Peritoneal dialysis (PD) is a therapeutic nephrology procedure used for primarily intracorporeal (inside the body) blood purification. Decisive for the functional principle of peritoneal dialysis are the anatomical and physiological conditions of the peritoneal membrane (lining of the inner abdominal wall). This lining mesothelium (synonym: tunica serosa) forms a cavity, the cavitas peritonealis (abdominal cavity), which is always filled with a low-volume fluid film even under physiological conditions. Using the various procedures and systems of peritoneal dialysis, this physiological cavity can be used for detoxification (detoxification) of the blood by applying approximately one to three liters of dialysate, which consists of an electrolyte solution, into the peritoneal cavity. To achieve the desired blood purification, diffusion and ultrafiltration are used to transport toxic metabolites, as well as electrolytes, buffer substances and water, from the patient’s blood across the peritoneal membrane into the dialysate. Removal of toxic (harmful) substances from the organism is achieved by draining the dialysate to the outside. Compared with hemodialysis (HL), peritoneal dialysis (PD) offers the following advantages: urinary substances and excess water are continuously removed from the body, so there is no drop in performance as with HL. In addition, other advantages of PD are that residual renal function is preserved longer, there is no heparinization or blood loss, and there are fewer dietary restrictions. Furthermore, studies have shown that patients on PD live slightly longer than those on HL. Peritoneal dialysis is used relatively rarely in Germany.
Indications (areas of application)
- The indications for hemodialysis and peritoneal dialysis differ only slightly. However, the preferred indications for peritoneal dialysis are the treatment of patients who have difficulty creating a viable AV fistula (connection of artery and vein).
- Chronic terminal renal failure in proliferative diabetic retinopathy – of course, peritoneal dialysis can be used in renal failure patients without retinopathy, but the procedure is particularly suitable for this group of patients. The reason for this is that with conventional hemodialysis, anticoagulation (anticoagulation) with heparin can cause retinal hemorrhage and vitreous hemorrhage, which can lead to deterioration of visual acuity (vision) and ultimately to amaurosis (blindness).
- Chronic terminal renal failure in severe heart failure – by using peritoneal dialysis, patients with severe heart failure (cardiac insufficiency) especially benefit, because peritoneal dialysis involves a continuous withdrawal of fluid, where conventional hemodialysis, on the other hand, involves a withdrawal of fluid that is interrupted several times. The continuous withdrawal of volume is better tolerated by these patients.
- Acute renal failure (ANV) – this emergency indication for the use of peritoneal dialysis is when, in addition to loss of renal function, symptoms of pericarditis, pulmonary edema, potassium levels above 6.5 mmol/l, massive acidosis, or uremic encephalopathy (disease or damage to the brain) are present. In these cases, the implementation of therapy must be immediate.
Contraindications
- Exsiccosis – hemodiafiltration should not be performed in patients with a serious underlying condition associated with significant exsiccosis (dehydration).
The procedure
The various systems of peritoneal dialysis are considered to be particularly gentle on the circulation, which means that even elderly patients and especially patients with heart disease can be subjected to elimination of harmful substances by peritoneal dialysis. Furthermore, this procedure offers an additional advantage by improving the independence of the treated patients from a dialysis center. However, in order for this advantage to be utilized, the patient must be suitable for the procedure. If this does not pose a problem, this form of dialysis can be performed both at home and on vacation.Nevertheless, it must be mentioned that peritoneal dialysis involves the risk that the peritoneal cavity (abdominal cavity) may become contaminated with pathogenic (disease-causing) germs in the event of contact with the environment. This can result in the peritoneum (abdominal cavity) becoming inflamed, which can be associated with serious complications. In addition to possible peritonitis (inflammation of the peritoneum), however, there are other undesirable effects associated with the use of peritoneal dialysis. If the procedure is used continuously over several years, there is an increased risk of suffering from a pathological change in the peritoneum associated with increasing reabsorption of fluid, including sodium, from the dialysis solution. The indwelling catheter
- The basis for the function of any peritoneal dialysis procedure is a catheter system. This catheter system fulfills the requirement for chronic peritoneal dialysis treatment to have permanent access to the peritoneal cavity. In the vast majority of cases, a peritoneal dialysis catheter is made of silicone.
- These catheters have so-called Dacron sleeves on the surface, which serve to fix the catheter and thus prevent a change in the catheter position. To achieve a rapid and sufficient for treatment fluid exchange, the catheter end piece has a large number of holes.
- To minimize the occurrence of complications such as an inflammatory reaction due to infection or the formation of hernias (hernia sac formation), the surgical implantation technique is preferred nowadays. The laparoscopic implantation technique is considered particularly gentle, but is often used only by specialized surgeons.
