ELSO Adult ECMO Certification Exam — Questions and Answers

Question 1: Which of the following represents a unique and immediate challenge when establishing peripheral VA ECMO during active CPR (ECPR)?

Preventing hypothermia due to the extracorporeal circuit.
Achieving adequate circuit anticoagulation before initiation.
Difficulty in identifying and cannulating collapsed femoral vessels. (Correct answer)
Managing left ventricular distention after flow is established.

Correct answer: Difficulty in identifying and cannulating collapsed femoral vessels.

During cardiac arrest, the absence of pulsatile arterial flow and the collapse of the venous system make vessel identification and cannulation extremely challenging, even with ultrasound guidance. This is a primary procedural hurdle that distinguishes ECPR from elective ECMO initiation and requires a highly skilled team to perform rapidly. Anticoagulation, hypothermia, and LV distention are all important considerations, but they are typically managed after vascular access is secured and ECMO flow has been initiated.

Question 2: What is the physiological basis for using prone positioning concurrently with VV-ECMO in severe ARDS?

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

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

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

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

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

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 5: A patient on ECMO develops fever to 39.8°C with positive blood cultures for Candida. The most appropriate step regarding the ECMO circuit is:

Continue current circuit and treat with antifungals only
Change the entire ECMO circuit and cannulas (Correct answer)
Add antifungal coverage to circuit priming solution
Increase circuit flows to reduce stasis

Correct answer: Change the entire ECMO circuit and cannulas

Fungal bloodstream infections in ECMO patients require circuit and cannula change, as biofilm on surfaces cannot be sterilized with systemic antifungals alone.

Question 6: What is the Seldinger technique in the context of ECMO cannulation?

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

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 7: 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
Circuit recirculation causing venous mixing
Evidence of myocardial recovery with improving native cardiac output (Correct answer)
Sepsis-induced peripheral vasodilation

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 8: What is the most appropriate strategy for managing hyperglycemia in an ECMO patient receiving continuous enteral nutrition?

Use a continuous insulin infusion titrated per a validated insulin protocol (Correct answer)
Discontinue enteral nutrition until glucose normalizes
Switch to parenteral nutrition with reduced dextrose concentration
Administer subcutaneous sliding-scale insulin only

Correct answer: Use a continuous insulin infusion titrated per a validated insulin protocol

Continuous insulin infusion with a validated ICU insulin protocol provides the most consistent glycemic control in ECMO patients receiving continuous nutrition.

Question 9: Which neurological assessment tool provides real-time detection of cerebral ischemia or seizure in ECMO patients?

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

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 10: A 'chatter' or 'flutter' in the ECMO tubing during a drainage phase typically signals:

Adequate preload
Venous inflow obstruction or hypovolemia (Correct answer)
Systemic hypertension
Membrane oxygenator failure

Correct answer: Venous inflow obstruction or hypovolemia

Tubing chatter occurs when the centrifugal pump generates intermittent high negative pressure due to inadequate venous return, indicating hypovolemia or cannula obstruction.

Question 11: What landmark is used to estimate the optimal venous cannula tip position in the right atrium during fluoroscopic-guided femoral VV-ECMO cannulation?

The left hilum
The carina or right mainstem bronchus at the cavoatrial junction (Correct answer)
The aortic knob
The level of the diaphragm

Correct answer: The carina or right mainstem bronchus at the cavoatrial junction

Fluoroscopically, the cavoatrial junction correlates with the level of the carina, guiding optimal venous drainage cannula tip placement.

Question 12: Which laboratory finding during ECMO warrants the most urgent evaluation for heparin-induced thrombocytopenia (HIT)?

Mild elevation in ACT to 230 seconds
Platelet count drop from 180,000 to 140,000 over 7 days
Platelet count drop of greater than 50% on days 5–10 despite no circuit changes (Correct answer)
Elevated plasma-free hemoglobin

Correct answer: Platelet count drop of greater than 50% on days 5–10 despite no circuit changes

A >50% platelet count drop on days 5–10 of heparin exposure is the classic temporal pattern raising strong suspicion for HIT, warranting a 4T score assessment and HIT antibody testing.

