ELSO Adult ECMO Certification Exam — Questions and Answers

Question 1: A VV ECMO patient develops sudden increase in transmembrane pressure gradient from 20 to 80 mmHg over 6 hours. What is the most likely cause?

Hypovolemia
Increased cardiac output
Thrombosis within the oxygenator (Correct answer)
Kinking of the drainage cannula

Correct answer: Thrombosis within the oxygenator

Progressive clot formation within the oxygenator increases resistance to blood flow, causing the transmembrane pressure gradient to rise.

Question 2: Loop diuretics such as furosemide are used in ECMO patients primarily to:

Correct metabolic alkalosis
Reduce fluid overload and improve oxygenation (Correct answer)
Prevent circuit thrombosis
Increase cardiac output

Correct answer: Reduce fluid overload and improve oxygenation

Fluid overload is common in ECMO patients due to capillary leak and transfusion requirements; furosemide promotes diuresis to reduce lung edema.

Question 3: The 'north-south syndrome' in VA-ECMO via femoral cannulation describes:

Migration of the arterial cannula toward the aortic arch
Bilateral renal ischemia from reduced pulsatile flow
Differential hypoxia where upper body receives poorly oxygenated native cardiac output while lower body receives well-oxygenated ECMO flow (Correct answer)
Pressure gradient between upper and lower body cannulas

Correct answer: Differential hypoxia where upper body receives poorly oxygenated native cardiac output while lower body receives well-oxygenated ECMO flow

When the recovering heart ejects poorly oxygenated blood, a mixing zone forms in the aorta creating a differential: hypoxic upper body (brain, coronaries) versus oxygenated lower body from ECMO.

Question 4: During ECMO, the team notices pink frothy fluid in the sweep gas exhaust. What does this indicate?

Normal condensation in the sweep gas line
Air leak in the venous drainage cannula
Plasma leak through the oxygenator membrane (Correct answer)
Retrograde flow in the circuit

Correct answer: Plasma leak through the oxygenator membrane

Pink frothy fluid in the sweep gas exhaust indicates plasma leakage across the oxygenator membrane, which can reduce gas exchange efficiency and require oxygenator replacement.

Question 5: Which test best differentiates heparin resistance from disseminated intravascular coagulation (DIC) in ECMO patients?

Platelet count alone
Prothrombin time (PT)
Anti-Xa level with concurrent AT III assay (Correct answer)
D-dimer level alone

Correct answer: Anti-Xa level with concurrent AT III assay

Measuring anti-Xa activity alongside AT III levels distinguishes heparin resistance (low AT III, low anti-Xa despite adequate heparin dose) from DIC (multiple factor deficiencies).

Question 6: During ECMO, a sudden rise in the pre-membrane pressure with a normal post-membrane pressure indicates:

Pump head thrombosis
Venous drainage line kink
Clot formation within the oxygenator fiber bundle (Correct answer)
Arterial cannula obstruction

Correct answer: Clot formation within the oxygenator fiber bundle

A rising gradient between pre- and post-membrane pressures signals increasing resistance within the oxygenator, most commonly due to clot accumulation in the fiber bundle.

Question 7: A patient has been on VV ECMO for 14 days. Platelet count drops from 120,000 to 48,000 over 5 days despite no obvious bleeding. What is the most likely cause?

Marrow suppression from prolonged critical illness
Heparin-induced thrombocytopenia (HIT)
Consumptive thrombocytopenia from circuit contact activation (Correct answer)
Platelet sequestration in the spleen

Correct answer: Consumptive thrombocytopenia from circuit contact activation

Chronic contact of blood with artificial circuit surfaces activates platelets and causes ongoing consumption, making thrombocytopenia a common feature of prolonged ECMO.

Question 8: We can potentially use ECPR (refractory arrest) for cardiac arrests in V-fib and V-tach, why can’t we use it for asystole?

Asystole is not amenable to treatment with ECMO.
ECPR is only effective for shockable rhythms like V-fib and V-tach.
Asystole often indicates non-cardiogenic causes of arrest. (Correct answer)
Asystole is a less common cause of cardiac arrest.

Correct answer: Asystole often indicates non-cardiogenic causes of arrest.

Explanation: <br> Generally, we think of V-fib and V-tach as potential cardiac causes of cardiac arrest. For ECPR (refractory arrest, “ECMO Alert”) to be effective, there needs to be something to fix in the cath lab such as a blocked coronary artery. Asystole, along with other causes of arrest, are less likely to be cardiogenic. Other types of arrests that are excluded are traumatic arrests and police arrests.

Question 9: The oxygenation index (OI) threshold commonly used to consider ECMO in neonates is:

>40 (Correct answer)
>20
>30
>60

Correct answer: >40

An OI >40 (calculated as MAP × FiO2 × 100 / PaO2) on two or more blood gases indicates severe respiratory failure warranting ECMO consideration.

Question 10: In the context of ECMO weaning, what does the term 'circuit holiday' refer to?

A brief period of complete ECMO flow cessation (with circuit clamping) to assess native cardiopulmonary function (Correct answer)
Planned temporary cessation of anticoagulation to reduce bleeding risk
Scheduled circuit change to prevent membrane oxygenator failure
Reduction in sweep gas to the minimum possible level for 24 hours

Correct answer: A brief period of complete ECMO flow cessation (with circuit clamping) to assess native cardiopulmonary function

A circuit holiday (clamp trial) briefly stops all ECMO flow with the circuit clamped to evaluate whether native heart and lung function can sustain the patient.

Question 11: Which of the following correctly describes the 'bridge-to-decision' scenario in which ECMO decannulation is deferred pending further evaluation?

The patient is extubated and ambulatory on ECMO
Decannulation site is infected, delaying the procedure
ECMO supports a patient awaiting heart transplant listing or durable LVAD implantation (Correct answer)
The patient has recovered myocardial function and wishes to stop ECMO

Correct answer: ECMO supports a patient awaiting heart transplant listing or durable LVAD implantation

Bridge-to-decision ECMO maintains perfusion while the team evaluates candidacy for definitive therapy such as transplant or durable mechanical support.

Question 12: The purpose of the heat exchanger integrated into the ECMO oxygenator is to:

Remove lipid microemboli before return to the patient
Regulate sweep gas humidity to prevent fiber desiccation
Maintain normothermia or induce therapeutic hypothermia by warming or cooling circulating blood (Correct answer)
Increase oxygen solubility before arterial reinfusion

Correct answer: Maintain normothermia or induce therapeutic hypothermia by warming or cooling circulating blood

The heat exchanger circulates water at a controlled temperature around the blood path, enabling precise temperature management including therapeutic cooling.

Question 13: A team member notices the ECMO pump is running but there is no visible flow in the tubing and the flow meter reads zero. The MOST likely explanation is:

Massive air lock in the circuit
Centrifugal pump decoupling or mechanical failure (Correct answer)
Oxygenator membrane rupture
Extreme vasodilation reducing venous return

Correct answer: Centrifugal pump decoupling or mechanical failure

Centrifugal pumps can decouple or fail mechanically, causing the motor to spin without generating flow, which requires emergency pump head replacement.

Question 14: A patient on VV-ECMO for ARDS requires urgent surgical tracheostomy. How should anticoagulation be managed perioperatively?

Hold heparin 4–6 hours before and restart 2–4 hours post-procedure (Correct answer)
Switch to oral anticoagulation 12 hours before the procedure
Reverse heparin with protamine before incision
Continue heparin unchanged throughout the procedure

Correct answer: Hold heparin 4–6 hours before and restart 2–4 hours post-procedure

For surgical procedures on ECMO, heparin is typically held 4–6 hours pre-procedure and restarted 2–4 hours post-procedure once hemostasis is achieved, balancing thrombotic and bleeding risk.

Question 15: A patient on VV ECMO is undergoing an "off-sweep" trial. After 30 minutes with the sweep gas turned off, an arterial blood gas (ABG) is drawn. Which of the following ABG results would indicate the patient has failed the trial and is not ready for decannulation?

pH 7.38, PaCO2 42 mmHg, PaO2 85 mmHg
pH 7.45, PaCO2 35 mmHg, PaO2 150 mmHg
pH 7.21, PaCO2 75 mmHg, PaO2 90 mmHg (Correct answer)
pH 7.35, PaCO2 45 mmHg, PaO2 78 mmHg

Correct answer: pH 7.21, PaCO2 75 mmHg, PaO2 90 mmHg

The primary purpose of the off-sweep trial is to assess the native lungs' ability to clear carbon dioxide. A PaCO2 of 75 mmHg leading to significant respiratory acidosis (pH 7.21) is a clear indication that the patient's lungs are not yet capable of adequate independent gas exchange, thus signifying a failed trial.

