Dialysis


Fig. 18.1

Diffusion is driven by the concentration gradient over the membrane


../images/393863_1_En_18_Chapter/393863_1_En_18_Fig2_HTML.png

Fig. 18.2

Ultrafiltration driven by the osmotic agent over the membrane



Lactate dialysates with different concentrations of glucose, thereby with different osmotic pressure, are used in clinical practice. Composition of commonly used glucose lactate dialysates is shown in Table 18.1.


Table 18.1

Compositions of commonly used glucose lactate dialysate












































 

Glucose (C6H12O6·H2O) (g)


Osmotic pressure (mOsmol/L)


pH


Ion concentration


Na


Ca


Mg


Chloride


Lactate


1.5% glucose lactate dialysate


1.5


346


5.2 (4.5–6.5)


132


1.75/1.25


0.25


95–106


35–40


2.5% glucose lactate dialysate


2.5


396


4.25% glucose lactate dialysate


4.25


485


18.3 Catheter Design and Insertion Techniques


Several different types of catheters and catheter insertion techniques are used in PD. The advantages and disadvantages of different techniques for catheter insertion are summarized in Table 18.2.


Table 18.2

Advantages and disadvantages of different catheter insertion techniques




































 

Advantages


Disadvantages


Percutaneous (bedside)


• Can be performed at bedside, allowing rapid initiation of dialysis


• Risk of bowel or bladder injury


• Physician or nurse can be trained to perform the procedure


• Not suitable for patients with previous midline surgical scars or risk of adhesions


Open surgical


• Available in most centers


• Requires surgical scheduling, with available operating theater time at a premium


• Lower cost of consumables than that with laparoscopy

 

Laparoscopic


• Lower incidence of leakage


• Requires skilled personnel


• Ability to perform adjunctive procedures


• High cost of consumables


• Ability to place the catheter in the pelvis under vision

 

Flexible catheters—As the gold standard for PD access, Tenckhoff catheter is the most widely used in patients with chronic dialysis.


Rigid catheters—By using a trocar device, the catheter can be inserted directly to the iliac fossae. Dialysis using these catheters is less efficient although they are easy to be inserted. Also, this catheter design tends to generate some complications, such as bladder or bowel perforation, bleeding, leakage of dialysate, and obstruction owing to the small side holes and lumen [4].


18.4 Indications and Contraindications for PD


18.4.1 Indications


PD is recommended as the first-line treatment modality of renal replacement theraphy for the following patients with CKD stage 5: (1) children aged ≥2 years, (2) individuals with residual renal function, and (3) adults with no significant related comorbidities.


18.4.2 Contraindications


Contraindications for PD are summarized in Table 18.3.


Table 18.3

Contraindications for peritoneal dialysis
































Absolute


Relative


• Loss of peritoneal function


• Recent abdominal aortic graft


• Producing inadequate clearance


• Ventriculoperitoneal shunt


• Adhesions blocking the dialysate flow


• Intolerance to intra-abdominal fluid loading


• Surgically uncorrectable abdominal hernia


• Large muscle mass


• Abdominal wall stoma


• Morbid obesity


• Diaphragmatic fluid leakage


• Severe malnutrition


• Inability to perform exchanges in the absence of suitable assistant


• Skin infection


• Bowel disease


18.5 PD Modalities


Several major PD modalities exist, which include the following:


  1. 1.

    Continuous ambulatory peritoneal dialysis (CAPD)—Patients undergo PD throughout the day.


     

  2. 2.

    Continuous cycling peritoneal dialysis (CCPD)—Patients undergo PD throughout the day, which is assisted by automated machines overnight.


     

  3. 3.

    Intermittent peritoneal dialysis (IPD)—Patients undergo intermittent PD.


     

  4. 4.

    Automated peritoneal dialysis (APD)—Patients undergo PD assisted by automated machines.


     

Since the invention of Tenckhoff catheter in 1968 and appearance of wearable/portable equilibrium dialysis technique in 1976, CAPD has been used as a feasible modality of renal replacement therapy in the long-term treatment of patients with end-stage renal disease (ESRD). Twin bags are used in CAPD patients to reduce the number of connections and disconnections required to be established everyday [5].


CCPD is suitable for patients requiring help (such as children, blind individuals, and the elderly) or daytime workers. Patients can carry out their own activities and work with the peritoneal dialysate in the abdominal cavity throughout the day and have good sleep assisted by automated machines overnight.


IPD is applied to acute or chronic renal failure for the initial 3–10 days of CAPD. IPD removes more water, is associated with fewer complications of peritonitis, and can discharge more nitrogen.


The advantage of APD is that it needs less intensive nursing care, but the disadvantage is that it increases the financial burden. During APD, a variety of highly efficient treatment arrangements can be provided by the use of high flows of dialysate, individualized intraperitoneal fluid volumes, and short residence times.


Overall, there exists no evidence on significant differences in critical outcomes among modalities, such as quality of life, mortality, adverse events, nutritional status, and technique survival for patients treated with CAPD and APD. Therefore, adults and children can opt for CAPD, CCPD, or APD. However, APD has been recommended as the preferred option for infants and children on a liquid diet based on clinical experience. The National Kidney Foundation–Dialysis Outcomes Quality Initiative (NKF–DOQI) guidelines recommended Kt/V target of 2.0 for CAPD and 2.1 for CCPD every week in 1997. Because higher daily dialysis solution volumes can be easier and more convenient delivered by using automated machines, cycler utilization is increased in order to achieve these high targets. Nevertheless, in recent NKF–DOQI guidelines, the Kt/V targets for CAPD have been mildly reduced to 1.7. The use of APD has significantly increased since its reintroduction, probably because its use promotes positive changes in the lifestyle of dialysis patients [2].


18.6 Assessment


18.6.1 Peritoneal Equilibration Test (PET)


The most commonly used method for evaluating the transport characteristic of peritoneal membrane is PET. As a simple clinical method, PET is widely used to assess the rapidity of urea, creatinine, and other solutes diffusion across the peritoneal membrane. It has become a routine method for the evaluation of clinically important alterations in peritoneal transport characteristics. In this test, the dialysate to plasma solute concentration (D/P) ratio for particular solutes is measured during an exchange with conventional PD fluid [5].


The standard procedure for PET is listed below [8]:
Oct 20, 2020 | Posted by in NEPHROLOGY | Comments Off on Dialysis
Premium Wordpress Themes by UFO Themes