Exhalation Condensate Collection System for a Patient Ventilator

1. Field of the Invention

This invention relates generally to breathing ventilators, and more particularly concerns a ventilator airway fluid collection system, including a fluid collector vial that is connected to an airway of the ventilator for controlling condensation through the exhalation circuit.

2. Description of Related Art

Modern patient ventilator systems conventionally provide a breathing gas to the patient airway at elevated pressure levels. Breathing gas is also often supplemented with a higher proportion of oxygen than is found in the ambient atmosphere, and is commonly humidified to prevent discomfort to the patient and drying out of the patients respiratory system. As the patient breathes, assisted by the ventilator, moisture in the exhaled breath is carried through the patient airway and out the exhalation path. Consequently, moisture regularly condenses in a ventilator airways, and one or more fluid collector vials can be placed in strategic locations in the airway to collect such fluid condensate.

A common problem with such fluid collection systems is that when such collector vials are removed to dispose of collected fluid, fluid can be sprayed out of the airway if the ventilator is operating when the fluid collection vial is removed, which can be unpleasant and unhygienic.

One known solution to this problem has been to provide spring loaded seals which close off the fluid collection opening in the airway when a collection vial is removed. However, such spring loaded seals can be expensive, difficult to clean, and can fail due to blockage of the seal, cracking of the seal, failure of the spring, and similar problems.

It is therefore desirable to provide a ventilator airway fluid collection system which is less complex and less expensive than prior art systems, is more robust and reliable than spring loaded seal systems, and that will allow collection and disposal of fluid from a ventilator, without requiring that the fluid collector vial be removed for emptying. It would also be desirable to provide such a ventilator airway fluid collection system that can readily be substituted for existing fluid collection systems. The present invention meets these needs.

Briefly, and in general terms, the present invention provides for a ventilator airway fluid collection system that permits the control of condensation in the exhalation circuit of a ventilator without the necessity of removing a fluid collector vial to dispose of fluid condensate.

Accordingly, the invention provides for a ventilator exhalation gas condensate collection and drainage system including a fluid collector vial with a drain port for removal of fluid condensate from the collector vial. The drain port can be capped by a drain port cap or plug, or can be connected to a drain tube. In a presently preferred embodiment, the collector vial includes a maximum fill line to indicate when the collector vial should be emptied. An exhalation filter can be provided that minimizes the particles and bacteria in the patient's exhaled gas, and protects the ventilator's exhalation and spirometry components.

In one presently preferred embodiment, the exhalation filter comprises a filter housing having a locking ring that can be turned to secure or release the fluid collector vial to the filter housing. The filter housing has a base with an opening to allow flow of exhalation breathing gas through the collector vial for collection of condensate from the exhalation breathing gas. The filter housing also contains a curved baffle deflector for the entry port which prevents direct flow of the exhalant towards the filter, thus avoiding unnecessary wetting of the filter and direct deposit of fluid into the collector vial.

In one currently preferred embodiment, an optional drain bag can be connected to the drain port of the collector vial via the drain tube. A clamp is typically installed on the tube. When the collector vial is to be emptied, the clamp on the tube to the drain bag can be unclamped to drain liquid from the collector vial to a disposable bag, providing a safe way of disposing of condensate.

These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings, which illustrate by way of example the features of the invention.

FIG. 1 is a perspective view of the exhalation condensate collection system of the invention;

FIG. 2 is a top plan view of the exhalation filter and locking ring of the exhalation condensate collection system of FIG. 1;

FIG. 3 is a cross-sectional view of the exhalation condensate collection system of the invention taken along line 3--3 of FIG. 2;

FIG. 4 is an elevational partial sectional view of the interface of the locking ring, filter housing and collector vial of the exhalation condensate collection system of the invention taken along line 4--4 of FIG. 3;

FIG. 5 is a cross-sectional view of the exhalation filter of the exhalation condensate collection system of the invention taken along line 5--5 of FIG. 3; and

FIG. 6 is an enlarged, fragmentary sectional view of the interface of the locking ring, filter housing and collector vial of the exhalation condensate collection system of the invention taken along line 6--6 of FIG. 4.

