From Big Medical Encyclopedia

NITROUS OXIDE (Nitrogenium oxydulatum; synonym: laughing gas, Di-nitrogen oxide, Nitrogen monoxide, Nitrous oxide, Oxydum nitrosum, Protoxyde d’Azote, Stickoxydal; GFH) — means for an inhalation anesthesia, N 2 O.

Colorless gas, is heavier than air (specific weight 1,527), with a light characteristic smell and sweetish on taste; let's dissolve in water (1:2); t ° kip — 89 °, t ° froze 102 °. At t ° 0 ° and pressure of 30 atm it is condensed in a colorless liquid. Does not ignite, but at high temperatures sustains combustion. Mixes 3. ampere-second diethyl ether, cyclopropane and Aether chloratus as well as mixes with oxygen, in certain concentration are explosive with a high pressure in the presence of oils.

3. and. has weak narcotic activity. Even at inhalation it only the initial stage of a stage of a surgical anesthesia is in pure form reached, and it is possible to support an anesthesia at this level no more than 30 — 90 sec. since develops hypoxia (see) and asphyxia (see). Inhalation of mix 3. ampere-second oxygen in the ratio 80: 20 it is possible for an appreciable length of time without the phenomena of a hypoxia, but at the same time in most cases it is not possible to reach the sufficient depth of an anesthesia. The mixes with oxygen containing 40 — 60 about. % 3. and., cause a deep analgesia.

An anesthesia at inhalation 3. and. develops very quickly. The stage of excitement is absent. In a blood plasma 3. and. is in the dissolved state, does not contact hemoglobin. Awakening after the termination of inhalation 3. and. begins in 1 — 3 min.

From an organism 3. and. it is completely allocated in not changed look through lungs within 10 — 15 min. after the termination of inhalation,

Unlike other means for an inhalation anesthesia, 3. and. does not irritate respiratory tracts, practically does not oppress breath and does not exert negative impact on parenchymatous bodies and a metabolism. Side effects are observed seldom, generally during the use of mixes 3. ampere-second the insufficient content in them of oxygen, are also caused by a hypoxia. 3. and. is issued in steel cylinders under pressure (in the liquid state). Cylinders are painted in gray color.

Use of nitrous oxide in anesthesiology

for the purpose of anesthesia 3. and. it was for the first time used by H. Wells in 1844, and in Russia — in 1880 S. K. Klikovich for a labor pain relief.

Broad use in anesthesiology 3. and. received after justification of advantages of a superficial anesthesia and implementation * in practice of muscle relaxants with use of adequate artificial ventilation of the lungs. At the strengthened premedication inhalation of gas mixture 3. ampere-second oxygen in the ratio 3: 1 or 4: 1 provides the anesthesia sufficient for performance of various operations, including on bodies of belly and chest cavities.

At an anesthesia 3. and. ventilation is carried out on a semiopen or half-closed circuit of breath (see. Inhalation anesthesia ). During the carrying out ventilation on the closed contour with absorption of carbon dioxide gas in the conditions of a long anesthesia inevitably there is a hypoxia (in connection with gradual increase in concentration 3. and. at the expense of the exhaled gas).

In modern anesthesiology at big operative measures 3. and. it is applied in combination with other anesthetics (Ftorotanum, cyclopropane, ether, barbiturates) and against the background of neyroleptanalgeziya (see). Purely gas mixture 3. ampere-second oxygen use hl. obr. for stopping of severe pains, in particular at acute coronary insufficiency, a myocardial infarction, in the postoperative period, and also at traumatic shock.

At the beginning of anesthesia 3. and. the patient feels slight dizziness, a sonitus; sometimes there are signs of euphoria, edges can be followed by psychomotor excitement. Analgetichesky effect 3. and. it is shown even before switching off of consciousness. In induction period (introduction to an anesthesia) tachycardia and increase in the ABP is noted. At stable composition of gas mixture 3. the ampere-second oxygen saturation of fabrics drug occurs within 4 — 8 min. Depth of an anesthesia at the same time does not exceed the limit of the first level of a surgical stage. Breath, pulse and the ABP during this period show a tendency to normalization, motor reaction on pain disappears.

Contraindication to use of an anesthesia 3. and. out of a combination with other means the states demanding the increased delivery of oxygen (acute blood loss, limited respiratory reserves, etc.) are.

See also Drugs .

Bibliography: Petrovsky B. V. and Efuni S. N. Medical anesthesia, page 67, 161, 185, M., 1967; The Guide to anesthesiology, under the editorship of T. M. Darbinyan, M., 1973.

N. A. Kruglov; S. N. Efuni (anest.).