Question 16: The primary determinant of CO2 removal in the ECMO circuit is:

Membrane lung surface area
Sweep gas flow rate (Correct answer)
FiO2 of the sweep gas
Pump blood flow rate

Correct answer: Sweep gas flow rate

Sweep gas flow (measured in L/min) is the primary control for CO2 removal; increasing sweep gas flow directly increases CO2 elimination.

Question 17: Flow monitoring via ultrasonic flow probes on the ECMO circuit measures flow based on:

Pressure differential across a fixed orifice
Electromagnetic induction proportional to blood conductivity
Doppler shift frequency from red blood cell velocity
Transit-time ultrasound detecting changes in sound wave travel time caused by moving blood (Correct answer)

Correct answer: Transit-time ultrasound detecting changes in sound wave travel time caused by moving blood

Transit-time ultrasound flow probes measure the time difference between upstream and downstream ultrasonic pulses, which correlates directly to volumetric blood flow.

Question 18: When performing ECPR on a patient with a known bleeding disorder (hemophilia A), the anticoagulation strategy should be modified to:

Replace UFH with bivalirudin and target lower ACT (Correct answer)
Switch to warfarin infusion
Use double-dose heparin to compensate for factor deficiency
Use no anticoagulation at all

Correct answer: Replace UFH with bivalirudin and target lower ACT

Bivalirudin avoids heparin resistance and allows direct thrombin inhibition while targeting a lower ACT to reduce bleeding risk in coagulopathic patients.

Question 19: What is the most common cause of heparin resistance in ECMO patients?

Elevated Factor VIII levels
Protein C deficiency
Antithrombin III deficiency (Correct answer)
High fibrinogen levels

Correct answer: Antithrombin III deficiency

Antithrombin III (AT III) deficiency is the most common cause of heparin resistance in ECMO patients, as heparin requires AT III to exert its anticoagulant effect.

Question 20: A patient fails multiple VA-ECMO weaning trials over 14 days. The ECMO team should next consider:

Switching to VV-ECMO to rest the heart further
Indefinite continuation of ECMO support
Increasing anticoagulation intensity to prevent circuit thrombosis
Evaluation for durable ventricular assist device implantation or heart transplantation (Correct answer)

Correct answer: Evaluation for durable ventricular assist device implantation or heart transplantation

Repeated weaning failure after 2 weeks indicates the heart is unlikely to recover; escalation to a durable VAD or transplant evaluation is the appropriate next step.

Question 21: What is the clinical significance of detecting a rising D-dimer trend in an ECMO patient whose ACT is therapeutic?

It confirms adequate fibrinolysis and circuit patency
It reflects normal heparin metabolism
It indicates heparin overdose
It may indicate developing circuit thrombosis or DIC requiring circuit inspection (Correct answer)

Correct answer: It may indicate developing circuit thrombosis or DIC requiring circuit inspection

Rising D-dimer despite therapeutic ACT suggests active thrombus formation and fibrinolysis within the circuit or patient vasculature, warranting urgent circuit inspection.

Question 22: What ventilator strategy is recommended for native lung protection during VV ECMO support?

Pressure-controlled ventilation targeting PaCO2 of 35–45 mmHg
High-frequency oscillatory ventilation as standard
Ultra-protective ventilation: low Vt (2–4 mL/kg), low rate, permissive hypercapnia (Correct answer)
High PEEP (18–22 cmH2O) with normal tidal volumes

Correct answer: Ultra-protective ventilation: low Vt (2–4 mL/kg), low rate, permissive hypercapnia

ECMO allows ultra-protective ventilation with very low tidal volumes and rates, minimizing ventilator-induced lung injury while the circuit maintains gas exchange.

Question 23: Polymethylpentene (PMP) hollow fiber oxygenators have largely replaced silicone membrane oxygenators in ECMO because PMP offers:

Higher heparin binding capacity
Lower cost of manufacture
Greater CO2 permeability at lower sweep flows
Lower resistance to blood flow and reduced plasma leakage (Correct answer)

Correct answer: Lower resistance to blood flow and reduced plasma leakage

PMP fibers are true diffusion membranes that minimize plasma leakage (weeping) while providing low resistance and efficient gas exchange.

Question 24: Which neonatal cardiac diagnosis most commonly requires ECMO support in the immediate post-operative period?

Coarctation of the aorta repair
Patent ductus arteriosus ligation
Atrial septal defect repair
Hypoplastic left heart syndrome (HLHS) after Norwood procedure (Correct answer)

Correct answer: Hypoplastic left heart syndrome (HLHS) after Norwood procedure

HLHS after Norwood palliation carries the highest rate of post-operative ECMO requirement due to single-ventricle physiology and complex hemodynamics.

Question 25: Why does the right ventricle typically dilate and fail before the left ventricle in massive pulmonary embolism requiring ECMO?

Pulmonary embolism directly damages RV myocardium via inflammatory mediators
The RV coronary supply is more vulnerable to ischemia than the LV
The RV free wall has less myocardium than the LV
Acute pulmonary vascular obstruction causes sudden RV pressure overload beyond its adaptive capacity (Correct answer)

Correct answer: Acute pulmonary vascular obstruction causes sudden RV pressure overload beyond its adaptive capacity

The RV is a thin-walled, low-pressure chamber not adapted to acute pressure loads; sudden obstruction of the pulmonary vascular bed raises RV afterload acutely, causing dilation, ischemia, and failure.

Question 26: Which of the following best explains why pulsatility is important to maintain during VA-ECMO support?

Non-pulsatile flow increases ECMO circuit thrombosis risk
Pulsatility improves oxygenator gas transfer efficiency
Pulsatility prevents oxygenator membrane fouling
Pulsatile flow preserves microvascular function and organ perfusion pressure waveforms (Correct answer)

Correct answer: Pulsatile flow preserves microvascular function and organ perfusion pressure waveforms

Pulsatile flow maintains physiologic microvascular tone and endothelial function; prolonged non-pulsatile VA-ECMO flow is associated with end-organ dysfunction.

Question 27: A patient on femoral VA ECMO for severe respiratory failure with secondary cardiac dysfunction begins to show signs of myocardial recovery. The monitor shows a right radial SpO2 of 88% while the lower extremity SpO2 is 99%. Which is the most appropriate initial intervention to manage this differential hypoxia (Harlequin syndrome)?

Administer a negative inotrope to suppress native cardiac function
Optimize mechanical ventilation by increasing FiO2 and PEEP (Correct answer)
Increase the ECMO pump flow to maximum to override native cardiac output
Immediately convert the patient to a Veno-Venous (VV) ECMO configuration

Correct answer: Optimize mechanical ventilation by increasing FiO2 and PEEP

Differential hypoxia occurs when a recovering left ventricle ejects poorly oxygenated blood (due to underlying lung disease) preferentially to the upper body and coronaries. The first-line management is to improve the oxygenation of the blood passing through the native lungs by optimizing ventilator settings, such as increasing the FiO2 and PEEP.

Question 28: In VA-ECMO, retrograde aortic flow from a femoral arterial cannula creates a 'mixing zone.' What determines where this zone is located?

Balance between native cardiac output and ECMO pump flow (Correct answer)
Patient's blood pressure only
Venous cannula position
Sweep gas flow rate

Correct answer: Balance between native cardiac output and ECMO pump flow

The mixing zone (where oxygenated ECMO blood meets desaturated native cardiac output) is determined by the balance between anterograde native cardiac flow and retrograde ECMO flow.

Question 29: Which finding would prompt the ECMO team to assess for heparin-induced thrombocytopenia (HIT) in an ECMO patient?

Arterial oxygen saturation below 90%
Hemoglobin drop below 9 g/dL
Platelet count falling by >50% from baseline despite adequate heparin (Correct answer)
Elevated lactate above 4 mmol/L

Correct answer: Platelet count falling by >50% from baseline despite adequate heparin

A platelet count drop of >50% from baseline in a heparin-exposed patient raises concern for HIT, which can cause paradoxical thrombosis requiring alternative anticoagulation.

