Clinical Efficacy Observation of Low-Position Double-Tunnel Peritoneal Dialysis Catheterization

Introduction

An increasing number of patients are opting for peritoneal dialysis (PD) as their kidney replacement therapy for end-stage kidney disease (ESKD).¹ There are two methods for PD catheter placement, including laparotomy and laparoscopic PD catheterization.^2,3 These two methods have limitations, like a high rate of catheter displacement and kidney toxicity due to artificial CO₂ pneumoperitoneum.⁴ Therefore, we summarized the existing methods of peritoneal catheter placement and introduced the low-position double-tunnel PD catheterization, aiming to combine smaller surgical trauma and fewer postoperative complications.

Materials and Methods

Patients meeting the diagnostic criteria of KDOQI for stage V chronic kidney disease and undergoing PD treatment for the first time were included.⁵ Patients with surgical risks such as an inguinal hernia, which is difficult to treat surgically, active infection or space-occupying lesions in the abdominal and pelvic cavities, severe abdominal skin infection, severe cardiopulmonary and cerebral diseases that make them unable to tolerate surgery, and severe coagulation disorders were excluded.

Demographic and biochemical data, such as sex, age, body mass index (BMI), serum creatinine, and urea nitrogen before catheterization, were collected. Personal history of primary disease (chronic glomerulonephritis, diabetic nephropathy, hypertensive nephropathy, uric acid nephropathy, obstructive nephropathy, polycystic kidney disease, and other kidney diseases) and surgical history (no surgery, history of abdominal surgery, history of pelvic surgery) were collected.

The patients were retrospectively divided into experimental and control groups according to the surgical method applied. The experimental group underwent a low-position double-tunnel catheterization (low-position double-tunnel group), while the control group underwent a traditional laparotomy (laparotomy group) or laparoscopic PD catheterization (laparoscopic group).

Catheterization method

Low-position Double-tunnel Catheterization

The patient was placed in a supine position. After routine disinfection and draping, using the symphysis pubis as an anatomical landmark, a 2-cm transverse incision was made on the right side beside the umbilicus at 13 cm from the symphysis pubis. The skin, fascia, and anterior sheath were successively incised. Then, a 4 cm parallel transverse incision was made about 5 cm below this transverse incision, and the skin, fascia, and anterior sheath were successively incised again. The rectus abdominis muscle was separated, the posterior sheath and peritoneum were incised, and the PD catheter was smoothly inserted into the Douglas pouch. The posterior sheath and peritoneum were sutured with absorbable purse-string suture. The head end of the PD catheter was tunneled from the lower incision along the back of the anterior sheath of the rectus abdominis muscle to the upper incision. The dialysis catheter was led out of the body through a subcutaneous tunnel about 5.0 cm beside the upper incision. The patency of the lumen was checked, and the incisions were closed layer by layer [Figure 1]. Figure 2 displayed the abdominal X-ray images taken postoperatively from the patients.

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Figure 1:

Low-position double-tunnel catheterization methods. (a) Determine the surgical site: Mark the skin at the right paraumbilical area, and at 13 cm and 8 cm above the pubic symphysis respectively. (b) Routine disinfection and draping. (c) Incise and dissect the tissue. (d) Peritoneal dialysis catheter placement: The peritoneal dialysis catheter was inserted into the Douglas pouch through the lower incision, and the posterior sheath and peritoneum were sutured with an absorbable purse-string suture. The tip of the catheter was then tunneled from the lower incision along the posterior aspect of the anterior rectus sheath to the upper incision. The white arrows indicates the path of peritoneal dialysis catheter from the lower incision to the upper incision. (e) The catheter external segment: The external segment of the catheter was exteriorized through a subcutaneous tunnel created approximately 5.0 cm lateral to the upper incision. The dashed line presents the approximate trajectory of peritoneal dialysis catheter within the subcutaneous tunnel, with the black arrow indicating the director of its exit from the skin. (f) Abdominal cavity closure: The patency of the lumen was checked, and the incisions were closed layer by layer.

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Figure 2:

Postoperative abdominal X-ray following low-position double-tunnel catherization. The position indicated by the white arrow shows the internal orifice of the peritoneal dialysis catheter.

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Laparotomy

The patient was placed in a supine position. After routine disinfection and towel laying, a 4-cm right paramedian incision was made. The skin, fascia, and anterior sheath were successively cut. The rectus muscle was separated, then the posterior sheath and peritoneum were cut, and the PD tube was placed into Dow's fossa. The posterior sheath and peritoneum were sutured with absorbable thread, and the dialysis tube was drawn out of the body through a subcutaneous tunnel of about 4 cm beside the incision. Finally, the patency of the tube was checked, and the peritoneal cavity was closed layer by layer.

