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Dialysis is a renal replacement treatment that cleans the body of waste products and removes excess water when the kidneys are unable to perform their functions. Currently used methods of dialysis are hemodialysis and peritoneal dialysis. How are they different from each other? How is dialysis done? What are the complications?

Dialysis(Greekdiálysismeaning dissolving, separating) is a renal replacement therapy, which in the case of patients suffering from end-stage renal disease, enables the purification of the blood from metabolites and excess water. Dialysis can also be used in patients who have been poisoned, for example, with ethyl glycol. What dialysis methods are currently in use? What are the indications for their use? And what are the dangers of dialysis?

Hemodialysis

Hemodialysis is the dominant treatment for acute and chronic renal failure, and its purpose is to remove toxins from the patient's blood. It is performed using a hemodialysis machine called an artificial kidney. Thanks to it, substances present in the blood pass through the semipermeable membrane into the dialysis fluid by diffusion, and the excess water contained in the plasma is removed by oxidation.

The time of starting dialysis treatment depends on the results of biochemical blood tests of the patient and the presence of clinical symptoms. Typically, hemodialysis is started when creatinine clearance is less than 10 ml / min, which corresponds to a serum creatinine concentration of 8-10 mg / dl, and in diabetic nephropathies - 6-7 mg / dl.

Hemodialysis: vascular access

For hemodialysis, access to the patient's circulation is necessary, which will ensure the blood flow in the range of 200-450 ml / min. Ideally, access should be created before chronic dialysis is required. In the event of urgent dialysis, it is advisable to obtain a temporary vascular access by inserting a catheter into the internal or femoral jugular vein.

The preferred access in chronic dialysis is an arteriovenous fistula that can be maintained for years. It is formed by the surgical connection of an artery and a vein - most often a radial artery with a cephalic vein. Is itend of the vein to end of artery connection, end of vein to side of artery, or side of vein to side of artery.

It is extremely important not to use the newly created fistula for a period of about 2-4 months - during this time it becomes wider - "arterialized". Interestingly, palpation of an active arteriovenous fistula can reveal a ripple, and auscultation shows a characteristic vascular murmur.

It is worth remembering about the complications of chronic vascular access. These include narrowing leading to impaired blood flow, thrombosis, skin infections and / or erosions, insufficient venous outflow, limb ischemia due to blood stealing, venous hypertension, pseudoaneurysms, and heart failure.

Hemodialysis: indications

Indications for hemodialysis can be divided into absolute and relative indications. The absolute indications include:

  • uremic pericarditis
  • severe hyperkalemia (>6.5 mmol / l)
  • serum urea concentration>250 mg / dl
  • overhydration unresponsive to diuretics (pulmonary edema)
  • refractory acidosis (carbohydrate concentration<13 mmol/l)

The relative ones include:

  • symptomatic azotaemia (including encephalopathy)
  • presence of dialyzable toxins (e.g. drug poisoning)

Drugs and toxins removed by hemodialysis are:

  • acetaminophen
  • alcohols (ethanol, methanol, isopropanol, ethylene glycol)
  • amphetamine
  • arsenic
  • barbiturates
  • monoamine oxidase inhibitors
  • carbamazepine
  • acetylsalicylic acid
  • valproic acid
  • lit
  • antiarrhythmic drugs (procainamide, sotalol)
  • antibacterial drugs
  • antihypertensive drugs (ACE inhibitors, beta-blockers)
  • anticancer drugs (busulfan, cyclophosphamide, 5-fluorouracil)
  • mannitol
  • theophylline

Hemodialysis: contraindications

Contraindications include:

  • severe infectious conditions, resistant to treatment (e.g. decaying pulmonary tuberculosis)
  • irreversible damage to other organs
  • hypotension not responding to pressure medication
  • disseminated neoplastic disease (presence of metastases), end stages of neoplastic disease
  • psycho-organic syndrome
  • status after severe stroke
  • mental disorders (lack of patient cooperation)
  • advanced dementia
  • disagreement with the patient

Hemodialysis: complications

For complicationshemodialysis sessions include:

  • dialysis hypotension
  • muscle cramp
  • Dialysis Compensation Syndrome
  • hypoxemia
  • heart rhythm disturbance
  • bleeding
  • hepatitis B and hepatitis C
  • HIV and cytomegalovirus infection
  • metabolic bone disease
  • acquired cystic kidney disease
  • pericarditis
  • anemia

Peritoneal dialysis

When we say peritoneal dialysis, we mean either continuous ambulatory peritoneal dialysis or automated peritoneal dialysis.

