LINCOLN RENAL
UNIT
STUDENT
INFORMATION
&
OBJECTIVES
ANATOMY & PHYSIOLOGY OF THE KIDNEY
We have two kidneys that lie behind the peritoneum, either side of the
vertebral column. They extend from the e level of the 12 th thoracic
vertebra to the 3rd lumber vertebra. The right kidney is usually lower that
the left, due to the liver on that side. Both kidneys are bean-shaped
organs, about 11cm long, 6 cm wide and 3 cm thick. They also weigh
about 150g. They are embedded in, and held in position by a mass of fat.
Position of the kidneys in the body
On the concave surface of the kidneys lies the hilus, from which the
ureter and main blood vessels and nerves access the kidney. The ureter
runs from each kidney to the bladder in the lower part of the abdomen.
The renal artery branches off from the aorta and brings oxygenated
blood to them. The renal vein takes deoxygenated blood away from the
kidneys to the vena Cava.
If you were to slice the kidney in half, the kidney reveals two distinct
regions; a dark outer region, the cortex, which is covered by a fibrous
capsule, and a pale inner region called the medulla.
The cortex contains the filtering and re-absorption components of the
nephrons, whilst the medulla contains the concentrating and diluting
components of the nephrons and a system of collecting ducts, which
funnel he urine into the pelvis at the heart of the medulla, where it moves
down the ureter into the bladder.
The nephron is the functional unit of the kidney and each kidney
contains about 1 million nephrons. The basic function of the nephron is
to clean and clear the blood plasma of unwanted substances as it passes
through the kidney. The unique structure of the nephron contains 5
distinct components, each performing a distinct process.
The Nephron
The Bowman’s capsule – forming a blind ending capsule around the
knot of capillaries called the glomerulus (the site of filtration).
The Proximal Convoluted Tubule – (the site of “bulk phase” reabsorption and some secretion).
The Loop of Henle (where the concentration and filtration of urine
mainly occurs).
The Distal Convoluted Tubule – (the site of “fine tuning” re-absorption
and more secretion).
The Collecting Duct – (also important for the concentration of urine and
for carrying urine into the renal pelvis).
The blood arrives through the renal artery, it is distributed through the
tiny breaching arterioles into millions of capillaries, which are coiled and
intertwined in a ball- shaped mass (glomerulus).
As the blood passes through these blood vessels, water, salts and waste
products leak through the walls into capsule, to produce a plasma-like
mixture that drains into the first of a series of tiny tubes.
As fluid flows into the first tubule (the proximal convoluted tube),
glucose, amino acids, vitamins and salt are absorbed back into the
bloodstream to circulate around the body.
The remaining fluid trickles into the second tubule, loop of Henle. here
the re-absorption of water and salts continues so that, by the time the
fluid reaches the last tubule, the distal convoluted tubule, all that is
needed is a little fine tuning of salt content before urine drips into a
collecting tube ready for transport to the bladder, through the ureter.
FUNCTIONS OF THE KIDNEY
 Regulation of water and electrolyte balance
 Regulation of acid base balance
 regulation of blood pressure
 Regulation of red blood cell production (erythopoeitin)
 Regulation of calcium absorption
 Removal of end products of metabolism
 Removal of foreign chemicals
NORMAL VALUES (mmol/L)
Sodium
Na+
135-145
Potassium
K+
3.5-5.0
Chloride
Cl
96-106
HC03
23-29
Bicarbonate
Urea
2.5-7.0
Creatinine
60-120
Osmalality
280-295
Calcium
Ca++
2.12-2.62
Phosphate
PO4
0.8-1.4
Albumin
35-50
Alkaline Phos
20-90
Aluminium
0.07-0.55
WHAT IS KIDNEY(RENAL) FAILURE
Kidney failure is a state in which kidney function is no longer able to
maintain the body chemistry within normal limits. The function of the
kidneys is, among other things, to get rid of waste products, which result
from the body’s metabolism . If the kidney function fails, the waste
products accumulate in the blood and the body.
WHAT CAUSES KIDNEY (RENAL) FAILURE
Renal failure can happen rapidly, over days, weeks or months (Acute
renal Failure ARF) or slowly over a periods of years (Chronic Renal
Failure CRF), eventually leading to End Stage Renal Failure (ESRF).
ACUTE RENAL FAILURE (ARF)
This may occur with any serious illness or operation, particularly those
complicated by severe infection. If the blood supply to the kidneys is
reduced considerably from blood loss, a fall in blood pressure, severe
dehydration or lack of salt, then the kidneys may be damaged. If this
problem lasts long enough, there can be permanent damage to the kidney
tissue.
