What Is the Difference Between Hemodialysis and Peritoneal Dialysis?

Peritoneal dialysis (PD) is the use of the characteristics of the peritoneum as a semi-permeable membrane. The prepared dialysate is regularly and regularly injected through the catheter into the patient's peritoneal cavity through gravity. Due to the difference in concentration gradients of solutes on both sides of the peritoneum, high concentration The solute on one side moves to the low-concentration side (dispersion); the water moves from the low-osmosis side to the high-osmosis side (osmosis). The peritoneal dialysis fluid is continuously replaced to achieve the purpose of removing metabolites and toxic substances in the body and correcting water and electrolyte balance disorders.

Basic Information

Chinese name: Peritoneal dialysis
Foreign name: PD
Principle: Use of the peritoneum as a dialysis membrane

Indication: Acute kidney injury, chronic renal failure
Contraindications: Reduced peritoneal clearance due to various abdominal lesions
complication: Peritonitis, metabolic complications, lung infections

Principle of peritoneal dialysis

The basic principle of peritoneal dialysis is to use the peritoneum as a dialysis membrane to separate the dialysate from the blood into the abdominal cavity from the blood. The peritoneum is semi-permeable and has a large area and rich capillaries. The peritoneal capillaries are immersed in the dialysate. Extensive material exchange between the blood in the cavity and the dialysate, in order to achieve the purpose of removing metabolites and poisons in the body, and correcting the imbalance of water electrolytes and acid-base balance. In peritoneal dialysis, the solutes are mainly exchanged by means of diffusion and convection, and the removal of water mainly depends on increasing the osmotic pressure for ultrafiltration.

Influencing factors of peritoneal dialysis

Factors affecting peritoneal dialysis include: the concentration gradient of the dialysate is different; the volume and flow rate of dialysate; the residence time of dialysate in the abdominal cavity; the contact area of peritoneum and dialysate: dialysate temperature; dialysate glucose concentration and Peritoneal blood circulation and so on.

Indications for peritoneal dialysis

1. Acute kidney injury: For early renal injury, early dialysis should be promoted. It is mainly applicable to non-high catabolic types. If the following clinical manifestations or various biochemical indicators reach the following levels, peritoneal dialysis should be performed: oliguria for 3 days Or no urine for 2 days; there is diffuse intravascular coagulation; obvious retention of water and sodium; severe edema, cerebral edema, acute pulmonary edema; symptoms of uremia are obvious; severe electrolyte disorders, acid-base imbalances such as hyperkalemia, Metabolic acidosis, etc .; serum creatinine> 354 mol / L, serum urea nitrogen> 23.8 mmo / L.
2. Chronic renal failure endogenous creatinine clearance rate Ccr <10ml / min, blood creatinine 707.2mol / L, and peritoneal dialysis treatment can be started with symptoms of uremia.
(1) Uremia: when Ccr <10ml / min, or Scr707.2mol / L (8mgl / dl), accompanied by one of the following conditions: obvious symptoms of uremia (such as nausea, vomiting); obvious Water and sodium retention (high edema, high blood volume heart failure or hypertension); severe electrolyte disorders (such as blood potassium 6.5mmol / L); severe metabolic acidosis (CO2-CP 15mmol / L ); before and after kidney transplantation; chronic kidney failure in several special cases: diabetic nephropathy; child patients; elderly patients.
(2) Acute drug and poisoning: Peritoneal dialysis can remove drugs and poisons with the following properties: dialyzability, molecular weight less than 5000 Daltons; exist in the blood in unbound form. Compared with hemodialysis and hemoperfusion, peritoneal dialysis has a weaker effect on treating poisoning. When there is no such device, it can be tried.
(3) Others: when there is no blood purification equipment for acute drug or poisoning; water and electrolyte disorders, acid-base balance disorders, hyperthyroidism, severe acute pancreatitis, extensive purulent peritonitis, hepatic encephalopathy, hyperbilirubinemia, Refractory heart failure, multiple myeloma, psoriasis (psoriasis), etc.

Contraindications for peritoneal dialysis

1. Absolute contraindications: Peritoneal clearance is reduced due to various abdominal diseases; extensive infection of the abdominal wall or severe burns cannot be intubated.
2. Relative contraindications Within 3 days of abdominal surgery, if the wound does not heal, the incision leaks during peritoneal dialysis; there are localized inflammatory lesions in the peritoneum, which can spread inflammation; late pregnancy or huge tumors in the peritoneal cavity due to the decrease in the abdominal cavity The effect of peritoneal dialysis is not ideal; vascular diseases in the abdominal cavity, such as multiple vasculitis, severe arteriosclerosis, scleroderma, etc., will reduce the dialysis effectiveness; severe respiratory dysfunction, excessive fluid intake will increase respiratory dysfunction For example, if the amount of fluid for peritoneal dialysis is less, those who have insufficient protein and calorie intake for a long period of time should not perform long-term chronic peritoneal dialysis, because peritoneal dialysis loses more than 6g of protein per day.

Peritoneal dialysis complications

1. Peritonitis: It is the most common complication in peritoneal dialysis, and its occurrence is related to factors such as inadequate aseptic operation, incision and tube infection, low immunity, contamination of the dialysate, and advanced age. The microorganisms that cause peritonitis mainly enter the abdominal cavity through the dialysis lumen, and can also enter the abdominal cavity from the skin leakage around the outlet of the dialysis tube, or directly spread to the abdominal cavity from the intestine, pelvic cavity and other inflammations, even from blood. Can be divided into bacterial, fungal, chemical peritonitis and so on.
2. Metabolic complications: water and electrolyte disorders, which can cause sodium and sodium retention symptoms such as pulmonary edema and brain edema, and hypokalemia; hyperglycemia and reactive hypoglycemia; hypertonic dehydration; Malnutrition syndrome is caused by loss of protein, amino acids, and water-soluble vitamins. It is manifested as weakness, lack of appetite, drowsiness, and coma in severe cases. Therefore, patients with peritoneal dialysis should pay attention to nutritional supplements.
3. Pulmonary infection: the incidence is about 25%, which is related to factors such as diaphragmatic elevation and bed rest.
4. Mechanical complications: manifested as poor drainage of dialysate, blockage of dialysis tube, abdominal pain, bloating, leakage of dialysate, bleeding, visceral damage, etc., often cause local irritation, improper positioning, and poor suture with dialysate and dialysis tube. And other factors.