Hypokalaemia

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Is  defined  as  plasma  potassium  below  3.5mmol/l.  It  includes:  Weakness,  constipation,  paralysis,  bradycardia and reduced tendon reflexes. 

Investigations 

POC ECG, serum creatinine and urea, serum electrolytes and/or bedside ultrasound 

Additional investigations may be required basing on the clinical presentation. 

Non-pharmacological Treatment 

  • Perform  both  primary  and  secondary  assessment  and  provide  necessary  interventions needed.
  • Give oxygen if hypoxic or increased work of breathing
  • Connect the patient to the monitor and obtain Vital signs
  • Place IV access

Pharmacological management 

Mild (3.0-3.5mmol/l) 

C:  potassium  chloride  (PO):  Adult  20-40  mEq  8hourly  (dissolved  in  100-150mL  water);  Paediatrics 2 mEq/kg 8hourly diluted in oral fluids or food. In case of diarrhea, give ORS  (5ml/kg/hr) 

Moderate (2.5-2.9mmol/l) 

C:potassium chloride (IV): Adult 10mEq/hour; Paediatrics 0.5 mEq/kg/hour diluted in 25-

50mls of 0.9% sodium chloride or DNS or 5% dextrose solutions via peripheral vein.  Do  not exceed 10 mEq/hour. 

Severe (<2.5mmol/l) 

Both IV & Oral Replacement 

C:  potassium  chloride(PO):  Adult  (28mmol  K+)  per  hour  if  tolerated  (dissolved  in  100- 150mL water) dilutedpotassium; Paediatrics (PO) 2mEq/kg 8hourly. 

OR 

C:potassium chloride (IV): Adult 20 mEq in 100mL fluid over 1 hour via cubital fossa vein. 

Continue  to  measure  serum  potassium  every  1  to  2  hours  until  K+  >  2.8  mmol/L.  Paediatrics 1mEq/kg/hour.  

The calculated hourly dose is multiplied by 12.5ml volume for dilution with NS/DNS/D5%.  Do not exceed 10 mEq/hr 

Note 

  • 20 mEq of Potassium will raise K+ by 0.25 mEq/L. Aim to replace 25% of K+ deficit in 6 hours 
  • potassium chloride must never be given as IM or IV push 
  • Oral potassium (Slow K) 600mg tab is equivalent to 8 mEq 
  • Injection potassium chloride 7.5% 1ml = 1 mEq  

Role of Magnesium 

Magnesium should be checked. IF LOW, give Magnesium as follows: 

A: magnesium sulphate 50% (IV): Adult Initially give 4ml diluted to 10ml with 0.9% sodium  chloride run over 20 minutes, then potassium chloride infusion, then magnesium sulphate  50% (IV) 0.12ml/kg/day; Paediatrics 0.1 ml/kg/dose administered over 2hours 

Hypokalemia in CARDIAC ARREST in Adults: KCl 10 mEq IV over 5 min; the dose may be repeated  once 

Note: ECG changes in hypokalemia 

  • Increased P wave amplitude, Prolonged PR interval, 
  • ST segment depression, 
  • QT prolongation, flattening or T wave inversion, and prominent U waves.