From Big Medical Encyclopedia

CYCLOPROPANE (Cyclopro panum;

a synonym of Cyclopropane) — anesthetic; C3H6:

Colorless gas with a characteristic smell. Pier. weight (weight) 42,08. Relative density 1,879. At t ° 20 ° and pressure of 5 atm turns into liquid state; temperature of boiling with an atmospheric pressure — 34,5 °. We will dissolve in water a little (1 volume of gas at t ° 20 ° we will dissolve in 2,85 water volumes). it is easily alcohol-soluble, petroleum ether, chloroform and fatty oils. C. it is very flammable, its mixes with oxygen, nitrous oxide, air are explosive. In this regard use of C. in modern medical practice it is sharply limited.

At inhalation of C. the quantity — through skin is easily soaked up and removed in not changed look through lungs, a nek-swarm. Apprx. 0,5% of the entered quantity is exposed to biotransformation and it is allocated in the form of carbon dioxide gas and water. By the time of return of consciousness at the patient contains in the exhaled mix apprx. 1 about. % of cyclopropane. In 3 hours after the termination of inhalation of C. in expired air traces of drug are found.

C. is active anesthetic (see). In concentration 3 — 5 about. the % causes an analgesia, 6 — 8 about. the % — switches off consciousness, 8 — 14 about. the % — causes a superficial anesthesia (a stage of Illi), 15 — 20 about. % — an anesthesia of moderate depth (a stage of Sh2), 20 — 30 about. % — a deep anesthesia (a stage of P13).

For introduction to an anesthesia concentration of C. in the inhaled gas mixture gradually (within 1 min.) increase to 15 — 20 about. %. At the same time patients usually fall asleep within 2 — 4 min.

Awakening after an anesthesia comes in 5 — 10 min. after the termination of inhalation of drug. Due to the bystry awakening patients can feel severe pain after operation. In this regard it is recommended at long operation in 30 min. prior to its termination to enter anesthetic, napr, Promedolum. After an anesthesia the headache, nausea, vomiting, arterial hypotension is quite often noted.

In small concentration of C. exerts the weak oppressing impact on breath. In process of increase in concentration of C. significantly the minute volume of lung ventilation decreases that can lead to a respiratory acidosis (see). However degree of respiratory depression is less, than at an anesthesia Ftorotanum (see) or metoksiflurany (see), and spontaneous breath can provide adequate ventilation on grades of anesthesia of C., allowing to carry out operative measures.

In average concentration of C. influences contractility of a myocardium a little. Heart rate significantly does not change. Cordial emission also does not change, but at certain patients can increase. Decrease in cordial emission is observed only at a deep anesthesia. C. increases sensitivity of a myocardium to catecholamines (see) that is shown by developing of arrhythmias during an anesthesia. Frequency of arrhythmias increases at a hypercapnia (see). C. promotes also increase in maintenance of catecholamines in blood. Administration of adrenaline (see) at an anesthesia of C. can cause fibrillation of ventricles of heart (see).

Arterial pressure, especially systolic, against the background of a tsiklopropa-new anesthesia tends to increase in connection with increase in peripheric resistance that is in turn caused by increase in a tone of a sympathetic nervous system, and also a direct impact of C. on unstriated muscles of a vascular wall. The central venous pressure also increases.

At an anesthesia of C. decrease in a blood-groove in a liver, strengthening of bile secretion is observed. The damaging action on a parenchyma of a liver and kidneys of C. does not render. The oliguria observed during an anesthesia (see) is caused by decrease in a renal blood-groove.

C. can cause the short-term hyperglycemia caused by strengthening of adrenergic influences. However this effect is less expressed, than during the use of ether.

Anesthesia of C. it is contraindicated at the expressed thyrotoxicosis (see) and a pheochromocytoma (see Hromaffinom), bronchial asthma (see), arrhythmias (see Arrhythmias of heart), Kommersant situations when there can be a need for use of adre-nomimetichesky substances (adrenaline, noradrenaline, etc.), in cases of use during operation of electrothermic coagulation or an electroknife.

