clinical: electrolytes Flashcards
describe hypotonic fluid
- dilute fluid
- pushes fluid into a cell
- e.g. 5% dextrose
describe hypertonic fluid
- pushes fluid out of cells
- less dilute, stronger concentration
- only really given in ICU
describe isotonic fluid
- free flow as tonicity is the same as cells
- e.g. 0.9% SodChlr or plasma-lyte
what are ways of assessing volume status
- BP
- weight (change over time)
- JVP
why do we give patients IV fluid
- maintenance (keeping them euvolemic as they cant drink)
- replacement of losses
- resuscitation (e.g. shock)
describe hyponatraemia
- low Na+
mainly due to excess water
causes of sodium loss
- GI loss (vomiting, diarrhea)
- hypo-aldosteronism
- sweat (rare)
- diuretics
describe pseudohyponatremia
Na+ looks low but is due to a lab error
having hypertriglyceridemia or hyperproteinemia can cause Na+ to look low
causes of water excess
water overload from:
- cirrhosis
- heart failure
- nephrotic syndrome
SIADH (normal BP)
Polydipsia (over drink water)
steps in identifying the fluid state of patient’s
- history e.g. GI symptoms, medication, dehydration
- examination of fluid status
- osmolality (would be low in hyponatremia)
symptoms and causes of water excess with euvolaemia
- no signs of dehydration or edema
- no elevation of JVP
- no evidence of fluid overload
causes:
- SIADH
- polydipsia
- diuretics
- hypotonic fluid overload
describe SIADH and its causes
- ADH release despite not being dry or hypotensive
causes:
- tumours
- CNS
- drugs
- lung disease
how do we treat patients with hyponatremia
dehydrated patients with Na+ loss
= saline
patients with water excess
= fluid restriction (1L daily)