Dry bottle drainage system

#This invention relates to fluid pressure regulating systems, including systems for measuring gas pressure and for controlling the pressure of the gas. The invention further relates to wound drainage systems for draining fluids from medical patients, such as from the chest cavity, by means of gas pressure differentials using low pressure gas systems.

#In many situations involving gases, it is important and often mandatory to measure the pressure of the gas. A typical example of the need to measure gas pressure exists in hospitals, where the vacuum or suction distributed in the hospital from a central vacuum supply must be monitored as it is used. Such suction is used, for example, in conjunction with wound drainage devices, where fluids such as blood, water and gas from a wound victim's pleural cavity are withdrawn using a pressure differential established between the suction source and the internal pressure in the victim. Such suction pressure and pressure differentials must be precisely measured because of the dangerous conditions which could result if unduly high or low pressure differentials should occur. In this application as in many other pressure measuring applications, it is desirable to incorporate a pressure measuring device which is compact, which makes the pressure measurements with precision, which is capable of functioning reliably for long periods of time, and which is economical to manufacture. Presently available gas pressure measuring devices which have the desired reliability and precision are generally expensive because of their intricacy or bulk due to their incorporation of manometer tubes. Wound drainage systems incorporating manometers having water whose level indicates fluid pressure are inconvenient because of the need to add water prior to use, as well as because of their size and weight.

#For many years, a standard apparatus for performing the evacuation of the pleural cavity was an underwater seal drainage system known as the "3-bottle set-up". The 3-bottle set-up consists of a collection bottle, a water seal bottle and a suction control bottle. A catheter runs from the patient's pleural cavity to the collection bottle, and the suction bottle is connected by a tube to a suction source. The three bottles are connected in series by various tubes to apply a predetermined suction to the pleural cavity to withdraw fluid and air, and discharge the same into the collection bottle. Gases entering the collection bottle bubble through water in the water seal bottle. The water in the water seal also prevents the back flow of air into the chest cavity.

#FIG. 1 is a schematic diagram of a chest drainage system according to the invention.

#FIG. 2 is a schematic diagram of a suction regulator according to the invention.

#FIG. 3 is a schematic diagram of a device according to the invention for measuring suction pressure in suction chambers such as those of the devices in FIGS. 1 and 2.

#Referring to FIG. 1, a wound drainage system 1 is disclosed comprising a suction chamber 3 from which air can be evacuated by an external vacuum source such as a centrally located vacuum pump in a hospital, a suction port 4 for interconnecting chamber 3 with the external vacuum source, a suction regulator 5 for controlling the pressure in chamber 3, a suction measuring device 6, a collection chamber 7 for collecting fluids withdrawn from a patient, and an inlet port 9 for connecting chamber 7 to the patient. A patient airflow flap valve 11 mounted on a hinge 13 extends over a patient air flow port 15 between collection chamber 7 and suction chamber 3. Air evacuated from a patient through inlet port 9 passes through port 15 whenever the pressure in chamber 7 exceeds that in chamber 3, and the extent of that air flow is reflected by the amount flap valve 11 opens. Valve 11 is configured to close and seal port 15 when the pressure in suction chamber 3 exceeds that in collection chamber 7. A dial 17 mounted on a pivot 19 and movable by a push rod 18 attached to flap valve 11 cooperates with a calibrated scale 21 to indicate the patient air flow rate (generally in liters per minute) through port 15 according to the extent valve 11 opens. When it is a pleural chest cavity being drained, the patient air flow is usually the result of air flowing through a hole in the patient's lung into chamber 7. Suction chamber 3 communicates with suction regulator 5 via a passage 77.

#Occasionally, as when a hole in the patient's lung closes during the drainage process, chamber 7 develops a pressure even more negative than the control suction of suction chamber 3, and flap valve 11 locks shut to isolate the two chambers from each other. It is important for the medical personnel to know the extent of that negativity, and a patient negativity measuring device 23 is provided for this purpose. Device 23 includes a patient negativity diaphragm 25 extending over an opening in the outer wall of chamber 7, a push rod 26 attached to diaphragm 25 and a dial 27 mounted on a pivot 29 movable by push rod 26 for cooperating with an appropriately calibrated scale 31. When the atmospheric pressure outside of chamber 7 exceeds the air pressure in chamber 7, diaphragm 25 flexes inwardly, rotating dial 29 clockwise according to the amount the diaphragm flexes to measure and indicate the extent of patient negativity. The pivot point of dial 27 or the connection point to push rod 26 can be equipped with a spring to urge the dial back to its zero position if a non-linkage connection is preferred.

#The regulation and measurement of the suction in chamber 3 are important functions of system 1. Suction regulator 5 for performing these functions is shown both in FIG. 1 and in further detail (in slightly modified form) as regulator 5' in FIG. 2. (The suction regulator in FIG. 2 is shown as an independent unit which would be modified for a particular application such as incorporation in the system of FIG. 1.) Suction regulator 5 includes a wall 41; a horizontal partition 43 dividing regulator 5 into an upper chamber 45 and a lower chamber 47; an opening 49 in partition 43 in which is seated a collar 51, the collar being a section of a sphere and having a diameter which increases from top to bottom; a light ball 53 whose diameter is slightly more than the diameter of the sphere of which collar 51 is a section so that the ball can fit and be seated in the collar but not pass upwardly through it; a cantilever support arm 55 having a threaded bore through which extends a threaded bolt 57 with an adjustment knob 58 (which could have detents to avoid accidental changes) and disposed on a support shelf 59; a vertical guide rod 60 mounted between shelf 59 and the top wall of the unit for extending through a smooth bore in arm 55 to guide the vertical movement of arm 55; a spring 61 attached at one end to a flange 63 on ball 53 and at its other end to support arm 55 for biassing ball 53 upwardly; and a dashpot 65 composed of a piston 67 attached to ball 53 and a cylinder 69 receiving the piston in sliding engagement and mounted on a support block 71 by means of a pivot 73. Collar 51 preferably includes a set of notches 72 for enhancing the stabilizing effect of collar 51 on ball 53 as air flows between the collar and the ball. A piston chamber 74 is defined between the head of piston 67 and the closed bore of cylinder 69. Atmospheric air flow at pressure P.sub.A enters chamber 45 through an entrance port 75. Lower chamber 47 includes an entrance port 78 from a chamber 103 at subatmospheric pressure such as the pressure of collection chamber 7, and is connected to the hospital suction source through a port 79 at pressure P.sub.S. The path of flow is shown by the dotted arrows "a".