Weaning from bypass and low cardiac output

Model answer

Transfusion (4). TRICS III (5,243 cardiac-surgery adults, EuroSCORE I ≥ 6): restrictive 7.5 g/dL from induction versus liberal 9.5 g/dL (theatre/ICU) or 8.5 g/dL (ward); composite death/MI/stroke/new dialysis 11.4% vs 12.5% (OR 0.90, P < .001 noninferiority); transfused 52.3% vs 72.6%. Transfuse for delivery failure, individualise for bleeding, low BSA, or ischaemia.

TOE phenotypes (5). Comprehensive-examination views applied to the rescue: hypovolaemia (small hyperdynamic cavities — volume), LV failure (dilated, poorly thickening — inotropes, careful afterload reduction, early IABP), RV failure (dilated RV, underfilled LV, high CVP, TR jet — aortic pressure, low PVR, inhaled vasodilators, inodilators), SAM (LVOTO, dagger Doppler — fill, raise SVR, cut inotropes), technical/air, closing tamponade. Cavity size beats CVP alone.

Vasoplegia (1). Persistent low SVR despite normal or high cardiac index: noradrenaline first-line, vasopressin and methylene blue per protocol, per the vasoplegia review's catecholamine-plus-adjunct ladder.

Protamine (3). Only when stable off CPB: ~1 mg per 100 IU heparin, slow peripheral route; dosing strategies span empiric, pharmacokinetic, and point-of-care heparin measurements. Reactions span vasodilation to cardiopulmonary dysfunction and shock (IgE/IgG, complement) — stop the drug, support the circulation, consider return to CPB.

Structure (2). Pre-wean checklist, RRRAC out loud, failed-wean sequencing (full flow, TOE survey, labs, surgical look, phenotype drugs, second attempt, then IABP/ECMO) are fellowship teaching frameworks around the three owned facts above.