Peritoneal dialysis Health Dictionary

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Peritoneal Dialysis: From 2 Different Sources

(PD) a form of renal replacement therapy (see dialysis) that utilizes the peritoneum as the semipermeable membrane separating blood and *dialysate. Peritoneal dialysis can be given as a temporary and emergency treatment using a rigid percutaneous cannula to deliver fluid into the peritoneal cavity; this cannula usually needs removal and/or replacement within a few days. Alternatively, PD can be used as a chronic treatment, either in the form of chronic ambulatory peritoneal dialysis (see CAPD) or automated peritoneal dialysis (APD), in which case fluid delivery is through a soft silastic catheter that is tunnelled subcutaneously out of the peritoneal cavity and is designed to stay in place for years. In all cases, the dialysis fluid is left within the peritoneal cavity for a period of time during which substances in the bloodstream diffuse into the fluid according to their concentration gradient and the permeability of the peritoneal membrane.
Health Source: Oxford | Concise Colour Medical Dictionary
Author: Jonathan Law, Elizabeth Martin

Dialysis

A procedure used to ?lter o? waste products from the blood and remove surplus ?uid from the body in someone who has kidney failure (see KIDNEYS, DISEASES OF). The scienti?c process involves separating crystalloid and COLLOID substances from a solution by interposing a semi-permeable membrane between the solution and pure water. The crystalloid substances pass through the membrane into the water until a state of equilibrium, so far as the crystalloid substances are concerned, is established between the two sides of the membrane. The colloid substances do not pass through the membrane.

Dialysis is available as either haemodialysis or peritoneal dialysis.

Haemodialysis Blood is removed from the circulation either through an arti?cial arteriovenous ?stula (junction) or a temporary or permanent internal catheter in the jugular vein (see CATHETERS). It then passes through an arti?cial kidney (‘dialyser’) to remove toxins (e.g. potassium and urea) by di?usion and excess salt and water by ultra?ltration from the blood into dialysis ?uid prepared in a ‘proportionator’ (often referred to as a ‘kidney machine’). Dialysers vary in design and performance but all work on the principle of a semi-permeable membrane separating blood from dialysis ?uid. Haemodialysis is undertaken two to three times a week for 4–6 hours a session.

Peritoneal dialysis uses the peritoneal lining (see PERITONEUM) as a semi-permeable membrane. Approximately 2 litres of sterile ?uid is run into the peritoneum through the permanent indwelling catheter; the ?uid is left for 3–4 hours; and the cycle is repeated 3–4 times per day. Most patients undertake continuous ambulatory peritoneal dialysis (CAPD), although a few use a machine overnight (continuous cycling peritoneal dialysis, CCPD) which allows greater clearance of toxins.

Disadvantages of haemodialysis include cardiovascular instability, HYPERTENSION, bone disease, ANAEMIA and development of periarticular AMYLOIDOSIS. Disadvantages of peritoneal dialysis include peritonitis, poor drainage of ?uid, and gradual loss of overall e?ciency as endogenous renal function declines. Haemodialysis is usually done in outpatient dialysis clinics by skilled nurses, but some patients can carry out the procedure at home. Both haemodialysis and peritoneal dialysis carry a relatively high morbidity and the ideal treatment for patients with end-stage renal failure is successful renal TRANSPLANTATION.... dialysis

Diagnostic Peritoneal Lavage

the instillation of saline directly into the abdominal cavity and its subsequent aspiration a few minutes later. If the fluid is bloodstained on recovery an intra-abdominal haemorrhage is indicated. This is a useful diagnostic tool in trauma patients.... diagnostic peritoneal lavage

Retinal Dialysis

separation of the retina from its insertion at the ora serrata (the anterior margin of the retina, lying just posterior to the ciliary body). This acts as a retinal tear and causes a *retinal detachment.... retinal dialysis

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