An Easily Inserted Flexible Cannula

Abstract

In the development of a technique for constant intravenous injection a cannula was devised which is easily manipulated and which has proved useful for the injection and removal of fluids over extended periods of time. It is introduced into a vein through a needle, after the manner of a trocar and cannula, and, when in place, provides a flexible, elastic, and resilient channel for the passage of liquid. It has been found satisfactory not only for intravenous work but also—by Dr. Henry N. Harkins of our Department of Surgery—for experimentation with cerebrospinal fluid through cisterna puncture. No doubt it will prove to be a useful instrument for the cannulation of many of the spaces in the body.The cannula is made of high grade anode rubber in the form of a capillary tube. Although there is no theoretical limit to the size of a cannula which may be used in this manner, one with an outside diameter of 0.04 inch has been found satisfactory. The cannula is inserted in the following way. First, the cannula is...