- After opening the peritoneal cavity (abdominal cavity) between the navel and symphysis (cartilaginous pelvic component), the catheter is placed with the tip in the Douglas space (pocket-shaped bulge of the peritoneum) and fixed at the point of passage through the peritoneum with a special suture technique. Of particular importance is now the approximately 12 cm tunneling in the intramuscular (inside the muscle) and subcutaneous tissue (deep skin layer). In an optimal implantation, the exit point of the catheters is localized to the side of the navel.
Forms of peritoneal dialysis
- Continuous ambulatory peritoneal dialysis (CAPD) – this system is a manual (non-machine) and continuous peritoneal dialysis procedure in which a precisely defined amount of dialysis fluid is introduced into the peritoneal cavity by means of a previously implanted permanent peritoneal dialysis catheter. This application is performed four to five times a day, with elimination of the added fluid after several hours of residence time. Diffusion (transport process in which an even distribution of particles and thus complete mixing of two substances is achieved) is the primary path of substance exchange between blood and dialysis fluid during the indwelling period. Precise regulation of fluid removal is possible by adjusting the osmolarity (direction of flow of molecules through a membrane) in the dialysate by changing the concentration of glucose or other osmotically active substances.
- Continuous cyclic peritoneal dialysis (CCPD) – A special feature of this system is that dialysate is still applied to the peritoneal cavity (abdominal cavity) with the help of the dialysis machine at the end of a night treatment in the early morning before getting up and thus before the treatment is completed. This fluid remains in the peritoneal cavity during the day. If the treatment is continued, the fluid can be eliminated from the organism when the cycler is connected the following evening. Based on this, this treatment method can achieve a detoxification effect (similar to CAPD) over 24 hours.
- Intermittent peritoneal dialysis (IPD) – intermittent peritoneal dialysis (IPD) takes place by means of an 8-12 hour treatment with a machine on approximately three days per week. Outside the dialysis period, dialysis fluid does not usually remain in the peritoneal cavity (abdominal cavity). Normally, intermittent peritoneal dialysis is not used as a home dialysis procedure, as the procedure requires care in a dialysis center.The duration of treatment is usually eight to ten hours, and it should be mentioned in particular that dialysis is performed with a cycler. This procedure is used only rarely and as a bridging measure when other dialysis treatments are temporarily not possible. A variation of this procedure can be understood as nocturnal intermittent peritoneal dialysis (NIPD). The basic principle of this subform is that no fluid is applied to the peritoneal space during the day. The actual detoxification takes place at night, with the dialysate being withdrawn at the end of a nocturnal treatment cycle.
- Continuous flow peritoneal dialysis (CFPD) – currently, this system is still an experimental procedure in the testing phase, however, using CFPD, detoxification similar to daily hemodialysis can be achieved. However, the disadvantages of this procedure are the high cost and the large amount of dialysate. The function of CFPD is based on the use of either a catheter with two lumens (orifices) or on two implanted catheters through which fresh dialysate is constantly admitted and discharged through the second lumen or catheter. A cycler-like device is also used.
Potential complications
- Peritonitis – in this inflammation of the peritoneum, the patient notes abdominal pain (abdominal pain), less commonly nausea and vomiting, fever, chills, constipation (constipation), or diarrhea (diarrhea). Depending on the duration of peritonitis and bacterial type, guarding and release pain may occur. In some cases, leukocytosis (increase in the number of white blood cells) is detectable. For early diagnosis, the detection of the decrease in the amount of ultrafiltration serves.
- Tunnel infection – infectious complications, these include catheter exit and tunnel infections (clinical picture: tenderness, erythema (redness of the skin) or induration in an area > 2 cm from the catheter entry site starting along the subcutaneously located catheter, without accompanying bloodstream infection).
- Hernias (“hernia”) – if the implantation of the catheter is not performed by laparoscopic surgery, the risk of developing a hernia is increased. Inguinal and umbilical hernias can also develop during the performance of peritoneal dialysis, because of high intraperitoneal pressure (pressure in the abdominal cavity).
- Electrolyte Derailment – Electrolyte derailment can result from the incorrect administration of electrolyte solutions. Moreover, patients are predisposed to electrolyte derailment who have a catabolic (higher protein breakdown than buildup) metabolic state.
- Weight gain due to the glucose in the dialysis solution.
Other notes
- A meta-analysis on Korean patients suggests that peritoneal dialysis is associated with a higher mortality risk (risk of death) than hemodialysis in elderly patients.
- A randomized clinical trial demonstrated that neither treatment with acetylsalicylic acid (ASA; 100 mg/die) nor intake of fish oil capsules (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), 4 g/die) reduced the failure rate of an AV shunt.
