A 73 year old man presents with altered mental state, vomiting and chest tightness.
His blood results show:Severe life threatening hyponatraemia
hypochloraemia
severe respiratory alkalosis, likely additional metabolic acidosis
- pH high, CO2 low
- low HCO3
Hyponatraemia approach:
- Hypovoalemia – GI loss (urine Na <20 mmol/l), Renal (Na>20)
- Euvolaemia – Endocrine/SIADH (urine osmolality high), water intoxication (low urine osmolality)
- Hypervolaemia – CCF/liver failure/ nephrotic syndrome (urine Na<20), renal failure/ saline (urine Na>20)
Supersalt indications:
to treat cerebral oedema, raised ICP, seizures, focal neurologic signs without another cause
or if Na loss is large – cerebral salt wasting, large GI losses
Administration:
Active seizures – 100mls of 3% Saline over 30 minutes, can be repeated after 10 minutes if no response (each 100ml will increase Na by 2 mmol/l, usually an increase 0f 4-6mmol/l is sufficient to stop seizures)
General aim – increase Na by 0.5-1 mmol/l/hr to a maximum of 10-12 mmol per day to avoid CPM (risk is usually high if Na is low for more than 48 hours) up to 120mmol/l. If hypovolaemic, then use 0.9% Saline. If euvolaemic then fluid restrict.