ELSO Adult ECMO Certification Exam — Questions and Answers

Question 1: A patient on VA ECMO develops sudden bright red blood in the ECMO circuit tubing after a position change. This most likely represents:

Accidental connection of the drainage and return lines (Correct answer)
Air entrainment causing oxygenated appearance
Oxygenator malfunction causing over-oxygenation
Hemolysis producing red-tinged plasma

Correct answer: Accidental connection of the drainage and return lines

Bright red blood in the drainage line (which should be dark venous blood) suggests the drainage and return cannulas have been accidentally switched, a life-threatening error.

Question 2: Which statement correctly describes the role of intra-aortic balloon pump (IABP) in VA-ECMO weaning?

IABP provides additional LV unloading and hemodynamic support to facilitate ECMO weaning in borderline candidates (Correct answer)
IABP is contraindicated in patients with femoral arterial ECMO cannulas
IABP replaces the need for echocardiographic assessment during the weaning trial
IABP increases ECMO afterload and should never be used concurrently

Correct answer: IABP provides additional LV unloading and hemodynamic support to facilitate ECMO weaning in borderline candidates

IABP augments diastolic coronary perfusion and reduces LV afterload, serving as a bridge device to facilitate VA-ECMO weaning in patients with marginal ventricular recovery.

Question 3: A sudden decrease in ECMO venous drainage pressure (more negative) with unchanged pump speed most likely indicates:

Oxygenator thrombosis
Hypovolemia or cannula malposition (Correct answer)
Increased cardiac recovery
Pulmonary hypertension

Correct answer: Hypovolemia or cannula malposition

Increasingly negative inlet pressures with unchanged RPM suggest inadequate venous return due to hypovolemia, tamponade, or cannula migration causing 'chatter.'

Question 4: What is the recommended ECMO blood flow rate (as % of cardiac output) to achieve adequate systemic support in cardiogenic shock?

100%
20–40%
60–80% (Correct answer)
10–20%

Correct answer: 60–80%

VA ECMO typically targets 60–80% of the patient's estimated cardiac output (approximately 3–4 L/min) to provide adequate systemic perfusion.

Question 5: What is the recommended target activated clotting time (ACT) range for most adult VV ECMO patients using unfractionated heparin?

120–140 seconds
160–200 seconds (Correct answer)
280–320 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 6: Which intervention is indicated when a VV-ECMO patient's sweep gas is at maximum FiO2 but SaO2 remains below 80%?

Begin vasopressor therapy
Evaluate for recirculation and consider cannula repositioning or flow adjustment (Correct answer)
Increase heparin infusion
Decrease PEEP immediately

Correct answer: Evaluate for recirculation and consider cannula repositioning or flow adjustment

Persistent hypoxia despite maximum sweep gas suggests high recirculation fraction; repositioning cannulas to increase the distance between drainage and return reduces recirculation.

Question 7: A patient on peripheral VA ECMO for acute myocardial infarction develops progressive pulmonary edema, a pulse pressure of less than 10 mmHg, and an echocardiogram showing a persistently closed aortic valve. These findings are most indicative of which critical complication?

Aortic dissection from the arterial cannula
Left ventricular (LV) distension (Correct answer)
Massive pulmonary embolism
Inadequate venous drainage from cannula malposition

Correct answer: Left ventricular (LV) distension

The combination of increased afterload from retrograde flow and a severely stunned myocardium can lead to an inability of the left ventricle to eject blood. This causes the aortic valve to remain closed, leading to a dangerous increase in LV end-diastolic pressure and volume (LV distension), which manifests as pulmonary edema and a non-pulsatile arterial waveform.

Question 8: Prolonged aminoglycoside use in ECMO patients requires monitoring for which organ-specific toxicity?

Nephrotoxicity and ototoxicity (Correct answer)
Bone marrow suppression
Hepatotoxicity
Pulmonary fibrosis

Correct answer: Nephrotoxicity and ototoxicity

Aminoglycosides accumulate in renal tubular cells and cochlear tissue, causing dose-dependent nephrotoxicity and ototoxicity requiring TDM.

Question 9: What physiological parameter best guides ECMO flow titration to ensure adequate oxygen delivery (DO2) in VA-ECMO?

Arterial lactate concentration as a static threshold
Urine output as a surrogate for cardiac output
Mean arterial pressure alone
Mixed venous oxygen saturation (SvO2) reflecting the balance between DO2 and VO2 (Correct answer)

Correct answer: Mixed venous oxygen saturation (SvO2) reflecting the balance between DO2 and VO2

SvO2 integrates oxygen delivery and consumption; a falling SvO2 indicates tissues are extracting more oxygen to compensate for inadequate delivery, signaling the need to increase ECMO flow or hemoglobin.

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

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

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 11: What is the primary goal of parallel venoarterial-venous (VAV) ECMO configuration?

Allow LV venting through the venous return limb
Increase total circuit flow above single-pump capacity
Treat both respiratory failure and cardiogenic shock simultaneously (Correct answer)
Reduce circuit priming volume in pediatric patients

Correct answer: Treat both respiratory failure and cardiogenic shock simultaneously

VAV ECMO simultaneously addresses biventricular failure and severe respiratory failure by delivering oxygenated blood to both the pulmonary and systemic circulations.

Question 12: In post-cardiotomy cardiogenic shock, VA ECMO is initiated. After 72 hours, there is no evidence of cardiac recovery. What is the next appropriate step?

Evaluate for advanced therapies: LVAD or cardiac transplantation (Correct answer)
Reduce ECMO flow and accept lower MAP
Continue VA ECMO indefinitely until recovery
Convert to VV ECMO for lung recovery

Correct answer: Evaluate for advanced therapies: LVAD or cardiac transplantation

Absence of cardiac recovery at 72–96 hours should prompt evaluation for durable mechanical circulatory support (LVAD) or cardiac transplantation as bridge therapies.

Question 13: What is the physiological consequence of 'North-South syndrome' (Harlequin syndrome) in femoral VA-ECMO?

The coronary arteries are preferentially perfused by ECMO flow
Lower body receives poorly oxygenated blood from the ECMO circuit
Cerebral autoregulation is abolished by retrograde flow
Upper body receives poorly oxygenated blood from the native failing heart while lower body receives oxygenated ECMO blood (Correct answer)

Correct answer: Upper body receives poorly oxygenated blood from the native failing heart while lower body receives oxygenated ECMO blood

In femoral VA-ECMO, oxygenated retrograde ECMO flow may not reach the upper body if the recovering heart ejects deoxygenated blood antegrade, creating a watershed zone of hypoxemia in the upper extremities and brain.

Question 14: How does increased ECMO blood flow affect the recirculation fraction in VV-ECMO?

