Method for producing unsupported fiber bundles for HME and other filtration applications

#This application claims priority from application Ser. No. 60/014,647 filed Apr. 1, 1996, now abandoned.

#The subject invention relates to a method for manufacturing hollow fiber bundles for use in assisted breathing apparatus, and to the hollow fiber bundles created by the inventive manufacturing process. More specifically, the invention relates to a method for coating the exterior of the hollow fibers to increase fiber stability and bundle strength, to increase active fiber area and also bundle size, and to reduce manufacturing costs and complexity.

#In many medical applications, oxygen or air is administered to a patient on a long term basis, either through breathing tubes or an apparatus applied to the patient's mouth or nasal cavities, or more directly to the trachea of the patient by way of a tracheotomy. In such instances, however, there is oftentimes a problem with the drying out of the patient's nasal passages and lungs. This is a result of the patient's air supply having by-passed the patient's mouth and nasal cavities where natural breathing activity provides heat and moisture exchange mechanism for the inhaled oxygen.

#FIG. 1 represents a cross-sectional view of a Prior Art assisted breathing device, comprising wrapped corrugated paper;

#FIG. 2 represents a cross-sectional view of the hollow fiber bundle constructed in accord with the subject inventive method; and

#FIG. 3 represents a schematic for the test system used to compare the inventive device which is the subject hereof to existing devices.

#The subject invention relates to a method of manufacturing hollow fiber bundles of the type intended for use in assisted breathing apparatus. Specifically, the invention relates to a method for manufacturing hollow fiber bundle units for use in assisted breathing devices or apparatus comprising: spinning hollow fibers; filling the hollow fiber walls of the fibers with a solution of a highly water absorptive material, i.e. an humectant; and then binding the bundle with a coating on the fiber exteriors of a polymeric adhesive. The filler assists in increasing the heat and moisture exchange function or capability of the bundle. The binder or coating is intended to serve several functions. For instance, the binder or coating will eliminate problems due to fiber crushing which may occur when using wrapping material to stabilize and contain the bundle. Also, the need for such wrapping is eliminated, thereby reducing cost and affording an increase in active fiber bundle size. The inventive coating further affords the use of fibers having a parallel orientation, thereby increasing the amount of fiber which can be used in a bundle of a given size. Finally, larger, thinner fiber wafers may be constructed because the coating provides greater stability in cutting and handling the bundles.

#The design of the housing of the assisted breathing unit is not intended to be a part of this invention as such housing units are well known in the art to which this invention pertains. Therefore, while no detail of the housing and exterior connections for the housing into which the subject hollow fiber units are intended to be inserted will be set forth herein, it is assumed that the skilled artisan will readily appreciate the manner in which the units will be usable in such existing devices.

#The hollow fibers themselves may be prepared according to known methods for spinning or drawing hollow fibers. Suitable hollow fiber materials include cellulosics, polyvinylidenedifluoride (PVDF), polysulfone, polyethersulfone, polyimides, polyamides, polyesters, polyphenyleneoxide, polyphenylenesulfide, polycarbonate, and the like. Preferred herein are polysulfone and polyethersulfone.