Question 13: 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:

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

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 14: Oxygenator post-membrane pO2 is measured at 85 mmHg with FiO2 of 1.0 and sweep at 10 L/min. This finding indicates:

Adequate oxygenator function
Inadequate sweep gas flow
Excessive recirculation
Oxygenator membrane failure (Correct answer)

Correct answer: Oxygenator membrane failure

A post-membrane pO2 of 85 mmHg with 100% FiO2 and high sweep indicates severely impaired membrane gas exchange, consistent with oxygenator failure.

Question 15: During VV-ECMO weaning, which parameter most reliably indicates adequate native lung recovery before a trial off?

SpO2 > 95% on FiO2 ≤ 0.4 with sweep gas off (Correct answer)
Tidal volume > 8 mL/kg IBW on pressure support
Static lung compliance > 20 mL/cmH2O
PaO2/FiO2 ratio > 100 on full ECMO support

Correct answer: SpO2 > 95% on FiO2 ≤ 0.4 with sweep gas off

SpO2 >95% with acceptable PaCO2 on room-air sweep-off conditions demonstrates that native lungs can sustain gas exchange independently.

Question 16: 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 humidify sweep gas and prevent membrane desiccation
To regulate sweep gas pressure to avoid barotrauma

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

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

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 18: A patient on VA-ECMO develops low ECMO flows with high RPM, and the circuit pressure alarm activates. After ruling out hypovolemia, the next assessment should be:

Reduce heparin infusion
Inspect for cannula kinking or positional obstruction (Correct answer)
Increase sweep gas flow
Increase ventilator PEEP

Correct answer: Inspect for cannula kinking or positional obstruction

High RPM with low flows and elevated pressures despite adequate volume suggests mechanical obstruction such as cannula kinking, migration, or outflow obstruction requiring immediate inspection.

Question 19: A patient on peripheral VA-ECMO via femoral artery cannulation develops ipsilateral limb ischemia. The best intervention is to:

Remove the arterial cannula immediately
Increase ECMO flow to improve perfusion
Administer systemic vasodilators
Place an antegrade perfusion cannula distal to the ECMO cannula (Correct answer)

Correct answer: Place an antegrade perfusion cannula distal to the ECMO cannula

A distal perfusion cannula placed in the superficial femoral artery restores antegrade limb perfusion while maintaining ECMO support.

Question 20: Milrinone is sometimes used in ECMO patients because it improves cardiac function by:

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

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

Patient oxygenation
Patient temperature
CO2 removal (Correct answer)
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 22: Which cannulation strategy is preferred when ECPR is performed during active CPR in a pediatric patient under 10 kg?

Transcaval approach
Subclavian artery cannulation
Neck (carotid-jugular) cannulation (Correct answer)
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 23: During emergent bedside percutaneous ECMO cannulation without fluoroscopy, which bedside imaging tool is considered the standard of care for real-time guidance?

Point-of-care ultrasound (POCUS) (Correct answer)
Magnetic resonance imaging
Computed tomography angiography
Nuclear perfusion scanning

Correct answer: Point-of-care ultrasound (POCUS)

POCUS enables real-time vessel visualization, needle guidance, and cannula tip confirmation at the bedside without radiation or contrast.

Question 24: A 60-year-old male is decannulated after 10 days of femoral Veno-Arterial (VA) ECMO. The arterial cannulation site was repaired surgically. Four hours post-procedure, the patient's right foot becomes cool and pale, with non-palpable pedal pulses confirmed by Doppler silence. What is the most likely cause of these findings?

Venous air embolism from the decannulation site.
Acute arterial thrombosis or stenosis at the cannulation repair site. (Correct answer)
Systemic inflammatory response syndrome from the ECMO run.
Phlegmasia cerulea dolens due to a massive deep vein thrombosis.

