| 摘要 |
PROBLEM TO BE SOLVED: To enable an internal canula to be inserted into an external tube without deformation by curving the intermediate region of a tube for forming trachea burrow by the coefficient of curvature of changing it over the whole length, and aligning the patient end of tube with the trachea substantially. SOLUTION: An outer tube 4 is composed of a shaft 40 and a joint 41 positioned at a rear end or mechanical end of the shaft 40. The shaft 40 is made of plastic material somewhat hard but capable of being bent and having a shape memory characteristic. The shaft 40 is short in length and is composed of a mechanical end region 42 extending straight coaxially with a joint 41, a straight patient end region 43 having the angle of about 105 degrees to the region 43, and a curved intermediate region 44. The curvature of the region 44 is changed over the whole length thereof. The region 44 is divided into a mechanical end side sub region 45 dominating 1/3 of the whole length of the region 44 and the remaining patient end 43 side sub region 46, and the radius of curvature of the region 46 is made three times the region 45.
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