MANAGEMENT OF HYPERKALAEMIA

Transcription

1 ABC of Intravenous Fluids, Electrolyte Disorders and AKI Management in Adults WASD 6 MANAGEMENT OF HYPERKALAEMIA Hyperkalaemia is a serum potassium concentration (s[k])$5.5mmol/l. It is the most serious of all electrolyte disorders. It is often asymptomatic, even if severe. It can cause cardiac arrest without warning [1 7]. Hyperkalaemia is the commonest electrolyte disorder causing cardiorespiratory arrest [8]. Symptoms and Signs (S/S) (s[k] in mmol/l) [1 10] Common Causes: A thorough history and physical examination usually discloses the cause and guides the management [1 10] Are uncommon, non-specific, and tend to occur at s[k] of $7.0. S/S are prominent when the increase in s[k] occurs rapidly or is large. Muscle: weakness ascending, flaccid paralysis DD: GBS Cardiac (*ECG Changes): conduction abnormalities and arrhythmias, cardiac arrest without warning 1. Reduced urinary K excretion, (the commonest causes): Renal failure, GFR < 20ml/min 75% cases [9]. Decreased mineralocorticoid activity: Hyporeninaemic hypoaldosteronism (damaged JGA) CKD, diabetic nephropathy, NSAIDs Drugs: reduced aldosterone secretion ACE inhibitors, Heparin, NSAIDs, CNIs Drugs: aldosterone receptor blockers SPL, Eplerenone Mineralocorticoid deficiency Drugs: Epithelial Sodium Channel (ENaC) blockers: Ameloride, Trimethoprim 39 C06-Hyperkalaemia.indd 39 26/3/ :08:00 AM

2 40 ABC of Intravenous Fluids 2. Increased K release from cells (IC to EC shift): Uncontrolled hyperglycaemia (hyperosmolality, insulin deficiency) Metabolic acidosis Drugs: Na-K-ATPase inhibitors Digoxin toxicity, suxamethonium, β blockers (rare) Tissue necrosis/lysis: rhabdomyolysis/tls/severe burns Spurious (pseudo-hyperkalaemia) the commonest cause of reported hyperkalaemia [3] : delayed analysis; haemolysis via small needle; release from blood cells in haematological disorders Hyperkalaemic Periodic Paralysis 3. Increased K intake (rare, unless concurrent decreased K excretion): High K diet in CKD; Blood transfusion, etc Investigations [1 7] Obtain an ECG looking for signs* of hyperkalaemia if s[k] $6 [4]. Urgent repeat K on plasma sample (lithium heparin), especially if the result is unexpected or isolated with no ECG changes Emergency s[k]: a BG analyzer can be used pending lab result [4]. FBC/HCO 3 in venous blood Urine K; sosm as appropriate *The ECG changes: their presence, severity and progression correlate poorly with s[k] [1 3,9]. Thus calcium salts are given in severe hyperkalaemia, even without ECG changes [2,3]. Changes associated with Hyperkalaemia: none (majority [9] ); early peaked T, prolonged P-R interval; late flattened or absent P wave, widening QRS complex to a sine wave pattern, VT, VF and asystole. Abbreviations: DD5Differential Diagnosis; GBS5Guillain-Barré Syndrome; NSAIDs5Non-Steroidal Anti- Inflammatory Drugs; ACEi5Angiotensin Converting Enzyme inhibitors; CNIs5Calcineurin Inhibitors; IC5Intracellular; EC5Extracellular; TLS5Tumour Lysis Syndrome; TPN5Total Parenteral Nutrition TREATMENT Treatment is based mainly on clinical experience and accepted practice rather than controlled trials [1,4,11]. The classification into mild, moderate and severe hyperkalaemia provides a guide to clinical decision-making. However, treatment decisions should consider the cause, speed and the degree of s[k] elevation [4]. This is illustrated in the following two examples: 1. Mild hyperkalaemia in patients with stable CKD (1/2 RAASi), is common and well tolerated maintain low K diet, consider diuretics, optimise RAASi dose, consider oral NaHCO3 to maintain near normal s[hco3], stop RAASi during acute illness, monitor [1 3,12]. 2. In contrast, even a mild hyperkalaemia in association with, for instance, tissue breakdown, may require emergency treatment if it is acute, rapidly increasing and/or symptomatic [3]. C06-Hyperkalaemia.indd 40

