ICU · Cardiovascular

Acute cardiorenal syndrome in ICU

Also known as Cardiorenal syndrome · CRS · Type 1 CRS · Worsening renal function in heart failure · Venous congestion · Type 2 CRS · Type 3 CRS · Type 4 CRS · Type 5 CRS · Renocardial syndrome · Sequential nephron blockade · Diuretic resistance

Cardiorenal syndrome (CRS): disorders of heart and kidneys whereby acute/chronic dysfunction of one causes dysfunction of the other. FIVE TYPES — TYPE 1 (acute cardiorenal): acute heart failure → AKI (most ICU-relevant). TYPE 2 (chronic cardiorenal): chronic heart failure → CKD. TYPE 3 (acute renocardial): AKI → acute heart failure. TYPE 4 (chronic renocardial): CKD → chronic heart failure. TYPE 5 (secondary): systemic disease (sepsis, diabetes, amyloid) → both. Pathophysiology: VENOUS CONGESTION (raised CVP → renal interstitial pressure → reduced GFR) is as important as low cardiac output; RAAS and sympathetic overactivation drive a vicious cycle; intra-abdominal hypertension, inflammation and oxidative stress amplify injury. Management: DECONGESTION (high-dose loop diuretics ± thiazide sequential nephron blockade), vasodilators (nitrates), inotropes (if low output), SGLT2 INHIBITORS (disease-modifying — DAPA-HF, EMPEROR, DAPA-CKD), avoid nephrotoxins, ultrafiltration only for refractory cases (CARRESS-HF — worse than pharmacological therapy), renal replacement therapy if refractory. KEY INSIGHT: VENOUS CONGESTION (not just low output) drives AKI — decongestion is the primary target; a creatinine rise during effective decongestion is acceptable and prognostically favourable.