Fluid + Fluid Balance

Question 1

What does the renal system consist of?

Answer 1

2 kidneys
2 ureters
Urinary bladder
Urethra

Question 2

What is the function of the renal system?

Answer 2

Production of varying quantities of urine confusing adjustable quantities of waste allows the body to regulate fluid, electrolyte and pH balances.

Kidneys maintain homeostasis.

Question 3

What do the kidneys consist of?

Answer 3

Renal capsule
Renal cortex
Renal pyramids
Calyces
Renal pelvis
Ureter

Question 4

Where are the pyramids in the kidney located?

Answer 4

Renal medulla

Question 5

What is the pathway or urine in the kidneys?

Answer 5

Urine drips from top of each pyramid to:
calyces
pelvis
ureter 
Ureter propels urine to the bladder

Question 6

What is the main function of the kidneys?

Answer 6

To filter blood

Question 7

What is the body water content?

Answer 7

50-60% of total body weight

Females less than males

Decreased in elderly

Higher in babies and infants (75-80%)

Question 8

What % of body water is intracellular fluid + what electrolytes does it contain?

Answer 8

66% of total body water

Potassium, magnesium, phosphate

Question 9

What % of body water is extracellular fluid + what electrolytes does it contain?

Answer 9

33%

Sodium, chloride, bicarbonate

Question 10

How does the cell membrane allow for the exchange of ions?

Answer 10

It is selectively permeable.

Some ions are pumped out of the cell (Na+)

In exchange for other ions entering the cell (K+)

This uses energy from ATP

Question 11

What is external and internal fluid balance?

Answer 11

External - matches input with output from body

Internal - means there is the correct volume of fluids

Question 12

How is fluid exchanged across membranes?

Answer 12

Water distributed by osmosis

This is dependent on the osmotic pressure inside and outside the cells.

Question 13

What are the most numerous solutes dissolved in body fluids + how does this affect fluid balance?

Answer 13

Electrolytes

Fluid balance is dependent on electrolyte balance.

Question 14

What is an isotonic solution?

Answer 14

Same pressure inside and outside the cell

= normal RBC

Question 15

What is a hypotonic solution?

Answer 15

Outside pressure lower than inside pressure

= swollen RBC

Question 16

What is a hypertonic solution?

Answer 16

Inside pressure lower than outside pressure

= shrunken RBC

Question 17

Why is extracellular fluid osmolality important?

Answer 17

It determines whether cells shrink, swell or are normal.

Question 18

What solutes (and concentrations of these) does extracellular fluid contain?

Answer 18

NA+           140 
Cl-             140
Urea          5
Glucose    5
Others      5 

equals = 300 mosmol/l

Question 19

What is normal saline?

Answer 19

An isosmotic solution.

Contains 150 NA+ and 150 Cl-, same osmolarity as ECF.

Question 20

How does fluid exchange at capillary?

Answer 20

Electrolytes and water in ECF exchange freely across capillary wall.

This makes interstitial fluid and plasma very similar.

However plasma pressure slightly higher due to presence of albumin.

Question 21

Why is the difference in osmotic pressure of the plasma and interstitial fluid helpful?

Answer 21

It ensures correct plasma volume and normal fluid exchange between blood and tissue.

Question 22

What is fluid balance?

Answer 22

The same amount of fluid enters the body as leaves the body.

Question 23

How is water lost through the skin?

Answer 23

Sweating

• affected by environment, physical activity, fever
• losses of 2-3l/hour can occur
• risk of dehydration higher in children

Question 24

How is water lost through the lungs?

Answer 24

Evaporation

-affected by humidity, altitude, exercise, artificial ventilation.

Question 25

How is much water is lost through faeces?

Answer 25

Low levels 2l a day can occur with diarrhoea *GI losses via surgical drain should be noted*

Question 26

How much water is lost through urine?

Answer 26

Excretion of urea + sodium requires certain amount of water for excretion High protein/salt diet = increase in urine Small volume-high alcohol drinks can cause dehydration due to diuretic effect (increase in urine)

Question 27

What are the adult fluid requirements? | 18-60, over 60

Answer 27

Adults - 30-35ml per kg 18-60 - 35ml/kg Over 60 - 30ml/kg

Question 28

What are the corrective responses when dehydrated?

Answer 28

Increase osmotic pressure stimulates osmoreceptors causing: Increased thirst ADH secretion (anti diuretic hormone) -this tells kidneys to retain water

Question 29

What are the corrective responses when hypovalemic?

Answer 29

Thirst + ADH secretion Drop in blood volume + renal blood flow stimulates renin-angiotensin-aldosterone Salt and water retained by kidneys

Question 30

What is the correct responses when fluid overloaded?

Answer 30

Thirst reduced Dilute urine produced Stretch of heart atria releases: - atrial natriuretic hormone which acts on the kidney and more water and salt is excreted .

Question 31

What can cause disorders of fluid balance + why?

Answer 31

``` Conditions affecting: Kidneys Brain GI system Lungs Skin Cardiac output ``` Due to abnormal intake/losses and inadequate/counter productive corrective responses

Question 32

What to assess when checking skin for assessment of fluid status?

Answer 32

``` Turgor Mucous membranes Fontanelle Eyes Dry skin ```

Question 33

What cardiovascular signs to look for when assessing fluid status?