Correct answer: Acute arterial thrombosis or stenosis at the cannulation repair site.

The classic signs of acute limb ischemia (pain, pallor, pulselessness, poikilothermia) point directly to an obstruction of arterial blood flow. Following femoral arterial decannulation, the most probable cause for these acute signs is the formation of a thrombus or the development of stenosis at the arteriotomy repair site, impeding distal perfusion.

Question 25: What is the recommended target activated clotting time (ACT) range for most adult VV ECMO patients using unfractionated heparin?

120–140 seconds
220–260 seconds
160–200 seconds (Correct answer)
280–320 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 26: What is the primary purpose of the raceway tubing in a centrifugal ECMO pump?

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

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 27: 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 28: Which ECMO circuit component is responsible for removing CO2 from the patient's blood?

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

Correct answer: Oxygenator membrane

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

Question 29: 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)?

Clopidogrel
Bivalirudin (Correct answer)
Fondaparinux
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 30: What is the primary reason aPTT is considered an inferior monitoring tool compared to anti-Xa for heparin dosing in ECMO?

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

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 31: What is 'Harlequin syndrome' (differential hypoxia) in the context of VA-ECMO?

Upper body hypoxia while lower body is well-oxygenated due to competing blood flows (Correct answer)
Hemolysis caused by shear stress in the pump
Paradoxical hypertension due to increased afterload
Differential limb ischemia from cannula placement

Correct answer: Upper body hypoxia while lower body is well-oxygenated due to competing blood flows

Harlequin syndrome occurs when the native heart ejects desaturated blood that perfuses the upper body while the ECMO circuit oxygenates lower body blood, creating differential oxygenation.

Question 32: Beyond the effects of administered anticoagulants, a significant contributor to the acquired coagulopathy in patients on ECMO is:

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

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 33: The ELSO (Extracorporeal Life Support Organization) Registry primarily serves to:

Certify individual ECMO specialists
Regulate ECMO equipment manufacturing standards
Collect multicenter outcomes data to guide ECMO practice and quality improvement (Correct answer)
Manage ECMO organ allocation protocols

Correct answer: Collect multicenter outcomes data to guide ECMO practice and quality improvement

The ELSO Registry is an international database that collects ECMO case data from member centers to support research, benchmarking, and evidence-based practice improvement.

Question 34: 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 7.35, PaCO2 45 mmHg, PaO2 78 mmHg
pH 7.45, PaCO2 35 mmHg, PaO2 150 mmHg
pH 7.21, PaCO2 75 mmHg, PaO2 90 mmHg (Correct answer)
pH 7.38, PaCO2 42 mmHg, PaO2 85 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 35: When initiating enteral nutrition in an ECMO patient, what is the recommended timing after circuit initiation in a hemodynamically stable patient?

After 72 hours once vasopressors are weaned
Only after ECMO flows are reduced below 3 L/min
Immediately within 1 hour
Within 24–48 hours (Correct answer)

Correct answer: Within 24–48 hours

Early enteral nutrition within 24–48 hours of ECMO initiation is recommended in hemodynamically stable patients to reduce gut ischemia and support immunity.

Question 36: During VA ECMO, which strategy is used to vent the left ventricle percutaneously without additional surgery?

Transaortic catheter placed via the femoral artery
Impella device placed across the aortic valve (Correct answer)
Intra-aortic balloon pump insertion
Percutaneous pulmonary artery balloon occlusion

Correct answer: Impella device placed across the aortic valve

An Impella device positioned across the aortic valve provides active LV unloading and venting, reducing distension during VA ECMO support.

Question 37: Which hemodynamic goal during a VA-ECMO weaning trial best predicts successful decannulation?

Heart rate < 60 bpm with no vasopressor support
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
CVP < 5 mmHg and PCWP < 8 mmHg at full 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 38: 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 sweep gas flow on the ECMO circuit was accidentally increased.
The CRRT machine is adding excess volume to the circuit.
The CRRT machine's ultrafiltration rate is too high, causing patient hypovolemia. (Correct answer)
A large clot has formed in the ECMO oxygenator.

