|ECG - Hyperkalaemia
|Hyperkalaemic and Hypokalaemic Periodic Paralysis
|Resuscitation - Advanced Life Support
Medical emergency as increased plasma [K+] leads to a partial membrane depolarization that may eventually cause cardioplegia and skeletal muscle paralysis and death. Calcium gluconate is preferred as less damaging to veins.
|Initial Hyperkalaemia Management Summary: see below|
- Commence Telemetry. ECG. IV access. Resend bloods if unexplained ?error?haemolysis
- If K ≥ 6.5 mmol/L or ≥ 6.0 mmol with ECG changes (below) then
- 10-20 ml 10% Calcium Gluconate IV slow over 5-10 min. Titrate to ECG changes which should resolve. Reduces cardiac excitability. May be repeated if ECG changes not resolving.
- 10 U short acting (Actrapid) Insulin in 50 ml of 50% Glucose syringe driver over 15-30 mins
- Salbutamol [US Albuterol] Nebulised 2 x 5 mg. IV fluids. Look for and manage cause
- Exchange resin: Calcium Resonium 15 g QDS PO or Lokelma 10 g TDS.
- Consider Dialysis if continues (Call renal)
- Consider NaHCO3 if severe acidosis so see below
- Stop K retaining drugs e.g. Spironolactone
- Potentially lethal so act quickly if ECG changes or level > 6.5 mmol/L
- Tented T waves, Broad QRS, Bradycardia, Absent flat P waves, Sinewave, VT then treat
- As the K+ level rises further, it inactivates too many Na+ channels to allow for an effective action potential. It is at this point that we see the QRS interval on the ECG begin to widen and start to take on a sine wave appearance.
- The benefit of administering IV calcium to patients with hyperkalemia is due to enhanced conduction through the L-type calcium channels and not due to membrane stabilization. The L-type calcium channels are much more resistant to hyperkalemia and are quite capable of initiating an action potential in the conducting tissue (His-Purkinje system) and the working myocytes.
Aetiology: Check all drugs in BNF or equivalent
- Chronic renal disease and perhaps failure to attend dialysis
- Causes (most commonly drugs check drug chart) [can get falsely high result: haemolysed sample, laboratory or sampling error]
- AKI, CKD, digoxin poisoning (poor prognostic sign).
- Rhabdomyolysis, tissue damage from trauma, burns, tumour lysis syndrome, vigorous exercise, haemolysis, blood transfusion.
- Drugs: ACE inhibitors, AT2 blockers, Spironolactone, Eplerenone, Amiloride, NSAIDs, Ciclosporin, depolarising muscle relaxants, Trimethoprim, Heparin/LMWH
- Metabolic acidosis, Addison's disease (pigmented, ?BP, fatigue),
- Type 4 RTA (diabetes) with low renin and low aldosterone and CKD
- Hyperkalaemic periodic paralysis (AD familial).
- Blood transfusion
- C-21 hydroxylase deficiency
- Congenital adrenal syndromes, e.g. 3-ß hydroxydehydrogenase deficiency
- Asymptomatic, arrhythmias, muscle weakness, cramps, paraesthesia.
- Low BP, Low HR, cardiac arrest.
- Mild (K 5.5-5.9 mmol/L)
- Moderate (K 6.0-6.4 mmol/L)
- Severe (K >6.5 mmol/L) or if ECG changes or symptoms. Emergency treatment needed
- FBC: low may suggest haemolysis. LDH also high
- Raised CK: rhabdomyolysis. LDH also high
- U&E, Ca, Mg: repeat it unexpected. Check ECG normal if high K
- Venous blood gases: metabolic acidosis.
- ECG signs: peaked tented T waves, widened QRS, sine waves, agonal rhythm and V T/VF.
Generally Calcium Gluconate preferred when only a peripheral line is available for venous access.
ECG signs of Hyperkalaemia
- Peaked tented T waves, Absent P waves, Broad QRS, Sine waves, Bradycardia
- Agonal rhythm, Cardiac arrest with VT/VF.
- ABC. Assess ECG changes. Stop all potentially offending drugs or infusions immediately. This is easily overlooked.
- Ensure IV access, repeat any sample if surprise result. Start IV fluids 0.9% Saline if not overloaded (consider Furosemide)
- If K >6.0 mmol/L or ECG changes needs telemetry and defibrillator are available.
- if K > 6.5 mmmol/L or ECG changes then IV 10-20 ml 10% Calcium Gluconate IV. Use a large vein. Give over 5-10 min and see ECG changes resolve. This intervention will not lower the potassium, but if ECG changes are present, there should be improvement seen within 1 to 3 minutes. If not consider repeating.
- Next give 10 units of Soluble Insulin with 50 ml of 50% Glucose or 100 ml of 20% Glucose to counteract the hypoglycaemia. Consider a 10% glucose infusion if higher doses of insulin are given.
- Consider Salbutamol 10 mg in 4 ml saline nebulised with caution in those with IHD/arrhythmias.
- Furosemide 20 mg IV may be considered if not dehydrated. Consider more if overloaded.
- U&E needs to be repeated every 2 h and blood gas, capillary blood glucose for 6-12 h. The remainder needs ECG and underlying cause to be found and close monitoring.
- These actions only lower K for 4 hours.
- If metabolic acidosis (low HCO3) 15-19 then NaHCO3 1 g BD. If HCO3 < 15 then 500 mls NaHCO3 1.26% over 6 hrs. In extremis pH < 6.9 consider IV 50 mL sodium bicarbonate 8.4% over 1 h. Take expert guidance. Can cause fluid overload.
- Exchange resins
- Calcium resonium 30 g initially and then 15 g QDS
PR/PO. PR route is possibly more effective than PO. When given rectally the calcium resonium must be retained for 9 h followed by irrigation to remove resin from the colon to prevent faecal impaction. Bowel perforation can be a rare complication.
- Lokelma (initial) 10 g 3 times a day, for up to 72 hours
- AKI assess and manage cause: renal referral needed. If AKI/CKD and refractory/
severe hyperkalaemia despite treatment, then discuss suitability for haemodialysis/ haemoperfusion.
- Adopt a low potassium diet, e.g. avoid chocolate, fruit juices. Ensure that any amiloride, spironolactone, ACE inhibitor, ARB or similar has been stopped. See AKI, Section 10.4.
Hyperkalaemia and Cardiac arrest
- Confirm hyperkalaemia > 6.5 mmol/L on blood gas analyser
- Give 10 mL calcium chloride 10% IV by rapid bolus injection. Repeat if cardiac arrest is refractory or prolonged.
- Give 10 units soluble insulin and 25 g glucose IV by rapid injection. Monitor blood glucose. Start 10% glucose infusion guided by blood glucose to avoid hypoglycaemia.
- Give 50 mmol sodium bicarbonate (50 mL 8.4% solution) IV by rapid injection.
- Consider dialysis for refractory hyperkalaemic cardiac arrest.
- Consider mechanical chest compression device if prolonged CPR is needed.Consider ECLS or ECPR for patients who are peri-arrest or in cardiac arrest as a rescue therapy in those settings where it is feasible.