Question 30: Which feeding approach is recommended for ECMO patients who are prone positional or have impaired gastric emptying?

Gastric feeding at high rates with prokinetic agents
Post-pyloric (small bowel) enteral feeding (Correct answer)
Total parenteral nutrition exclusively
Intermittent bolus gastric feeds

Correct answer: Post-pyloric (small bowel) enteral feeding

Post-pyloric feeding bypasses the stomach and is preferred when gastric emptying is impaired or prone positioning makes aspiration risk prohibitive.

Question 31: A patient on ECMO develops heparin-induced thrombocytopenia (HIT). Which anticoagulant is preferred as a replacement?

Argatroban or bivalirudin (Correct answer)
Warfarin
Fondaparinux
Low-molecular-weight heparin

Correct answer: Argatroban or bivalirudin

Direct thrombin inhibitors such as argatroban or bivalirudin are the preferred alternatives when HIT is confirmed during ECMO, as all heparin products must be avoided.

Question 32: In cardiogenic shock treated with VA ECMO, which laboratory value most directly reflects tissue oxygen delivery adequacy?

Arterial pH
Hemoglobin concentration
Mixed venous oxygen saturation (SvO2)
Serum lactate trend (Correct answer)

Correct answer: Serum lactate trend

Serial lactate trending is the most direct indicator of whether tissue oxygen delivery is adequate, with falling lactate confirming successful resuscitation.

Question 33: What is the theoretical advantage of using heparin-bonded ECMO circuits regarding anticoagulation management?

They prevent all forms of circuit clotting indefinitely
They provide therapeutic anticoagulation equivalent to full-dose heparin
They eliminate the need for systemic anticoagulation in all patients
They reduce circuit thrombogenicity, potentially allowing lower systemic heparin doses (Correct answer)

Correct answer: They reduce circuit thrombogenicity, potentially allowing lower systemic heparin doses

Heparin-bonded circuits reduce surface thrombogenicity, allowing some programs to use lower systemic heparin doses or, in select stable patients, brief anticoagulation-free periods.

Question 34: A 28-year-old patient with blunt chest trauma develops severe ARDS and requires VV ECMO. The patient has multiple rib fractures and a small, stable pulmonary contusion. The trauma team is concerned about bleeding risk. What is the most appropriate initial anticoagulation strategy for this patient?

Use a completely heparin-free circuit and monitor for signs of clotting.
Start a bivalirudin infusion as it has a more predictable response.
Withhold systemic anticoagulation for the first 24-48 hours while monitoring for bleeding. (Correct answer)
Initiate a standard heparin infusion with a target aPTT of 60-80 seconds.

Correct answer: Withhold systemic anticoagulation for the first 24-48 hours while monitoring for bleeding.

In trauma patients on ECMO, the risk of life-threatening hemorrhage often outweighs the risk of circuit thrombosis, especially in the early phase. A common approach is to withhold systemic anticoagulation for at least 24-48 hours, or until the sources of bleeding are controlled and the patient is stable. Modern heparin-bonded circuits can often tolerate this period without systemic anticoagulation.

Question 35: Which neurological assessment tool provides real-time detection of cerebral ischemia or seizure in ECMO patients?

Cranial CT scan
MRI brain
Lumbar puncture
Continuous EEG monitoring (Correct answer)

Correct answer: Continuous EEG monitoring

Continuous EEG is the gold standard for detecting subclinical seizures and ischemic changes in real time at the bedside in ECMO patients at neurological risk.

Question 36: Chatter (intermittent collapsing) of the venous drainage tubing is observed during ECMO. The FIRST corrective action is:

Reduce pump speed (Correct answer)
Increase intravascular volume with fluid administration
Reposition the venous cannula
Increase sweep gas flow

Correct answer: Reduce pump speed

Reducing pump speed immediately decreases the suction force causing venous collapse and chatter, which is the fastest corrective step before addressing the underlying cause.

Question 37: Which neurological monitoring tool is most commonly used at the bedside during neonatal ECMO?

Bispectral index (BIS)
Near-infrared spectroscopy (NIRS) (Correct answer)
Continuous EEG
Transcranial Doppler ultrasound

Correct answer: Near-infrared spectroscopy (NIRS)

NIRS is widely used during neonatal ECMO to continuously monitor cerebral regional oxygen saturation (rSO2) and detect neurological compromise non-invasively.

Question 38: Which of the following best describes the 'Y-connector' configuration used in some ECMO venous drainage setups?

A connector linking the pump to two oxygenators in parallel
A pressure-relief valve preventing circuit over-pressurization
Two drainage cannulas (femoral + jugular) joined to a single drainage limb to increase flow (Correct answer)
Two return cannulas feeding into one oxygenator

Correct answer: Two drainage cannulas (femoral + jugular) joined to a single drainage limb to increase flow

A Y-connector combines drainage from both femoral and jugular veins into a single line, increasing total venous return when one cannula is insufficient.

Question 39: What is the significance of the 'venous inlet pressure' (P-in) alarm during ECMO, and what does it indicate?

Highly negative P-in indicates inadequate venous return, risking cavitation and hemolysis (Correct answer)
P-in reflects oxygenator transmembrane pressure gradient
P-in measures arterial afterload on the pump
High P-in indicates circuit obstruction distal to the pump

Correct answer: Highly negative P-in indicates inadequate venous return, risking cavitation and hemolysis

A very negative inlet (drainage) pressure indicates hypovolemia, cannula malposition, or kinking, and can cause circuit cavitation, hemolysis, and 'chatter' (intermittent collapse of the venous line).

Question 40: Beyond the effects of administered anticoagulants, a significant contributor to the acquired coagulopathy in patients on ECMO is:

A deficiency of Vitamin K due to poor nutrition.
Continuous platelet activation and consumption due to shear stress and contact with circuit surfaces. (Correct answer)
An increase in circulating antithrombin produced in response to inflammation.
Hypothermia from the heat exchanger impairing clotting factor function.

Correct answer: Continuous platelet activation and consumption due to shear stress and contact with circuit surfaces.

The ECMO circuit itself induces a complex coagulopathy. The non-biologic surfaces and the high shear forces, particularly from the pump, cause continuous contact activation of the coagulation cascade and lead to platelet activation, consumption, and dysfunction. This state of 'consumptive coagulopathy' contributes significantly to both bleeding and thrombotic risks, independent of heparin therapy.

Question 41: Left ventricular distension (LV dilation) during VA-ECMO is most commonly managed by:

Increasing ECMO pump speed
LV venting via an Impella device or atrial septostomy (Correct answer)
Repositioning the arterial return cannula
Reducing sweep gas flow

Correct answer: LV venting via an Impella device or atrial septostomy

LV venting with an Impella or atrial septostomy decompresses the distended LV, reduces wall stress, and may improve myocardial recovery.

Question 42: When ECMO pump RPM is increased but flow does not increase proportionally, the most likely cause is:

Oxygenator membrane rupture
Pump head thrombosis or increased circuit resistance (Correct answer)
Excessive anticoagulation causing vasodilation
Venous cannula tip in the right ventricle

Correct answer: Pump head thrombosis or increased circuit resistance

Increased RPM without proportional flow increase suggests elevated circuit resistance, often from clot formation in the pump head or oxygenator.

Question 43: How does the 'oxygen transfer capacity' of an ECMO oxygenator change over time during prolonged use?

It decreases due to plasma leak, protein deposition, and thrombus formation (Correct answer)
It fluctuates based on blood flow rate only
It increases as the fibers become conditioned
It remains stable for the device's rated lifespan

Correct answer: It decreases due to plasma leak, protein deposition, and thrombus formation

Over time, plasma leakage through membrane pores, protein deposition, and thrombus formation on fibers progressively reduce the oxygenator's gas transfer efficiency.

Question 44: While assessing a patient on VA ECMO, a large bolus of air is accidentally introduced into the venous drainage line just before the pump. What is the most critical and immediate sequence of actions?

Clamp the arterial and venous lines, and take the patient completely off ECMO support. (Correct answer)
Place the patient in Trendelenburg and administer a fluid bolus.
Increase pump flow to push the air through the oxygenator quickly.
Decrease the sweep gas to zero and observe the circuit.

Correct answer: Clamp the arterial and venous lines, and take the patient completely off ECMO support.