Increases recirculation as more oxygenated blood is drawn back into the circuit (Correct answer)
Has no effect on recirculation
Decreases recirculation by improving drainage
Eliminates recirculation entirely

Correct answer: Increases recirculation as more oxygenated blood is drawn back into the circuit

Higher ECMO flow increases recirculation because a larger volume of already-oxygenated blood returning to the right atrium is re-aspirated by the drainage cannula before reaching the pulmonary circulation.

Question 15: A VA ECMO patient develops white discoloration of the toes on the cannulated leg despite a functioning distal perfusion cannula. The next step is:

Increase heparin dose to therapeutic PTT
Reassess DPC position and flow with Doppler ultrasound (Correct answer)
Apply topical vasodilators to the foot
Remove the arterial cannula immediately

Correct answer: Reassess DPC position and flow with Doppler ultrasound

Persistent limb ischemia despite a DPC requires Doppler assessment to confirm cannula patency and adequate flow, as the DPC may be kinked, clotted, or malpositioned.

Question 16: The sweep gas flow rate in ECMO primarily controls which parameter?

CO2 removal (Correct answer)
Patient oxygenation
Patient temperature
Circuit blood flow

Correct answer: CO2 removal

Sweep gas flow (the gas flowing through the oxygenator fiber lumen) is the primary determinant of CO2 clearance from the blood.

Question 17: Which of the following clinical findings is the most direct and visually apparent indicator of significant intravascular hemolysis in a patient on ECMO?

A progressive drop in the patient's platelet count.
Dark, tea-colored urine in the urinary drainage bag. (Correct answer)
An increase in the oxygenator pressure gradient.
A gradual decrease in the patient's hematocrit.

Correct answer: Dark, tea-colored urine in the urinary drainage bag.

Significant intravascular hemolysis releases large amounts of cell-free hemoglobin into the plasma. This free hemoglobin is filtered by the kidneys, resulting in hemoglobinuria. This classically presents as dark reddish-brown or "tea-colored" urine and is often the most striking and earliest visual sign of severe hemolysis. While falling platelets, rising oxygenator pressures, and falling hematocrit can be associated with hemolysis, they are less specific and not as visually direct as hemoglobinuria.

Question 18: In percutaneous cannulation, serial dilation of the vessel is performed to:

Gradually expand the access site to accommodate the final cannula (Correct answer)
Flush the cannula with heparin solution
Increase anticoagulation effect
Test vessel compliance before ECMO initiation

Correct answer: Gradually expand the access site to accommodate the final cannula

Sequential dilators progressively enlarge the puncture site so the large-bore ECMO cannula can be inserted without tearing the vessel.

Question 19: Which ECMO circuit component is responsible for removing CO2 from the patient's blood?

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

Correct answer: Oxygenator membrane

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

Question 20: Which clinical sign during a VA-ECMO low-flow weaning trial indicates right ventricular failure and should prompt aborting the trial?

Rising central venous pressure with hepatomegaly and worsening systemic hypotension (Correct answer)
Mild decrease in urine output from 80 to 60 mL/hr
Sinus tachycardia at 100 bpm
Widened pulse pressure on the arterial waveform

Correct answer: Rising central venous pressure with hepatomegaly and worsening systemic hypotension

Elevated CVP with hepatomegaly and systemic hypotension during flow reduction signals right ventricular failure, mandating return to full ECMO support.

Question 21: In a patient on ECMO with suspected HIT, a 4T score of 6 is calculated. What is the appropriate next step?

Continue heparin and recheck platelet count in 24 hours
Switch to low-molecular-weight heparin
Reduce heparin dose by 50%
Stop heparin immediately and start a direct thrombin inhibitor while confirmatory testing is sent (Correct answer)

Correct answer: Stop heparin immediately and start a direct thrombin inhibitor while confirmatory testing is sent

A 4T score of 6 represents high probability of HIT; heparin must be stopped immediately and an alternative anticoagulant started while awaiting confirmatory anti-PF4 antibody results.

Question 22: Which parameter should be checked when a VV ECMO patient receiving therapeutic anticoagulation unexpectedly develops widespread circuit clotting?

D-dimer concentration
Protein C and S levels
Antithrombin III (AT-III) level (Correct answer)
Factor V Leiden mutation status

Correct answer: Antithrombin III (AT-III) level

Heparin requires antithrombin III to exert its anticoagulant effect; AT-III deficiency causes heparin resistance and circuit thrombosis despite therapeutic dosing.

Question 23: When weaning VV-ECMO, the clinician assesses readiness by:

Removing the oxygenator from the circuit while maintaining pump flow
Clamping the venous cannula and monitoring SvO2
Reducing sweep gas flow to zero and observing native gas exchange on the ventilator (Correct answer)
Measuring cardiac output with a pulmonary artery catheter

Correct answer: Reducing sweep gas flow to zero and observing native gas exchange on the ventilator

A VV-ECMO weaning trial involves turning sweep gas to zero so the oxygenator is bypassed functionally, allowing assessment of whether the native lungs can sustain adequate gas exchange.

Question 24: Which of the following is a direct thrombin inhibitor commonly used as an alternative anticoagulant for patients on ECMO who have confirmed Heparin-Induced Thrombocytopenia (HIT)?

Bivalirudin (Correct answer)
Fondaparinux
Clopidogrel
Warfarin

Correct answer: Bivalirudin

Bivalirudin is a direct thrombin inhibitor (DTI) that is frequently used as a first-line alternative to heparin in patients with HIT. It directly binds to thrombin to prevent fibrin formation and does not require antithrombin for its effect. Warfarin is an oral medication unsuitable for acute ECMO. Fondaparinux is a Factor Xa inhibitor and clopidogrel is an antiplatelet agent.

Question 25: 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
Consistent arterial line pulsatility and an LV outflow tract VTI > 10 cm on echocardiography (Correct answer)
A chest X-ray showing resolution of pulmonary edema
Normalization of the patient's body temperature and white blood cell count

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 26: When performing an emergency hand-crank during a centrifugal pump power failure, the specialist should:

Maintain a minimum of 1.5–2 L/min flow to prevent circuit thrombosis and clamp lines if unable to hand-crank (Correct answer)
Convert to a roller pump using backup tubing
Administer a protamine dose to reverse anticoagulation
Increase sweep gas to maximum FiO2 immediately

Correct answer: Maintain a minimum of 1.5–2 L/min flow to prevent circuit thrombosis and clamp lines if unable to hand-crank

During pump failure, maintaining minimal flow via hand-crank prevents stasis thrombosis; if hand-cranking is not feasible, clamping both limbs prevents backflow and air entrainment.

Question 27: In a patient on peripheral VA-ECMO, which monitoring site best reflects cerebral oxygenation?