Laparoscopic PD Catheterization

An incision of about 1 cm was made on the right side of the median umbilical line at 12 cm above the pubic union, and a pneumoperitoneum needle was inserted to establish artificial pneumoperitoneum. Tzocaz, with a diameter of 1 cm, was inserted, and the inner core was pulled out and implanted into the laparoscope. Under the direct vision of the camera, an incision of about 0.5 cm was made on the left side of the median umbilical line 6 cm above the pubic union, and a slightly oblique incision was made along the pelvic direction into the 5 mm Trocar to establish a tunnel. After that, 5 mm Trocar was removed, and the PD tube was placed into the Dow fossa with the guiding needle from the 5 mm orifices. The guiding needle was removed. Exit the operating instrument and release CO₂. A tunnel needle was used to enter from the lower incision and exit from the upper incision through the rectus sheath. The PD tube was led out of the upper incision through the tunnel needle, and then the dialysis tube was drawn out of the body by using the tunnel needle as the subcutaneous tunnel next to the incision for about 4.0 cm. Finally, the patency of the tube was checked, and each incision was closed layer by layer.

The three groups of patients gradually transitioned from intermittent peritoneal dialysis (IPD) to continuous ambulatory peritoneal dialysis (CAPD) after the operation. The standard transition period typically spans postoperative days 7-12, with duration adjustments permitted based on individual patient status. All patients were followed up for more than 6 months, and the situations of the three groups at 6 months and 2 years after the operation were observed.

Multiple occurrences of the same event in the same patient were counted as one occurrence. PD-related complications, including catheter dysfunction (displacement, poor drainage), and PD-related peritonitis, residual renal function (RRF), urea clearance index (Kt/V): PD Kt/V, total Kt/V, catheter survival (PD via the initial peritoneal dialysis catheter) rate, and basic survival rate were considered outcome indicators.

Results

A total of 156 patients were included in this report. Among them, 42 underwent low-position double-tunnel peritoneal catheterization under the experimental group, while the other 114 underwent the traditional laparotomy (n = 84) or laparoscopic PD catheterization (n = 32) under the control groups. As shown in Table 1, there were no statistically significant differences in sex composition among the three groups. The average age of the low-position double-tunnel group was 58.93 years old, while the laparotomy group was 62.17 years old, and the laparoscopic group was 61.22 years old. There was no statistically significant difference in age among the three groups. The average BMI was 23.54 kg/m² in the low-position double-tunnel group, 21.16 kg/m² in the laparotomy group, and 24.47 kg/m² in the laparoscopic group. The difference among the three groups was not statistically significant. The renal functions, including serum creatinine and urea nitrogen levels, were detected before catheterization. Patients in the low-position double-tunnel group had the lowest serum creatinine and urea nitrogen levels than the controls. Through comparison, it was found that there was no obvious difference in renal function among the three groups before catheterization.

In addition, we compared the primary diseases of the enrolled patients [Table 2]. The primary kidney diseases of the enrolled patients mainly included chronic glomerulonephritis, diabetic nephropathy, hypertensive nephropathy, uric acid nephropathy, obstructive nephropathy, polycystic kidney disease, and some other kidney diseases caused by alternative issues like drug-related nephropathy. There was no obstructive nephropathy or polycystic kidney disease in the low-position double-tunnel group and no uric acid nephropathy or obstructive nephropathy in the laparoscopic group. The most common primary kidney disease was diabetic nephropathy. There was no significant difference among the three groups of patients in terms of primary diseases. Abdominal and pelvic surgeries would especially influence our outcome indicators, so we also compared the differences. There were eight patients in the low-position double-tunnel group with a history of abdominal (n = 7) and pelvic (n = 1) surgeries before the operation, and in the laparotomy group and the laparoscopic group, there were respectively 11 and 12 patients with relevant surgical histories. No statistically significant difference was found in surgical history among the three groups.

We retrospectively collected the PD-related complications of the three groups of patients after the operation, including catheter displacement, poor catheter drainage, and PD-related peritonitis. The follow-up time points were 6 months and 2 years. As shown in Table 3, 6 months after the operation, in the low-position double-tunnel group, there were no cases with catheter displacement, three with poor catheter drainage, and two with PD-related peritonitis. In the laparotomy group, there were 15 cases with catheter displacement, two with poor catheter drainage, and eight with PD-related peritonitis. In the laparoscopic group, there were three cases with catheter displacement, none with poor catheter drainage, and three with PD-related peritonitis. Two years after the operation, excluding the PD complication events that occurred in the first 6 months after the operation, there were two cases with PD-related complications in the experimental group, with one case each of poor drainage and peritonitis, and no catheter displacement event was found. During the 2-year follow-up in the laparotomy group, a total of 18 cases with PD-related complications occurred, including five with catheter displacement, three with poor drainage, and 10 with PD-related peritonitis. By the end of 2 years after the operation, there were two cases with catheter displacement, three with poor drainage, and four with PD-related peritonitis in the laparoscopic group. Statistical analysis showed that the low-position double-tunnel PD catheterization could significantly reduce the occurrence of catheter displacement events at half a year after the operation, although this difference was not statistically significant during the 2-year follow-up after the operation. There was no statistically significant difference in the events of poor catheter drainage and peritonitis between the low-position double-tunnel group and the control group at 6 months and 2 years after the operation.