The immediate, life-saving priority is to prevent the massive air bolus from being pumped to the patient, which would cause a catastrophic systemic air embolism. Clamping both lines and stopping the pump (taking the patient off support) isolates the circuit and contains the air. Subsequent steps would involve attempting to aspirate the air before cautiously resuming support.

Question 45: In VA ECMO, the 'mixing cloud' refers to:

Turbulence visible on ECMO circuit imaging
The zone in the aorta where ECMO and native cardiac output blood mix (Correct answer)
Air-blood interface in the oxygenator
Clot formation at the venous cannula tip

Correct answer: The zone in the aorta where ECMO and native cardiac output blood mix

The mixing cloud is the aortic zone where retrograde oxygenated ECMO blood meets antegrade native cardiac output; its position determines differential oxygenation.

Question 46: In VA ECMO, the drainage cannula is typically positioned in which location?

Right atrium via femoral vein (Correct answer)
Left atrium via transseptal puncture
Inferior vena cava at the hepatic vein level
Superior vena cava near the right atrium

Correct answer: Right atrium via femoral vein

The venous drainage cannula tip is ideally positioned at the right atrial/IVC junction via femoral vein to maximize venous return.

Question 47: A pediatric ECMO patient on heparin develops catheter-site bleeding with an ACT of 190 seconds and platelet count of 110,000/μL. What additional test helps identify platelet dysfunction as a contributor?

Platelet function assay (PFA-100) or TEG platelet mapping (Correct answer)
Anti-Xa level
Prothrombin time/INR
Fibrinogen level

Correct answer: Platelet function assay (PFA-100) or TEG platelet mapping

Platelet function assays or TEG platelet mapping can identify acquired platelet dysfunction from ECMO circuit exposure even when platelet count appears adequate.

Question 48: During VV ECMO, the sweep gas FiO2 is increased from 0.6 to 1.0 but CO2 remains elevated. What adjustment should be made?

Increase sweep gas flow rate (Correct answer)
Increase ECMO blood flow
Decrease ECMO blood flow
Switch to VA ECMO

Correct answer: Increase sweep gas flow rate

CO2 removal on ECMO is primarily determined by sweep gas flow rate (not FiO2), so increasing sweep gas flow enhances CO2 elimination.

Question 49: What is the recommended target activated clotting time (ACT) range for most adult VV ECMO patients using unfractionated heparin?

160–200 seconds (Correct answer)
280–320 seconds
120–140 seconds
220–260 seconds

Correct answer: 160–200 seconds

Most centers target an ACT of 160–200 seconds on VV ECMO, balancing thrombosis prevention against bleeding risk.

Question 50: Which factor most directly determines the maximum blood flow achievable in a VA ECMO circuit?

Venous cannula size and venous drainage (Correct answer)
Arterial cannula pressure rating
Patient's native cardiac output
Oxygenator membrane surface area

Correct answer: Venous cannula size and venous drainage

Venous drainage is the limiting factor in ECMO flow; the venous cannula size and position determine how much blood can be returned to the pump.

Question 51: What is 'chattering' of the ECMO circuit, and which cannula is most often implicated?

Intermittent venous line collapse due to inadequate preload at the drainage cannula (Correct answer)
Oxygenator membrane flutter from high sweep gas flows
Arterial cannula vibration causing hemolysis
Pump head vibration from air in the circuit

Correct answer: Intermittent venous line collapse due to inadequate preload at the drainage cannula

Chattering refers to cyclical collapse and re-expansion of the venous drainage line when the cannula cannot provide sufficient blood to the pump.

Question 52: During ECMO decannulation, protamine is administered to reverse heparin. What is the most feared complication of protamine administration?

Severe pulmonary hypertension and cardiovascular collapse (Correct answer)
Acute kidney injury from protein precipitation
Rebound anticoagulation 4–6 hours later
Prolonged thrombocytopenia lasting weeks

Correct answer: Severe pulmonary hypertension and cardiovascular collapse

Protamine can trigger complement activation, thromboxane release, and pulmonary vasoconstriction, causing acute severe pulmonary hypertension and cardiovascular collapse, especially in right-heart-failure patients.

Question 53: What is the physiological consequence of severe 'LV distension' that can occur during VA-ECMO, and how does it manifest clinically?

Reduced risk of arrhythmias due to decreased catecholamine release
Increased LV wall stress, subendocardial ischemia, pulmonary edema, and thrombus formation in the stagnant LV (Correct answer)
Decreased myocardial oxygen demand due to reduced wall tension
Improved coronary perfusion from elevated aortic root pressure

Correct answer: Increased LV wall stress, subendocardial ischemia, pulmonary edema, and thrombus formation in the stagnant LV

LV distension from afterload increase and blood accumulation raises wall stress and myocardial oxygen demand, worsens pulmonary edema, and creates stagnant LV blood prone to thrombus formation.

Question 54: When Continuous Renal Replacement Therapy (CRRT) is integrated into the ECMO circuit, where are the access and return lines typically placed to minimize risks of air embolism and circuit pressure disturbances?

Access post-pump (pre-oxygenator), return pre-pump (in the venous drainage line) (Correct answer)
Access pre-pump, return post-oxygenator
Access post-oxygenator, return post-oxygenator
Access post-pump, return pre-pump

Correct answer: Access post-pump (pre-oxygenator), return pre-pump (in the venous drainage line)

The safest and most common configuration is to access blood from a positive-pressure area of the circuit (post-pump, but before the oxygenator) and return it to a negative-pressure area (pre-pump, on the venous drainage line). Drawing from a positive pressure area prevents air from being entrained into the circuit if a connection becomes loose. Returning to the low-pressure venous line minimizes the resistance the CRRT machine must pump against, preventing alarms and circuit disruption.

Question 55: What is the primary reason aPTT is considered an inferior monitoring tool compared to anti-Xa for heparin dosing in ECMO?

aPTT cannot detect heparin levels above 0.3 IU/mL
aPTT requires arterial blood sampling
aPTT is affected by many non-heparin variables including factor deficiencies and acute phase reactants (Correct answer)
Anti-Xa testing is faster and cheaper

Correct answer: aPTT is affected by many non-heparin variables including factor deficiencies and acute phase reactants

aPTT is influenced by multiple variables common in ECMO patients — factor consumption, lupus anticoagulant, elevated factor VIII — making it an unreliable surrogate for heparin effect.

Question 56: A VV ECMO patient's sweep gas accidentally becomes disconnected for 3 minutes. What is the expected physiologic consequence?

No significant change if native lung function is partial
Hypoxemia only with compensatory respiratory alkalosis
Rapid hypoxemia and hypercapnia (Correct answer)
Hypercapnia only with maintained oxygenation

Correct answer: Rapid hypoxemia and hypercapnia

Loss of sweep gas eliminates both O2 transfer and CO2 removal across the membrane, causing rapid hypoxemia and hypercapnia.

Question 57: What is the significance of a widening pulse pressure on the arterial line of a VA ECMO patient over 48 hours?

Worsening aortic regurgitation from the arterial cannula
Sepsis-induced peripheral vasodilation
Circuit recirculation causing venous mixing
Evidence of myocardial recovery with improving native cardiac output (Correct answer)

Correct answer: Evidence of myocardial recovery with improving native cardiac output

Widening pulse pressure indicates the native heart is generating increasing stroke volume, which is a positive sign of myocardial recovery during VA ECMO.

Question 58: A visible clot is noted in the ECMO tubing near the pump head. The appropriate immediate action is to:

Increase pump speed to dislodge the clot
Administer tPA through the circuit
Clamp the circuit and prepare for emergency circuit change (Correct answer)
Increase heparin infusion rate and continue monitoring

Correct answer: Clamp the circuit and prepare for emergency circuit change

A visible thrombus in the circuit poses an immediate risk of systemic embolism or pump failure, requiring circuit change rather than acceleration.

Question 59: After successful decannulation from VA-ECMO, anticoagulation management typically involves:

High-dose heparin infusion for 48 hours to prevent rebound thrombosis
Continuation of therapeutic anticoagulation per underlying cardiac condition and thromboembolic risk (Correct answer)
Transition to antiplatelet therapy only, regardless of underlying condition
Immediate discontinuation of all anticoagulation for 72 hours

Correct answer: Continuation of therapeutic anticoagulation per underlying cardiac condition and thromboembolic risk

Post-decannulation anticoagulation is individualized based on the underlying cardiac pathology, residual thrombus risk, and bleeding status.