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 39: During VV-ECMO, what is the primary determinant of oxygen delivery to the patient's tissues?

ECMO blood flow rate
Membrane lung surface area
Native cardiac output (Correct answer)
Sweep gas flow rate

Correct answer: Native cardiac output

In VV-ECMO, oxygen delivery to tissues depends on native cardiac output because the oxygenated blood returning from the ECMO circuit must be pumped by the patient's own heart.

Question 40: What is the standard ICU blood glucose target for ECMO patients receiving insulin infusion therapy?

180–220 mg/dL
140–180 mg/dL (Correct answer)
60–100 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 41: Which hemostatic complication is uniquely associated with centrifugal pump ECMO circuits and involves destruction of von Willebrand factor multimers?

Thrombotic thrombocytopenic purpura
Acquired von Willebrand syndrome (Correct answer)
Disseminated intravascular coagulation
Heparin-induced thrombocytopenia

Correct answer: Acquired von Willebrand syndrome

Continuous shear stress from centrifugal pumps cleaves high-molecular-weight von Willebrand factor multimers, causing acquired von Willebrand syndrome and mucocutaneous bleeding.

Question 42: Which intervention is indicated when a VV-ECMO patient's sweep gas is at maximum FiO2 but SaO2 remains below 80%?

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

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 43: During ECMO transport, the centrifugal pump controller alarms 'low flow' and flow drops to 0.5 L/min. The first action should be:

Assess for tubing kinks, positional cannula obstruction, or hypovolemia (Correct answer)
Increase RPM to maximum
Administer 1L normal saline rapidly through the venous limb
Clamp both cannulas and perform emergency CPR

Correct answer: Assess for tubing kinks, positional cannula obstruction, or hypovolemia

Low flow during transport is most commonly due to mechanical obstruction from kinked tubing or positional cannula issues, and a systematic circuit check must occur before escalating interventions.

Question 44: A VV ECMO patient has adequate oxygenation but develops progressive hypercapnia despite maximum sweep gas settings. What is the next step?

Evaluate for membrane oxygenator clot or plasma leak (Correct answer)
Administer sodium bicarbonate
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 45: Which ultrasound view is most useful for confirming guidewire position in the inferior vena cava during femoral venous cannulation?

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

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 46: 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 is unchanged since ECMO bypasses the left heart
LV afterload decreases due to blood volume offloading

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 47: Which complication is most specifically associated with axillary artery cannulation for VA-ECMO compared to femoral artery cannulation?

Aortic dissection
Distal leg ischemia
Brachial plexus injury (Correct answer)
Retroperitoneal hematoma

Correct answer: Brachial plexus injury

The brachial plexus lies adjacent to the axillary artery, making nerve injury a specific risk of this cannulation approach.

Question 48: Which pharmacokinetic property of bivalirudin makes it advantageous over argatroban in patients with hepatic failure on ECMO?

Bivalirudin is renally cleared and not hepatically metabolized
Bivalirudin is primarily metabolized by enzymatic cleavage in plasma, independent of liver function (Correct answer)
Bivalirudin is protein-bound, reducing free drug accumulation
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 49: In neonatal ECMO for persistent pulmonary hypertension of the newborn (PPHN), what is the primary pathophysiological target?

Reducing pulmonary vascular resistance to enable transition from fetal to neonatal circulation (Correct answer)
Eliminating intracardiac shunting through the foramen ovale
Correcting metabolic acidosis to normalize pH
Increasing systemic vascular resistance to maintain coronary perfusion

Correct answer: Reducing pulmonary vascular resistance to enable transition from fetal to neonatal circulation

PPHN results from failure of the pulmonary vasculature to dilate at birth, maintaining high PVR that drives right-to-left shunting; ECMO buys time while strategies to reduce PVR (inhaled NO, alkalosis, oxygen) take effect.