3 Management of Hyperkalaemia 41 Treatment: Follow the sequential flowchart: s[k] (mmol/l) ECG Changes (Mild) No [1 12] Treatment Acute in-patient set up: do not wait for a repeat plasma [K] especially if ECG signs present Urgent management using ABCDE approach, EWS system and appropriate referral/plan formulation [4]. Prompt identification and treatment of the cause: Stop offending drugs, ensure low K diet avoid fruits Ensure good hydration/relief OUP etc Consider calcium resonium 15gqds PO/lactulose or 30g enema, refer to local drug formulary [4,8]. Monitor s[k] for treatment efficacy and rebound hyperkalaemia. NB: many patients are total body K deplete, may develop hypokalaemia during correction Measures to prevent recurrence: re-assess diet and dialysis access Non-resolving or worsening AKI: refer to the renal team (Moderate) No Apply all treatment measures listed above Cardiac monitoring if rapid elevation in s[k] is anticipated: Consider insulin/dextrose, doses given next box [3 4]. $6.5 (Severe) Urgent treatment for severe HrK: s[k] $6.5; and/ or ECG changes present; and/ or symptoms present: Give calcium gluconate, etc steps 1 7 No Emergency treatment: (Refer to hospital if in the community) 1. Apply all treatment measures listed above1 2. Cardiac monitoring ideally in HDU. Secure proper IV access a large vein or CV line if access poor 3. Give 10ml of Calcium Gluconate 10% IV (or calcium chloride) over five minutes [2,3]. Repeat calcium gluconate after five minutes as necessary until the ECG normalises may need up to 50ml; while awaiting definitive s[k] correction. Caution if patient on digoxin 4. Give 10u of actrapid insulin 150ml of 50% D IV over 5 10 minutes Insulin can be administered as a single agent without dextrose if blood glucose.15mmol Watch for, avoid hypoglycaemia consider 500ml 10% D IV over 10hrs [3]. 5. Add: nebulised salbutamol 10-20mg, caution in IHD patients. β2 agonists: weakened effect if on BB and/or digoxin, and ineffective in some dialysis patients hence, not recommended as a single agent [2,3,9]. 6. Consider HD early if persistent hyperkalaemia or RF present (oligo/anuric UOP, rising scr, or severe acidosis) 7. Refer to renal team as s[k] will rebound. C06-Hyperkalaemia.indd 41

4 42 ABC of Intravenous Fluids Any ECG Changes Yes 1. Apply all treatment measures listed above Cardiac arrest: hyperkalaemia should be considered as part of identifying and treating a reversible cause using the 4 Hs and 4 Ts approach. Start treating for hyperkalaemia in high risk patients even before the laboratory results [4,5,8] Monitoring treatment: Monitor serum U&Es two hourly (and blood glucose at 30 minutes and hourly for six hours, after IV insulin) until s[k] stable and,6.0. Monitor UOP. Seek expert advice as appropriate. Calcium gluconate 10%, 10ml diluted in 100ml 5% D, is given slowly over 20 minutes. Rapid calcium administration (hypercalcaemia) may precipitate myocardial digoxin toxicity. Digoxin toxicity: can cause hyperkalaemia and arrhythmias and the administration of digoxin antibody (Fab) fragments may represent the preferred approach [3], and consider HD. Abbreviations: RAASi5Renin/Angiotensin/Aldosterone inhibitors; OUP5Obstructive Uropathy; D5Dextrose; IV5Intravenous; CV5Central Venous; hr5hour; IHD5Ischaemic Heart Disease; BB5Beta Blockers; HD5Haemodialysis; scr5serum Creatinine; 4 Hs5Hypovolaemaia, Hypoxia, Hyper-hypokalaemia, Hypothermia; 4 Ts5Toxins, Tamponade, Tension pneumothorax, Thrombosis - pulmonary and coronary. CONCLUSION Due concern and appropriate management should be given to patients with the most serious electrolyte disorder. REFERENCES [1] Nyirenda, M.J., Tang, J.I., Padfield, P.L. and Seckl, J.R. Hyperkalaemia. British Medical Journal (2009), pp.339. doi: [2] McVeigh, G., Maxwell, P. and O Donnell, S. Guidelines and Audit Implementation Network (GAIN). Guidelines for the treatment of Hyperkalaemia in Adults August (2014). [3] Uptodate. Causes and evaluation/treatment and prevention of hyperkalemia in adults. (Accessed ). [4] Alfonzo, A., Soar, J. and MacTier, R. Treatment of Acute Hyperkalaemia in Adults. The Renal Association (March 2014). [5] Alfonzo, A., Isles, C. and Geddes, C. Potassium disorders - clinical spectrum and emergency treatment. Resuscitation (2006), Vol. 70, pp [6] British Medical Journal Best Practice. Assessment of Hyperkalaemia us.bestpractice.bmj.com/best-practice/monograph/60.html. C06-Hyperkalaemia.indd 42

5 Management of Hyperkalaemia 43 [7] Rastegar, A. and Soleimani, M. Fluid, Electrolytes and Acid-Base Disturbances. Nephrology Self- Assessment Program, ASN (2015), Vol. 14, No. 1. [8] Soar, J., Deakin, C.D. and Nolan, J.P. European Resuscitation Council guidelines for resuscitation Section 7. Cardiac arrest in special circumstances. Resuscitation (2005), Vol. 67 (Supplementary. 1), pp.s [9] Acker, C.G., Johnson, J.P. and Palevsky, P.M. Hyperkalemia in hospitalised patients: causes, adequacy of treatment and results of an attempt to improve physician compliance with published therapy guidelines. Archives of Internal Medicine (1998), Vol. 158, pp [10] Mahoney, B.A., Smith, W.A. and Lo, D.S. Emergency interventions for hyperkalaemia. Cochrane Database Syst Rev2005;(2):CD DOI: / CD pub2. [11] Kim, H.J. and Han, S.W. Therapeutic approach to hyperkalaemia. Nephron (2002), 92 (supplementary) Vol. 1, pp [12] Reardon, L.C. and Macpherson, D.S. Hyperkalemia in outpatients using angiotensin-converting ensyme inhibitors. How much should we worry? Archives of Internal Medicine (1998), Vol. 158, No. 26. C06-Hyperkalaemia.indd 43