Registration number Ï/98/14/1 Nitrous oxide - colourless gas, heavier than air, with specific smell. Related density is 1,527. It is dissolved in water (1:2). At 0 Â°C and pressure 30 atm., and also at usual temperature and pressure 40 atm., it thickens to colourless liquid. From 1 kg of liquid nitrous oxide 500 l of gas form. It does not catch fire, but keeps burning. In mixture with ether, cyclopropane, chlorethyl in certain concentrations it is burst-dangerous.
Nitrous oxide belongs to anaesthetic medicines. Small concentrations of it cause feeling of intoxication (name \"laughing gas\") and light sleepiness. Under breathing of clean gas, especially in large concentrations, narcotic state and asphyxia quickly develop. In mixture with oxygen under correct dosage it causes narcosis without preliminary irritation and side effects. Nitrous oxide possesses weak narcotic activity; in connection with this it\'s necessary to use it in large concentrations. In most cases combined anaesthesia is used, under which nitrous oxide is combined with other more powerful medicines for anaesthesia and miorelaxantes. Nitrous oxide does not cause irritation of respiratory tract. In organism it does not almost change, does not bind with hemoglobin. After the finishing of breathing in 10 - 15 min it fully excretes through respiratory tract in unchanged kind.
Indications for usage
Anaesthezia with usage of nitrous oxide is carried out in surgical practice, operative gynecology, surgical stomatology, and also for anaesthetization of childbirth. \"Medicinal analgesic narcosis\" with usage of mixture of nitrous oxide and oxygen is used in post-operation period for prophylactics of traumatic shock, and also for release of pangs under acute coronary insufficiency, infarct myocardium, acute pancreatitis and other pathological states, which are not released with usual medicines.
Way of administration and doses
Nitrous oxide is used in mixture with oxygen with the help of special devices for gas narcosis. It usually begins with mixture, containing 70 % - 80 % of nitrous oxide and 30 % - 20 % of oxygen, then quantity of oxygen is increased to 40 % - 50 %. If under the concentration of nitrous oxide 70 % - 75 % it is not possible to achieve the necessary depth of anaesthezia, other more powerful narcotic medicines are added - phtorotan, ether, barbiturates.
For more full weakening of muscles miorelaxantes are used. Under this not only muscles weaken, but also the anaesthezia current is improved.
After finishing of giving of nitrous oxide to avoid hypoxia oxygen should be given during 1 - 5 min.
For anaesthetization of childbirth the method of interrupted autoanalgesia is used with usage of mixture of nitrous oxide (40 % - 75 %) and oxygen with the help of special narcosis devices. Woman in childbirth begins to breathe mixture under appearance of precursors of birth pang and stops breathing on height of pang or up to its end.