Sudden blockage to the drainage of urine from the kidney cause damage.
A kidney stone is a cause of this.
Acute kidney damage can occur as a rare side effect of some medications
and other rare conditions.
CHRONIC RENAL FAILURE (CRF)
CRF occurs when the kidneys are progressively and irreversibly
destroyed over a period of time. The most common causes in CRF are
Glomerulonephritis (GN), Pyelonephritis, and Polycycstic kidney
disease. It may also arise as a complication of high blood pressure,
diabetes mellitus and many other diseases. Infections, nephrotoxic drugs
and chronic obstruction of the urinary tract are additional causes.
WHAT ARE THE SYMPTOMS
ARF
Here the symptoms are largely those of the condition causing kidney
failure, such as:
 Blood loss, causing a drop in blood pressure
 Vomiting and Diarrhoeas, causing dehydration
 Crush injuries, if large amount of muscle is damaged there is a
release of protein substance, which are harmful to the kidneys.
CRF
The damage to the kidneys is usually ‘silent’ and not noticed at an early
stage. It may be discovered incidentally from blood or urine tests done
for other reasons. High blood pressure very commonly occurs with it.
Symptoms are uncommon unless kidney failure is far advanced, when
any of the following may be present:







Tiredness
itching
Loss of appetite
Nausea & Vomiting
Breathlessness
Fluid retention, shown as ankle oedema (swelling)
Weakness
HOW IS RENAL FAILURE TREATED
ARF
Most causes of renal failure can be treated and the kidney function will
return to normal with time. Replacement of the kidney function by
dialysis may be necessary until kidney function has returned.
CRF
Chronic kidney damage is usually not reversible and if extensive, the
kidneys may eventually fail completely.
Dialysis or kidney
transplantation will then become necessary.
Chronic kidney failure is therefore a serious condition which needs
urgent attention when it is diagnosed but the kidney damage is usually
‘silent’ and not noticed at an early stage.
Occasionally it may be possible to identify and treat the cause of the
renal failure itself. More commonly the treatment has to be non-specific.
In all cases, careful blood pressure control is extremely important in
slowing the progress of kidney failure.
Changes in diet may be necessary and include a reduction in salt intake,
avoiding foods containing a lot of potassium and reduction in protein and
phosphate in the diet.
Anaemia commonly results from CRF but can be easily treated with
injection of the hormone Erythropoietin.
Supplements of vitamin D help prevent a bone condition which can occur
in CRF.
It is important to avoid certain medications (such as anti-inflammatory
painkillers) which may worsen kidney function.
END STAGE RENAL FAILURE
In end stage renal failure, the maintenance of life can be ensured by
dialysis (Haemodialysis or Continuous Ambulatory Peritoneal Dialysis)
or Renal transplantation.
HAEMODIALYSIS
Haemodialysis is a procedure that cleans and filters the blood. It rids the
body of harmful wastes and extra salts and fluids. It also controls blood
pressure and helps the body keep proper balance of chemicals such as
potassium, sodium and urea.
Haemodialysis uses a dialyser or special filter to clean the blood. The
dialyser connects to a machine. During treatment, the blood travels
through tubes into the dialyser. The dialyser filters out wastes and extra
fluids. Then the newly cleaned blood flows through another set of tubes
and back into the body.
Before the first treatment, an access to the bloodstream must be made.
The access provides a way for blood to be carried from the body to the
dialysis machine and then back into the body. The access can be internal
(inside the body-usually under the skin known as arterio-venous fistula
AVF) or external (outside the body-usually a vascath temporary or
permcath permanent).
Haemodialysis can be
done at home or at the
dialysis unit. At the
unit nurses perform the
treatment. At home the
patient will perform
haemodialysis with the
help of a partner,
usually
a
family
member or friend. If the
patient decides to do
home
dialysis,
the
patient and their partner
will receive special
training.
Haemodialysis
is
usually done three times
a week. Each treatment
lasts from 2-4 hours.
During treatment the
patient can read, write
sleep, talk or watch TV.
POSSIBLE COMPLICATIONS
Side effects can be caused by rapid changes in the body’s fluid and
chemical balance during treatment. Muscle cramps and hypotension are
two common side effects. Hypotension, a sudden drop in blood pressure,
can make the patient feel weak, dizzy or sick to their stomach.
It usually takes a few months to adjust to Haemodialysis. The patient can
avoid many side effects if they follow the proper diet and take their
medicines as directed.