Answer 33

Increased HR decreased BP Poor peripheral perfusion Increased respiratory rate

Question 34

What neurological signs to look for when assessing fluid status?

Answer 34

``` Conscious level Irritability Agitation Lethargy Confusion ```

Question 35

What renal sings to look for when assessing fluid status?

Answer 35

Urine output Colour of urine Specific gravity of urine Smell of urine

Question 36

What is dehydration?

Answer 36

Insufficient body fluid due to: Inadequate intake Excessive loss of fluids Combination of both

Question 37

How is dehydration calculated?

Answer 37

% of dehydration calculated from changes in body weight (litre of water = 1kg) Mild - <5% Moderate - 5-10% Severe - >10%

Question 38

What are the clinical signs of mild dehydration?

Answer 38

Thirst Alert but restless Normal HR/mild tachycardia Slow skin retraction

Question 39

What are the clinical signs of moderate dehydration?

Answer 39

``` +/- tears Dry mucous membranes Low urine output Thirst Irritable Rapid pulse/tachy/rapid resps Slightly depressed eyes/fontanelle Postural hypotension Slow skin retraction Capillary refill time >2 ```

Question 40

What are the clinical signs of severe dehydration?

Answer 40

``` No tears Very dry mucous membranes Low urine output Lethargic/sleepy Severe tachycardia, deep/rapid resps Severely sunken eyes/fontanelle Hypotension Very slow skin retraction Capillary refill time >3 ```

Question 41

What is the treatment for the three stages of dehydration?

Answer 41

Mild - oral rehydration Moderate - oral and IV rehydration Severe - accurate IV fluid replacement

Question 42

What is isotonic dehydration?

Answer 42

NA+ and h2o lost equally Loss of plasma or ECF e.g hemorrhage, burns May need urgent fluid replacement due to hypovalemia

Question 43

What is hypernatreamic dehydration?

Answer 43

High plasma sodium levels, more h2o lost than Na+. Body fluids more concentrated Can occur in unconscious patient unable to drink Water loss shared between ECF + ICF so there is less of a drop in blood volume.

Question 44

What is hyponatraemic dehydration?

Answer 44

More Na+ than h2o lost e.g loss of sodium rich fluid through alimentary canal Less common Fluid loss from ECF can cause hypovalemia

Question 45

What are the 5 R’s of IV fluids?

Answer 45

Resuscitation Routine maintenance Redistribution Replacement Reassessment *type + concentration of fluid must be correct for purpose*

Question 46

What are the 3 main types of IV fluids?

Answer 46

Crystalloids Colloids Blood + blood products

Question 47

What are crystalloids and what are examples of these?

Answer 47

Clear solutions, move between blood stream and tissues. Contain no plasma proteins. Range of types, generally differing strengths of normal saline. Examples: 0.9% normal saline 5% dextrose 0.45% normal saline + 5% dextrose

Question 48

What are colloids and what are examples of these?

Answer 48

Contain solutes that stay in blood because that are too big to pass through capillary walls. Used to increase blood volume. Examples: Human albumin solution (4.5%)

Question 49

What are examples of blood+blood products?

Answer 49

Whole blood Packed cells Platelets Fresh frozen plasma Given for serious haemorrhage or to increase Hb, low platelet count, couagulopathy.

Question 50

What IV therapy is used for resuscitation?

Answer 50

500mls 0.9% saline over 15mins (up to 2L can be given) This rapidly expands blood volume then interstitial fluid more slowly. There is no fluid shift into cells as it is an isotonic solution.

Question 51

What IV therapy is used in routine maintenance?

Answer 51

Sodium chloride 0.18% in 4% glucose with added potassium. Or 2 bags 5% glucose to 1 bag of 0.9% sodium chloride with added potassium. Hypotonic solution given to maintain ICF (hydrate cells) Glucose to prevent ketosis Potassium to prevent hypokalemia

Question 52

What is redistribution in IV fluid therapy?

Answer 52

Excess fluid collects in 3rd spaces (interstitial fluid, peritoneal cavity) Decrease maintenance fluid to prevent worsening. In septic shock fluid resuscitation may be needed as much of the fluid given moves into interstitial space

Question 53

What is replacement in IV therapy?

Answer 53

Increased maintenance fluids to replace excessive losses from body (sweating, D+V) Extra electrolyte losses need to be estimated - blood urine check helps with this, U+E’s

Question 54

What is reassessment in IV fluid therapy?

Answer 54

Check U+E’s prior to infusion if appropriate. Check weight. Check U+E’s every 24hr minimum while IV fluids are being administered. (If abnormal consider 4-6hrly) Add supplement if required. *maintain accurate fluid balance charts*

Question 55

What effects can excessive isotonic saline have?

Answer 55

Circulatory overload is more likely with sodium containing solutions because isotonic solutions stays in ECF boosting blood and interstitial fluid. Increase in total body sodium.

Question 56

What effects can excessive dextrose solution have?

Answer 56

Neurological dysfunction due to hyponatremia - headache, N+V, lethargy, confusion, drowsiness. Cause: it is a hypotonic fluid so glucose enters cells and is catabolised leaving free water that dilutes ECF that enters cells by osmosis and caused neurones to swell.