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

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 28: You respond to a call at a nursing home for an unresponsive 88-year-old male. When you arrive, you are unable to palpate a pulse. While you are preparing to start chest compression, your partner places the patient on the monitor. When you perform a rhythm check, you notice ventricular fibrillation. After giving epinephrine and defibrillations, you start transporting to the nearest hospital. Is this patient a good candidate for eCPR?

Yes, this patient is a good candidate for eCPR.
Yes, this patient is a good candidate for eCPR due to the administration of epinephrine.
No, this patient is not a good candidate for eCPR due to age and residing in a nursing home. (Correct answer)
No, this patient is not a good candidate for eCPR due to the presence of ventricular fibrillation.

Correct answer: No, this patient is not a good candidate for eCPR due to age and residing in a nursing home.

Explanation: <br> No, this patient would not be a good candidate for ECPR (refractory arrest, “ECMO Alert”). The patient is excluded due to age and residing in a nursing home. As a reference, ECMO for any indication is not recommended for patients older than 75 years old.

Question 29: Which hemodynamic goal during a VA-ECMO weaning trial best predicts successful decannulation?

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

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 30: Which cannulation strategy is preferred when ECPR is performed during active CPR in a pediatric patient under 10 kg?

Neck (carotid-jugular) cannulation (Correct answer)
Subclavian artery cannulation
Transcaval approach
Femoral-femoral VA-ECMO

Correct answer: Neck (carotid-jugular) cannulation

Carotid artery and internal jugular vein cannulation is the preferred approach in small pediatric patients due to vessel size limitations at the femoral site.

Question 31: Which of the following is a standard, non-invasive, continuous monitoring modality used for the early detection of cerebral malperfusion or ischemic events in an adult patient on VA ECMO?

Daily transcranial Doppler (TCD) ultrasounds
Continuous electroencephalography (EEG)
Near-infrared spectroscopy (NIRS) for cerebral oximetry (Correct answer)
Serial serum S100B protein measurements

Correct answer: Near-infrared spectroscopy (NIRS) for cerebral oximetry

Near-infrared spectroscopy (NIRS) is a non-invasive technology that continuously monitors regional cerebral oxygen saturation (rSO2) at the bedside. It allows for real-time detection of imbalances in cerebral oxygen delivery and consumption, serving as an early warning for potential ischemic or hypoxic brain injury, which is a significant risk for patients on VA ECMO.

Question 32: Which sign on physical examination specifically suggests cannula-site venous thrombosis in a femoral ECMO patient?

Redness at the cannula exit wound only
Unilateral leg swelling, warmth, and discoloration distal to the cannula site (Correct answer)
Systemic fever above 38.5°C
Bilateral ankle edema

Correct answer: Unilateral leg swelling, warmth, and discoloration distal to the cannula site

Unilateral swelling, warmth, and discoloration of the limb distal to the femoral cannula indicate deep vein thrombosis or limb ischemia from venous outflow obstruction.

Question 33: What is the primary hemodynamic difference between VA-ECMO and VV-ECMO?

VV-ECMO increases afterload while VA-ECMO reduces it
VV-ECMO requires arterial cannulation
VA-ECMO provides both cardiac and respiratory support while VV-ECMO provides respiratory support only (Correct answer)
VA-ECMO can only be used in pediatric patients

Correct answer: VA-ECMO provides both cardiac and respiratory support while VV-ECMO provides respiratory support only

VA-ECMO bypasses both the heart and lungs providing cardiorespiratory support, whereas VV-ECMO only supports gas exchange with no direct cardiac output augmentation.

Question 34: What is the most common cannulation site for peripheral VA ECMO in adults?

Femoral vein and radial artery
Femoral vein and femoral artery (Correct answer)
Right internal jugular vein and subclavian artery
Femoral vein and axillary artery

Correct answer: Femoral vein and femoral artery

Femoral vein to femoral artery cannulation is the most common approach for peripheral VA ECMO due to accessibility and speed of insertion.

Question 35: A patient on ECMO develops a new right pleural effusion with progressive respiratory failure. The most appropriate diagnostic step is:

Obtain a ventilation-perfusion scan
Thoracentesis with fluid sent for analysis including triglycerides (Correct answer)
Increase ECMO flows and sweep gas
Perform a contrast CT chest

Correct answer: Thoracentesis with fluid sent for analysis including triglycerides

Thoracentesis both diagnoses and treats the effusion; triglyceride analysis helps identify chylothorax, a recognized ECMO complication from superior vena cava or thoracic duct involvement.

Question 36: Why is systemic anticoagulation typically administered before the first dilator is placed during ECMO cannulation?

To increase cardiac output during the procedure
To prevent clot formation on instrumentation and in the cannula (Correct answer)
To reduce vasospasm at the puncture site
To lower blood pressure for easier vessel access

Correct answer: To prevent clot formation on instrumentation and in the cannula

Heparin is given prior to dilation to prevent thrombus formation on the guidewire, dilators, and cannula surfaces during insertion.

Question 37: Which coagulation factor is most significantly consumed during ECMO due to continuous contact with the circuit surface?

Factor V
Factor XIII
Fibrinogen (Correct answer)
Factor VIII

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

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

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 39: Hemolysis in an ECMO circuit is best monitored by measuring:

Activated clotting time and anti-Xa levels
Plasma-free hemoglobin and lactate dehydrogenase (LDH) levels (Correct answer)
Post-membrane PO2 and PCO2
Serum potassium and sodium levels

Correct answer: Plasma-free hemoglobin and lactate dehydrogenase (LDH) levels

Plasma-free hemoglobin and LDH are direct markers of red cell destruction, indicating mechanical trauma from pump cavitation, high negative pressures, or circuit thrombosis.

Question 40: What is the target range for activated partial thromboplastin time (aPTT) in most adult ECMO protocols?

60-80 seconds (Correct answer)
20-40 seconds
150-180 seconds
100-120 seconds

Correct answer: 60-80 seconds

Most adult ECMO programs target an aPTT of 60-80 seconds to balance clot prevention within the circuit against systemic bleeding risk from anticoagulation.

Question 41: Which factor most reliably predicts the ability to successfully wean a patient from VV ECMO?

Return of normal cardiac ejection fraction
Normalization of chest X-ray
Resolution of systemic inflammatory markers
Maintenance of adequate SpO2 during a spontaneous breathing trial with sweep gas off (Correct answer)

Correct answer: Maintenance of adequate SpO2 during a spontaneous breathing trial with sweep gas off

A weaning trial with sweep gas reduced or off tests the native lung's ability to maintain gas exchange independently, which is the best predictor of successful decannulation.

