Fluid and Electrolyte Balance

Question 1

total body water should be what percentage for man and woman

Answer 1

average man 60 percent

average woman should be 50-55 percent

Question 2

what is blood as a fluid made up of

Answer 2

blood cells and plasma

Question 3

what can be put in to extracellular fluids, what is counted as intake

Answer 3

fluid, food, metabolism adds to extracellular volume

Question 4

what can be considered as output from extracellular volume

Answer 4

urine, skin faeces, lungs

Question 5

what is average water loss from average man via lungs and skin

Answer 5

400 and 500 ml respectively

Question 6

what is extracellular na conc

Answer 6

135-145 mmol/l in ecf

Question 7

what is intracellular icf conc of potassium

Answer 7

120-145

Question 8

what regulates sodium excretion

Answer 8

Renin-Angiotensin-Aldosterone
• Natriuretic Peptides
• Intrinsic Renal mechanisms

Question 9

what is function of raas

Answer 9

to increase blood pressure and blood volume

Question 10

outline what happens in dehydration with adh

Answer 10

dehydration increases osmolarity. this causes adh secretion from brain in homeostatsis attempt to restore osmolarity. increases aquaducts in collecting duct causing more water to be re absorbed

Question 11

how do natriuretic peptides work

Answer 11

fluid overload, cardiac distension, sympathetic stimulation angiotensin 2, causes anp and bnp relase.

this decreases renin and causes vasodilation lowering blood volume as GFR is also increased.

Question 12

why do you give iv fluids

Answer 12

maintain euvolaemia when oral intake is reduced

replacement when you have lost fluids or predicted to lose fluids, drains urine, skin lose, sweat

resuscitation to rapidly restore intravascular compartment after haemorrghage, marked dehydration vasodilation, shock

Question 13

what are the aims of fluid replacement

Answer 13

Maintain normovolaemia
• Maintain normal electrolyte concentrations
• Compensate for any extra fluid losses with like for like

Question 14

what fluids do you use during suspected resuscitation

Answer 14

0.9% sodium chloride, balanced crystalloid solutions such as hartmanns, colloids

Question 15

what fluids do you use for maintenance

Answer 15

5% glucose, glucose and saline solutions such as 0.18% saline 4%glucose

Question 16

when do you use resuscitation therapy on a patient

Answer 16

Resuscitation therapy is used when a

patient is hypotensive.

Question 17

outline how you monitor a patient receiving resuscitation therapy iv fluids

Answer 17

test response to fluid with fast iv bolus of a crystalloid, reassess patient using abcde, use blood as soon as patient bleeds, seek expert help

Question 18

what are the rules of replacement fluid therapy

Answer 18

prescribe for routine maintenace plus additional fluid and electrolyte supplements to replace measured abnormal losses.

monitor fluid and biochemical status using clinical and lab monitoring. e.g fluid charts

Question 19

when carrying out a fluid balance assessment after taking a detailed history and examination what would you expect to find in a hypovolaemic patient

Answer 19

history
gi losses, thirst, lethargy, less urine volume, dizzy, confusion

examination
fast weak pulse, bp postural drop, loss of skin turgor, sunken eyes, dry mucous membranes

Question 20

when carrying out a fluid balance assessment after taking a detailed history and examination what would you expect to find in a hypervolaemic patient

Answer 20

history -breathlessness, periphial oedma, weight gain, abdo bloating, confused

examination- skin turgor maintained, peripherial oedma maybe, jvp elevated? ascites, fast bounding pulse

Question 21

what is hyponatraemia

Answer 21

Hyponatraemia Na <135 mmol/L

Question 22

what can cause hyponatraemia

Answer 22

• The intake and subsequent retention of water. Excess of water in relation to Na
• Depletion of total body Na in excess of concurrent body water losses

Question 23

what is key feature of hyponatraemia

Answer 23

volume status of patient is it a lot have they lost a lot of water?

