Capd

Peritoneal dialysis has been used as an intermittent form of clinic-bound application since the 1960s (Geberth 2011). In 1976, Moncrief and Popovitch described continuous outpatient peritoneal dialysis for the first time. A little later, in 1978, CAPD as described by Oreopoulos made continuous peritoneal dialysis treatment possible, thus laying the foundation for CAPD performed in the home in its current form (Hepp 2009).

Continuous ambulatory peritoneal dialysis (CAPD) is one of the forms of peritoneal dialysis (PD). It is the only non-machine-assisted form of PD (Herold 2020). It is driven by gravity (Kuhlmann 2015).

At 65% (Hepp 2009), CAPD is the most common form of peritoneal dialysis (Kuhlmann 2015).

The peritoneum is the dialysis membrane in CAPD.

Through the capillaries of the peritoneum, substances from the blood accumulate in the dialysis solution by diffusion and are eliminated.

Small molecular parts can either diffuse or be transported by convection into the dialysis solution or peritoneal cavity.

Large-molecular parts leave the capillaries by convection. This usually requires a longer retention time of the dialysate, which is the case with CAPD (Geberth 2011).

Water, on the other hand, is primarily removed osmotically by the hypertonic dialysis solution (Moor 2018).

The clearance performance by CAPD is in the:

• small molecule range are significantly higher than those of hemofiltration (HF)
• medium molecular range above that of haemodialysis (HD). However, it must be taken into account that the majority of CAPD patients still have a residual renal function through which medium molecular weight parts can also be excreted (Keller 2010) (Streicher 1982).

The following complications can occur in PD in general:

• CAPD-associated peritonitis (occurs more frequently than in other forms of peritoneal dialysis due to the long retention time of the dialysate)
  • the contamination can be intraluminal, periluminal (along the catheter [Geberth 2011]) or gastrointestinal
  • mainly caused by gram-positive germs (especially staphylococci)
  • the patients complain of abdominal pain, cloudy dialysate; the dialysate contains a laboratory chemical detection of > 100 leukocytes / µg with > 50 % granulocytes and positive dialysate cultures
  • the therapy consists of broad-spectrum antibiotics according to an antibiogram, administration preferably intraperitoneal, otherwise i. v.
  • the dose should be adjusted to the residual renal function
  • Therapy duration at least 2 weeks, for S. aureus, enterococci, gram-negative pathogens at least 3 weeks
  • intraperitoneal heparin should be administered due to the risk of adhesion and catheter obstruction
• exit- side infections
  • this leads to a purulent secretion with or without redness, swelling and crusts
  • the diagnosis is made clinically
  • the systemic antibiosis should be carried out according to the smear or antibiogram (Kuhlmann 2015)
• Tunnel infections
  • In this case, infections of the abdominal wall in the area of the tissue surrounding the catheter occur with swelling, redness, pain and purulent secretion (Kuhlmann 2015)
  • the frequency of exit- side infections or tunnel infections varies between 0.1 % - 1 % episodes / year
  • the diagnosis is made sonographically (low-echo area around the catheter and / or the socket)
  • after a germ smear, antibiotic treatment adapted to the antibiogram
  • the follow-up should also be sonographic (Herold 2020)

The application of silver nitrate, which used to be common to prevent tunnel infection, is no longer recommended because silver nitrate attacks the catheter material (Kasper 2015).

• unintentional weight increase due to overwatering
• metabolic disorders
• Hyperkalemia is very rare in peritoneal dialysis, however, because the dialysate solutions are potassium-free (Kasper 2015).

For CAPD, a catheter is implanted into the abdominal cavity surgically, laparoscopically or percutaneously using the Seldinger technique approximately 2 weeks before dialysis is started (Geberth 2011).

Indications:

• Patients with infectious diseases such as hepatitis C, HIV etc.
• elderly patients (Hepp 2009).

Advantages:

• Independence from clinic times etc.
• CAPD is a gentle form of treatment for the patient.
• the residual function of the kidneys is preserved for longer
• there are only minor restrictions on the amount of fluid that can be drunk (Hepp 2009)
• CAPD is more cost-effective than haemodialysis (HD)
• Is associated with certain advantages for diabetics such as:
  • more stable blood glucose control
  • fewer hypoglycaemias (Hörl 2004)

Night disadvantages:

• technical survival (this refers to the period during which CAPD can be performed without switching to another form of dialysis) varies between 63% - 71% after 5 years, which is lower than with HD
• time-consuming dialysate changes several times a day
• particular disadvantages in diabetics:
  • resorption of glucose with increased insulin requirement as a result
  • higher rate of catheter infections than with APD
  • deterioration of lipid metabolism possible (Hörl 2004)

Contraindications to peritoneal dialysis include:

• existing diseases with an increased risk of peritonitis
• chronic inflammatory bowel disease (CED)
• COPD
• non-curable hernias
• protein deficiency
• psychoses (Herold 2020) anamnestically known diverticulitis
• body weight > 90 kg
• lack of hygienic behaviour
• Difficulties with material storage (e.g. due to cramped living conditions)
• Colostoma
• Nephrostoma
• high renal protein loss with malnutrition
• numerous previous operations with adhesion abdomen
• very large cystic kidneys (Hepp 2009)

Implementation:

In classical CAPD, 4 - 5 changes of dialysate take place per day, usually every 4 h during the day and after 8 h at night (Geberth 2011). It is possible to adapt this schedule to individual needs to some extent (Schärer 2002). Since there is no complete emptying in the meantime, the abdominal cavity is constantly filled with dialysate during CAPD (Geberth 2011).

The dialysate itself often consists of glucose-containing solutions with a low concentration of glucose degradation products, so-called glucose degradation products = GDPs (Herold 2020).

CAPD uses higher volumes than automated peritoneal dialysis ( APD). The retention time of the dialysate is between 4 - 10 h, which is longer than with APD (Kuhlmann 2015). Due to the longer retention time, higher molecular weight parts can be better eliminated (Geberth 2011).

CAPD is sometimes used in combination with APD (Kasper 2015).

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