Question 42: Differential hypoxia (Harlequin syndrome) in VA-ECMO via femoral cannulation is characterized by:

Oxygenated upper body from native lungs and hypoxic lower body from ECMO
Hypoxia in the lower extremities only
Bilateral upper and lower extremity cyanosis
Oxygenated lower body from ECMO and hypoxic upper body from native lungs (Correct answer)

Correct answer: Oxygenated lower body from ECMO and hypoxic upper body from native lungs

In femoral VA-ECMO, oxygenated ECMO blood enters the aorta retrogradely and perfuses the lower body, while the upper body receives deoxygenated blood from the recovering but still-dysfunctional native lungs.

Question 43: Which echocardiographic finding would prompt emergent LV venting in a VA ECMO patient?

Hyperdynamic LV with LVEF >55%
Spontaneous echo contrast in the LA
Severely dilated, non-contracting LV with mitral regurgitation (Correct answer)
Small pericardial effusion without tamponade

Correct answer: Severely dilated, non-contracting LV with mitral regurgitation

A severely dilated, non-contracting LV with MR indicates LV distension that can cause pulmonary edema and myocardial injury, requiring urgent venting.

Question 44: The pre-pump (inlet) pressure on an ECMO circuit is characteristically:

Positive, reflecting aortic backpressure
Equal to central venous pressure
Negative, reflecting the suction generated by the drainage cannula (Correct answer)
Atmospheric (zero) during normal operation

Correct answer: Negative, reflecting the suction generated by the drainage cannula

The inlet (drainage) limb operates at subatmospheric (negative) pressure as the pump generates suction to pull blood from the venous circulation.

Question 45: A patient being weaned from VA-ECMO develops LV distension confirmed by echo. Before decannulation, the priority intervention is:

Increase ECMO flow to decompress the ventricle
Insert an Impella or intra-aortic balloon pump to unload the LV (Correct answer)
Reduce vasopressor support to decrease afterload
Perform urgent aortic valve replacement

Correct answer: Insert an Impella or intra-aortic balloon pump to unload the LV

LV distension during VA-ECMO unloading failure requires a dedicated LV unloading device (Impella or IABP) to prevent pulmonary edema and myocardial injury.

Question 46: In neonatal ECMO for meconium aspiration syndrome, the most important criterion indicating readiness to wean is:

Birth weight exceeding 3.5 kg
Decreasing oxygen requirement and improving native lung compliance on ventilator (Correct answer)
Normalization of serum lactate to < 1.0 mmol/L
Chest X-ray clearance of all opacities

Correct answer: Decreasing oxygen requirement and improving native lung compliance on ventilator

Improved pulmonary compliance and reduced FiO2 requirement on the ventilator indicate recovery of native lung function in neonates.

Question 47: What is the most common indication for ECMO in neonates in the United States?

Meconium aspiration syndrome (MAS) (Correct answer)
Congenital diaphragmatic hernia (CDH)
Congenital heart disease
Group B Streptococcal sepsis

Correct answer: Meconium aspiration syndrome (MAS)

Meconium aspiration syndrome causing severe respiratory failure and pulmonary hypertension is the most frequent neonatal ECMO indication in the US.

Question 48: Which component of the ECMO circuit is directly responsible for both oxygenating the blood and removing carbon dioxide?

Blender
Heat exchanger
Centrifugal pump
Membrane oxygenator (Correct answer)

Correct answer: Membrane oxygenator

The membrane oxygenator, also called the membrane lung, is the component that performs gas exchange. It contains a semipermeable membrane that separates the blood path from the gas path, allowing oxygen to diffuse into the blood and carbon dioxide to diffuse out, mimicking the function of the alveoli in the lungs.

Question 49: A VV ECMO patient has adequate oxygenation but develops progressive hypercapnia despite maximum sweep gas settings. What is the next step?

Administer sodium bicarbonate
Evaluate for membrane oxygenator clot or plasma leak (Correct answer)
Convert to VA ECMO
Increase native ventilator respiratory rate

Correct answer: Evaluate for membrane oxygenator clot or plasma leak

Plasma leak or thrombus within the oxygenator impairs gas exchange efficiency, causing CO2 retention despite maximal sweep settings.

Question 50: 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?

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

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 51: A patient on VV-ECMO develops worsening hypercapnia despite maximal sweep gas flow. What is the most likely explanation?

Plasma leak into the gas phase of the oxygenator
Excessive recirculation washing out CO2
Patient's metabolic rate has decreased
Oxygenator thrombosis reducing effective membrane surface area (Correct answer)

Correct answer: Oxygenator thrombosis reducing effective membrane surface area

Oxygenator thrombosis progressively reduces functional membrane surface area, impairing both oxygen transfer and CO2 elimination despite maximal sweep gas flows.

Question 52: When selecting cannula size for a patient requiring VA ECMO, the primary goal is to choose a size that allows for:

The lowest possible prime volume for the circuit.
A target blood flow equivalent to a cardiac index of 2.2-2.5 L/min/m2 without causing excessive shear stress. (Correct answer)
The longest duration of use without needing to be changed.
The easiest and quickest possible insertion.

Correct answer: A target blood flow equivalent to a cardiac index of 2.2-2.5 L/min/m2 without causing excessive shear stress.

The fundamental goal of VA ECMO is to provide adequate circulatory support. Cannulas must be large enough to achieve a target blood flow that meets the patient's metabolic demands (typically a cardiac index of 2.2-2.5 L/min/m2), but not so large as to cause significant vascular injury or so small that high pressures lead to hemolysis from shear stress.

Question 53: Which ECMO configuration carries the highest risk of arterial thromboembolism due to retrograde aortic blood flow interactions?

VAV-ECMO configuration
VV-ECMO with bicaval dual-lumen cannula
VA-ECMO with femoral artery return cannula (Correct answer)
VV-ECMO with right internal jugular cannulation

Correct answer: VA-ECMO with femoral artery return cannula

Femoral VA-ECMO creates a watershed zone where oxygenated retrograde ECMO flow meets anterograde native cardiac output, increasing thrombus and watershed infarction risk.

Question 54: In venoarterial ECMO, retrograde flow through the femoral artery can cause what phenomenon in patients with recovering cardiac function?

Left ventricular thrombus
Pulmonary hypertension
Venous air embolism
Differential hypoxia (Harlequin syndrome) (Correct answer)

Correct answer: Differential hypoxia (Harlequin syndrome)

When the recovering heart ejects deoxygenated blood that meets retrograde ECMO flow in the aorta, the upper body may receive hypoxic blood — Harlequin syndrome.

Question 55: Which hemodynamic finding on a pulmonary artery catheter would indicate left ventricular distension in a VA-ECMO patient?

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

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 56: Which intervention most directly reduces recirculation in a patient on dual-lumen bicaval VV ECMO?

