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a device that forces the delivery of a gas (air, oxygen, nitrous oxide) to the lungs and ensures the saturation of the blood with oxygen and the removal from the lungs of carbon dioxide gas.
The respirator is connected either to a mask placed on the patient’s face or to an intubator that is introduced into the respiratory tract. The AMBU and the “accordion” are respirators that are worked manually by the physician-anesthesiologist. The AMBU consists of a rubber or plastic pouch with valves at both ends. One valve admits air (oxygen) from outside into the pouch, and the second opens when the pouch is compressed and the gas is forced into the patient’s respiratory tract; exhalation occurs passively. The accordion apparatus forces exhalation as well. Respirators that operate on the basis of compressed gases (as a rule made of metal) are of two types: those that regulate the delivery of air by pressure and those that regulate it by volume. Pressure-regulated delivery (for example, in the DP-1) produces inhalation and exhalation according to the capacity of the lungs into which the gas is blown. When the lung capacity is decreased (with pneumonia, atelectasis), with a consequent increase in resistance, exhalation occurs more rapidly. Respirators that regulate the delivery of air by volume (for example, the Soviet RD-200) always deliver a fixed volume of gas, regardless of the condition of the lungs.
The most widely used in clinical practice are the Soviet electrical respirators that regulate the delivery of air by volume (RO-1, RO-3, RO-5) and permit the maintenance of a precisely fixed volume of delivered gas; when there is a change in a frequency of respiration (inhalation of gases) there is also a change in the per-minute volume of lung ventilation, while the respiratory volume remains constant (fixed). These respirators make for inhalation and exhalation of fixed duration and, by changing the pressure on exhalation, allow for the discharge of any remaining air from the lungs (for example, in bronchial asthma). In some respirators, such as the Engstrom and the AND-2, the perminute frequency lung ventilation is regulated independently of the per-minute volume of lung ventilation, which remains stable. The ROA-1 automatically maintains a per-minute volume of ventilation that provides the normal content of carbon dioxide in the exhaled (alveolar) gas. Respirators for auxiliary ventilation (when respiration is preserved) bring about supplementary inhalation when their volume is decreased (for example, in barbiturate poisoning). This apparatus is attached, as an independent unit, to other stationary respirators, such as the RO-3 and the RO-5.
T. M. DARBINIAN
an apparatus that protects the respiratory organs from dust and harmful substances. Insulating (tubular or oxygen) respirators are used when the oxygen content of the air is insufficient (less than 16 percent) and when the air is highly contaminated, as during rescue operations at the site of accidents. Filtering respirators, which filter out dust, are lightweight and portable but less efficient than insulating respirators when the air is highly contaminated. Various fibrous materials, such as felt, cotton, corrugated paper, porous cardboard, and natural and synthetic fabrics, are used in respirators to filter out radioactive dust. Hood respirators and face masks as well may be used for this purpose.
The simplest respirator used in the USSR is the Shb-1 Lepestok respiratory mask, which consists of a filtering fabric between two layers of gauze. Widely used in factories and laboratories, this mask affords excellent protection and is very light, weighing about 10 g.