The general awareness of cancer treatment until the late twentieth century was that cancer is incurable, except at an early stage; however, as the recent trend of survival rates and mortality [1]-[3] of cancer patients with long-term treatment has indicated, recent improvements in medical technology have suggested positive prospects for cancer treatment [4]-[7]. However, the positive prospect and high mortality rate of terminal cancer patients in stage IV is still complex.

The terminal state of patients with cancer suffers from diverse symptoms. One of those symptoms, especially in gastrointestinal cancers such as stomach, colorectal, and pancreas, is ascites of the peritoneal cavity that occupying ten percent of the entire as cites [8]. In addition, inconveniences from peritoneal cavity distension and nausea, dyspepsia, pain, and orthopnea with the increasing pressure of the peritoneal cavity caused by ascites [9] decreases the quality of life of patients [10]. Commonly utilized methods to alleviate ascites include diet control, utilization of a diuretic, and large-volume paracentesis, [11] among paracentesis is considered an effective method [12] for this purpose, owing to the simple procedure [13]-[14]. However, various complications, such as bleeding, infection, and bowel perforation, can occur.

The time to take the treatment was not fixed, and varied from 30 min to 24 h [15]-[16]. Patients who undergo paracentesis treatment spend a considerable amount of time from an hour to a day, if the time required to go to the hospital is considered. The time to take paracentesis is relatively long if the survival time of the patient is not very long, approximately 20 weeks from the time of diagnosis [17]-[18].

Patients who prepare for death evaluate that sharing good emotional communication and time is essential to prepare for death among various attributes [19]. In this prospect, a novel and more comfortable method needs to be developed into a more time-savable method because current methods take significant amount of time, and it is not a good method if patients who undergo paracentesis want to save more time to share with people around them.

Solbach et al. [20] researched another conventional type of “paracentesis catheter implantation” and positive effects on paracentesis frequency and time, even though they drained a similar quantity of ascites. The research also indicates that an implantable paracentesis system can provide a new experience that can conduct paracentesis anywhere if they have proper devices. However, we want to determine another method or device to deliver ascites outside the patient, such as the continuous delivery of ascites to the urinary bladder. One alternative device was “Alfapump” (Sequana Medical NV), which delivers ascites using the pigtail and pump. Stirnimann et al. [21] and Fotopoulou et al. [22] researched a novel type of drainage, by utilizing “Alfapump,” continuous low-flow drainage through the urinary bladder, and found positive effects on paracentesis frequency and flow rate by reducing paracentesis frequency and quantity of drained ascites. However, these devices require electrical circuits and regular battery charging. In addition, it can break down, and the patient may bear the inconvenience of inserting an instrument into the body. We discovered the main idea of a permanently implantable catheter that can deliver ascites directly into the bladder. We believe that this idea can play a significant role in time-efficient paracentesis.

According to that need, we devised one of the novel drain methods, “Implantable ascites drainage stent,” as illustrated in Figure 1. Abdominal pressure increases if ascites is caused. In this situation, the stent that we devised will emit ascites into the bladder directly, the closest organ responsible for waste discharge, utilizing pressure differences. More specifically, after implantation of the stent into the bladder wall between the peritoneal cavity and bladder, ascites are moved into the bladder by pressure differences if the pressure of the peritoneal cavity increases, and the patient excretes waste, including ascites and urine.

Figure 1: 
The main idea of implantable drain stent

In this study, we designed two types of implantable stents, and confirmed the performance of the stent utilizing an instrumental experiment that had a similar construct to the peritoneal cavity and bladder.

The main purpose of these stents was to allow flow when the peritoneal cavity has a higher pressure than the bladder, instead of the opposing cases. In addition, the actual experimental results need to be illustrated as an ideal plot in Figure 7. However, most of the results indicate that both stents allow flow, even if the bladder has a higher pressure. These results indicate that the designed stent can control forward direction flow, but not the opposing case, and additional improvements will be needed to supplement the experimental conditions. In addition, a transparent thin membrane was coated outside the stent structure, in the case of stent 2. This membrane was a very vulnerable structure for force and pressure, and the membrane was damaged when slotting the stent for the experiment or allowing pressure, and it was expected to be the main reason for the experimental failure of backflow control.

Figure 7: 
Average “Actual / Target flow rate” in experimental results

Nevertheless, the main idea that implantable ascites drainage instruments, which can reduce treatment time and increase the convenience of users, is still a valid and challenging question. Therefore, the idea can be realized if we experiment with more sophisticated stents and experimental instruments. Therefore, we will conduct additional experiments to validate the idea with a sophisticated setup, such as an improved stent and experimental instrument.

In this study, we designed two types of implantable stents, and confirmed the performance of stents with an exclusive experimental instrument to confirm the feasibility of the newly revised ascites drainage method, which is considered as a time-efficient method, compared to current methods. Accordingly, the main idea of the implantable ascites drain instrument is still challenging; however, experiments suggest that the design of the stent and experimental setup need to be improved to validate the novel type of ascites drainage instrument. Therefore, we plan to conduct additional research to compensate for the lack of this experiment, and to validate the idea of “implantable ascites drainage stent.”