Increasing sweep gas flow
Increasing anticoagulation
Raising ECMO blood flow
Repositioning the return jet away from the drainage port (Correct answer)

Correct answer: Repositioning the return jet away from the drainage port

Directing the return jet toward the tricuspid valve and away from the drainage port minimizes recirculation of oxygenated blood.

Question 57: Which condition is ECMO primarily used for in respiratory failure?

Asthma exacerbation
Chronic obstructive pulmonary disease (COPD)
Pneumonia
Acute respiratory distress syndrome (ARDS) (Correct answer)

Correct answer: Acute respiratory distress syndrome (ARDS)

Explanation: <br> ECMO is commonly used in cases of ARDS where conventional mechanical ventilation is inadequate to oxygenate the blood.

Question 58: The centrifugal pump used in modern ECMO circuits generates flow by:

Pneumatic pressure applied to a blood sac
Magnetically levitated or bearing-mounted impeller creating a pressure gradient via centrifugal force (Correct answer)
Electromagnetic induction in a metal chamber
Sequential compression of tubing by rotating rollers

Correct answer: Magnetically levitated or bearing-mounted impeller creating a pressure gradient via centrifugal force

Centrifugal pumps use a spinning impeller (constrained or magnetically levitated) to impart kinetic energy to blood, generating flow through centrifugal force.

Question 59: A patient on Veno-Arterial (VA) ECMO with femoral artery cannulation develops signs of limb ischemia, including coolness and pallor in the cannulated leg. Which of the following is the most appropriate immediate intervention?

Increase the ECMO pump flow to improve perfusion.
Elevate the affected limb above the level of the heart.
Place a distal perfusion cannula (DPC) in the ipsilateral femoral artery. (Correct answer)
Administer a bolus of an anticoagulant.

Correct answer: Place a distal perfusion cannula (DPC) in the ipsilateral femoral artery.

Femoral artery cannulation for VA ECMO can obstruct antegrade blood flow, leading to limb ischemia. A distal perfusion cannula (DPC) is inserted antegrade into the artery distal to the main ECMO cannula to provide oxygenated blood flow to the limb, directly addressing the cause of the ischemia.

Question 60: What hemostatic change occurs specifically during the transition from VA-ECMO to VV-ECMO configuration in a recovering cardiac patient?

Von Willebrand factor levels rapidly normalize within 1 hour
Anticoagulation requirements double due to added circuit length
Immediate normalization of all coagulation parameters
Increased turbulence and shear from circuit reconfiguration may transiently worsen platelet consumption (Correct answer)

Correct answer: Increased turbulence and shear from circuit reconfiguration may transiently worsen platelet consumption

Circuit reconfiguration introduces turbulence and new surface contact areas, which can transiently increase platelet activation and consumption during and immediately after the transition.

Question 61: Succinylcholine use in critically ill ECMO patients carries a risk of life-threatening:

Bronchospasm
Malignant hyperthermia
Prolonged paralysis due to circuit sequestration
Hyperkalemia-induced cardiac arrest (Correct answer)

Correct answer: Hyperkalemia-induced cardiac arrest

Critically ill patients often have upregulated acetylcholine receptors, and succinylcholine depolarization releases enough potassium to cause cardiac arrest.

Question 62: Which vasopressor is considered first-line for maintaining mean arterial pressure (MAP) in VA-ECMO patients with vasodilatory shock?

Dopamine
Norepinephrine (Correct answer)
Phenylephrine
Epinephrine

Correct answer: Norepinephrine

Norepinephrine is the first-line vasopressor in VA-ECMO due to its potent alpha-adrenergic vasoconstriction with modest beta-1 activity.

Question 63: A patient on VA-ECMO develops a sudden drop in arterial line pressure with unchanged ECMO flows. What is the most likely cause?

Pump thrombus
Oxygenator failure
Cardiac tamponade (Correct answer)
Venous cannula migration

Correct answer: Cardiac tamponade

Cardiac tamponade reduces native cardiac output, causing a drop in arterial pulsatility and blood pressure despite maintained ECMO flow.

Question 64: During ECMO circuit change-out, the most critical step to prevent air embolism is:

Ensuring all tubing connections are primed and bubble-free before unclamping (Correct answer)
Converting from VV to VA configuration temporarily
Administering a heparin bolus 30 minutes before the procedure
Reducing pump speed to minimum RPM throughout the exchange

Correct answer: Ensuring all tubing connections are primed and bubble-free before unclamping

Any air introduced during circuit change-out can cause fatal embolism, so meticulous priming and de-airing of all new components is mandatory before reconnecting to the patient.

Question 65: What is the standard ICU blood glucose target for ECMO patients receiving insulin infusion therapy?

140–180 mg/dL (Correct answer)
100–140 mg/dL
180–220 mg/dL
60–100 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 66: Serial chest X-rays in a VV-ECMO patient show progressive improvement in bilateral infiltrates. This finding suggests:

Circuit recirculation
Worsening ARDS
Oxygenator failure
Lung rest and potential recovery (Correct answer)

Correct answer: Lung rest and potential recovery

Clearing bilateral infiltrates on serial imaging indicate lung rest from reduced ventilator settings enabled by ECMO, suggesting potential native lung recovery.

Question 67: What is the physiological rationale for targeting a lower 'lung-protective' ventilator strategy (ultra-protective ventilation) during VV-ECMO?

ECMO eliminates the need for any ventilation
Reduced ventilation decreases sweep gas requirements
ECMO assumes gas exchange, allowing the lungs to rest and potentially recover from VILI (Correct answer)
Lower ventilation reduces recirculation

Correct answer: ECMO assumes gas exchange, allowing the lungs to rest and potentially recover from VILI

With ECMO handling gas exchange, tidal volumes and pressures can be minimized to prevent ventilator-induced lung injury (VILI) and promote lung recovery.

Question 68: What is the primary purpose of the raceway tubing in a centrifugal ECMO pump?

To oxygenate blood passing through the circuit
To house the heat exchanger coils
To serve as the segment compressed by the pump head (Correct answer)
To measure circuit flow via ultrasonic sensors

Correct answer: To serve as the segment compressed by the pump head

Raceway tubing is the specialized, crush-resistant segment that sits within a roller pump head and is repeatedly compressed to propel blood.

Question 69: Which ultrasound view is most useful for confirming guidewire position in the inferior vena cava during femoral venous cannulation?

Subcostal or transesophageal bicaval view (Correct answer)
Parasternal short-axis at the aortic valve
Apical four-chamber
Parasternal long-axis

Correct answer: Subcostal or transesophageal bicaval view

The subcostal or TEE bicaval view provides direct visualization of the guidewire and cannula tip within the IVC and right atrium.

Question 70: During femoral veno-arterial ECMO cannulation, what is the primary concern when selecting the arterial cannula size?