Fluid condensate from ventilator airways is typically collected by one or more fluid collector vials. However, fluid can be sprayed out of the airway if the ventilator is operating when a fluid collection vial is removed to dispose of collected fluid. Spring loaded seals to close off a fluid collection opening in the airway when a collection vial is removed can be expensive, difficult to clean, and can fail due to blockage of the seal, cracking of the seal, failure of the spring, and similar problems. Accordingly, the invention provides for an improved ventilator airway fluid collection system that allows collection and disposal of fluid from a ventilator without removal of the fluid collector vial.

As is illustrated in the drawings, in a currently preferred embodiment, the exhalation condensate collection system 10 for a patient ventilator includes an exhalation filter 12 having a filter housing 14 with an inlet connector 16, an exterior chamber portion 17, and an interior chamber 18. The exhalation filter minimizes the particles and bacteria in the patient's exhaled gas, and protects the ventilator's exhalation and spirometry components. The filter housing also has a filter support member 20 or base disposed within a lower portion of the interior chamber for supporting a filter element 22. The filter support member is spaced apart from the interior walls of the interior chamber of the filter housing, so that breathing gas can enter through the inlet connector 16, and flow through the fluid collector vial 32, the exterior chamber portion 17 and the filter element 22, into the interior chamber portion 18 and out the outlet 24 of the filter housing. A curved baffle deflector 23 continues internally from the inlet connector 16, curving toward the fluid collector vial 32 to deflect fluid condensate from the patient airway away from the filter and into the collector vial, with minimum resistance to air flow through the assembly of the filter and collector vial. The filters are reusable, and can be steam sterilized in an autoclave before the first use, and after each patient use. The filter element preferably has a particle filtration efficiency of a minimum of 99.97% of 0.3-.mu.m nominal particle size at 100 L/min flow, and a viral and bacterial filtration efficiency of greater than 99.999%. The exhalation filter is also preferably designed to withstand repeated autoclave sterilization cycles at temperatures up to 135.degree. C.(275.degree. F.).

The filter housing inlet connector 16 for attaching the exhalation limb of the ventilator breathing circuit typically has an inner conical taper 26 that narrows slightly inwardly from the outside end 27, and an outer conical taper.

A locking mechanism is also provided for securing a collector vial to the filter housing, and for removing the collector vial from the filter housing, when necessary. The filter housing includes a plurality of bottom key flanges 28, extending below the inlet connector 16. A rotatable locking ring 30 is disposed on the bottom key flanges of the filter housing, and has tabs 31 generally extending perpendicularly from the locking ring for securing the fluid collector vial 32 to the filter housing. The collector vial has a top key flange 34 that interfits with a pair of adjacent bottom key flanges 28 of the filter housing, and a plurality of elongated locking flanges 36 having lower inclined sliding surfaces adapted to slidably interfit with the tabs 31 of the locking ring. A seal 37 is also provided between the bottom of the filter housing and the top of the collector vial to provide a tight assembly of the two.

The collector vial has a drain port 38 located at a lower portion of the collector vial for draining fluid from the collector vial. As is shown in FIG. 1, the drain port can be capped by a drain port cap or plug 40 attached to the drain port. In one currently preferred embodiment, the collector vial also includes a maximum fill line 42, to indicate when the collector vial is full of liquid 44 and should be emptied. The collector vial typically has a capacity (to the maximum fill line) of approximately 200 mL usable volume. The maximum fill line can be structurally molded in the collector vial, and is typically defined by a slightly raised shoulder or groove formed on the interior wall of the collector vial. The filter housing and collector vial can be molded from transparent plastic, such as polysulfone plastic, for example.

Referring to FIG. 1, an optional drain bag (not shown) can also be connected to the collector vial drain port by a drain tube 46, typically formed of flexible silicone or PVC tubing, for example. One end of the tube is secured to the collector vial drain port, and the other end of the tube is connected to the drain bag. The drain bag can have a connector (not shown) for connecting with the tubing. A reusable clamp 48 can be installed on the tube. When the collector vial is to be emptied, the clamp on the tube to the drain bag can be unclamped to drain liquid from the collector vial to the drain bag. Alternatively, the tubing can be connected to another type of fluid disposal container.

It will be apparent from the foregoing that while particular forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims.