IV fluids & electrolytes & tranfusions

Question 1

when would you not use 0.9% saline as fluid replacement?

Answer 1

• ↑ Na+ or ↓ glucose: give 5% dextrose instead
• ascitic: give human-A- solution (HAS) instead (A- maintains oncotic P, and the Na+ content of saline worsens)
• ↓ BP<90 shocked: gelofusine (colloid) (has high osmotic content so stays IV)
• shocked from bleeding: blood transfusion

Question 2

where to begin when assessing fluid replacement needs?

Answer 2

HR, BP, urine output

Question 3

fluid replacement if ↑ HR or ↓ BP?

Answer 3

500ml bolus immediately

(250ml if HF)

then reassess HR, BP, urine output

Question 4

fluid replacement if only ↓ urine output?
(solely oliguria)
(and not due to BPH)

Answer 4

1 litre over 2-4 hrs

reassess HR, BP, urine output

Question 5

define:

1) anuria

2) oliguria

Answer 5

1) 0 ml/hr

2) < 30 ml/hr

Question 6

predictions of fluid depletion if:

1) ↓ urine output
2) ↓ urine output and ↑ HR
3) ↓ urine output and ↑ HR and shocked (↓ BP)

Answer 6

1) 500 ml
2) 1 litre
3) >2 litres

Question 7

what is the limit to quantity of fluid to prescribe to sick patient?

Answer 7

> 2 litres

Question 8

what does symbol ° mean?

Answer 8

number of hours over which a bag of fluid should be given, e.g. 0.9% saline 1 L 2° means 1 L of 0.9% saline over 2 h

in PSA write “2 hours” or “2-hourly” or “2-hrly”

Question 9

maintenance dose of fluids that adults need over 24 hours?

elderly?

Answer 9

3 litres, 2 sweet, 1 salty

• firstly, 1 litre 0.9% NaCl + 20mmol KCl over 8 hours
• then 1 litre 5% dextrose + 20mmol KCl over 8 hours
• again 1 litre 5% dextrose + 20mmol KCl over 8 hours

elderly or very underweight - 2 litres

Question 10

daily K+ requirements?

Answer 10

40mmol KCl (20mmol KCl in two bags)
(IV K+ shouldn't be given at more than 10mmol/hr)

Question 11

IRL - how to assess pt before giving fluids?

Answer 11

• check patient’s U+E
• check not fluid overloaded (↑ JVP, peripheral and pulmonary oedema)
• ensure bladder not palpable (signifies urinary obstruction)

Question 12

if a patient if hypovolaemic - what do you give?

Answer 12

500ml 0.9% NaCl over 15 mins

Question 13

what to give if a patient is ↓ glucose or ↑ Na+?

Answer 13

5% glucose

Question 14

how much is the maintenance fluid requirement of a 70kg adult?

Answer 14

25-30ml/kg per day
so 25 x 70 = 1750
so round it up to two 12 hourly one litre bags

(if they needed 3 litres, 3 x 8 hourly bags)

Question 15

IMPORTANT what is the max rate of K+ infusion?

Answer 15

10mmol/hr

Question 16

what’s the mmol/kg for addition of KCl or NaCl?

Answer 16

1mmol/kg

80kg = 80mmol/24 hours

Question 17

1) how to approach fluid resuscitation?
2) what to give?
3) when to call for help?

Answer 17

1) check for causes in Hx/Ex
- D, V, syncope, fluid intake, polyuria, fever, hyperventilation, drain, thirst

2) 500ml 0.9% fluid bolus (250ml if renal impairment/frail/cardiac) <15 mins
3) reassess and repeat <2000ml and CALL FOR HELP if shock or if persistent hypovolaemia even after 2 litres given

Question 18

how is insulin given/route?

Answer 18

S/C (not IV!)

Question 19

define acute severe ↑hyperkalaemia?

Answer 19

> 6.5 mmol/l or in the presence of ECG changes

Question 20

Tx acute severe ↑hyperkalaemia? (4)

Answer 20

1) 10-20ml calcium gluconate 10% by slow IV injection (cardioprotective)
2) 10 units actrapid IV
3) 100ml of 20% IV dextrose
4) nebulised salbutamol 10mg

Question 21

causes ↓hypokalaemia?

“DIRE”

Answer 21

D - diuretics (loop, thiazide)
I - inadequate intake or intestinal loss
R - renal tubular acidosis
E - endocrine (Cushings/Conns)

Question 22

causes ↑hyperkalaemia? (4)

“DREAD”

Answer 22

D - diuretics (ACEi + K+ sparing)
R - renal failure
E - endocrine (Addison's)
A - artefact
D - DKA

Question 23

if someone has ↓↓↓↓ BP, what do you give first?

Answer 23

fluids FIRST stat

then consider blood transfusion

Question 24

when to transfuse a patient with Fe def anaemia? (2)

Answer 24

1) if severely Sx, eg angina, and can’t wait for Fe replacement to kick in
2) Hb <70g/L

Question 25

how much does Hb usually rise per week on Fe replacement therapy?

Answer 25

10/g/L/week

Question 26

how long to give oral Fe for ↓Hb?

Answer 26

until Hb is normal

then 3 months thereafter

Question 27

Tx AKI?

Answer 27

cannula + catheter, fluid monitoring
IV fluid 500ml stat, 1 litre 4 hrly
cause: bloods, ABG, DHx, US kidneys, urinalysis

check for life threatening complication:

1) pulmonary oedema/fluid overload
2) ↑K+
3) acidosis

Question 28

what to write as insulin prescription for acute ↑K+?

Answer 28

“10 units Actrapid in 100ml of 20% dextrose, over 30 min”

IV

Question 29

effect of LMWH on K+?