Haemodialysis and proper diet help reduce the waste that build up in the
blood. The patient should remember to :
 Watch the amount of potassium they eat. potassium is a mineral
found in salt substitutes, some fruits, vegetables, milk, chocolate and
nuts. Too much or too little potassium can be harmful to the heart
 limit how much they drink. Fluids build up quickly in the body
when the kidneys are not working. Too much fluid makes the tissues
swell. It can also cause high blood pressure and heart trouble.
 Avoid salt. Salty foods make you thirsty and cause the body to hold
water.
FORMATION OF ARTERIO-VENOUS FISTULA (AVF)
Arterio-venous fistula is the long term access of choice since it involves
the patient’s own blood vessels and, as such, is unlikely to be a source of
infection (Williams et al 1991). An AVF is formed by a surgical
subcutaneous anastomosis of an artery to a vein. Because the vein is not
adapted tot he high pressure associated with arterial circulation, it swells
and its walls become thicker, making the insertion of two wide –bore
needles easier. It takes 6-8 weeks for a fistula to mature before it can be
used for the first time.
TYPES OF FISTULAS
There are three types of fistulas performed, mainly on the patient’s nondominant arm.
 Radio-Cephalic AVF – most commonly
done
 Brachio-Cephalic AVF
 Brachio-Basillic AVF
PERCUTANEOUS ACCESS
Percutaneous access is the term used to describe the insertion on a
cannula or catheter into a major vein.
Permanent tunnelled percutaneous catheter
HAEMOGLOBIN (HB)
 Normal Levels
- 13-17mmol/s (males)
- 12-15.5mmol/s
(females)
 Anaemia
when Hb below 10
Signs and Symptoms
- tiredness
- loss of stamina
- short of breath
- anorexia
 Causes and treatment
1. Uremic toxins – dialysis
2. Nutritional defiencies
 diet
 substitutes
3. Blood loss
 residual blood in lines
 blood test
 anticoagulation
 occult blood
UREA
Normal levels 2.5-6.4mmol/L
 Urea is an end product of protein metabolism
 Formed in the liver and excreted by the kidneys
 Urea rises in
- renal failure
- excessive protein intake
- infection
- dehydration
- certain drugs
CREATININE
Normal values 70-120mmol/L
 Creatinine is produced by the breakdown of creatinine phosphate
in muscle and is excreted by the kidneys

reliable indicator of kidney malfunction as it is unaffected by
- tissue damage
- infection
- protein intake

Creatinine naturally increases with age
SODIUM (Na+)
Normal levels 135-145 mmol/L
 Provided by diet regulated and excreted by kidneys
 Functions
- Maintains osmotic pressure
- acid-base balance
- aids transmission of nerve impulses
 Hyponatremia <135mmol/L
- Excess body fluid
- burns
- diarrhoea/vomiting
 Hypernatremia >145 mmol/L
- dehydration
- diabetes insipidus

Profiling in dialysis
CALCIUM (Ca+)
Normal levels 2.1-2.6 mmol/L
 Provided by diet an excreted by kidneys
 the main mineral in bone responsible for
- muscle contraction
- cardiac function
- blood clotting
 Hypercalcaemia
- high levels precipitate in soft tissues
- red itchy eyes
 Hypocalcaemia
- Chronic Renal Failure where phosphate excretion is high
- Excess release of PTH
- Vitamin D
POTASSIUM (K+)
Normal levels 3.5-5 mmol/L
 Provided by diet and extracted by kidneys
 Functions
- nerve conduction
- cardiac output
 Hypokalaemia <3.5 mmol/L
- Vomiting/diarrhoea
- diuretic usage
- IV fluid without added K+
 Can cause cardiac arrhythmias
- requires prompt action
PHOSPHATE (PO4)
Normal levels 0.8-1.5 mmol/L
 Provided by diet and execrated by kidneys
 Phosphate and calcium work together
- when Ca up then PO4 is down
- when Ca down the PO4 is up
 Patient complains of pruritis
 Treatment
- more effective dialysis
- phosphate binders which must be taken with food
PERITONEAL DIALYSIS
Peritoneal dialysis is a form of renal replacement therapy (RRT) which
takes place within the patient’s body using the peritoneum as the dialysis
membrane.
The peritoneum is a natural lining and has two layers. The visceral
peritoneum lines the internal abdominal organs and the parietal
peritoneum lines the inside of the abdominal wall. The space within these
two layers is called the peritoneal cavity. It is within this space that the
peritoneal dialysis fluid is placed for dialysis to occur.
