FIELD OF THE INVENTION

The invention relates generally to medical devices and, in particular, to retention drainage catheters.

BACKGROUND OF THE INVENTION

In the medical field, catheters are generally used to drain fluids from a body cavity. In the urology field, a Foley retention drainage catheter, which may be interchangeably referred to as a Foley catheter or drainage catheter, is commonly used to drain a human bladder. There are many medical conditions that necessitate the use of a Foley catheter. The collection of urine and other fluids after a surgical procedure is such a condition. For the past seventy to eighty years the Foley retention drainage catheter, as depicted inFIG. 18and labeled “PRIOR ART,” has been the preferred option to drain and collect urine and other fluids from the bladder. The basic design of a Foley catheter comprises an elongated cylindrical element containing a central drainage lumen running the length of the elongated cylindrical element, having one or more drainage ports in series at or near the distal end, and an expandable retention element, located proximal to the drainage ports, for securing the catheter within the bladder. The retention element is expanded with fluid via an inflation lumen running from the inflation valve located on the proximal end of the elongated cylindrical element to the retention element. The design of the Foley catheter has not undergone significant changes other than changes to the base materials and attempts to give the materials antibacterial properties. Despite its continued use in the health care industry without significant design changes the Foley catheter does have some acknowledged weaknesses.

Firstly, the Foley catheter is susceptible to obstruction of the drainage ports and the drainage lumen of the catheter due to plugging and/or buildup of debris (debris is defined as loose tissue, sediments, clotted blood, redundant bladder mucosa, and any other materials or viscous fluids in the clinical setting). The drainage ports are generally at least twice the cross sectional area of the drainage lumen. This can result in a funneling effect with debris draining into smaller and smaller spaces, thus, resulting in plugs and blockages causing catheter obstruction. Further, due to the drainage ports being in series, if the most proximal drainage port becomes obstructed by debris that extend from the port into the drainage lumen, thus obstructing the drainage lumen, any remaining unobstructed drainage ports are rendered ineffective as they are upstream of the obstruction. Incomplete emptying/drainage of the bladder caused by obstructions in the catheter are significant causes of catheter associated urinary tract infections (UTIs).

Secondly, the drainage ports in the catheter, being limited in number and limited in cumulative cross sectional area as related to the cross sectional area of the drainage lumen, create a suction effect so that when the force of the suction is projected on the bladder mucosa the suction can cause a disruption in the mucosal integrity. This can result in increased risk of pain, bladder spasms, discomfort, and catheter associated UTIs.

Thirdly, yet another problem is the inability of the Foley catheter to completely drain the bladder, even when the drainage system is completely free of obstruction. Due to the aforementioned drainage port locations, when the bladder is actively drained during catheterization, and the bladder wall closes around the retention element, the bladder retains a residual volume of fluid that is not able to reach the drainage ports. This volume of stagnant fluid can contain urine, blood, bacteria, and/or other pathogens that, when not regularly flushed out of the bladder, can set up an infection in the surrounding tissues, form blood clots in the bladder, and/or other conditions detrimental to the patient. It should be understood that catheter associated UTIs are now the most expensive hospital acquired infection according to the Centers for Disease Control and Prevention.

SUMMARY OF THE INVENTION

The aforementioned problems are solved and a technical advance is achieved in an illustrative novel multi-lumen filter membrane internal interstitial drainage channel catheter (also referred to herein as a FMID catheter) for insertion into and draining a body cavity, that mitigates the risk of obstruction of the drainage ports and drainage lumen of the catheter and also reduces the detrimental effects caused by the suction forces of the drainage ports on the body cavity being drained, and reduces the risk of infection of the body cavity being drained by decreasing the residual volume of fluid retained in the body cavity being drained. These advantages and more are achieved by the novel approach of disposing a membrane (which may be perforated) over a retention element (which may be segmented), the proximal drainage ports, and the distal drainage ports of the drainage lumen of the catheter, such that when the retention element is expanded, the membrane creates one or more interstitial spaces or cavities between the membrane and the elongated cylindrical element (catheter tube).

When the retention element and membrane are in their expanded state, expandable cavities (henceforth referred to as internal interstitial drainage cavities) are created between the membrane and the elongated cylindrical element and expand as the membrane is pushed away from elongated cylindrical element. Also, when a segmented retention element and membrane are in their expanded state, other expandable cavities (henceforth referred to as internal interstitial drainage channels) are created between the expanded wedges of the retention element and the membrane in some embodiments. Alternatively, the interstitial drainage channels can be disposed on a segmented retention element such that they are not under the membrane when in the expanded state. The internal interstitial drainage channels are disposed from the distal end of the segmented retention element to the proximal end of the segmented retention element and expand proportionally as the expanded state of the segmented retention element and the membrane is reached. The drainage ports communicate with the internal interstitial drainage cavities. The internal interstitial drainage cavities communicate with the internal interstitial drainage channels. The internal interstitial drainage cavities and/or the internal interstitial drainage channels communicate with the body cavity being drained through the membrane.

The membrane, in the expanded state, provides entry port(s) for fluid to enter into the interstitial drainage cavities and then through the drainage ports of the FMID catheter. One or more entry ports may be larger than the cross sectional area of the drainage ports and the drainage lumen. While the relatively larger entry port size may allow for debris (clots, tissue, etc.) larger than the drainage ports and the drainage lumen to enter the interstitial drainage cavities and/or channels, the relatively larger entry port size allows for decreasing the suction force applied to the wall of the organ being drained. This decreased force prevents unnecessary damage to the organ wall. In some embodiments, the membrane may also have portions, in the expanded state, that have a plurality of perforations wherein the individual perforations in the membrane have an equal or smaller cross sectional area than that of the drainage ports and the drainage lumen so that debris smaller than the perforations can pass through the membrane, the drainage ports, and the drainage lumen without obstructing either. Debris larger than the perforations is stopped by the membrane while still leaving a plurality of perforations in the membrane unblocked, thus creating a drainage system in parallel rather than in series. Due to there being a plurality of perforations in a portion of the membrane of these embodiments, the suction force produced by the drainage ports is distributed amongst all the perforations, thus mitigating the detrimental effects of suction force on the tissues of the body cavity being drained. This FMID catheter is particularly advantageous when patients require an indwelling catheter and/or are at risk of having a catheter obstruction. Because the presently disclosed device improves the basic function of current Foley catheters without changing the way it is implemented by the health care professional, it is expected to replace the current Foley catheters as the standard of care.

