Fluid management Flashcards
Normal volumes and percentages.
a) Intracellular
b) Extracellular - interstitial and intravascular
a) Two-thirds (~ 28 L)
b) One-third:
- 75% interstitial (~ 10-12 L)
- 25% intravascular (~ 3-4 L)
Composition of extracellular/intracellular fluid.
a) Sodium and chloride
b) Potassium
c) Calcium
d) Bicarbonate
a) Low IC, high EC
b) High IC, low EC
c) Very low IC, higher EC
d) ?
Fluid management.
a) The 5 Rs
Add 50–100 grams/day glucose (e.g. glucose 5% contains 5g/100ml
Requirements per hour/per day.
a) Sodium (and chloride)
b) Potassium
c) Fluid (water)
d) Urine output
e) Glucose
a) 1 - 2 mmol/kg/day
b) 1 mmol/kg/day
c) - General: 25 - 30 ml/kg/day
(so approx 2L per day)
d) > 0.5 ml/kg/hr
e) 50–100 g/day
Fluid resuscitation.
a) Indications
b) Administration
c) Additional management and monitoring
d) When should you escalate?
e) Options for fluids
a) Signs of hypovolaemia (and cannot maintain adequate oral or enteral intake); for example:
- Systolic BP < 100 (check for postural drop if normal)
- HR > 90 (check for postural rise if normal)
- CRT > 2 secs or peripheries cool
- RR > 20
- NEWS of 5 or more
- Low urine output (<0.5ml/kg/hr)
- Other features of dehydation
- Passive leg raising suggests fluid responsiveness
b) - Assess fluid status (obs, examination, fluid balance charts, etc.)
- Gain IV access
- Bolus of 250 - 500 ml NaCl 0.9% STAT (over < 15 mins)
- Reassess - A-E, obs, etc.
- Repeat up to 2L - then need to escalate
c) - A-E: escalate if necessary
- Bloods: FBC, U+Es, ?septic screen
- Monitor response via BP (and other obs), clinical signs of dehydration, and biochemical (U+Es, etc.)
- Monitor for signs of SHOCK or OVERLOAD (new creps, breathlessness or pitting oedema)
d) - In uncomplicated cases: poor response to 2L
- Sepsis
- Severe oedema
- Cardiac, renal or liver failure
- Hyponatraemia or hypernatraemia
e) Isotonic fluids*:
- Normal saline (0.9% NaCl), or
- Hartmann’s
*So as to keep fluid in vascular compartment. In reality, 75% will distribute into interstitial space and 25% will stay in the intravascular space
Fluid maintenance.
a) Usual requirement per day
b) Lower requirement in who? (how much?)
c) Obese patients - calculating requirement
d) Normal fluid rate (1L over…?)
e) Maintenance fluids options
f) If patient NBM, after how long must you think about NG or TPN feeds?
g) Important considerations when prescribing maintenance fluids
a) 25 - 30 ml/kg/day
- e.g. 70kg = 1750 - 2100 ml per day (~ 2L)
b) 20 - 25 ml/kg/day in:
- Elderly and frail
- Renal or cardiac impairment
- Malnourished an risk of refeeding syndrome
c) Use ideal body weight (IBW), based on height (Devine formula)
d) 8 hours (longer if overloaded, shorter if dehydrated)
e) - Dex/saline (0.18% NaCl, 4% dextrose)
- NaCl 0.9% + (KCl) + (glucose)..?
- Other
f) 1 week
g) - Observations
- Fluid status
- Urine output, ongoing losses (stomas, drains, diarrhoea, pyrexia, etc.)
- PMHx - heart failure, CKD, diabetes, etc.
- Are they eating and drinking?
- Blood results - FBC, U+Es, lactate, etc.
- Do they need senior review?
Ongoing losses.
a) ‘Pure’ water loss - examples? - results in what biochemical abnormality?
b) Gastrointestinal loss
- examples?
- average fluid loss in stool per day?
c) Vomiting/ NG tube loss results in what biochemical abnormality? - hence usual treatment is…?
d) Urinary losses
- average loss per day (in 70 kg person)
- monitoring
- replacement strategy
e) Insensible losses per day on average
a) - Dehydration, fever, sweating, hyperventilation
- Mainly water loss (very few electrolytes); hence it leads to hypernatraemia
- Consider burns - high risk of dehydration
b) - Vomiting/NG tube loss
- Diarrhoea/ high-output stoma
- GI bleeding - overt or covert
- Pancreatic fistulae/drain
- Biliary drainage (drain lots including electrolytes)
Average fluid loss in stool = 100 ml/day
c) Hypokalaemic, hypochloraemic metabolic alkalosis
- Rx: potassium chloride (KCl) replacement
d) - Average urine output: 1 ml/kg/hr = 70 ml/hr (approx 1700 ml per day)
- Consider oliguria (< 0.5 ml/kg/hr) and polyuria (approx > 2.5 - 3 L/day)
- Measure urine output and replace losses: urine output per hour minus 50 ml??
