IV fluids & electrolytes & tranfusions Flashcards
when would you not use 0.9% saline as fluid replacement?
- ↑ 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
where to begin when assessing fluid replacement needs?
HR, BP, urine output
fluid replacement if ↑ HR or ↓ BP?
500ml bolus immediately
(250ml if HF)
then reassess HR, BP, urine output
fluid replacement if only ↓ urine output?
(solely oliguria)
(and not due to BPH)
1 litre over 2-4 hrs
reassess HR, BP, urine output
define:
1) anuria
2) oliguria
1) 0 ml/hr
2) < 30 ml/hr
predictions of fluid depletion if:
1) ↓ urine output
2) ↓ urine output and ↑ HR
3) ↓ urine output and ↑ HR and shocked (↓ BP)
1) 500 ml
2) 1 litre
3) >2 litres
what is the limit to quantity of fluid to prescribe to sick patient?
> 2 litres
what does symbol ° mean?
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”
maintenance dose of fluids that adults need over 24 hours?
elderly?
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
daily K+ requirements?
40mmol KCl (20mmol KCl in two bags) (IV K+ shouldn't be given at more than 10mmol/hr)
IRL - how to assess pt before giving fluids?
- check patient’s U+E
- check not fluid overloaded (↑ JVP, peripheral and pulmonary oedema)
- ensure bladder not palpable (signifies urinary obstruction)
if a patient if hypovolaemic - what do you give?
500ml 0.9% NaCl over 15 mins
what to give if a patient is ↓ glucose or ↑ Na+?
5% glucose
how much is the maintenance fluid requirement of a 70kg adult?
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)
IMPORTANT what is the max rate of K+ infusion?
10mmol/hr
what’s the mmol/kg for addition of KCl or NaCl?
1mmol/kg
80kg = 80mmol/24 hours
1) how to approach fluid resuscitation?
2) what to give?
3) when to call for help?
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
how is insulin given/route?
S/C (not IV!)
define acute severe ↑hyperkalaemia?
> 6.5 mmol/l or in the presence of ECG changes
Tx acute severe ↑hyperkalaemia? (4)
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
causes ↓hypokalaemia?
“DIRE”
D - diuretics (loop, thiazide)
I - inadequate intake or intestinal loss
R - renal tubular acidosis
E - endocrine (Cushings/Conns)
causes ↑hyperkalaemia? (4)
“DREAD”
D - diuretics (ACEi + K+ sparing) R - renal failure E - endocrine (Addison's) A - artefact D - DKA
if someone has ↓↓↓↓ BP, what do you give first?
fluids FIRST stat
then consider blood transfusion
when to transfuse a patient with Fe def anaemia? (2)
1) if severely Sx, eg angina, and can’t wait for Fe replacement to kick in
2) Hb <70g/L
how much does Hb usually rise per week on Fe replacement therapy?
10/g/L/week
how long to give oral Fe for ↓Hb?
until Hb is normal
then 3 months thereafter
Tx AKI?
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
what to write as insulin prescription for acute ↑K+?
“10 units Actrapid in 100ml of 20% dextrose, over 30 min”
IV
effect of LMWH on K+?
Dalteparin (and all heparins) can contribute to hyperkalaemia
some drugs that ↓Na+?
bendroflumethiazide
citalopram (SSRIs) -SIADH
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?
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
how to ensure 40mmol/litre K+ in 12 hours?
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)
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?
- 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
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?
- 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)
when is compensation for potassium loss is especially necessary?
- 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
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.
- 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
drugs that ↑K+?
spirinolactone (and amiloride)
ACEi
ARBs
trimeth
NSAIDs
ciclosporin
drugs that cause ↓K+?
thiazide
loop
laxatives
salbutamol
theophyll steroids mineralocorticoids aminoglyc amphotericin B insulin liquorice
drugs causing ↓Na+
thiazide
loop
ARBs
ACEi
carbamaza PPIs SSRIs sulfonylurea venlafaxine