Question 60: Which hemodynamic finding on a pulmonary artery catheter would indicate left ventricular distension in a VA-ECMO patient?

Low pulmonary capillary wedge pressure (PCWP)
High PCWP with low cardiac output (Correct answer)
High mixed venous saturation only
Low central venous pressure

Correct answer: High PCWP with low cardiac output

Elevated PCWP with low native cardiac output in VA-ECMO indicates LV distension from afterload mismatch, potentially requiring LV unloading.

Question 61: What is the standard ICU blood glucose target for ECMO patients receiving insulin infusion therapy?

60–100 mg/dL
140–180 mg/dL (Correct answer)
180–220 mg/dL
100–140 mg/dL

Correct answer: 140–180 mg/dL

Current critical care guidelines recommend targeting blood glucose of 140–180 mg/dL to balance glycemic control with hypoglycemia risk.

Question 62: What is the primary purpose of the 'blender' on the sweep gas inlet of a VV ECMO oxygenator?

To control the FiO2 of sweep gas for oxygenation regulation (Correct answer)
To mix blood with anticoagulant before it enters the membrane
To regulate sweep gas pressure to avoid barotrauma
To humidify sweep gas and prevent membrane desiccation

Correct answer: To control the FiO2 of sweep gas for oxygenation regulation

The sweep gas blender adjusts oxygen concentration (FiO2) to regulate the amount of oxygen transferred across the membrane to the blood.

Question 63: Which ECMO parameter directly reflects the efficiency of the membrane oxygenator's gas exchange capacity?

Inlet pressure (P-inlet)
Post-oxygenator PaO2 and PaCO2 (Correct answer)
ECMO blood flow rate (L/min)
Sweep gas FiO2 setting

Correct answer: Post-oxygenator PaO2 and PaCO2

Post-oxygenator blood gas values directly measure how effectively the membrane is transferring oxygen and removing CO2 from the blood passing through it.

Question 64: What term describes ECMO support initiated specifically to support a patient through a reversible cause of cardiac arrest when conventional CPR has failed?

LVAD bridging
Bridge-to-recovery ECMO
Resuscitative ECMO
ECPR (Extracorporeal CPR) (Correct answer)

Correct answer: ECPR (Extracorporeal CPR)

ECPR is the specific term for VA-ECMO deployed as an adjunct to conventional CPR for refractory cardiac arrest.

Question 65: Nitric oxide (NO) can be administered to ECMO patients by delivering it through which component of the circuit?

The arterial return cannula
The sweep gas inlet of the oxygenator (Correct answer)
The venous drainage cannula
The hemofilter port

Correct answer: The sweep gas inlet of the oxygenator

Inhaled nitric oxide can be blended into the sweep gas of the ECMO oxygenator to achieve selective pulmonary vasodilation.

Question 66: A VA ECMO patient's ACT target is typically maintained between:

220–280 seconds
160–200 seconds (Correct answer)
100–140 seconds
300–360 seconds

Correct answer: 160–200 seconds

ACT is generally maintained at 160–200 seconds on VA ECMO to balance thrombosis prevention against bleeding risk.

Question 67: Which finding on echocardiography is most indicative of a properly functioning ECMO circuit with adequate unloading of the right ventricle in VV-ECMO?

Reduced RV dilation and improved septal position (Correct answer)
Hyperdynamic LV function
Mitral regurgitation
Pericardial effusion

Correct answer: Reduced RV dilation and improved septal position

In VV-ECMO, improving RV dilation and restoration of normal interventricular septal position indicate reduced RV afterload from improved oxygenation and CO2 removal.

Question 68: What is the primary mechanism by which bivalirudin anticoagulates ECMO patients?

Blocking platelet ADP receptors
Directly and reversibly inhibiting free and clot-bound thrombin (Correct answer)
Inhibiting vitamin K-dependent factor synthesis
Activating antithrombin III to inhibit thrombin

Correct answer: Directly and reversibly inhibiting free and clot-bound thrombin

Bivalirudin is a direct thrombin inhibitor that binds both free and fibrin-bound thrombin directly without requiring antithrombin as a cofactor.

Question 69: In a patient on peripheral VA-ECMO, which monitoring site best reflects cerebral oxygenation?

Central venous oxygen saturation
Pulse oximetry on the left foot
Femoral arterial line (ECMO return side)
Right radial arterial blood gas (pre-mixing zone) (Correct answer)

Correct answer: Right radial arterial blood gas (pre-mixing zone)

The right radial artery reflects blood ejected from the native heart before it mixes with retrograde ECMO flow, providing the best estimate of oxygen delivery to the brain and coronary arteries.

Question 70: Which parameter best reflects native cardiac recovery during VA ECMO weaning trials?

Pulse pressure amplitude on arterial waveform (Correct answer)
Mean arterial pressure at full ECMO flow
Central venous oxygen saturation
ECMO pump RPM

Correct answer: Pulse pressure amplitude on arterial waveform

Increasing pulse pressure amplitude on the arterial waveform indicates the native heart is generating stroke volume, a key sign of myocardial recovery.

Question 71: In VA-ECMO, pulse pressure monitoring on the arterial line is used to assess:

Anticoagulation adequacy
Venous cannula position
Native cardiac contractility and LV ejection (Correct answer)
Oxygenator efficiency

Correct answer: Native cardiac contractility and LV ejection

Progressive widening of pulse pressure on the arterial waveform during VA-ECMO indicates improving native LV systolic function, a sign of cardiac recovery.

Question 72: A patient on peripheral VA ECMO develops limb ischemia in the cannulated leg. What is the primary intervention?

Increase ECMO flow to improve perfusion
Administer IV heparin bolus and observe
Switch to central cannulation immediately
Place a distal perfusion cannula in the superficial femoral artery (Correct answer)

Correct answer: Place a distal perfusion cannula in the superficial femoral artery

A distal perfusion cannula (DPC) inserted antegrade into the superficial femoral artery restores distal limb perfusion while maintaining ECMO support.

Question 73: Which echocardiographic finding during a VA-ECMO weaning trial would most strongly support proceeding to decannulation?

Left ventricular ejection fraction of 15%
LVEF ≥ 35% with no severe valvular abnormality (Correct answer)
Right ventricular free wall akinesis
Severe mitral regurgitation with LA dilation

Correct answer: LVEF ≥ 35% with no severe valvular abnormality

LVEF ≥ 35% without severe valvular disease suggests sufficient cardiac reserve to sustain circulation without ECMO support.

Question 74: Which ECMO circuit component is responsible for removing CO2 from the patient's blood?

Oxygenator membrane (Correct answer)
Centrifugal pump
Servo-regulation sensor
Bladder reservoir

Correct answer: Oxygenator membrane

The oxygenator membrane facilitates both oxygen delivery and CO2 removal via diffusion across hollow fiber membranes.

Question 75: Air is detected in the ECMO circuit approaching the patient. The immediate response is to:

Clamp the arterial limb and stop the pump immediately (Correct answer)
Tilt the patient into Trendelenburg position
Increase pump speed to push the air through quickly
Administer 100% FiO2 to absorb the air

Correct answer: Clamp the arterial limb and stop the pump immediately

Clamping the arterial limb and stopping the pump immediately prevents air from entering the patient's circulation and causing a fatal air embolism.

Question 76: Milrinone is sometimes used in ECMO patients because it improves cardiac function by:

Directly stimulating myocardial calcium channels
Activating alpha-adrenergic receptors to increase afterload
Inhibiting phosphodiesterase III to increase cAMP and improve contractility with vasodilation (Correct answer)
Blocking beta-receptors to reduce myocardial oxygen demand

Correct answer: Inhibiting phosphodiesterase III to increase cAMP and improve contractility with vasodilation

Milrinone's PDE-III inhibition raises intracellular cAMP, producing positive inotropy and systemic vasodilation, useful for low cardiac output states.

Question 77: Which coagulation factor is most significantly consumed during ECMO due to continuous contact with the circuit surface?

Fibrinogen (Correct answer)
Factor VIII
Factor V
Factor XIII

Correct answer: Fibrinogen

Fibrinogen is rapidly consumed during ECMO due to adsorption onto circuit surfaces and ongoing fibrinolysis, making it a critical monitoring parameter.