Ensuring the cannula reaches the ascending aorta
Matching cannula diameter to the patient's body weight only
Selecting the largest cannula to reduce resistance
Maximizing flow while minimizing distal limb ischemia risk (Correct answer)

Correct answer: Maximizing flow while minimizing distal limb ischemia risk

Femoral arterial cannula selection balances adequate ECMO flow with preservation of native limb perfusion to prevent distal ischemia.

Question 71: A patient is placed on peripheral VA ECMO via the femoral artery and vein for cardiogenic shock. Which of the following cannulation-related complications is a direct consequence of the retrograde blood flow delivered by the arterial cannula?

Limb ischemia in the cannulated leg.
Increased left ventricular afterload. (Correct answer)
Deep vein thrombosis in the non-cannulated leg.
Recirculation between the arterial and venous cannulas.

Correct answer: Increased left ventricular afterload.

In peripheral VA ECMO, the arterial cannula returns blood into the femoral artery, creating retrograde flow up the aorta. This flow opposes the native ejection from the left ventricle, thereby increasing the pressure the LV must pump against (afterload). This can lead to LV distention, stasis, and pulmonary edema, especially in patients with poor ventricular function.

Question 72: During VV ECMO, a patient develops acute hemolysis (plasma-free hemoglobin >500 mg/dL). What is the FIRST action?

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

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 73: What is the preferred alternative anticoagulant for ECMO patients diagnosed with heparin-induced thrombocytopenia (HIT)?

Warfarin
Bivalirudin (Correct answer)
Rivaroxaban
Fondaparinux

Correct answer: Bivalirudin

Bivalirudin is a direct thrombin inhibitor that does not cross-react with HIT antibodies and is the preferred heparin alternative during ECMO.

Question 74: What is the typical target activated clotting time (ACT) range during standard ECMO anticoagulation?

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

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

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

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 76: Argatroban, used in HIT patients on ECMO, is monitored using which laboratory test?

Activated clotting time (ACT) or aPTT (Correct answer)
Thromboelastography (TEG) only
Platelet function assay
Anti-Xa level

Correct answer: Activated clotting time (ACT) or aPTT

Argatroban is monitored via aPTT (target 1.5–3× baseline) or ACT, as it directly inhibits thrombin and prolongs clot-based assays.

Question 77: What is the primary advantage of a percutaneous over a surgical cutdown approach for ECMO cannulation in most adults?

Faster access, lower bleeding risk at the site, and no surgical wound (Correct answer)
Larger cannulas can be placed percutaneously
Percutaneous cannulas are easier to remove at decannulation
Surgical cutdown provides worse visualization of vessel anatomy

Correct answer: Faster access, lower bleeding risk at the site, and no surgical wound

Percutaneous Seldinger-based cannulation is faster in an emergency, avoids a surgical incision, and is associated with lower local complication rates in experienced hands.

Question 78: Which anticoagulation monitoring strategy is most commonly used during VV ECMO in adults?

Thromboelastography only
Activated partial thromboplastin time (aPTT) with unfractionated heparin (Correct answer)
Anti-Xa levels with low-molecular-weight heparin
INR monitoring every 6 hours

Correct answer: Activated partial thromboplastin time (aPTT) with unfractionated heparin

Unfractionated heparin titrated to aPTT (typically 60–80 seconds) is the most widely used anticoagulation strategy in adult VV ECMO.

Question 79: Which packed red blood cell (pRBC) transfusion threshold is commonly targeted in stable VV-ECMO patients without active hemorrhage?

Hgb <10 g/dL (Correct answer)
Hgb <12 g/dL
Hgb <14 g/dL
Hgb <7 g/dL

Correct answer: Hgb <10 g/dL

Most ECMO centers target hemoglobin >10 g/dL to optimize oxygen delivery through the circuit to the patient.

Question 80: What is the most common cause of heparin resistance in ECMO patients?

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

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

Circuit recirculation causing venous mixing
Sepsis-induced peripheral vasodilation
Worsening aortic regurgitation from the arterial cannula
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 82: A VA-ECMO patient on 80% support develops left ventricular distension on echocardiogram with worsening pulmonary edema. The preferred intervention is:

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

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

Smaller oxygenator to reduce resistance
Larger cannula sizes with higher flow-rated tubing (Correct answer)
Removal of the heat exchanger
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 84: A patient is supported with a dual-lumen single cannula via the right internal jugular vein for VV ECMO. The clinical team notes that the pre-membrane (drainage) oxygen saturation is rising, while the patient's systemic arterial saturation (SpO2) is simultaneously falling. This pattern is most indicative of:

Significant recirculation due to cannula malposition. (Correct answer)
Impending oxygenator failure.
Improving native lung function.
Worsening right ventricular failure.

Correct answer: Significant recirculation due to cannula malposition.

This clinical picture is the classic sign of significant recirculation. It occurs when the oxygenated blood being returned through the reinfusion port is immediately drawn back into the drainage port of the cannula without circulating through the patient's body. This leads to progressively 'more red' blood entering the circuit (higher pre-membrane saturation) while less oxygenated blood reaches the patient, causing systemic hypoxemia (falling SpO2). Improving lung function would raise SpO2. Oxygenator failure would cause post-membrane saturation to fall.

Question 85: How does increasing ECMO blood flow affect plasma-free hemoglobin levels?

Higher flows reduce hemolysis by decreasing turbulence at the pump inlet
Flow rate has no effect; hemolysis depends entirely on anticoagulation status
Higher flows decrease hemolysis by reducing suction pressure on red cells
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 86: A VV ECMO patient requires a blood transfusion. Which hemoglobin threshold is most appropriate for initiating transfusion in a stable patient?

Hgb < 8 g/dL (Correct answer)
Hgb < 12 g/dL
Hgb < 7 g/dL
Hgb < 10 g/dL

Correct answer: Hgb < 8 g/dL

Most ECMO centers use a hemoglobin threshold of 8 g/dL for transfusion, as higher hemoglobin improves oxygen-carrying capacity on ECMO support.

Question 87: Air is detected in the ECMO circuit approaching the patient. The immediate response is to:

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

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 88: On VV ECMO, a patient's SaO2 is 88% with ECMO flow at 5 L/min. The native cardiac output is estimated at 8 L/min. What is the approximate recirculation fraction?

10%
50%
25%
37% (Correct answer)

Correct answer: 37%

Recirculation fraction = (ECMO flow – effective flow) / ECMO flow; with total venous return mixed with ECMO flow, approximately 37% recirculation yields this oxygen delivery.

Question 89: Which intervention is most appropriate for managing harlequin syndrome in VA-ECMO?

