Renal System

The kidneys are essentially regulatory organs which maintain the volume and composition of body fluid by filtration of the blood and selective reabsorption or secretion of filtered solutes.

the kidneys are retroperitoneal organs (ie located behind the peritoneum) situated on the posterior wall of the abdomen on each side of the vertebral column, at about the level of the twelfth rib. The left kidney is lightly higher in the abdomen than the right, due to the presence of the liver pushing the right kidney down.

The kidneys take their blood supply directly from the aorta via the renal arteries; blood is returned to the inferior vena cava via the renal veins. Urine (the filtered product containing waste materials and water) excreted from the kidneys passes down the fibromuscular ureters and collects in the bladder. The bladder muscle (the detrusor muscle) is capable of distending to accept urine without increasing the pressure inside; this means that large volumes can be collected (700-1000ml) without high-pressure damage to the renal system occuring.
When urine is passed, the urethral sphincter at the base of the bladder relaxes, the detrusor contracts, and urine is voided via the urethra.

Structure of the kidney


On sectioning, the kidney has a pale outer region- the cortex- and a darker inner region- the medulla.The medulla is divided into 8-18 conical regions, called the renal pyramids; the base of each pyramid starts at the corticomedullary border, and the apex ends in the renal papilla which merges to form the renal pelvis and then on to form the ureter. In humans, the renal pelvis is divided into two or three spaces -the major calyces- which in turn divide into further minor calyces. The walls of the calyces, pelvis and ureters are lined with smooth muscle that can contract to force urine towards the bladder by peristalisis.

The cortex and the medulla are made up of nephrons; these are the functional units of the kidney, and each kidney contains about 1.3 million of them.

The nephron is the unit of the kidney responsible for ultrafiltration of the blood and reabsorption or excretion of products in the subsequent filtrate. Each nephron is made up of:

* A filtering unit- the glomerulus. 125ml/min of filtrate is formed by the kidneys as blood is filtered through this sieve-like structure. This filtration is uncontrolled.

* The proximal convoluted tubule. Controlled absorption of glucose, sodium, and other solutes goes on in this region.

* The loop of Henle. This region is responsible for concentration and dilution of urine by utilising a counter-current multiplying mechanism- basically, it is water-impermeable but can pump sodium out, which in turn affects the osmolarity of the surrounding tissues and will affect the subsequent movement of water in or out of the water-permeable collecting duct.

* The distal convoluted tubule. This region is responsible, along with the collecting duct that it joins, for absorbing water back into the body- simple maths will tell you that the kidney doesn't produce 125ml of urine every minute. 99% of the water is normally reabsorbed, leaving highly concentrated urine to flow into the collecting duct and then into the renal pelvis.


  1. Fluid imbalance will be resolved.
  2. Client will exhibit improved sense of energy.
  3. Client will not exhibit unusual bleeding.
  4. Thought processes will improve.
  5. Integrity of mucous membranes will be maintained.
  6. Adequate nutritional status will be maintained.
  7. Client will remain free from infection.
  8. Adequate skin integrity will be maintained.
  9. Client will demonstrate restored urinary flow.
  10. Changes in sexual functioning will be accepted.


Urinary Catheterization

  1. General information
    1. Insertion of a catheter through the external meatus and the urethra into the bladder
    2. Purposes include relief from urinary retention, bladder decompression, prevention of bladder obstruction, instillation of medications into the bladder, and splinting the bladder.
  2. Nursing care: insertion
    1. Explain procedure to client and collect necessary equipment (catheter set).
    2. Wash hands and position client.
    3. Use sterile technique while inserting catheter.
    4. Observe for urine return and obtain specimen.
    5. Connect drainage tubing to catheter (indwelling) and tape.
  3. Nursing care: indwelling catheter
    1. Maintain catheter patency: place drainage tubing properly to avoid kinking or pinching.
    2. Observe for signs of obstruction (e.g., decreased urine in collection bag, voiding around the catheter, abdominal discomfort, bladder distension).
    3. Irrigate catheter as necessary.
    4. Ensure comfort and safety: relieve bladder spasms by administering belladonna suppositories (if ordered); ensure adequate fluid intake and provide perineal care.
    5. Prevent infection: maintain a closed drainage system and prevent backflow of urine by keeping drainage system below level of bladder.
    6. Empty collection bag at least every 8 hours.
    7. Promote acidification of the urine with acid-ash diet and ascorbic acid.
    8. Change catheter/drainage system only when necessary.