Question 78: During routine monitoring of a patient on VV ECMO, you observe 'chatter' or visible shaking in the venous drainage line, and the ECMO flow has intermittently decreased. Which of the following is the LEAST likely cause of this issue?

Increased sweep gas flow (Correct answer)
Hypovolemia or inadequate preload
Excessive pump RPM settings
Cannula migration against a vessel wall

Correct answer: Increased sweep gas flow

Chatter in the venous access line indicates access insufficiency, where the pump is trying to drain more blood than is available, causing the vein to collapse around the cannula. This can be caused by hypovolemia, excessive pump speed, or the cannula tip being positioned against a vessel wall. Sweep gas flow is related to gas exchange (CO2 removal) within the oxygenator and does not directly impact venous drainage or cause access insufficiency.

Question 79: Which of the following is a primary advantage of using a central cannulation strategy (e.g., aortic and right atrial cannulation) for VA ECMO compared to a peripheral (femoral) strategy?

It provides antegrade aortic flow, reducing the risk of differential hypoxia. (Correct answer)
It is associated with a lower risk of bleeding complications.
It can be performed more quickly at the bedside in an emergency.
It carries a lower risk of stroke and neurological complications.

Correct answer: It provides antegrade aortic flow, reducing the risk of differential hypoxia.

Central VA ECMO returns oxygenated blood directly to the ascending aorta, ensuring it travels antegrade to the coronary arteries and the great vessels supplying the brain. This avoids differential hypoxia (Harlequin syndrome), where the upper body receives poorly oxygenated blood from the native heart while the lower body is well-perfused by the ECMO circuit.

Question 80: In ECMO-supported patients, why does targeting a higher hemoglobin (>10 g/dL) improve oxygen delivery more efficiently than increasing pump flow alone?

Hemoglobin acts as a buffer preventing acidosis during high-flow states
High hemoglobin reduces recirculation fraction in VV-ECMO
Oxygen content is linearly related to hemoglobin concentration; each g/dL increase augments DO2 proportionally without the adverse pressure effects of higher pump flow (Correct answer)
Higher hemoglobin reduces blood viscosity, lowering pump workload

Correct answer: Oxygen content is linearly related to hemoglobin concentration; each g/dL increase augments DO2 proportionally without the adverse pressure effects of higher pump flow

Since DO2 = CO × CaO2 and CaO2 depends directly on hemoglobin, optimizing hemoglobin increases oxygen delivery without raising pump speed, which carries risks of hemolysis and afterload elevation.

Question 81: What is the Seldinger technique in the context of ECMO cannulation?

Direct surgical cutdown and cannula insertion under direct visualization
Needle puncture followed by guidewire insertion, then cannula advancement over the wire (Correct answer)
Cannula insertion using a sheath-based rapid deployment system
Two-stage dilation using balloon angioplasty

Correct answer: Needle puncture followed by guidewire insertion, then cannula advancement over the wire

The Seldinger technique involves placing a guidewire through an introducer needle, then advancing dilators and ultimately the cannula over the wire.

Question 82: Which characteristic of a wire-reinforced ECMO cannula reduces the risk of circuit failure?

The wire increases electrical conductivity for flow sensing
The wire coating increases biocompatibility
Wire reinforcement increases cannula rigidity to prevent malposition
The reinforcement prevents kinking under bending or positional changes (Correct answer)

Correct answer: The reinforcement prevents kinking under bending or positional changes

Wire reinforcement maintains cannula lumen patency under compression or bending, preventing flow interruption from kinking.

Question 83: After surgical decannulation of a femoral venous cannula, the preferred method for achieving hemostasis at the venous access site in a fully anticoagulated patient is:

Immediate removal of anticoagulation and surgical cut-down closure
Manual pressure for 30–45 minutes followed by a pressure dressing (Correct answer)
Deployment of a vascular closure device
Suture ligation of the femoral vein

Correct answer: Manual pressure for 30–45 minutes followed by a pressure dressing

Sustained manual compression for 30–45 minutes is standard practice for venous cannula sites, followed by a firm pressure dressing.

Question 84: Which metabolic disturbance is most commonly associated with ECMO-induced systemic inflammatory response?

Hypoglycemia
Hyponatremia
Hyperglycemia (Correct answer)
Hypercalcemia

Correct answer: Hyperglycemia

The systemic inflammatory response triggered by contact activation during ECMO promotes insulin resistance and stress hyperglycemia, making it the most common metabolic disturbance.

Question 85: In a VV ECMO patient with acute respiratory distress syndrome (ARDS), what respiratory quotient (RQ) target from indirect calorimetry suggests optimal substrate utilization?

RQ = 0.7 exactly
RQ 0.85–1.0 (Correct answer)
RQ < 0.7
RQ > 1.0

Correct answer: RQ 0.85–1.0

An RQ of 0.85–1.0 indicates balanced substrate oxidation of carbohydrates and fats, while RQ > 1.0 suggests overfeeding and net lipogenesis, increasing CO2 production.

Question 86: How should nutritional support be adjusted when an ECMO patient is transitioned from the acute inflammatory phase to the recovery phase?

Reduce protein intake to 0.8 g/kg/day to prevent uremia
Switch entirely to parenteral nutrition to ensure reliability
Restrict carbohydrates below 100 g/day to prevent hyperglycemia
Advance to full caloric targets and maintain high protein to support anabolism and rehabilitation (Correct answer)

Correct answer: Advance to full caloric targets and maintain high protein to support anabolism and rehabilitation

During the recovery phase, patients shift from catabolism to anabolism, and advancing to full caloric and protein targets supports muscle repair, weaning, and functional recovery.

Question 87: What is the significance of 'delta ACT' monitoring during ECMO circuit change-out?

It measures the time to re-prime the new circuit with blood
It detects the ACT drop when blood contacts the new uncoated circuit surface (Correct answer)
It monitors heparin washout from the old circuit
It guides protamine dosing after decannulation

Correct answer: It detects the ACT drop when blood contacts the new uncoated circuit surface

When blood contacts a new circuit surface, ACT drops as heparin is temporarily adsorbed and consumed, requiring a heparin bolus to re-establish therapeutic anticoagulation.

Question 88: When should anticoagulation be withheld or minimized during VA ECMO?

During echocardiographic assessment
During routine daily care
In the presence of active life-threatening hemorrhage (Correct answer)
When lactate levels are elevated

Correct answer: In the presence of active life-threatening hemorrhage

Active life-threatening hemorrhage may require temporarily reducing or withholding anticoagulation despite the risk of circuit thrombosis.

Question 89: A VA-ECMO patient on 80% support develops left ventricular distension on echocardiogram with worsening pulmonary edema. The preferred intervention is:

Increase ECMO flows to further unload the heart
Initiate aggressive diuresis alone
Reduce ECMO flows to allow more native ejection
Place an Impella or intra-aortic balloon pump for LV venting (Correct answer)

Correct answer: Place an Impella or intra-aortic balloon pump for LV venting

LV distension on VA-ECMO results from increased afterload and inadequate LV ejection; adding a direct LV vent such as an Impella or IABP is the definitive treatment.

Question 90: After decannulation from VV-ECMO, the patient develops hoarseness and difficulty swallowing. The most likely etiology related to the ECMO procedure is:

Phrenic nerve injury from left internal jugular cannulation
Esophageal perforation during transesophageal echocardiography
Tracheal stenosis from prolonged intubation
Recurrent laryngeal nerve injury or vocal cord dysfunction related to right internal jugular cannulation (Correct answer)

Correct answer: Recurrent laryngeal nerve injury or vocal cord dysfunction related to right internal jugular cannulation

The recurrent laryngeal nerve passes near the right internal jugular vein and can be injured during cannulation or decannulation, causing hoarseness.

Question 91: Which cannula configuration is used in VV-ECMO with a single dual-lumen cannula?

Pulmonary artery to left atrium
Bicaval dual-lumen cannula inserted via the internal jugular vein (Correct answer)
Femoral artery to femoral vein
Right atrium to ascending aorta

Correct answer: Bicaval dual-lumen cannula inserted via the internal jugular vein

The Avalon or similar bicaval dual-lumen cannulas are placed via the right internal jugular vein, with drainage from both caval veins and return to the right atrium.

Question 92: A VV ECMO patient on lung-rest ventilation (Vt 2–3 mL/kg, rate 10) suddenly desaturates to 70%. ECMO flows are unchanged at 5 L/min. What is the most important immediate assessment?

