Venous pressure indicator

Abstract

An intravenous infusion system combined with a venous pressure measuring instrument whereby the system is selectively capable of supplying fluid into the vein of a patient or of measuring his venous pressure without, however, exposing fluid in the system to the atmosphere and possible contamination. The instrument includes a transparent chamber interposed between an upstream line extending to the infusion fluid supply and a downstream line leading to the patient. A collapsible bulb disposed within the chamber is vented to the atmosphere, the bulb collapsing only when its internal pressure is less than external fluid pressure. In the infusion mode, supply fluid passing through the chamber is fed to the patient, the resultant fluid pressure in the chamber causing the normally-erect bulb to collapse. In the venous pressure mode, the upstream line is clampd to interrupt flow, the fluid pressure then exerted on the bulb being a function both of venous pressure and the height of the chamber relative to the heart, the higher the chamber the lower the pressure. By elevating or lowering the chamber to a point at which fluid pressure therein is equal to atmospheric pressure, a balance or reference pressure level is established, this level being indicated by the sudden erection or collapse of the bulb, depending on whether the bulb is moving upward or downward. Venous pressure is then determined by measuring the height of the chamber at this level along a scale formed on the downstream line.

Dependencies are inferred from the claim text.