Question 24

how do you treat hyponatraemia if accompanied by hypovolaemia

Answer 24

Correct volume depletion e.g. IV 0.9% saline

Question 25

how do you treat hyponatraemia if accompanied by euvolaemia

Answer 25

Underlying cause, fluid restriction

Question 26

how do you treat hyponatraemia if accompanied by hyperlaemia

Answer 26

– Underlying cause, fluid restriction, (vasopressin receptor antagonists)

Question 27

when may you have to consider using aggresive therapy for hyponatraemia treatment

Answer 27

Severe symptoms • Acute hyponatraemia (<24 hrs) • Goal = Careful monitoring. Raise serum Na by 4-6 mmol/L over few hrs, no more than 8 mmol/L/day • Hypertonic 3% saline may be indicated but seek expert help • Be aware of rapid correction of low Na – risk of central pontine myelinolysis

Question 28

what are symptoms of mild hyponatraemia

Answer 28

asymptomatic

Question 29

what are symptoms of moderate hyponatraemia

Answer 29

cramps weakness nausea

Question 30

what are symptoms of severe hyponatraemia

Answer 30

– Lethargy, Headache, Confusion

Question 31

what are symptoms of severe hyponatraemia and rapidly evolving

Answer 31

coma seizures respiratory arrest. if osmotic gradient forces water into cells intercranial pressure can increase causing neuro symptoms

Question 32

what is siadh

Answer 32

Syndrome of inappropriate ADH secretion (SIADH) can cause eurovolaemia urine na is greater than 30mmol but body fluid volume in body is normal

Question 33

what are 5 broad groups of causes of siadh

Answer 33

neoplastic, pulmonary, cns, drugs, other idiopathic hereditary

Question 34

define hypernatraemia

Answer 34

Hypernatraemia Na >145 mmol/L

Question 35

what can cause hypernatraemia

Answer 35

``` Net water loss • Hypertonic Na gain • Increase in plasma tonicity pulls water out of the cells, resulting in a decrease in intracellular volume • Severe if Na > 158 mmol/L ```

Question 36

name symptoms of hypernatraemia

Answer 36

* Thirst, anorexia, weakness | * Stupor, seizures, coma

Question 37

how do you treat chronic hypernatraemia

Answer 37

* Treat underlying cause * Use of hypotonic fluid e.g. 5% Dextrose givne slowly * Lower Na by maximum of 10 mmol/L per day * Always re-assess

Question 38

how do you treat acute emergency hypernatraemia

Answer 38

hypotonic fluid iv, #Lower Na by 1-2 mmol/L per hour to restore normal Na levels within 24 hrs • Because acute increase in the plasma Na can lead to irreversible neurologic injury

Question 39

what can cause hypokalaemia

Answer 39

* Decreased K intake (rare) * Increased entry into cells * Increased losses - GI / urine

Question 40

what can hypokalaemia cause

Answer 40

Muscle weakness – usually when <2.5 mmol/L – progresses from lower extremities • ECG changes and arrhythmias • If chronic - Renal abnormalities – impaired concentrating ability, raised BP

Question 41

how do you treat hypokalaemia especially when ecg have changed

Answer 41

``` Treatment • Correct Mg levels • K replacement – oral vs IV • If IV maximum 10-20 mmol/hr and cardiac monitoring • Address the cause ```

Question 42

what are symptoms of hyperkalaemia

Answer 42

Symptoms • Paraesthesiae • Muscle weakness – paralysis • Arrhythmias

Question 43

how do you treat hyperkalaemia

Answer 43

give calcium gluconate to stabilise cardiac membrane, iv insulin with glucose to drive k into cells, consider loop diuretics, sodium bicarbonate or beta agonists too, monitor condition treat underlying cause

Question 44

what happens to ecg when hypokalaemic

Answer 44

* Flat T wave * U waves * ST depression * PR interval prolonged * Prolonged QT intervals