Assess cannula position and circuit for obstruction (Correct answer)
Check for pneumothorax with chest X-ray
Immediately increase ventilator FiO2 to 1.0
Check for oxygenator failure by measuring post-membrane pO2

Correct answer: Assess cannula position and circuit for obstruction

Sudden desaturation with unchanged ECMO flows suggests acute cannula malposition, kinking, or obstruction reducing effective circuit flow.

Question 93: Which anticoagulant is used as an alternative to heparin in patients with heparin-induced thrombocytopenia (HIT) on ECMO?

Bivalirudin (a direct thrombin inhibitor) (Correct answer)
Fondaparinux (a factor Xa inhibitor)
Warfarin (a vitamin K antagonist)
Clopidogrel (a P2Y12 inhibitor)

Correct answer: Bivalirudin (a direct thrombin inhibitor)

Bivalirudin is the preferred anticoagulant alternative for ECMO patients with HIT because it directly inhibits thrombin and has a short half-life allowing rapid titration.

Question 94: How does increasing ECMO blood flow affect plasma-free hemoglobin levels?

Higher flows reduce hemolysis by decreasing turbulence at the pump inlet
Higher flows decrease hemolysis by reducing suction pressure on red cells
Flow rate has no effect; hemolysis depends entirely on anticoagulation status
Hemolysis increases with higher rpm as centrifugal pump shear stress rises proportionally (Correct answer)

Correct answer: Hemolysis increases with higher rpm as centrifugal pump shear stress rises proportionally

Centrifugal pump rpm and shear forces increase with flow; higher shear stress exceeds red cell membrane tolerance, causing progressive mechanical hemolysis that correlates with pump speed.

Question 95: How does the dissolved oxygen (Henry's Law) contribute to ECMO oxygenation at very high FiO2 sweep gas settings?

Dissolved O2 increases linearly with partial pressure, providing meaningful additional O2 delivery (Correct answer)
Dissolved O2 exceeds hemoglobin-bound O2 at FiO2 >0.8
Dissolved O2 contributes only to CO2 removal, not oxygenation
Dissolved O2 becomes negligible at high FiO2

Correct answer: Dissolved O2 increases linearly with partial pressure, providing meaningful additional O2 delivery

At high PaO2 values achievable via ECMO at FiO2 1.0, dissolved oxygen (0.003 mL/mmHg/dL) contributes meaningfully to total oxygen content, especially in severely anemic patients.

Question 96: In pediatric ECPR, which circuit component is most commonly downsized compared to adult configurations?

The oxygenator membrane surface area (Correct answer)
The heat exchanger
The sweep gas inlet
The centrifugal pump head size

Correct answer: The oxygenator membrane surface area

Pediatric ECPR uses smaller oxygenator membrane surface areas to match the lower blood flow requirements and reduce prime volume.

Question 97: Inlet pressure (P-in) monitoring on the venous drainage limb of ECMO is important because extreme negative pressures can cause:

Oxygenator plasma leakage
Arterial hypertension and increased cardiac afterload
Hyperthermia from increased pump work
Hemolysis, cavitation, and venous collapse around the cannula tip (Correct answer)

Correct answer: Hemolysis, cavitation, and venous collapse around the cannula tip

Excessive negative suction pressures on the venous drainage side cause red cell destruction, gas bubble formation (cavitation), and vessel wall collapse at the cannula.

Question 98: During VV ECMO, a patient develops acute hemolysis (plasma-free hemoglobin >500 mg/dL). What is the FIRST action?

Start plasmapheresis
Inspect the circuit for thrombus, kinks, or high negative inlet pressure (Correct answer)
Increase ECMO flow to reduce shear stress
Administer intravenous haptoglobin

Correct answer: Inspect the circuit for thrombus, kinks, or high negative inlet pressure

Hemolysis on ECMO is often caused by mechanical factors (thrombus, kinking, cavitation from excessive negative pressure), which must be identified and corrected first.

Question 99: Which hemodynamic goal during a VA-ECMO weaning trial best predicts successful decannulation?

Heart rate < 60 bpm with no vasopressor support
CVP < 5 mmHg and PCWP < 8 mmHg at full flow
Maintaining MAP > 65 mmHg on low-dose vasopressors with ECMO flow ≤ 1.5 L/min (Correct answer)
MAP > 80 mmHg on high-dose norepinephrine at full ECMO flow

Correct answer: Maintaining MAP > 65 mmHg on low-dose vasopressors with ECMO flow ≤ 1.5 L/min

Hemodynamic stability with minimal vasopressor support at low ECMO flows demonstrates sufficient native cardiac output to sustain perfusion.

Question 100: Which lab finding most strongly suggests successful ECPR resuscitation and adequate end-organ perfusion?

Falling serum lactate over 4–6 hours (Correct answer)
Rising white blood cell count
Increasing creatinine
Stable hematocrit

Correct answer: Falling serum lactate over 4–6 hours

A downward trend in serum lactate is the most reliable indicator of restored oxygen delivery and end-organ recovery after ECPR.

Question 101: In VA-ECMO, how does left ventricular (LV) afterload change compared to a patient without ECMO support?

LV afterload fluctuates with sweep gas adjustments
LV afterload increases because retrograde ECMO flow opposes ventricular ejection (Correct answer)
LV afterload decreases due to blood volume offloading
LV afterload is unchanged since ECMO bypasses the left heart

Correct answer: LV afterload increases because retrograde ECMO flow opposes ventricular ejection

Retrograde aortic flow from femoral VA-ECMO increases LV afterload, which can worsen LV distension and pulmonary edema in patients with severely impaired LV function.

Question 102: What does a persistently elevated pulmonary artery pressure on VA ECMO most likely indicate?

LV distension due to insufficient venting (Correct answer)
Circuit recirculation
Pulmonary embolism unrelated to ECMO
Adequate LV unloading

Correct answer: LV distension due to insufficient venting

Elevated PA pressures on VA ECMO suggest the left ventricle is distending because it cannot eject against the increased afterload imposed by the circuit.

Question 103: Which of the following findings is the most reliable indicator of sufficient myocardial recovery to begin a weaning trial from VA ECMO?

The ability to decrease the sweep gas flow to zero without a rise in PaCO2
A chest X-ray showing resolution of pulmonary edema
Normalization of the patient's body temperature and white blood cell count
Consistent arterial line pulsatility and an LV outflow tract VTI > 10 cm on echocardiography (Correct answer)

Correct answer: Consistent arterial line pulsatility and an LV outflow tract VTI > 10 cm on echocardiography

The primary goal of VA ECMO is cardiac support. The most reliable signs of cardiac recovery are the heart's ability to generate its own effective stroke volume. This is demonstrated by a return of consistent pulsatility on the arterial waveform and objective echocardiographic measures like the left ventricular outflow tract velocity time integral (LVOT VTI), with a value >10 cm indicating readiness to wean.

Question 104: A child on neonatal ECMO develops seizures. In addition to anticonvulsant therapy, the priority ECMO-related concern is:

Changing to a higher-capacity oxygenator
Evaluating for intracranial hemorrhage and adjusting anticoagulation (Correct answer)
Switching from VV to VA configuration
Increasing ECMO flow to improve cerebral perfusion

Correct answer: Evaluating for intracranial hemorrhage and adjusting anticoagulation

Seizures in neonatal ECMO patients frequently indicate intracranial hemorrhage, which requires urgent neuroimaging and anticoagulation reassessment.

Question 105: Which patient position is generally preferred during VV ECMO to optimize oxygenation in refractory ARDS?

Trendelenburg
Supine with head of bed at 30°
Lateral decubitus on the right side
Prone positioning (Correct answer)

Correct answer: Prone positioning

Prone positioning improves V/Q matching and recruits dorsal lung regions, complementing VV ECMO support in refractory ARDS.

Question 106: A patient with morbid obesity (BMI 55) requires ECPR. What circuit modification is most commonly necessary?

Larger cannula sizes with higher flow-rated tubing (Correct answer)
Removal of the heat exchanger
Smaller oxygenator to reduce resistance
Reduced heparin dosing

Correct answer: Larger cannula sizes with higher flow-rated tubing

Morbidly obese patients require larger cannulas and higher flow-rated tubing to achieve adequate perfusion for their increased body mass.

Question 107: What is the typical target activated clotting time (ACT) range during standard ECMO anticoagulation?