Answer 29

Dalteparin (and all heparins) can contribute to hyperkalaemia

Question 30

some drugs that ↓Na+?

Answer 30

bendroflumethiazide

citalopram (SSRIs) -SIADH

Question 31

what fluids to give patient who has received 2L bags of NaCl 0.9% in 24 hours, with 20mmol K+ in each, is NBM, 80kg, and normoglyaemic?

Answer 31

glucose 5%/potassium chloride 0.3% solution

• risk of NaCl overload - 154 mmol Na and Cl in each bag (80 kg = 80 mmol/day
• requires K+ (only 40mmol; requires 80mmol for maintainence)
• normoglycaemic and euvolaemic; hydrate using 5% glucose
• 2000–2400 mL/day (80-100 mL/h)
• the ideal infusion rate is 1 L over 8-12 h using a bag containing 0.3% (40 mmol/L) potassium

Question 32

how to ensure 40mmol/litre K+ in 12 hours?

Answer 32

infuse 1 L over 8-12 h using a bag containing 0.3% (40 mmol/L) potassium

(diluted by 10 - KCl 3% 40mmol/100ml 100ml bag)

Question 33

if recovering from AKI, fluid output (6 litres) is double input (3 litres), only able to tolerate 500ml oral intake, Na+ is higher end of normal and K+ is a little low?

Answer 33

• as part of recovery, patients may enter a ‘polyuric phase’ in which their urine output increases and fuid input may not keep pace, resulting in dehydration and electrolyte abnormalities
• urine output exceeding 200mL/h should always prompt consideration of this

1 simple rule: input should be similar to output (allowing 10–15% difference)

• if 250mL/hour (6L in 24 hours), oral intake of 500mL is inadequate
• low K+ and Na+ at the upper end of normal
• THEREFORE 5% dextrose with 20mmol KCl
• patient is losing 1L every 4hours (24/6)
• input should match, so a 1L bag over 4hours best

Question 34

patient admitted to hospital 7 hours after an acute stroke, unwell for 2 days and eating and drinking less than usual, PMH -HT (on ramipril), alert, dysphasic and has a right hemiparesis, unable to swallow and does not tolerate insertion of a nasogastric tube.

Na+ 144 mmol/L (137–144)
K+ 3.9 mmol/L (3.5–4.9)
U 7.5 mmol/L (2.5–7.0)
Cr 85 µmol/L (60–110)
Random plasma glucose 7.2 mmol/L

ONE IV fluid that is most appropriate for the patient at this stage?

Answer 34

• sodium chloride 0.9%/potassium chloride 0.15% solution
• 500 mL over 4-6 h or 1 L over 8-12 h. **faster dangerous (K+ in this bag)
• 15% KCl is 20mmol/10ml
• therefore 0.15% KCl is 0.2mmol/10ml (so 20mmol would be a 1 litre bag)
• ***WHY NaCl even though Na+ high??
• patient is unable to hydrate or nourish themselves, so requires maintenance IV water, electrolytes and nutrition
• patient may be fluid depleted (not been eating and drinking for 2 days) (causes ↑ Na+ and urea, but BP and HR okay)
• NaCl is a major component in initial IV fluid Tx to maintain extracellular volume and make up for any deficit
• should contain K+ as well (1 mmol/kg/day)
• no need for rapid fluid replacement as the patient is not in need of resuscitation

***WHY NOT GLUCOSE?
Patient will require some nutritional support (glucose) in the first 24 hrs.
BUT, glucose-containing fluids have the potential to EXACERBATE cerebral injury

(so this would not be a good choice of initial fluid replacement (the current glucose is elevated)

Question 35

when is compensation for potassium loss is especially necessary?

Answer 35

• digoxin or anti-arrhythmic drugs (↓ K+ may induce arrhythmias)
• secondary hyperaldosteronism (↑aldosterone AND ↑ renin):
• RAS, cirrhosis, nephrotic syndrome, severe HF
• excessive losses of K+ in the faeces, e.g. chronic D associated with intestinal malabsorption or laxative abuse

Question 36

Alcohol dependent patient is disorientated, irritable and confused. Temperature 37.3°C, HR 104/min and rhythm regular, BP 116/86 mmHg, O2 sat 98% breathing air. Jaundiced, marked tremor of the hands. Abdominal examination reveals 3 cm tender hepatomegaly with no evidence of shifting dullness on percussion.

↓ Na+ 133 mmol/L (137–144)
↑ K+ 3.7 mmol/L (3.5–4.9)
↑ U 2.6 mmol/L (2.5–7.0)
Cr 76 µmol/L (60–110)
↓ albumin 28 g/L (37–49)
↑ bili 86 µmol/L (1–22)
↑ ALT 450 U/L (5–35)
↑ ALP 188 U/L (45–105)
BM 5.1 mmol/L.

Answer 36

• vitamin B substances with ascorbic acid (Pabrinex® I/V High Potency) 2 pairs (10 mL) by IV infusion over 30 mins 8-hrly
• prophylactic for Wernicke’s encephalopathy
• ***Why not NaCl +/- KCl??
• eg potassium chloride 0.3%/sodium chloride 0.9% infusion 1 L IV over 2 h
• would provide an excessive rate of delivery of K+ and this Na+ load would be unwise in a patient with impaired liver function

Question 37

drugs that ↑K+?

Answer 37

spirinolactone (and amiloride)
ACEi
ARBs

trimeth
NSAIDs
ciclosporin

Question 38

drugs that cause ↓K+?

Answer 38

thiazide
loop
laxatives
salbutamol

theophyll
steroids
mineralocorticoids
aminoglyc
amphotericin B
insulin
liquorice

Question 39

drugs causing ↓Na+

Answer 39

thiazide
loop
ARBs
ACEi

carbamaza
PPIs
SSRIs
sulfonylurea
venlafaxine