Abstract: A catheter for guiding a body fluid of a subject includes an elongated body, an adjusting mechanism, and a valve mechanism. Moreover, the elongated body further includes a first portion, a second portion and a flexible portion between the first and the second portions. The second portion includes a passageway for the body liquid. The valve mechanism closes to the inlet of the passageway. Furthermore, the flexible portion expands when the adjusting mechanism is in a first state to prevent the catheter from being removed from the subject, and the flexible portion retracts when the adjusting mechanism alters to a second state to allow the catheter to be removed from or inserted into the subject. Hence, the body fluid is directed to enter the passageway via the inlet and exit via the outlet when the adjusting mechanism is not in the second state.

Abstract: The present invention discloses a pressure-depending clutching device for locating and safely positioning a needle in a body cavity. The device is capable of automatically engaging and disengaging the needle from a driving force depending on the pressure experienced by needle. The device has a body with an interior space, a pressure-sensing element disposed in the body defining a portion of a pressure chamber, and a force-receiving element operatively connected to the pressure-sensing element. The force-receiving element has a shape complimentary to a portion of a force-sending element operatively connected to a force-applying structure such as a handle for a user to apply a driving force. The pressure-sensing element, the force-receiving element, and the complementary force-sending element form a driving force engaging mechanism for coupling the force-applying structure to the needle during operation.