Abstract: In order to keep the opening for inserting a catheter into a blood vessel as small as possible, a catheter insertion tube is used which coaxially surrounds the puncturing canula and consists, at least in a circumferential area and/or at least along a portion of its length, of one or several dilatable or expandable areas permitting enlargement of its internal diameter. The diameter of the catheter insertion tube, at the front end where it is inserted into the blood vessel, is approximately equal or smaller than the outer diameter of the catheter. The catheter insertion tube is expandable at least over the front or forward portion of its length by the catheter. The catheter insertion tube i removable from the puncture over the catheter while the catheter is advanced into the puncture and is tighty sealed by the catheter because the catheter has an external diameter equal to or larger than the puncture previously occupied by the insertion tube.

Abstract: A catheter connecting head with at least one duct in a base member for the connection of an infusion system, such as a catheter or the like and for the introduction of a puncture cannula, is provided with a closure member mounted for movement between a first position opening the cannula introduction duct and a second position blocking said duct. The connecting head is provided with a device for retaining the closure member in the first position until the puncture cannula is withdrawn after which the closure element is automatically shifted into its second position. Once the closure member is in its second position blocking the cannula insertion duct, a locking arrangement retains the closure member in this position so that reintroduction of a puncture cannula into said insertion duct is not possible. In accordance with preferred embodiments, the closure member can be constructed as a lever member pivotally mounted to the base member or as a disc mounted upon the base member in a rotatable manner.

Abstract: A transmitter for mechanical oscillations of variable frequency and an oscillation pickup for determination of the mechanical characteristic frequency of blood vessels, tendons, bones or similar organs in a body, by which these organs act as coupling members between the transmitter and the oscillation pickup. The transmission means from the transmitter to the body and from the body to the oscillation pickup are accommodated inside of a common support tube. One end of the support tube is rigidly connected with the support frame, in which support frame, the transmitter and the oscillation pickup are installed mutually decoupled, with even amplifiers or the like being installed, connected after the oscillation pickup, if necessary under the circumstances. The other end of the support tube is able to be set on the body.