Question 50: What is the significance of the 'mixed venous saturation' (SvO2) measured from the ECMO drainage limb?

It determines the need for anticoagulation adjustments
It reflects the balance between systemic oxygen delivery and consumption, guiding adequacy of ECMO support (Correct answer)
It measures oxygenator efficiency by comparing pre- and post-membrane O2 content
It indicates the degree of pulmonary shunting in VV-ECMO

Correct answer: It reflects the balance between systemic oxygen delivery and consumption, guiding adequacy of ECMO support

Drainage line SvO2 represents the mixed venous blood entering the circuit and indicates whether oxygen delivery meets metabolic demand across the whole body.

Question 51: During ECMO weaning trials, which clinical parameter best confirms readiness to separate from VV-ECMO support?

Normal chest X-ray with ECMO at maximum flow
SpO2 > 88% at ECMO flows of 1 L/min with FiO2 0.5 and moderate vent settings (Correct answer)
PaO2 > 200 mmHg on ECMO
SpO2 > 95% with ECMO at full flows

Correct answer: SpO2 > 88% at ECMO flows of 1 L/min with FiO2 0.5 and moderate vent settings

Maintaining acceptable oxygenation at minimal ECMO flows (1 L/min) with reduced FiO2 and moderate ventilation confirms sufficient native lung recovery for safe decannulation.

Question 52: Which of the following best describes the primary goal of mechanical ventilation for a patient fully supported on VV ECMO for severe ARDS?

To ensure the patient remains apneic to prevent patient-ventilator asynchrony.
To achieve a normal PaO2 by using high levels of PEEP and FiO2.
To maximize minute ventilation to assist the ECMO circuit with CO2 clearance.
To promote lung rest and minimize ventilator-induced lung injury (VILI). (Correct answer)

Correct answer: To promote lung rest and minimize ventilator-induced lung injury (VILI).

The fundamental purpose of using VV ECMO in ARDS is to allow the injured lungs to heal. This is achieved by using 'lung rest' or 'ultra-protective' ventilator settings. These settings involve low tidal volumes, low driving pressures (Plateau Pressure - PEEP), and low FiO2 to prevent further damage from mechanical stress (barotrauma, volutrauma) and oxygen toxicity. Since ECMO provides the majority of gas exchange, normalizing blood gases with aggressive ventilator settings is unnecessary and counterproductive.

Question 53: Argatroban, used in HIT patients on ECMO, is monitored using which laboratory test?

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

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 54: 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 <7 g/dL
Hgb <12 g/dL
Hgb <14 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 55: In the context of ECMO physiology, what is 'sweep gas' and what is its primary purpose?

CO2-enriched gas used to calibrate blood gas analyzers
Pressurized saline used to prime the circuit
A blend of O2 and air passed through the oxygenator to facilitate gas exchange across the membrane (Correct answer)
Nitrogen gas used to prevent air embolism

Correct answer: A blend of O2 and air passed through the oxygenator to facilitate gas exchange across the membrane

Sweep gas (typically blended O2 and air) flows through the gas side of the membrane oxygenator, creating the concentration gradient needed for O2 loading and CO2 removal from the blood.

Question 56: Which electrolyte disturbance is particularly problematic when using continuous renal replacement therapy (CRRT) concurrently with ECMO?

Hyperkalemia
Hypomagnesemia and hypophosphatemia (Correct answer)
Hypernatremia
Hypercalcemia

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 57: Which pharmacological agent is most commonly used to reduce LV afterload and facilitate LV ejection in VA ECMO patients?

Norepinephrine
Vasopressin
Phenylephrine
Nitroprusside or milrinone (Correct answer)

Correct answer: Nitroprusside or milrinone

Vasodilators like nitroprusside or inodilators like milrinone reduce systemic vascular resistance, helping the LV eject against the increased afterload imposed by VA ECMO.

Question 58: What is the recommended ECMO blood flow rate (as % of cardiac output) to achieve adequate systemic support in cardiogenic shock?

