Understanding BRASH Syndrome
BRASH syndrome describes the interaction of bradycardia, renal dysfunction, AV-nodal blockade, shock, and hyperkalemia. This adult clinical overview explains the reinforcing cycle; it is not a diagnostic calculator or a complete treatment protocol.
Treat this pattern as a working diagnosis. Obtain an ECG, continuous monitoring and a medication timeline; assess oxygenation and perfusion. Myocardial ischemia, intrinsic conduction disease, overdose and other causes of shock remain important alternatives. Modest hyperkalemia or absent peaked T waves does not establish safety. AHA; UKKA.
How the Factors Interact
Hyperkalemia and AV-nodal blocking drugs can act together to produce marked bradycardia. The effect varies between patients and can occur without a drug overdose or severe hyperkalemia.
Potassium
Raised potassium can impair cardiac conduction. A potassium value alone cannot predict the heart rate or exclude dangerous deterioration.
AV-Nodal Blockade
Examples include beta-blockers, verapamil and diltiazem. Atenolol can accumulate with renal impairment; metoprolol is mainly hepatically metabolized. Review the exact drug, dose, formulation and interactions rather than assuming renal failure raises every AV-blocker concentration. Atenolol label; metoprolol label.
Possible Reinforcing Cycle
Combined conduction effects may worsen bradycardia.
Reduced cardiac output and perfusion may worsen kidney function.
Impaired potassium excretion can reinforce the cycle.
This qualitative diagram does not predict heart rate, time course, or clinical stability. Assess the ECG, measured potassium, perfusion, renal function, medication history, and clinical trajectory; suspected unstable BRASH needs urgent assessment and treatment.
Sources: UK Kidney Association hyperkalemia guideline and Farkas et al., BRASH syndrome.
The Vicious Cycle
The reinforcing cycle can begin with an acute illness, a medication change or reduced renal perfusion.
Trigger
Hypovolemia, acute illness, or medication changes may trigger the cycle.
Renal Lag
AKI impairs potassium excretion and may reduce clearance of some AV-nodal blockers, depending on the drug. BRASH can occur at prescribed doses; review the specific medicine and renal dosing rather than assuming all AV blockers are renally cleared. BRASH review.
Synergy
Hyperkalemia and AV-nodal blockade can jointly slow cardiac conduction.
The Crash
Bradycardia with inadequate perfusion can worsen AKI and potassium retention.
Therapeutic Objectives
Treat impaired perfusion, hyperkalemia and the trigger in parallel, with repeated bedside reassessment.
Metabolic Correction
Immediate hyperkalemia care: IV calcium treats hyperkalemic ECG toxicity but does not lower potassium. Use insulin–glucose and adjunct nebulized salbutamol according to the hyperkalemia protocol; salbutamol alone is insufficient for severe hyperkalemia. Check glucose before treatment and repeatedly for at least six hours after insulin, longer when risk persists. Repeat potassium to detect inadequate response or rebound, and plan removal. Routine IV bicarbonate is not recommended. UKKA guideline.
Hemodynamic Support
Support for bradycardia and hypotension: Assess volume status. Replace volume when hypovolemic, reassessing lungs, perfusion and urine output. Renal impairment or congestion makes indiscriminate fluid loading hazardous. Ongoing shock needs monitored vasoactive support. BRASH review.
Etiologic Management
Treating triggering events: Hold implicated AV-nodal blockers during instability and review other potassium-raising or nephrotoxic medicines. Before restarting, reassess the indication, dose, kidney function and recurrence risk; arrange follow-up potassium and renal testing. UKKA prevention guidance.
Temporary Pacing in Unstable BRASH
In unstable bradycardia, give atropine when appropriate while treating reversible causes. If ineffective, use transcutaneous pacing and/or a titrated epinephrine or dopamine infusion according to the adult bradycardia protocol. Persistent instability despite medical treatment warrants expert assessment for transvenous pacing. Confirm mechanical capture and perfusion; do not wait for kidney function to normalize. See the AHA adult bradycardia algorithm.
When Dialysis Is Needed
Urgent renal or critical-care assessment is needed for life-threatening or refractory hyperkalemia, particularly with severe renal impairment. Hemodialysis removes potassium; stabilize the patient and provide indicated medical therapy while it is arranged.
Case reports and observational cohorts support recognition but do not establish a superior BRASH regimen. A recent single-center retrospective cohort describes treatment and outcomes without proving comparative benefit. Esteves et al., 2026.