Continuous Ambulatory Peritoneal Dialysisinvolves replacing 2-3 liters of fresh dialysis fluid, usually 4 times a day. The total amount of fluid changed daily includes about 2 liters of the ultrafiltrate obtained. In this method, pre-heated dialysis fluid is introduced through a special catheter into the peritoneal cavity, where it remains for 4-5 hours.

Automatic peritoneal dialysisis performed automatically with the use of a special device - the so-called cycler. This apparatus, according to a pre-programmed schedule including the number of changes and the aging time, performs multiple changes of the dialysis fluid during the night. In both types of peritoneal dialysis, the dialysis fluid contains a hypertonic glucose solution with sodium, calcium, magnesium and chlorine ions, as well as lactate. In addition, patients, following the principles of asepsis, must independently connect the catheter inserted into the peritoneal cavity with the drains leading to the next bags with fresh dialysis fluid.

How does peritoneal dialysis work?

As renal failure progresses, it is necessary to increase the replacement frequency and the total volume of dialysis fluid. The time of the single exchange is chosen such that, at the end of the aging of the fluid in the peritoneal cavity, the concentrations of substances such as urea in the blood and in the dialysis fluid are almost identical. The addition of glucose in the dialysis fluid ensures that 300-1000 ml of ultrafiltrate is removed for each dialysis fluid change. The concentration of glucose in individual fluid changes is determined on the basis of the patient's blood pressure and the level of hydration.

Peritoneal dialysis: indications

The indications for PD are based on the patient's lifestyle preferences and the technical conditions for using this method. Peritoneal dialysis is used in patients:

  • with an increased risk of cardiovascular complications
  • with contraindications to the use of anticoagulants
  • with difficult vascular access to hemodialysis
  • living far from a hemodialysis center

Peritoneal dialysis: contraindications

The absolute contraindications include :

  • peritoneal fibrosis
  • pleural fluid with peritoneal leak
  • presence of a colostomy or nephrostomy
  • recent surgical procedures on the chest or abdominal cavity
  • extensive adhesions in the peritoneal cavity

Relative contraindications include :

  • polycystic kidney disease
  • colon diverticulosis
  • obesity
  • peripheral vascular disease

Peritoneal dialysis: complications

Complications of peritoneal dialysis can be classified as mechanical, cardiovascular, pulmonary, inflammatory and metabolic complications.

  • Mechanical complications include pain during fluid changes, problems with draining the fluid, scrotal swelling, back pain and, rarely, intestinal perforation.
  • Cardiovascular complications include patient overload, as well as hypotension and arterial hypertension.
  • In the event of pulmonary complications, hypoxia, atelectasis and pleural effusion may occur.
  • The most important inflammatory complication is peritonitis, which can be bacterial, fungal or sclerotic in nature. In this case, turbidity of the dialysis fluid can be observed, and its Gram staining shows the presence of pathogens. The patient may also report gastrointestinal complaints, such as abdominal pain, cramps, constipation or diarrhea.
  • In addition, infection of the catheter tunnel, the outer outlet of the catheter and pancreatitis may occur.
  • Metabolic complications include hypertriglyceridemia and hyperglycemia.
Worth knowing

A dialysis method similar to the human kidney already in Poland

Extended hemodialysis, HDx for short, is a new method of hemodialysis. It is based on the use of the new THERANOVA dialyzer, which, thanks to the innovative technology of dialyzer membrane structure, effectively removes large medium particles and uremic toxins from the blood, which has not been achieved with conventional hemodialysis so far. The results of observational studies of patients undergoing extended hemodialysis were presented at the 54th Congress of the European Nephrology Society (ERA-EDTA) and during the Kidney Week Congress, organized by the AmericanNephrological Society (ASN).

- Research results have shown that extended hemodialysis (HDx) is effective at removing large medium particles and uremic toxins from the blood, which until now has not been achieved with conventional hemodialysis. This means that the new technology enables the purification of blood from toxic compounds to a degree similar to the work of a human kidney, explains Prof. Michał Nowicki, President of the Polish Nephrological Society, and adds - I hope that this new method may significantly contribute to the improvement of the clinical condition and quality of life of dialysis patients - adds the expert. The dialyzer can be integrated into the existing hemodialysis infrastructure and improve the quality of therapy without additional investment in specialized equipment.

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Category:

Urology and Nephrology