We continued to collect the preservation of residual renal function and dialysis adequacy of the three groups after the catheterization [Table 4]. Six months after the operation, the average residual renal function in the low-position double-tunnel group was 5.35 mL/min/1.73m², while in the laparotomy group the average was 3.10 mL/min/1.73m² and in the laparoscopic group the average was 3.79 mL/min/1.73m². The preservation of residual renal function in the low-position double-tunnel group was better than that in the control group, and the difference was statistically significant. The residual renal function of the three groups decreased significantly at 2 years compared with that at 6 months. In contrast, the decrease in the low-position double-tunnel group seemed to be more obvious. Two years after the operation, the residual renal function in the low-position double-tunnel group had reduced to 1.34 mL/min/1.73m², which was lower than that in the control group (1.73 mL/min/1.73m² in the laparotomy group and 1.54 mL/min/1.73m² in the laparoscopic group). However, this difference was not significant.

Regarding dialysis adequacy, we used Kt/V (the urea clearance index) for comparison, which referred to the ratio of urea clearance and volume of the dialyzer during a certain dialysis time. We calculated the PD Kt/V and Total Kt/V of the three groups respectively. The results indicated that there was no significant difference in dialysis adequacy among the three groups both at 6 months and 2 years after the catheterization.

To analyze the differences in catheter preservation and patient survival rates among the three groups with different surgical methods, we further counted the catheter preservation and patient survival situations of the patients. In the low-position double-tunnel group, 39 patients still retained the catheter for maintenance PD treatment, while 60 patients in the laparotomy group and 21 in the laparoscopic group retained the PD catheter. There was a significant difference among these three groups, while higher catheter survival rates correlated with reduced reoperation requirements. In the low-position double-tunnel group, one patient died, while nine patients in the laparotomy group and six patients in the laparoscopic group died. No statistically significant difference among the three groups was detected.

Discussion

The low-position double-tunnel PD catheterization is different from the traditional laparotomy. Innovatively, two parallel incisions are made beside the umbilicus. The depth of the upper incision reaches the anterior sheath, while the depth of the lower incision reaches the peritoneum. The PD catheter enters the abdominal cavity from the lower incision and serves as the "inner opening" for draining the PD fluid. The head end of the PD catheter is led out through the upper incision from the lower incision and serves as the "outer opening" for draining the PD fluid. So far, the difference in the depth of the upper and lower incisions takes a role in cross-fixation, therefore greatly reducing the incidence rate of catheter displacement events, further sparing patients additional medical trauma and reducing their financial burden. Our research has proved that during the follow-up period of 6 months and 2 years after the operation, there were no catheter displacement events in the patients of the low-position double-tunnel group. Moreover, during the high-risk period for catheter displacement (first 6 months post-insertion), intergroup differences reached statistical significance.

In addition, we also collected the situations of residual renal function and dialysis adequacy of the three groups of patients during the postoperative follow-up period. There was no significant difference in dialysis adequacy between the low-position double-tunnel catheterization and the control group, but the residual renal function in the low-position double-tunnel group was better preserved compared with that in the control group. This may be because the reduction in catheter displacement events could enable patients to maintain PD better, remove toxins more thoroughly, and thus reduce further damage to the kidneys. Moreover, the number of hospitalizations of patients is reduced, and further the psychological burden is reduced, which indirectly affects the physiological function of the kidneys. Even so, there is no denying that when reviewing the creatinine level before operation, the average level of serum creatinine is lower than the control groups. This may be due to the reason that in recent years, with the improvement of economic level, people are more concerned about their own health, and physical examination is more popular, which leads to early intervention in uremia. Hence, patients in the low-position double-tunnel group might have a better basal renal function than the controls. This would introduce bias in the results.

This retrospective study has limitations. The results indicated that the preservation of the PD catheter by the patients in the low-position double-tunnel group was better than that in the control group. However, it cannot be denied that since the low-position double-tunnel PD catheterization was carried out in 2020, and the operation time of the first patient included in the study was April 12, 2021, while the operation time of the earliest patient in the control group could be traced back to December 23, 2016. There is a time bias among the three groups. And considering that since 2019, the world has been repeatedly impacted by the COVID-19 pandemic, dialysis patients, who are a group with low immunity, have been hit harder in the face of the pandemic, which may have a certain impact on our data collection and results analysis.