  1. General information
    1. Removal by artificial means of metabolic wastes, excess electrolytes, and excess fluid from clients with renal failure
    2. Principles
      1. Diffusion: movement of particles from an area of high concentration to one of low concentration across a semipermeable membrane
      2. Osmosis: movement of water through a semipermeable membrane from an area of lesser concentration of particles to one of greater concentration
  2. Purposes
    1. Remove the end products of protein metabolism from blood
    2. Maintain safe levels of electrolytes
    3. Correct acidosis and replenish blood bicarbonate system
    4. Remove excess fluid from the blood
  3. Types: hemodialysis and peritoneal dialysis


  1. General information
    1. Shunting of blood from the client's vascular system through an artificial dialyzing system, and return of dialyzed blood to the client's circulation
    2. Dialysis coil acts as the semipermeable membrane; the dialysate is a specially prepared solution.
    3. Access routes (see Figure 4.19)
      1. External AV shunt: one cannula inserted into an artery and the other into a vein; both are brought out to the skin surface and connected by a U-shaped shunt.
      2. AV fistula: internal anastomosis of an artery to an adjacent vein in a sideways position; fistula is accessed for hemodialysis by venipuncture; takes 4-6 weeks to be ready for use.
      3. Femoral/subclavian cannulation: insertion of a catheter into one of these large veins for easy access to circulation; procedure is similar to insertion of a CVP line; temporary
      4. Graft: piece of bovine artery or vein, Gore-Tex material, or saphenous vein sutured to client's own vessel; used for clients with compromised vascular systems; provides a segment in which to place dialysis needles.
  2. Nursing care: external AV shunt
    1. Auscultate for a bruit and palpate for a thrill to ensure patency.
    2. Assess for clotting (color change of blood, absence of pulsations in tubing).
    3. Change sterile dressing over shunt daily.
    4. Avoid performing venipuncture, administering IV infusions, giving injections, or taking a blood pressure with a cuff on the shunt arm.
  3. Nursing care: AV fistula.
    1. Auscultate for a bruit and palpate for a thrill to ensure patency.
    2. Report bleeding, skin discoloration, drainage, and pain.
    3. Avoid restrictive clothing/dressings over site.
    4. Avoid administration of IV infusions, giving injections, or taking blood pressure with a cuff on the fistula extremity.
  4. Nursing care: femoral/subclavian cannulation
    1. Palpate peripheral pulses in cannulized extremity.
    2. Observe for bleeding/hematoma formation.
    3. Position catheter properly to avoid dislodgment during dialysis.
  5. Nursing care: before and during hemodialysis
    1. Have client void.
    2. Chart client's weight.
    3. Assess vital signs before and every 30 minutes during procedure.
    4. Withhold antihypertensives, sedatives, and vasodilators to prevent hypotensive episode (unless ordered otherwise).
    5. Ensure bed rest with frequent position changes for comfort.
    6. Inform client that headache and nausea may occur.
    7. Monitor closely for signs of bleeding since blood has been heparinized for procedure.
  6. Nursing care: postdialysis
    1. Chart client's weight.
    2. Assess for complications.
      1. Hypovolemic shock: may occur as a result of rapid removal or ultrafiltration of fluid from the intravascular compartment (see Shock).
      2. Dialysis disequilibrium syndrome (urea is removed more rapidly from the blood than from the brain): assess for nausea, vomiting, elevated blood pressure, disorientation, leg cramps, and peripheral paresthesias.

FIGURE 4.19 Hemodialysis sites

Peritoneal Dialysis

  1. General information: introduction of a specially prepared dialysate solution into the abdominal cavity, where the peritoneum acts as a semipermeable membrane between the dialysate and blood in the abdominal vessels
  2. Nursing care
    1. Chart client's weight.
    2. Assess vital signs before, every 15 minutes during first exchange, and every hour thereafter.
    3. Assemble specially prepared dialysate solution with added medications.
    4. Have client void.
    5. Warm dialysate solution to body temperature.
    6. Assist physician with trocar insertion.
    7. Inflow: allow dialysate to flow unrestricted into peritoneal cavity (10-20 minutes).
    8. Dwell: allow fluid to remain in peritoneal cavity for prescribed period (30-45 minutes).
    9. Drain: unclamp outflow tube and allow to flow by gravity.
    10. Observe characteristics of dialysate outflow.
      1. Clear pale yellow: normal
      2. Cloudy: infection, peritonitis
      3. Brownish: bowel perforation
      4. Bloody: common during first few exchanges; abnormal if continues
    11. Monitor total I&O and maintain records.
    12. Assess for complications.
      1. Peritonitis resulting from contamination of solution or tubing during exchange (see Peritonitis).
      2. Respiratory difficulty: may occur from upward displacement of diaphragm due to increased pressure in the peritoneal cavity; assess for signs and symptoms of atelectasis (see Atelectasis), pneumonia (see Pneumonia), and bronchitis (see Bronchitis)
      3. Protein loss: most serum proteins pass through the peritoneal membrane and are lost in the dialysate fluid; monitor serum protein levels closely

Continuous Ambulatory Peritoneal Dialysis

  1. General information
    1. A continuous type of peritoneal dialysis performed at home by the client or significant others.
    2. Dialysate is delivered from flexible plastic containers through a permanent peritoneal catheter.
    3. Following infusion of the dialysate into the peritoneal cavity, the bag is folded and tucked away during the dwell period.
  2. Provide client teaching and discharge planning concerning
    1. Need to assess the permanent peritoneal catheter for complications
      1. Dialysate leak
      2. Exit site infection
      3. Bacterial/fungal contamination
      4. Obstruction
    2. Adherence to high-protein (if indicated), well-balanced diet
    3. Importance of periodic blood chemistries
    4. Daily weights