3618614 is referenced by 110 patents and cites 12 patents.

Multiwall surgical tubing, especially for stomach, thoracic or rectal use, has an inner, relatively thick transparent tube encased in a relatively thin, visually transparent, outer shell which contains a radiopaque material, so that as the X-radiation passes through the lateral edges of the composite tube it must pass through a relatively long path at the side edges of the tubing, while the central portion remains substantially transparent. Thus, the position of the tube is readily observed by fluoroscopy, while the flow of contrast media or clots may be observed in the central portion. As used for a heart, ureteral or vein intubation catheter, the multiwall tubing is formed of extruded polyethylene containing a nontoxic, radiopaque-plasticizing compound such as bismuth, oxychloride, which is encased in an extruded outer shell of transparent polyethylene having a hardness and exterior smoothness superior to that of the inner tubing, which outer shell also increases the angular resistance to twisting in use.

Nontoxic radiopaque multiwall medical-surgical tubings
Application Number
Publication Number
Application Date
May 6, 1969
Publication Date
November 9, 1971
Flynn Vincent J
Scientific Tube Products
A61m 25/00
A61M 25/01
View Original Source