottles; Critically ill patients receive oxygen through ventilators. Oxygen is also used in high pressure chamber to treat diving disease, gas poisoning and for drug atomization.

(2) nitrous oxide

Nitrous oxide has the molecular formula N2O. It is a colorless, good smell, sweet gas, a small amount of inhalation, facial muscles will spasm, smile, so commonly known as 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, oil combustion occurs at pressures exceeding 15 atmospheres. Tianmao gas hints you: after a small amount of inhalation of laughing gas, there is anaesthetic analgesic effect, but a large number of inhalation will make the person asphyxiate. Medically, a mixture of nitrous oxide and oxygen is used as an anesthetic, administered by inhalation in an enclosed manner or on a ventilator. Using nitrous oxide as anaesthetic has the advantages of short induction period, good analgesic effect, quick recovery and no adverse effect on respiration, liver and kidney function. But it has a slight inhibitory effect on the myocardium, muscle relaxation is not complete, and general anesthesia is weak. Use laughing gas to make anaesthetic alone, apply to unplug tooth, fracture repair, abscess to cut, surgical sutures wait for dental, surgical small operation only. Major surgery is often performed in combination with barbiturates, succinylcholine, opiates, cyclopropane, and ether to enhance results.

(3) Carbon dioxide

The molecular formula of carbon dioxide is CO2, commonly known as carbonate gas. Medically, carbon dioxide is used to inflate the abdominal cavity and colon for laparoscopy and fibrocolonoscopy. In addition, it is used in the laboratory to grow bacteria (anaerobic bacteria). Carbon dioxide is pressurized (5.2 atmospheres) and cooled (below -56.6℃) to form dry ice. Medically dry ice is used for cryotherapy, cataract treatment, vascular disease, etc.

(4) Argon, helium

Argon has the formula Ar and helium He. They are a colorless, odorless, non-toxic inert gas. Used for argon knife, helium knife and other surgical instruments in medical treatment.

(5) compressed air

Compressed air is used to transfer power for oral surgical instruments, orthopedic instruments and ventilators.

(6) Nitrogen

The molecular formula for nitrogen is N2. It is a colorless, odorless, non-toxic, non-burning gas. It is not active at room temperature and does not react with common metals. Used in medicine to drive medical devices and tools. Liquid nitrogen is often used in surgery, stomatology, gynecology, ophthalmology cryotherapy, treatment of hemangioma, skin cancer, acne, hemorrhoids, rectal cancer, various polyps, cataracts, glaucoma and artificial insemination.

3. Departments that use medical gases in hospitals

The departments using medical gases in hospitals mainly include operating room, pre-anaesthesia room, recovery room, debridement room, obstetrics and gynecology ward, ICU ward and general ward.