Potassium - Hypokalaemia
Hypokalaemia is defined as a serum potassium of
Hypokalaemia generally means hypomagnesaemia, measure and replace Mg2+ as required.
Usually asymptomatic, but…
Weakness, lethargy, paralysis, tetany
Cardiac dysrhythmias if severe:
VT, VF, heart block, asystole
Bloods EUC ideally via Venous Blood Gas.
ECG done early on suspicion of electrolyte abnormalities:
Normal, flattened T waves, peaked P waves
Cardiac monitoring and treatment of cause are the underlying principles. The rate of replacement and methods are highly dependent on the symptoms and signs and degree of deficit.
Oral K replacement - 40mmol in 4-6 hours with K+ tablets, SlowK and SpanK ( swallowede whole and 8mmol per tablet) Chlorvescent (dissolved, 14 mmol/L)
Slow K not as effective as effervescent immediate release and less K+
Oral is usually best but can lead to GI upset
Replacement of magnesium - 10mmols over 20 minutes which is invariably low in hypokalaemia.
If moderate to severe K 2.5- 3.0mmol/L and asymptomatic
Replace as per mild if can take oral
Consider IV replacement as for severe
If moderate to severe K
IVI Potassium Chloride ideally use preloaded infusions e.g. 30mmol/L in 1000 mLs, or 10mmol/100 mLs, usually at rates of 10-20mmols per hour
Via central or large peripheral IV line, greater than 10 mmol/hr can cause discomfort and vein damage in peripheral lines
Maximum 40mmol per hour
Cardiac monitoring whilst infusing
Concurrent oral can be used if conscious
Note: 20mmol K will raise serum K by 0.5-0.75mmol l-1, this can vary and is only a guide depending on the cause ongoing losses and state of hydration.
If severe K
10mmol as a push dose
PulmCrit: Pulmonary Intensivist's Blog - Myth-busting: Lactated Ringers is safe in hyperkalemia, and is superior to NS