Abstract
During experiments designed to determine the effect of unilateral thymectomy on the unilateral development of thymic lymphoma in mice (1,2) an apparatus for artificial respiration with positive pressure oxygen in mice was developed. Use of the device permits wide surgical exposure of the thorax and approximates the conditions accomplished by modern anesthesia machines. Because the device decreases the hazard of pneumothorax during experimental surgery on mice and is inexpensive to construct, the apparatus is presented for possible interest to other investigators.
The apparatus consists of 3 parts: 1) a flow valve, bubble meter, and high pressure limit assembly; 2) a valve to provide intermittent oxygen flow, and 3) an endotracheal catheter (Fig. 1.)
1. Flow valve, bubble meter, and high pressure limit assembly. The regulation of small amounts of oxygen is accomplished by use of a screw clamp on the oxygen supply rubber tubing which leads directly from the reducing valve of a standard oxygen tank. The rate of flow of oxygen is visually observed by bubbling the gas through water. By means of a “T” tube, the high pressure limit tube is connected to the metered gas flow. This last device consists of a length of glass tubing immersed in a column of water. The height of water above the open lower end of the tube determines the pressure at which excess oxygen will blow off. The upper end of the pressure limit tube is twice as high as the water column to prevent water from rebounding into the supply line.
2.“Finger valve.” The intermittent flow of positive pressure oxygen is controlled by a manually operated open-type valve. This device is constructed by cutting a 2 cm round hole in a 4 inch length of 3/4′ polyethylene drying tube.
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