CSCP Clinical Perfusion cheat sheet

Heparin dosing for cardiopulmonary bypass is titrated to an activated clotting time (ACT) target, commonly 400–480 seconds for full bypass; celite and kaolin ACT assays are not interchangeable, so each program sets assay-specific thresholds.

Protamine reversal is dosed by heparin-to-protamine ratio (commonly 1–1.3 mg protamine per 100 units of total heparin); protamine excess can paradoxically anticoagulate and cause pulmonary vasoconstriction, so residual heparin is confirmed by ACT or heparin concentration assay.

Oxygen delivery formula: DO2 = cardiac index × (1.34 × hemoglobin × arterial oxygen saturation + 0.0031 × arterial oxygen partial pressure); indexed values are expressed per square meter of body surface area.

Oxygen consumption formula: VO2 = cardiac index × (arterial oxygen content − venous oxygen content); the DO2/VO2 ratio normally exceeds 4–5, and a falling ratio signals inadequate perfusion.

Pump flow during normothermic bypass is typically indexed at 2.2–2.5 L/min/m²; hypothermia reduces metabolic demand roughly 5–7% per degree Celsius and permits lower indexed flow.

Mean arterial pressure on bypass is the product of pump flow and systemic vascular resistance; hypotension at adequate flow indicates vasodilation, while hypotension with rising venous saturation and falling flow suggests hypovolemia or pump line obstruction.

Circuit prime dilution lowers hematocrit; the on-bypass hematocrit is estimated as (patient blood volume × starting hematocrit) ÷ (patient blood volume + prime volume), guiding transfusion decisions.

Cardioplegia delivery is monitored by aortic root or coronary sinus pressure (typically kept below 40–50 mmHg for antegrade root delivery) to avoid barotrauma and to confirm septal and coronary distribution.

Air embolus management during bypass: stop the pump, place the patient in Trendelenburg, vent the aortic root or superior vena cava, increase circuit pressure to reduce entrainment, and support perfusion until gas is evacuated.

Activated clotting time is measured at baseline, after the loading dose, and at regular intervals (commonly every 30 minutes) during bypass; a falling ACT with visible clot in the reservoir mandates additional heparin and circuit inspection.

Heparin-induced thrombocytopenia is managed by avoiding all heparin exposure and using a direct thrombin inhibitor such as bivalirudin, whose effect is monitored by dilute thrombin time or ecarin clotting time rather than ACT alone.

Antithrombin deficiency blunts the heparin response; options include antithrombin concentrate supplementation or switching to a direct thrombin inhibitor, and resistance should be suspected when escalating heparin fails to prolong ACT.

Point-of-care viscoelastic testing (thromboelastography or rotational thromboelastometry) guides post-bypass product replacement: prolonged reaction time suggests factor or heparin effect, reduced clot strength suggests fibrinogen or platelet deficit, and prolonged lysis suggests hyperfibrinolysis.

Retrograde autologous priming and minimized circuit volume reduce hemodilution and transfusion exposure; a hematocrit threshold for red cell transfusion is typically set near 18–21% on bypass, individualized to oxygen delivery.

Venous oxygen saturation below roughly 65–70% during bypass indicates inadequate oxygen delivery relative to demand and prompts increases in flow, hematocrit, or oxygen fraction, or reduction of temperature and metabolic demand.

The oxygenator is monitored for pressure gradient across the device; a rising transmembrane gradient with falling oxygen transfer suggests thrombosis or fiber failure and may require circuit exchange.

Massive air or clot in the arterial line is managed by immediately stopping the pump, clamping the arterial line distal to the air, and replacing or recirculating the circuit before restoring perfusion.

Emergency checklist priorities for pump failure: hand-crank or backup pump, backup oxygen supply, alternative power source, and a rehearsed plan for rapid transition to a backup circuit.