e) Approx 500 - 800 ml/day
Sepsis: signs
a) NEWS2 of what total score indicates possible sepsis ? (or what value in an individual criterion?)
b) Specific criteria
c) Mortality stratification - bedside, ITU
a) Score: 5 or more * (or… 3 or more in an individual parameter)
- 6 criteria: SpO2, RR, SBP, HR, AVPU/new confusion, temperature
- Note:
- NEWS = 1 - 4: nurse to review and decide on escalation
- NEWS of one parameter = 3: urgent clinical review
- NEWS = 5 - 6: urgent clinical review (‘think sepsis’)
- NEW = 7+: urgent critical care review
b) In any unwell patient, the following may indicate sepsis:
- Altered mentation (reduced GCS, AVPU or AMT)
- RR > 25
- Oxygen needed to maintain SpO2 > 92%
- HR > 130
- SBP < 90
- Lactate > 2
- Non-blanching rash, mottled, ashen, or cyanosed
c) - Bedside: qSOFA - alterated mental status, systolic blood pressure ≤100 mm Hg, or respiratory rate ≥22/min
- ITU: SOFA score
Composition of (in mmol):
a) Physiological (plasma)
b) Normal saline
c) Normal saline with potassium chloride
d) Hartmann’s
e) ORT
f) Dex/saline
a) Na 140, Cl 103, Bicarb 24, K 4.5, Ca 2.25
b) Na 154, Cl 150
c) Na 154, Cl 190, K 40
d) Na 131, Cl 111, Bicarb 29, K 5, Ca 2
e) Na 75, Cl– 65, K 20, citrate 10, glucose 75
(hypo-osmolar to prevent osmotic diarrhoea)
f) Na 30, Cl 30, K (nil), glucose (40 g)
Diuretics
- Give the channel, and effect on Na+, K+ and Ca2+
a) Loop (furosemide, bumetanide)
b) Thiazides
c) Amiloride
d) Spironolactone/eplerenone
Loop diuretics.
- Act on NKCC2 channel (sodium–potassium–chloride co-transporter) in thick ascending loop
- Low Na+, low K+, no effect on Ca2+
- Channel dysfunction = Bartter syndrome
Thiazides.
- Act on NCC (sodium–chloride co-transporter) in DCT
- Na+ and Ca2+ exchange occurs also, leading to hyponatraemia and hypercalcaemia
- Low Na+, low K+, raised Ca2+ (hypocalciuria - so can be helpful in recurrent kidney stones)
- Channel dysfunction = Gitelman syndrome
Amiloride.
- Act on ENaC (epithelial sodium channel) in the collecting duct
- Low Na+, high K+ (potassium-sparing), normal Ca2+
- Liddle syndrome (increased ENaC activity)
Spiro/eplerenone.
- Activates the mineralocorticoid receptor, which leads to ENaC up-regulation and Na+/K+ exchange
- This leads to hyponatraemia and hyperkalaemia (opposite effects to aldosterone - similar to Addison’s)
- To normalise potassium, K+/H+ ion exchange occurs, which leads to acidosis also
Loop diuretics often cause hyponatraemia. In which hyponatraemic patients may they be actually be beneficial?
Overloaded patients.
- They likely have a dilutional hyponatraemia
- Giving loop diuretics will proportionately offload more water than sodium, thereby INCREASING serum sodium and correcting the hyponatraemia
(the opposite is true in hypovolaemic patients)
People taking oral fluids
- Encourage this
- Don’t overload them
- Work out what they need and what they don’t
When sodium chloride 0.9% is administered, 25% of the volume administered will go to the intravascular compartment and 75% will go to the interstitial compartment.
6000 ml (i.e. 4x blood loss)
Give the common electrolyte abnormalities.
a) Sweating
b) Dehydration
c) Vomiting
d) Diarrhoea
e) Excessive diuresis*
*Depends on the diuretic
a) Hyponatraemia
b) Hypernatraemia
c) Hypokalaemia, hypochloraemia, alkalosis
(Hypochloraemic hypokalaemic metabolic acidosis)
d) Hypokalaemia, hyponatraemia, alkalosis
e) Hyponatraemia, hypo(or hyper)kalaemia, hypo(or hyper)calcaemia
Work out the fluid/electrolytes* provided.
a) 2 litres of 0.9% NaCl
b) 2 litres of 0.45% NaCl
c) 2 litres of 0.18% NaCl
d) 2 litres of Hartmann’s
e) 2 litres of Dex/saline (0.18% NaCl, 4% dextrose)
f) 2 litres of Dex/saline + 40 mmol/L of KCl
g) 2 litres of 0.9% NaCl + 40 mmol/L of KCl
*Water, Na+, K+, Cl-, glucose
a)
