Fluid and Electrolytes Flashcards
Describe the relationship of fluids
Describe the relationship of electrolytes balance and distribution
Normal Na range
Normal K range
Normal HCO3 range
Fluid balance
Input=Output
Electrolyte balance
Total cations=Total anions
Electrolyte distribution
-intracellular and extracellular concs vary
Na 135-145mmol
K 3.5-5.5mmol
HCO3 22-26
What are the 3 mechanisms that control fluid balance
Describe them
RAAS-dehydration and hypovolemia
- decreased GFR => RENIN
- Liver angiotensinogen =renin=> Ang1
- Ang1 =lung ACE=> Ang2
- VC of vessels (short term)
- Increased aldosterone => Na, water retention
ADH-dehydration and hypovolemia
- hypothalamic osmoceptors, aortic/carotid baroceptors
- ADH from neurohypophysis
- VC of vessels
- water retention
Natriuresis-fluid overload
- ANP, BNP => VD
- Increased GFR => decreased renin => decreased Ang2, Ald
- Increased diuresis
What are the 5 main types of fluids that we could use
0.9% saline 5% dextrose solution 0.18% saline 4% dextrose Hartmann solution/lactate ringer solution Colloids
How would you use 0.9% saline
Isotonic
Equilibrates in IV, IS
But excess => Cl excess
How would you use 5% dextrose solution
Hypotonic
Dextrose and water
Equilibrates in IV, IS, IC
Hydrate without electrolytes, only for maintenance
How would you use 0.18% saline, 4% dextrose
Hypotonic
Hydrate with electrolytes for maintenance
How would you use Hartmann solutions/Lactated ringer solution
Isotonic
Na K Cl Ca Lactate=>HCO3
Equilibrates in IV, IS
Maintenance and resuscitation
How would you use colloid
Maintain high oncotic pressure to keep fluid in IV
How would you do a fluid balance assessment for hypovolemia
- pulse
- BP
- turgor
- Gi, GU
- neuro
Pulse: fast, weak BP: postural drop Turgor: loss, dry mucus membranes GI, GU: GI loss, thirst, oliguria Neuro: confusion
How would you do a fluid balance assessment for hypervolemia
- pulse
- BP
- turgor
- resp
- neuro
Pulse: fast, bounding BP: high, increased JVP Turgor: edema, ascites, Resp: SOB Neuro; confusion
What are the sources of electrolyte and fluid changes
NG aspirate Vomit Drains Skin Blood Urine Diarrhea Stoma
What is the procedure for maintenance fluids
Keep euvolmeia and [electrolytes] if oral intake decreases/lost
25-30ml/kg/day + compensate for physiological loss
- saline
- dextrose saline
If for 3+ days, NG feed
What is the procedure for replacement fluids
Maintenance + fluid, electrolytes to replace ongoing loss
MUST MONITOR REGULARLY
What is the procedure for resuscitation fluids
Fast IV test bolus of crystalloid, see if BP rises
Reassess, ABCDE
If bleeding, use blood
Rapid restoration of IVF
What are the 3 main causes of hyponatraemia
What are the causes?
Hypovolemic
- burns, GI loss
- diuretics
- Addisons
Euvolemic
- polydipsia
- excess IV hypotonic sol
- SIADH
Hypervolemic
- CCF
- ascites
- nephrotic syndrome
- CKD
What are the 4 categories and associated symptoms of hyponatraemia
Mild- asymptomatic
Moderate- cramp, weak, nausea
Severe- tired, headaches, confused
Severe+rapid- seizure, coma, resp depression
How would you treat hyponatraemia
- hypovolemia
- euvolemia
- hypervolemia
Why would you want to treat this slowly
Hypovolemia
-Na crystalloid
Euvolemia
- fluid restriction
- find underlying cause
Hypervolemia
-same as euvolemia + diuretics
Risk of central pontine myelinolysis due to rapid brain shifts
What are the 2 main causes of hypernatraemia
What are the causes
Fluid loss
- GI loss, sweat, reduced intake
- central/nephrogenic DI
Na excess
- hypertonic IV
- Conns
How would you treat hypernatraemia
- acute
- chronic
Acute
- hypotonic fluid
- reduce Na slowly to reduce CPM risk
Chronic
-same as acute + treat underlying cause
What are the 3 main causes of hypokalemia
What are the causes
Increased cell entry
- alkalosis
- excess insulin
- excess b agonist
- hypothermia
- drugs
Increased GI loss
- vomit, diarrhoea, laxatives
- increased sweat
- decreased intake
Increase urine loss
- diuretics
- MC excess
- renal tubular acidosis I
- drugs
How would you treat hypokalaemia
Mg levels
K replacement
Underlying caus
What are the 2 main causes of hyperkalaemia
What are the causes
Increased cell release
- metabolic acidosis
- decreased insulin, increased glucose => osmolarity
- increased tissue catabolism
- increased Bb
- exercise
Decreased urine loss
- AKD, CKD
- decreased MC/response
- drugs
- renal tubular acidosis 4
How would you treat hyperkalaemia
Ca glucoronate
Insulin+dextrose
K out of body/into cells
MONITOR AND TREAT CAUSE
How would you recognize hypokalaemia, hyperkalaemia on ECG
Hypokalaemia
- increased PR, QT interval
- ST depressed
- Flat T
- U wave
Hyperkalaemia
- flat/no P
- increased PR,
- wide QRS
- Tall T
