BRASH syndrome

🧠 BRASH syndrome = Bradycardia + Renal failure + AV-nodal blockade + Shock + Hyperkalaemia. It’s a synergistic vicious cycle: even “moderate” hyperkalaemia plus an AV-nodal blocker can produce profound bradycardia → hypoperfusion → worse AKI → higher K⁺ → further bradycardia. :contentReference[oaicite:0]{index=0}

🔎 Why it matters (clinical pattern recognition)

• 👴 Typically older, comorbid, polypharmacy (β-blocker or diltiazem/verapamil ± ACEi/ARB ± MRA ± diuretic).
• 🧪 Potassium may be only mild–moderately raised, yet the bradycardia is dramatic (the “clue” to synergy rather than isolated hyperK).
• 🩺 Standard ACLS bradycardia steps (e.g. atropine) can be less effective because the mechanism is not primarily vagal. :contentReference[oaicite:1]{index=1}

🧬 Pathophysiology (the loop)

• 💊 AV-nodal blocker (e.g. β-blocker, diltiazem/verapamil, digoxin) slows conduction and blunts compensatory tachycardia.
• 🧂 Hyperkalaemia further depresses SA/AV node excitability → disproportionate bradycardia.
• 🫀 Bradycardia → ↓ cardiac output → renal hypoperfusion → AKI → ↓ K⁺ excretion → worsening hyperK and acidosis → more bradycardia/shock.
• 🚿 Trigger is often “small”: dehydration/diarrhoea, sepsis, NSAID, ACEi/ARB up-titration, spironolactone, trimethoprim, contrast, etc. :contentReference[oaicite:2]{index=2}

👀 Presentation (what you actually see)

• 😵 Light-headedness, syncope, weakness, “found down”, confusion; sometimes minimal symptoms despite HR 20–40.
• 🫀 Bradycardia with hypotension (often relative bradycardia for the degree of shock).
• 🧾 ECG: may show bradycardia/AV block; classic hyperK changes (peaked T, wide QRS) may be absent early.

🧪 Investigations (do fast, treat in parallel)

• 📈 ECG + continuous monitoring.
• 🩸 U&E (K⁺/creatinine), VBG/ABG (pH, HCO₃⁻), glucose, Mg²⁺; consider troponin, CRP/cultures if sepsis suspected.
• 💊 Medication reconciliation is part of the diagnosis (recent dose changes, missed fluids, new interacting drugs).

🧭 Differentials (and how BRASH differs)

• ☠️ AV-nodal blocker overdose: often much higher drug exposure; may have normal K⁺ initially.
• 🧂 Pure hyperkalaemia: ECG changes often track K⁺ more closely; bradycardia usually with more severe K⁺.
• 🫀 Inferior MI/AV block, sick sinus, drug-induced bradycardia without hyperK/AKI.

🚑 Management (UK-style, practical)

🎯 The winning strategy is to treat all components simultaneously: stabilise myocardium, shift/remove K⁺, restore perfusion, and hold AV-nodal blockers. :contentReference[oaicite:3]{index=3}

1) Immediate actions

• 🛑 Stop/withhold AV-nodal blockers (β-blocker, diltiazem/verapamil, digoxin) and K⁺-raising drugs where appropriate (ACEi/ARB, MRA, NSAID, trimethoprim) until stabilised.
• 🧯 ABCDE, IV access x2, consider urinary catheter + strict fluid balance.
• 📞 Early senior/ICU/renal input if shock, K⁺ ≥6.5, severe AKI/oliguria, or refractory bradycardia.

2) Treat hyperkalaemia (follow local protocol / UKKA / BNF)

• 🧲 IV calcium if ECG changes or instability (stabilises myocardium; does not lower K⁺). UK practice uses calcium gluconate or calcium chloride depending on access/urgency. {index=4}
• 🍬 Insulin + glucose to shift K⁺ intracellularly (and monitor glucose closely for hypoglycaemia).
• 💨 Nebulised salbutamol as an adjunct K⁺ shift (and it also supports chronotropy/contractility).
• 🧪 Consider bicarbonate if metabolic acidosis (case-dependent; follow renal/critical care guidance).
• 🚽 Promote K⁺ removal if appropriate: diuresis (if producing urine), potassium binders; dialysis if severe/refractory hyperK or oliguric AKI.

3) Treat bradycardia/shock (don’t fixate on atropine)

• 📉 If adverse features, follow Resus Council UK bradycardia pathway (atropine 500 micrograms IV up to 3 mg, then consider second-line drugs / pacing).
• ⚡ In BRASH, earlier use of adrenaline infusion (or isoprenaline where appropriate) is often more helpful than repeated atropine because catecholamines:
  • increase HR/CO (perfuse kidneys), and
  • via β-agonism, help shift K⁺ intracellularly.
• 🩹 Temporary pacing: may be needed, but can be less effective if the metabolic driver (hyperK) isn’t corrected—treat the chemistry in parallel. :contentReference[oaicite:10]{index=10}

4) Fluids and perfusion (choose wisely)

• 💧 If hypovolaemic, cautious crystalloid bolus with frequent reassessment (many patients have HF/CKD).
• 🌡️ Treat the trigger: sepsis bundle, stop nephrotoxins, address diarrhoea/bleeding/ACS/PE as appropriate.

🧾 High-yield bedside checklist

⚠️ Common pitfalls

• ❌ Assuming “K⁺ isn’t high enough to explain the bradycardia” → missing the synergy. :contentReference[oaicite:11]{index=11}
• ❌ Repeated atropine without treating hyperK/AKI/perfusion.
• ❌ Restarting AV-nodal blockers too early (before renal function and K⁺ are stable, and trigger addressed).
• ❌ Hypoglycaemia after insulin–glucose (build in glucose monitoring and follow guideline prophylaxis). :contentReference[oaicite:12]{index=12}

📚 References (good “Makindo” core set)

• Farkas JD et al. BRASH syndrome (review/definition). :contentReference[oaicite:13]{index=13}
• EMCrit: BRASH syndrome (practical management). :contentReference[oaicite:14]{index=14}
• LITFL: BRASH overview + pathophysiology graphic. :contentReference[oaicite:15]{index=15}
• Resuscitation Council UK: Adult bradycardia algorithm / ALS guidance. :contentReference[oaicite:16]{index=16}
• UK Kidney Association: Management of hyperkalaemia in adults (guideline + hospital algorithm). :contentReference[oaicite:17]{index=17}
• BNF: Hyperkalaemia treatment summary (insulin–glucose approach). :contentReference[oaicite:18]{index=18}