300–400 seconds
60–80 seconds
180–220 seconds (Correct answer)
90–120 seconds

Correct answer: 180–220 seconds

Most ECMO centers target an ACT of 180–220 seconds to balance thrombosis prevention in the circuit against bleeding risk in the patient.

Question 108: Which neuromuscular blocking agent is preferred for paralysis in VV-ECMO patients with severe ARDS?

Pancuronium
Rocuronium
Succinylcholine
Cisatracurium (Correct answer)

Correct answer: Cisatracurium

Cisatracurium is preferred in severe ARDS on ECMO because it undergoes Hofmann elimination independent of organ function and has fewer cardiovascular side effects.

Question 109: Following a circuit change for oxygenator failure, the ECMO specialist notes the new circuit's post-membrane pO2 is 500 mmHg on FiO2 1.0. This confirms:

Recirculation is now occurring
Excessive sweep gas is causing hypocapnia
The new oxygenator is functioning appropriately (Correct answer)
The patient has developed a pneumothorax

Correct answer: The new oxygenator is functioning appropriately

A post-membrane pO2 of approximately 500 mmHg on 100% FiO2 is the expected result of a fully functional oxygenator, confirming successful circuit exchange.

Question 110: What does ECMO treat?

ECMO is a permanent solution for severe heart failure
ECMO is a temporary support system while the underlying issue is addressed (Correct answer)
ECMO treats respiratory diseases exclusively
ECMO treats specific cardiac conditions directly

Correct answer: ECMO is a temporary support system while the underlying issue is addressed

Explanation: <br> ECMO does not actually “treat” anything. ECMO is used as a bridge to fix the actual problem. ECMO buys you time to figure out what is killing your patient. In some cases, it buys the patient time to heal. Sometimes, our patient’s lungs just need a break. For example, when used during refractory V-fib arrest treatment, it allows us to support the patient and oxygenate the brain while we take the patient to the cath lab to hopefully unblock one of the coronary arteries. It acts as a bridge and buys more time to solve the problem.

Question 111: A previously anticoagulated ECMO patient requires decannulation but has an INR of 3.2 and platelet count of 45,000/µL. What is the most appropriate preparatory step?

Correct coagulopathy with fresh frozen plasma and platelets before decannulation, targeting INR < 1.5 and platelets > 80,000/µL (Correct answer)
Proceed immediately; coagulopathy does not affect surgical decannulation safety
Administer protamine alone and proceed to decannulation
Delay decannulation for 7 days until coagulopathy resolves spontaneously

Correct answer: Correct coagulopathy with fresh frozen plasma and platelets before decannulation, targeting INR < 1.5 and platelets > 80,000/µL

Correcting coagulopathy before decannulation reduces the risk of life-threatening hemorrhage at cannula removal sites.

Question 112: During ECMO, which laboratory test specifically assesses fibrinolytic activity and can detect hyperfibrinolysis?

Anti-Xa level
Platelet aggregation study
Activated partial thromboplastin time (aPTT)
Thromboelastography (TEG) lysis index (Correct answer)

Correct answer: Thromboelastography (TEG) lysis index

TEG/ROTEM provides a lysis index (LY30 or ML) that quantifies clot lysis over time, directly detecting hyperfibrinolysis in ECMO patients.

Question 113: What is the primary concern with administering lipid emulsions (as part of parenteral nutrition) to ECMO patients?

Lipids cause hemolysis by altering red cell membrane fluidity
Lipid emulsions cause vasospasm at the cannulation site
Lipid particles can coat and degrade the oxygenator membrane, reducing gas transfer efficiency (Correct answer)
Lipids bind to heparin and reduce anticoagulation efficacy

Correct answer: Lipid particles can coat and degrade the oxygenator membrane, reducing gas transfer efficiency

Fat emulsion particles can deposit on the oxygenator membrane and circuit components, degrading gas transfer performance and potentially clogging the circuit.

Question 114: A patient on VA-ECMO for cardiogenic shock shows improving echo function. The correct weaning strategy involves:

Transitioning to VV-ECMO before decannulation
Increasing vasopressor doses before reducing ECMO flow
Abruptly stopping ECMO and observing hemodynamics
Gradually reducing ECMO flow while monitoring hemodynamic parameters and echo (Correct answer)

Correct answer: Gradually reducing ECMO flow while monitoring hemodynamic parameters and echo

VA-ECMO is weaned by stepwise flow reductions with concurrent hemodynamic and echocardiographic monitoring to confirm the heart can sustain adequate output.

Question 115: What does the 'clot amplitude at 10 minutes' (CA10) on ROTEM primarily reflect in ECMO patients?

Fibrinolytic activity only
Heparin concentration
Antithrombin levels
Platelet function and fibrin polymerization (Correct answer)

Correct answer: Platelet function and fibrin polymerization

CA10 on ROTEM reflects the combined contribution of platelet function and fibrin polymerization to clot strength at 10 minutes after clotting begins.

Question 116: After a successful ECMO decannulation, a patient develops a large hematoma at the femoral cannulation site. The initial management is:

Return to ECMO to restore hemostasis
Administration of thrombolytics to dissolve the hematoma
Manual compression and correction of any coagulopathy (Correct answer)
Immediate surgical re-exploration

Correct answer: Manual compression and correction of any coagulopathy

Post-decannulation hematomas are first managed with sustained manual compression and correction of underlying coagulopathy before escalating to surgical intervention.

Question 117: Cerebral regional oxygen saturation (rSO2) measured by NIRS falls below 50% in an ECMO patient. The first intervention should be:

Increase vasopressor dose
Perform emergent head CT
Discontinue sedation
Assess and optimize ECMO flow, MAP, hemoglobin, and arterial CO2 (Correct answer)

Correct answer: Assess and optimize ECMO flow, MAP, hemoglobin, and arterial CO2

A rSO2 below 50% signals cerebral oxygen debt; optimizing DO2 determinants — ECMO flow, mean arterial pressure, hemoglobin, and PaCO2 — is the first-line response.

Question 118: A patient on a stable femoro-jugular VV ECMO configuration for severe pneumonia develops acute hypoxemia (SpO2 drops from 95% to 86%). The ECMO circuit is functioning well, with a high post-oxygenator PaO2 and no signs of recirculation. Which patient-related factor is the most likely cause of this deterioration?

Migration of the reinfusion cannula.
A decrease in the sweep gas flow rate.
Development of oxygenator membrane failure.
A sudden increase in the patient's native cardiac output. (Correct answer)

Correct answer: A sudden increase in the patient's native cardiac output.

In VV ECMO, the patient's arterial oxygenation is determined by the mixture of oxygenated blood from the ECMO circuit and the deoxygenated blood that passes through the native lungs (shunt). If the patient's cardiac output increases (due to fever, sepsis, agitation, etc.), a larger proportion of blood bypasses the ECMO circuit and goes through the diseased lungs. This larger shunt of deoxygenated blood mixes with the ECMO blood, resulting in a lower systemic arterial oxygen saturation. Oxygenator failure or cannula migration are circuit issues, and a decrease in sweep gas would primarily affect CO2 removal.

Question 119: Plasma-free hemoglobin (pfHgb) elevation on ECMO is a marker of:

Normal ECMO priming
Improving renal function
Circuit-induced hemolysis (Correct answer)
Adequate red cell transfusion

Correct answer: Circuit-induced hemolysis

Elevated plasma-free hemoglobin indicates red blood cell destruction within the circuit, signaling hemolysis that can cause renal injury and must be investigated.

Question 120: What happens to PaCO2 when sweep gas flow is doubled while ECMO blood flow remains constant?

PaCO2 remains unchanged as it depends on blood flow
PaCO2 increases due to back-diffusion
PaCO2 increases proportionally
PaCO2 decreases, potentially causing hypocapnia (Correct answer)

Correct answer: PaCO2 decreases, potentially causing hypocapnia

Doubling sweep gas flow dramatically increases CO2 removal, often causing significant hypocapnia, so sweep adjustments require careful monitoring of blood gas values.

ELSO Adult ECMO Certification Exam

The ELSO Adult ECMO Certification Exam (E-AEC) validates the clinical knowledge and competency of ECMO specialists across circuit management, cannulation, anticoagulation, patient monitoring, and troubleshooting for extracorporeal membrane oxygenation.

120

Questions

180 min

Time Limit

80%

To Pass

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