OVERVIEW
Ultrafiltration failure is a complication that occurs when the peritoneum itself loses its ultrafiltration function, and is a serious complication in patients on maintenance peritoneal dialysis, who experience the clinical manifestations of volume overload.
Etiology
1. Decreased effective surface area and permeability of the peritoneum.
2. Increased peritoneal lymphatic reabsorption rate.
3. Selective impairment of transperitoneal cellular transport pore function.
Symptoms
1. Type I ultrafiltration failure
Type I is a hyperpermeable peritoneum. Patients with this type have a high peritoneal solute transport rate, and glucose and water in the dialysate are rapidly absorbed. The cause of type I ultrafiltration failure is unknown; it is present in some patients at the start of peritoneal dialysis and may be partly related to endogenous factors. It may also be caused by peritonitis, prolonged exposure of the peritoneum to peritoneal dialysis fluid, and chronic irritation from toxin release from the catheter biofilm.
2. Type II Ultrafiltration Failure
Type II is a low permeability peritoneum with multiple intraperitoneal adhesions and peritoneal sclerosis resulting in low solute transport rates. This type of ultrafiltration failure is caused by a decrease in the permeability of the peritoneum to water or by a decrease in the surface area of the peritoneum. Inadequately treated severe peritonitis, intraperitoneal inflammation of various causes, and encapsulated sclerosing peritonitis all present with type II ultrafiltration failure.
3. Type III ultrafiltration failure
Type III is the excessive lymphatic reflux type, which manifests as inadequate solute and water removal. This type of ultrafiltration failure is due to the loss or abnormal function of aquaporins in the peritoneum.
Examination
It mainly consists of physical examination and peritoneal dialysis monitoring. The patient has persistent edema and is unable to maintain a stable dry weight despite the application of excessive amounts of peritoneal dialysis fluid.
Diagnosis
Ultrafiltration failure should be considered when peritoneal dialysis patients have good control of water and salt intake but still have persistent edema and fluid overload.
International diagnostic criteria: ① 4.25% dextrose peritoneal dialysis fluid, 4h exchange, net ultrafiltration volume <400ml; ② application of 4.25% dextrose peritoneal dialysis fluid two to three times a day or more, still can not stably maintain the dry body weight, the presence of oedema, but should be excluded from the problems caused by the treatment itself, including the patient’s factor, the medical factor, the mechanical problem, and so on.
Treatment
1. Type I ultrafiltration failure
(1) Reduce retention time by changing continuous ambulatory peritoneal dialysis to automated peritoneal dialysis to reduce long retention time and increase ultrafiltration volume.
(2) Peritoneal rest: suspend peritoneal dialysis to allow the peritoneum to rest.
(3) Selection of osmotic agent: switch to peritoneal dialysis fluid with smaller absorption coefficient and better biocompatibility in the dialysis fluid.
(4) Drugs: peroxisome proliferator-activated receptor gamma agonists can increase the amount of ultrafiltration. 2. Type II ultrafiltration failure
(1) Conversion to automated peritoneal dialysis to reduce retention time and increase net ultrafiltration.
(2) Mildly ill patients maintain volume balance by limiting fluid intake and shortening retention time. Patients with compromised solute transport need to be converted to hemodialysis therapy.
(3) Hexoketone cocaine has obvious inhibitory effects on fibroblast proliferation, extracellular matrix synthesis and myofibroblast differentiation, providing a theoretical basis for clinical treatment of peritoneal fibrosis.
In addition, the traditional Chinese medicine Astragalus, Angelica sinensis and Salvia miltiorrhiza can prevent and delay the occurrence of peritoneal fibrosis.