CSCP Clinical Perfusion flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Oxygen delivery index

Oxygen delivery index equals cardiac index multiplied by arterial oxygen content, where content combines hemoglobin-bound and dissolved oxygen. Normal indexed values are roughly 500–600 mL/min/m², and falling values signal inadequate perfusion.

Oxygen consumption index

Oxygen consumption index is cardiac index multiplied by the arterial-to-venous oxygen content difference. Normal indexed values are about 110–160 mL/min/m², and rising values indicate increased metabolic demand or fever.

Activated clotting time

A whole-blood bedside test of heparin effect measured in seconds. Bypass targets are commonly 400–480 seconds, but celite and kaolin assays give different values and must not be substituted for one another.

Protamine-to-heparin ratio

The dose ratio used to reverse circulating heparin, commonly 1–1.3 mg protamine per 100 units of heparin given. Excess protamine can weaken clot formation and cause pulmonary vasoconstriction, so residual heparin is confirmed by testing.

Heparin-induced thrombocytopenia

An immune, antibody-mediated reaction causing platelet activation and thrombosis rather than simple bleeding. Management avoids all heparin and substitutes a direct thrombin inhibitor such as bivalirudin, monitored by dilute thrombin time or ecarin clotting time.

Antithrombin deficiency

A state in which heparin cannot adequately potentiate antithrombin, producing a blunted activated clotting time response. Management includes antithrombin concentrate supplementation or switching to a direct thrombin inhibitor.

Heparin resistance

Failure of escalating heparin doses to achieve the target activated clotting time. Causes include antithrombin deficiency, prior heparin exposure, and elevated clotting factor levels, and therapy is adjusted accordingly.

Heparin concentration assay

A protamine titration test that quantifies circulating heparin directly rather than by clotting time. It is useful when activated clotting time results are unreliable, such as during antithrombin deficiency or hemodilution.

Thromboelastography

A viscoelastic whole-blood test describing clot initiation, strength, and lysis. Prolonged reaction time suggests factor deficit, reduced clot strength suggests fibrinogen or platelet deficit, and increased lysis suggests hyperfibrinolysis.

Rotational thromboelastometry

A viscoelastic test using rotational movement to characterize clot formation and breakdown. Its parameters guide targeted fibrinogen, platelet, and antifibrinolytic therapy after separation from bypass.

Retrograde autologous priming

A technique in which the patient's own blood displaces crystalloid prime from the circuit before bypass. It reduces hemodilution, limits transfusion exposure, and lowers the fall in hematocrit at bypass onset.

On-bypass hematocrit estimate

Predicted hematocrit equals patient blood volume times starting hematocrit, divided by patient blood volume plus prime volume. This estimate guides transfusion thresholds, commonly near 18–21% on bypass.

Venous oxygen saturation

The oxygen saturation of blood returning to the oxygenator, reflecting the balance of oxygen delivery and consumption. Values below roughly 65–70% on bypass indicate inadequate delivery relative to demand.

Indexed pump flow

Pump flow divided by body surface area, typically 2.2–2.5 L/min/m² during normothermic bypass. Hypothermia lowers metabolic demand by roughly 5–7% per degree Celsius and permits lower indexed flow.

Mean arterial pressure on bypass

Mean arterial pressure equals pump flow multiplied by systemic vascular resistance. Low pressure with high flow suggests vasodilation, while low pressure with falling flow and rising venous saturation suggests hypovolemia or obstruction.

Oxygenator pressure gradient

The pressure difference between oxygenator inlet and outlet. A rising gradient with declining gas transfer suggests fiber thrombosis or failure and may require circuit or oxygenator exchange.

Antegrade cardioplegia pressure

Delivery pressure measured at the aortic root during antegrade cardioplegia administration. It is kept below roughly 40–50 mmHg to avoid barotrauma and to confirm distribution through coronary and septal vessels.

Air embolus response

Immediate actions include stopping the pump, placing the patient head-down, venting the aortic root or superior vena cava, raising circuit pressure to limit entrainment, and supporting perfusion until gas is evacuated.

Arterial line air or clot

Management begins by stopping the pump and clamping the arterial line distal to the contamination. The circuit is then replaced or recirculated and purged before perfusion is restored to the patient.

Pump failure checklist

Priority actions include switching to hand cranking or a backup pump, securing backup oxygen and power, and executing a rehearsed plan to transition to a backup circuit without interrupting perfusion.

Circuit prime volume

The crystalloid or colloid volume used to fill the circuit before bypass. Larger prime volumes increase hemodilution and lower hematocrit, so priming is minimized and often replaced with autologous blood.

Blood volume estimate

An estimate derived from body weight and patient category, roughly 70 mL/kg for adults. It is used with starting hematocrit and prime volume to predict on-bypass hematocrit and transfusion needs.

Systemic vascular resistance

The resistance opposing pump flow, derived from the pressure difference across the circulation divided by flow. It falls with vasodilation and warming and rises with hypothermia and vasoconstrictor administration.

Hypothermic metabolic reduction

Cooling reduces oxygen consumption by roughly 5–7% per degree Celsius, allowing lower indexed pump flow at lower temperatures while maintaining an adequate delivery-to-consumption ratio.

Delivery-to-consumption ratio

Oxygen delivery index divided by oxygen consumption index, normally above four to five. A falling ratio indicates that delivery is failing to keep pace with demand and prompts corrective action.

Arterial oxygen content

Content equals 1.34 times hemoglobin times arterial saturation plus 0.0031 times arterial oxygen partial pressure. The dissolved component is small, so hemoglobin and saturation dominate oxygen carriage.

Heparin loading dose

The initial heparin dose given before bypass, commonly 300–400 units/kg, adjusted to achieve the program's activated clotting time target. Response is verified by measuring activated clotting time after administration.

Dilute thrombin time

A clotting test sensitive to direct thrombin inhibitors such as bivalirudin, used when heparin is contraindicated. It provides dose monitoring that activated clotting time alone cannot reliably supply.

Ecarin clotting time

A test that activates prothrombin through ecarin venom and is used to monitor direct thrombin inhibitors. It responds predictably to bivalirudin levels and is an alternative to activated clotting time.

Antifibrinolytic administration

Agents such as tranexamic acid or epsilon-aminocaproic acid are given to limit hyperfibrinolysis and bleeding after bypass. Dosing is guided by bleeding risk and, when available, viscoelastic evidence of lysis.

Transmembrane oxygen transfer failure

A decline in oxygen transfer with a rising pressure gradient across the oxygenator. It suggests fiber thrombosis or plasma leakage and may require replacement of the oxygenator or the entire circuit.

Backup oxygen supply

A secondary gas source plumbed or cylinder-supplied to the oxygenator, independent of the primary hospital gas line. It is verified before every case as part of the emergency readiness check.