The peritoneum contains many blood vessels called peritoneal
capillaries, it also has small pores which allow molecules of a certain size
to pass through, thus allowing toxins and water to transport from the
blood stream, through the peritoneal membrane and into the peritoneal
fluid.
THE MAIN PRINCIPLES OF PERITONEAL DIALYSIS
Peritoneal dialysis involves the movement and transport of solutes and
water across a membrane, this occurs by:
DIFFUSION: toxins diffuse from the peritoneal capillaries down the
concentration gradient into the peritoneal dialysis fluid. Glucose, lactate
and some calcium diffuses in the opposite direction from the peritoneal
dialysis fluid into the patient’s bloodstream.
ULTRAFILTRATION: this occurs by osmosis due to the
hyperosmolarity of the peritoneal dialysis fluid which contains glucose.
This draws excess fluid from the blood stream. The amount of water
removal will depend on the strength of the glucose in the peritoneal
dialysis fluid,
HOW DOES IT WORK?
A catheter is surgically inserted through the abdominal wall and sits in
the peritoneal cavity. It is a permanent plastic tube about the width of a
pencil and is generally placed just below and to the side of the navel.
After insertion it is left for 2-4 weeks before use for healing to take place.
The place where the tube comes out of the abdomen is call the exit site.
PERITONEAL DIALYSIS COMPRISES OF A SEQUENCE,
COMMONLY CALLED AN EXCHANGE:
THE DRAIN: used peritoneal dialysis fluid (the effluent) is drained out
of the peritoneal cavity by gravity into an empty drainage bag and later
discarded down the toilet.
THE FILL: warm peritoneal dialysis fluid is drained into the peritoneal
cavity, on average this is 2 litres in volume. The catheter is then capped
off.
THE DWELL: the peritoneal dialysis fluid is left inside the body for
several hours for the dialysis to take place.
The cycle is then repeated.
TYPES OF PERITONEAL DIALYSIS
CAPD: Continuous ambulatory peritoneal dialysis.
This is a manual exchange procedure where after draining out used fluid,
new warm PD fluid is placed in the peritoneal cavity and left for 4-6
hours (longer overnight) for dialysis to occur. This used fluid is then
drained out and replaced by new fluid. In CAPD there is always fluid in
the peritoneal cavity and patients will generally do 4 exchanges a day.
APD: Automated peritoneal dialysis.
Generally used overnight, a patient connects to a machine which consists
of interconnecting lines and several bags of PD fluid. It is programmed to
perform several exchanges while the patient sleeps.
COMPLICATIONS OF PERITONEAL DIALYSIS
PERITONITIS. This is inflammation and infection of the peritoneum
which can be mild or severe. It can occur by poor technique and
contamination of the patients catheter but can also occur by bacteria
entering the catheter or from inside the body.
Patients are trained to look for signs of peritonitis by inspecting their
effluent (used peritoneal fluid) and checking that it is clear and not
cloudy. If it is cloudy they have to go to hospital and commence
antibiotic therapy while their effluent is sent for analysis. It is very
important to treat peritonitis promptly as it can damage the peritoneum
and therefore lessen the success of peritoneal dialysis for the future. If
infections are severe then some patients will have to rest their peritoneum
and have temporary haemodialysis. They may have to have their PD
catheter removed, hopefully they can have another one inserted at a later
date.
EXIT SITE INFECTIONS
The exit site is the area where the catheter comes out of the abdomen,
Patients are taught how to clean around their exit site to prevent
infection. It is also very important to keep the catheter securely taped to
prevent any trauma occurring. Exit site infections are generally treated
with a course of oral antibiotics. If an exit site infection is not treated
then it can travel down the PD catheter and cause a tunnel infection
which can be severe. The catheter may have to be removed and replaced.
Other complications
Fluid in the peritoneal cavity causes an increase in intra-abdominal
pressure. This can lead to hernias and leaks. If either of these problems
occur then patients may need temporary haemodialysis to allow the
hernia to be repaired or for the leak to seal. Peritoneal dialysis patients
have to be careful when lifting and are encouraged to do exercises to
protect their backs from strain.
Points to consider about peritoneal dialysis
It is a home based therapy rather than hospital based treatment. Patients
therefore have more control over their disease and can maintain their
independence
They do have to dialyse everyday on CAPD or overnight if on the APD
machine, however times can be flexible.
Because patients have more dialysis their diet and fluid intake is less
restrictive than patients on haemodialysis.
Storage space is needed for supplies and a clean area with a washable
surface to carry out exchanges.
Infection is a risk so cleanliness is very important.