Add a second venous drainage cannula to convert to VAV configuration or place the return cannula in the right subclavian/axillary artery (Correct answer)
Increase ECMO flow rate to maximum
Administer high-dose vasopressors
Reduce sweep gas FiO2 to match native cardiac output oxygen content

Correct answer: Add a second venous drainage cannula to convert to VAV configuration or place the return cannula in the right subclavian/axillary artery

Converting to a VAV configuration or using an upper-body arterial return ensures oxygenated blood reaches the coronary and cerebral circulations despite poor native cardiac function.

Question 90: In patients who undergo ECPR for out-of-hospital cardiac arrest (OHCA), which factor is most strongly associated with favorable neurological outcomes?

A short 'low-flow' time (duration of CPR until ECMO initiation). (Correct answer)
Total dose of epinephrine administered by EMS.
The use of a mechanical CPR device during transport.
Successful intubation in the field on the first attempt.

Correct answer: A short 'low-flow' time (duration of CPR until ECMO initiation).

The duration of the low-flow state (the time from the start of CPR to the establishment of ECMO flow) is one of the most powerful predictors of survival with good neurological outcome in ECPR. Shorter durations imply less time with suboptimal cerebral perfusion, reducing the risk of anoxic brain injury. ELSO guidelines suggest a goal of establishing ECMO flow within 60 minutes of the onset of cardiac arrest.

Question 91: What is the physiological basis for using prone positioning concurrently with VV-ECMO in severe ARDS?

Prone positioning reduces ECMO recirculation by changing cannula orientation
Prone positioning lowers intrathoracic pressure, increasing ECMO venous drainage
Prone positioning prevents oxygenator thrombosis by reducing blood viscosity
Prone positioning redistributes ventilation-perfusion matching and reduces dorsal alveolar overdistension, complementing ECMO's gas exchange support (Correct answer)

Correct answer: Prone positioning redistributes ventilation-perfusion matching and reduces dorsal alveolar overdistension, complementing ECMO's gas exchange support

Prone positioning recruits dorsal lung regions, improves V/Q matching, and reduces cyclic alveolar stress, providing additive benefit to VV-ECMO's extracorporeal gas exchange in ARDS.

Question 92: During ECMO, a sudden rise in the pre-membrane pressure with a normal post-membrane pressure indicates:

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

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 93: A patient on VV ECMO requires Continuous Renal Replacement Therapy (CRRT). The CRRT circuit is initiated, drawing blood from a pre-pump access port and returning it post-oxygenator. Shortly after initiation, the ECMO circuit's pre-membrane (access) pressure becomes significantly more negative, and the venous line begins to chatter. What is the most probable cause?

The CRRT machine's ultrafiltration rate is too high, causing patient hypovolemia. (Correct answer)
A large clot has formed in the ECMO oxygenator.
The sweep gas flow on the ECMO circuit was accidentally increased.
The CRRT machine is adding excess volume to the circuit.

Correct answer: The CRRT machine's ultrafiltration rate is too high, causing patient hypovolemia.

Aggressive fluid removal (ultrafiltration) by the CRRT machine can rapidly deplete the patient's circulating volume. This resulting hypovolemia leads to insufficient venous return to fill the ECMO circuit, causing the drainage cannula to suck against the vessel walls. This is manifested as an increasingly negative pre-membrane pressure and visible 'chatter' in the line.

Question 94: A patient on ECMO has a platelet count that drops from 180,000 to 30,000 over 48 hours. The MOST likely cause in this clinical context is:

Sepsis-related bone marrow suppression
Dilutional thrombocytopenia from transfusions
Heparin-induced thrombocytopenia (HIT)
ECMO circuit consumption (Correct answer)

Correct answer: ECMO circuit consumption

Platelet consumption due to contact activation within the ECMO circuit is the most common cause of thrombocytopenia in ECMO patients.

Question 95: Cerebral regional oxygen saturation (rSO2) measured by NIRS falls below 50% in an ECMO patient. The first intervention should be:

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

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 96: After ECPR for drug-induced cardiac arrest, weaning should be attempted when which criterion is met?

Lactate normalizes below 4 mmol/L
Patient regains consciousness
The causative drug has been metabolized and cardiac function recovers (Correct answer)
48 hours have elapsed since arrest

Correct answer: The causative drug has been metabolized and cardiac function recovers

Weaning is appropriate once the toxic drug is metabolized and intrinsic cardiac function demonstrates recovery on echo.

Question 97: 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:

Excessive sweep gas is causing hypocapnia
Recirculation is now occurring
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 98: Inlet pressure (P-in) monitoring on the venous drainage limb of ECMO is important because extreme negative pressures can cause:

Oxygenator plasma leakage
Hyperthermia from increased pump work
Arterial hypertension and increased cardiac afterload
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 99: In ECMO management, 'chatter' of the venous drainage cannula or tubing typically indicates:

Air embolism in the arterial limb
Oxygenator membrane failure
Hypovolemia or inadequate venous return to the circuit (Correct answer)
Excessive pump flow causing high pressures

Correct answer: Hypovolemia or inadequate venous return to the circuit

Chatter (intermittent collapse) of the venous drainage line reflects inadequate preload or hypovolemia limiting the circuit's ability to maintain continuous blood flow.

Question 100: Which pharmacokinetic property of bivalirudin makes it advantageous over argatroban in patients with hepatic failure on ECMO?

Bivalirudin is protein-bound, reducing free drug accumulation
Bivalirudin is primarily metabolized by enzymatic cleavage in plasma, independent of liver function (Correct answer)
Bivalirudin is renally cleared and not hepatically metabolized
Bivalirudin has a longer half-life, allowing less frequent dosing

Correct answer: Bivalirudin is primarily metabolized by enzymatic cleavage in plasma, independent of liver function

Bivalirudin is metabolized primarily by thrombin-mediated proteolysis and non-specific plasma proteases, not by hepatic enzymes, making it predictable in liver failure.

Question 101: Which anticoagulant is most commonly used to maintain circuit patency during ECMO?

Enoxaparin
Bivalirudin
Warfarin (Coumadin)
Unfractionated heparin (UFH) (Correct answer)

Correct answer: Unfractionated heparin (UFH)

Unfractionated heparin is the most widely used anticoagulant in ECMO due to its titrability, reversibility with protamine, and availability of established monitoring assays.

Question 102: 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-oxygenator, return post-oxygenator
Access post-pump, return pre-pump
Access pre-pump, return post-oxygenator
Access post-pump (pre-oxygenator), return pre-pump (in the venous drainage line) (Correct answer)

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

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

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 104: What is the recommended protein target for ECMO patients to support recovery and minimize muscle catabolism?

1.5–2.0 g/kg/day (Correct answer)
1.0–1.2 g/kg/day
2.5–3.0 g/kg/day
0.5–0.8 g/kg/day

Correct answer: 1.5–2.0 g/kg/day

ECMO patients are in a hypercatabolic state, and current guidelines recommend 1.5–2.0 g/kg/day of protein to support nitrogen balance and minimize muscle wasting.