Store C. in the cool place far from sources of fire in the steel seamless

cylinders with a capacity of 1 and 2 l painted in orange color and supplied with the label «Carefully. Cyclopropane. Flammablly»; its mix with oxygen or air can explode at contact with a flame or other sources able to cause ignition. It can be applied only by the medical staff which underwent the corresponding instructing».

Use of cyclopropane in anesthesiology. C. apply to the introduction and supporting anesthesia at short-term operations (a mask method); in combination with other general anesthetics and muscle relaxants — for an anesthesia (see) at long operative measures (an endotracheal method).

At a mask method C. in mix with oxygen moves in gradually increasing concentration (from 5 to 30 about. %) at a flow rate of gas mixture it is not higher than 3 l! min. In

3 — 5 min. after approach 1H2 — Sh3 of a grade of anesthesia concentration of C. reduce to 12 — 10 about. %.

At an endotracheal method against the background of an introduction anesthesia barbiturates for maintenance Н^ of a grade of anesthesia of C. apply in concentration

5 — 10 about. %.

For decrease in toxicity and potential of explosion, and also for achievement of analgetic effect of C. often use in mixes with nitrous oxide. Among such mixes the broadest practical application was found by Shane's mix — Ash-mana containing 0,4 l (11,7%) of cyclopropane, 1 l (29,4%) of nitrous oxide and 2 l (58,9%) of oxygen (see. Inhalation anesthesia). It is usually used at short-term operative measures and manipulations, and also for maintenance of a superficial anesthesia at the general combined anesthesia with muscle relaxants (see Muscle relaxants, use in anesthesiology).

C. apply preferential on the half-closed contour providing high precision of a dosage and the smallest allocation of C. in air of the operating room.

The wedge, a picture of a cyclopropane anesthesia is characterized by bystry switching off of consciousness and lack of excitement. At the beginning of a stage of a surgical anesthesia (the stage of III^ breath becomes superficial and speeded up, the ABP remains at the initial level or decreases by 20 — 30 mm of mercury., tachycardia develops. During the deepening of an anesthesia there comes respiratory depression, bradycardia, hypotension, arrhythmia. Pupils extend, their photoharmose weakens. There is a pink coloring of skin and mucous membranes (as manifestation of a hypercapnia).

In the concentration providing the sufficient depth of the general anesthesia, C. does not exert impact on mucous membranes of respiratory tracts, function of a liver and kidneys, does not change sokratitelny activity of a myocardium and does not cause frustration of a hemodynamics. In high concentration of C. reduces the speed of a renal blood-groove and raises a tone of bronchioles. In toxic doses of C. causes an apnoea and hearts.

At a cyclopropane anesthesia the following complications are possible: respiratory depression, cardiac arrhythmias (owing to sensitization of a myocardium to catecholamines), a laryngospasm (see), bronkhio-lospazm. During awakening nausea and vomiting can be observed. The heaviest complication in this period is the so-called tsik-lopropanovy shock which is shown sharp falling of the ABP, pallor of skin and mucous membranes. This complication arises, as a rule, at falloff rs02 at patients with the expressed hypercapnia during an anesthesia. Adequate ventilation of the lungs is necessary for prevention of cyclopropane shock during an anesthesia, the gradual termination of introduction of C. with partial replacement with its nitrous oxide and the dosed increase in content in respiratory mix of oxygen.

See also Inhalation anesthesia. Anesthesia.

Bibliography: The reference book on anesthesiology and resuscitation, under the editorship of. A. A. Bunyatya-na, page 148, M., 1982; Chervinsky

A. A. Cyclopropane anesthesia, M., 1973; The pharmacological basis of therapeutics, ed. by L. S. Goodman a. A. Gilman, L., 1975.

B. V. Churyukanov; O. A. Dolina (anest.