Question 105: During ECMO decannulation, protamine is administered to reverse heparin. What is the most feared complication of protamine administration?

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

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 106: What is the effect of hypothermia on oxygen-hemoglobin dissociation during ECMO?

Shifts curve leftward, increasing hemoglobin O2 affinity (Correct answer)
Has no effect on the dissociation curve
Eliminates the Bohr effect completely
Shifts curve rightward, improving O2 unloading

Correct answer: Shifts curve leftward, increasing hemoglobin O2 affinity

Hypothermia shifts the oxyhemoglobin dissociation curve to the left, increasing hemoglobin's affinity for oxygen and impairing tissue O2 delivery.

Question 107: The 'recirculation' phenomenon in VV-ECMO occurs when:

The heat exchanger overheats the blood
Oxygenated blood returning to the patient is re-entrained into the drainage cannula (Correct answer)
CO2 accumulates in the oxygenator fiber bundle
The pump spins in reverse direction

Correct answer: Oxygenated blood returning to the patient is re-entrained into the drainage cannula

Recirculation in VV-ECMO occurs when returned oxygenated blood is immediately suctioned back into the drainage cannula instead of circulating through the patient.

Question 108: What is the clinical significance of a sudden decrease in the pressure gradient across the ECMO oxygenator?

Reflects improved pump efficiency
Indicates a circuit air embolism
May signal oxygenator thrombosis or clot formation within the device (Correct answer)
Indicates improved patient lung function

Correct answer: May signal oxygenator thrombosis or clot formation within the device

An increasing or suddenly changing transmembrane pressure gradient across the oxygenator may indicate thrombus formation, prompting urgent evaluation and possible oxygenator exchange.

Question 109: A patient on VA-ECMO for cardiogenic shock undergoes a 30-minute clamp trial. During the trial, the arterial pressure waveform becomes pulsatile with a pulse pressure of 40 mmHg. This finding indicates:

Ventricular fibrillation has occurred
Adequate left ventricular recovery to consider decannulation (Correct answer)
The arterial line is dampened and needs troubleshooting
Severe aortic regurgitation has developed

Correct answer: Adequate left ventricular recovery to consider decannulation

A robust pulsatile waveform during VA-ECMO clamping reflects meaningful left ventricular stroke volume, suggesting cardiac recovery.

Question 110: Following decannulation from femoral VA-ECMO, a patient develops ipsilateral leg swelling and pain. Duplex ultrasound reveals deep vein thrombosis at the cannulation site. Appropriate management includes:

Therapeutic anticoagulation and monitoring for pulmonary embolism (Correct answer)
Observation alone; cannulation-site DVT never embolizes
Surgical thrombectomy immediately
Inferior vena cava filter placement as the first-line intervention

Correct answer: Therapeutic anticoagulation and monitoring for pulmonary embolism

Cannulation-site DVT is managed with therapeutic anticoagulation and surveillance for PE, similar to other lower-extremity DVT.

Question 111: Which of the following best explains why pulsatility is important to maintain during VA-ECMO support?

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

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

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

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

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

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 114: Which factor most significantly increases thrombin generation on ECMO beyond the circuit surface itself?

Therapeutic hypothermia
Supranormal oxygen delivery
Hyperglycemia
Systemic inflammatory response activating the extrinsic coagulation pathway (Correct answer)

Correct answer: Systemic inflammatory response activating the extrinsic coagulation pathway

ECMO triggers a systemic inflammatory response that activates tissue factor expression on monocytes and endothelium, driving extrinsic pathway thrombin generation beyond circuit contact activation alone.

Question 115: Which mechanism best explains why patients with severe right heart failure on VA-ECMO may paradoxically develop pulmonary edema?

ECMO increases pulmonary venous pressure by augmenting left atrial return
ECMO anticoagulation increases pulmonary capillary permeability
High ECMO flows cause pulmonary hypertension via increased pulmonary venous pressure
Improved RV unloading by ECMO increases pulmonary blood flow into the failing LV, which cannot accommodate the increased preload (Correct answer)

Correct answer: Improved RV unloading by ECMO increases pulmonary blood flow into the failing LV, which cannot accommodate the increased preload

When VA-ECMO decompresses the RV and restores pulmonary blood flow, a severely impaired LV that cannot empty adequately develops rising LVEDP transmitted back to the pulmonary capillaries, causing hydrostatic edema.

Question 116: Which hemodynamic finding is most consistent with the 'North-South syndrome' (Harlequin syndrome) in peripheral VA ECMO?

Hypoxic lower body with well-oxygenated upper body
Hypoxic upper body with well-oxygenated lower body (Correct answer)
Differential cyanosis of the left arm only
Global hypoxia despite adequate ECMO flow

Correct answer: Hypoxic upper body with well-oxygenated lower body

In Harlequin syndrome, retrograde ECMO flow oxygenates the lower body while the patient's own failing heart delivers desaturated blood to the upper body and coronary arteries.

Question 117: Which electrolyte disturbance is particularly problematic when using continuous renal replacement therapy (CRRT) concurrently with ECMO?

Hyperkalemia
Hypomagnesemia and hypophosphatemia (Correct answer)
Hypercalcemia
Hypernatremia

Correct answer: Hypomagnesemia and hypophosphatemia

CRRT removes magnesium and phosphate from the blood continuously; without supplementation, patients on combined ECMO-CRRT are at high risk for hypomagnesemia and hypophosphatemia.

Question 118: A patient on ECMO receiving unfractionated heparin has an aPTT of 220 seconds. The appropriate intervention is:

Administer protamine sulfate to fully reverse anticoagulation
Continue current heparin dose and recheck in 4 hours
Switch to bivalirudin immediately
Hold heparin infusion and recheck aPTT in 2 hours (Correct answer)

Correct answer: Hold heparin infusion and recheck aPTT in 2 hours

A supratherapeutic aPTT of 220 seconds greatly increases bleeding risk; holding the heparin infusion temporarily allows levels to fall while avoiding full reversal that risks circuit thrombosis.

Question 119: 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
Switch to VA ECMO
Decrease ECMO blood flow

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 120: Which monitoring parameter is most useful for assessing adequacy of nutrition support and metabolic response in ECMO patients?

Body weight measured every 48 hours
Indirect calorimetry measurement (Correct answer)
Daily urine urea nitrogen excretion only
Serum albumin levels weekly

Correct answer: Indirect calorimetry measurement

Indirect calorimetry provides the most accurate measure of resting energy expenditure in ECMO patients, guiding precise caloric prescription and avoiding over- or underfeeding.

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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