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

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 59: During routine monitoring of a patient on VV ECMO, which of the following laboratory values is the most sensitive and direct indicator of circuit-induced red blood cell damage (hemolysis)?

Total bilirubin
Plasma-free hemoglobin (PFH) (Correct answer)
Haptoglobin
Serum lactate dehydrogenase (LDH)

Correct answer: Plasma-free hemoglobin (PFH)

Plasma-free hemoglobin (PFH) is a direct measurement of hemoglobin released into the plasma from damaged red blood cells, making it the most sensitive and specific marker for acute, intravascular hemolysis occurring within the ECMO circuit. While LDH will also be elevated and haptoglobin will be consumed (decrease), these markers are less specific and can be affected by other organ dysfunction. Bilirubin is a later, indirect marker of red cell breakdown.

Question 60: Which circuit component is responsible for actively controlling temperature of blood returned to the patient?

Heat exchanger integrated into the oxygenator (Correct answer)
Centrifugal pump head
Bladder reservoir
Pre-pump tubing clamps

Correct answer: Heat exchanger integrated into the oxygenator

The heat exchanger, typically incorporated within the ECMO oxygenator, uses water from a heater-cooler unit to regulate the temperature of blood passing through the circuit.

Question 61: During VV ECMO, a patient develops acute hemolysis (plasma-free hemoglobin >500 mg/dL). What is the FIRST action?

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

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

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

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 63: What is the significance of a 'chattering' or 'sucking' cannula during VV ECMO?

It signals that drainage is impaired, usually from hypovolemia or cannula malposition (Correct answer)
It reflects normal pulsatile flow from cardiac contractions
It is caused by excessive anticoagulation causing blood thinning
It indicates optimal flow with maximal oxygenation efficiency

Correct answer: It signals that drainage is impaired, usually from hypovolemia or cannula malposition

Cannula chattering occurs when the circuit intermittently collapses venous inflow, indicating inadequate preload or a positional drainage issue requiring immediate attention.

Question 64: During VV ECMO, a patient develops severe hypokalemia (K+ 2.8 mEq/L). Which factor unique to ECMO contributes to electrolyte depletion?

High sweep gas flows causing transcutaneous electrolyte loss
Plasma leakage through the membrane oxygenator
Continuous renal replacement therapy often co-administered (Correct answer)
ECMO pump-induced hemolysis releasing intracellular potassium

Correct answer: Continuous renal replacement therapy often co-administered

Many ECMO patients receive concurrent CRRT, which significantly increases electrolyte clearance and requires aggressive electrolyte replacement.

Question 65: What is the primary goal of parallel venoarterial-venous (VAV) ECMO configuration?

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

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 66: The heat exchanger is an integral component of the ECMO circuit. What is its primary physiological purpose?

To cool the blood to reduce metabolic demand
To prevent clot formation within the oxygenator
To maintain patient normothermia (Correct answer)
To facilitate carbon dioxide removal

Correct answer: To maintain patient normothermia

Blood loses a significant amount of heat as it passes through the extracorporeal circuit, which is exposed to ambient room temperature. The primary function of the heat exchanger is to warm the blood before it returns to the patient, thereby maintaining normothermia.

Question 67: During ECMO, which laboratory test specifically assesses fibrinolytic activity and can detect hyperfibrinolysis?

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

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 68: Unfractionated heparin achieves its anticoagulant effect in the ECMO circuit primarily through which mechanism of action?

Binding to antithrombin, greatly accelerating its inactivation of thrombin and Factor Xa. (Correct answer)
Directly binding to and inhibiting thrombin (Factor IIa).
Chelating calcium ions, which are essential for the coagulation cascade.
Preventing the aggregation of platelets on the circuit surface.

Correct answer: Binding to antithrombin, greatly accelerating its inactivation of thrombin and Factor Xa.

Unfractionated heparin is an indirect anticoagulant. It works by binding to the endogenous anticoagulant antithrombin. This binding causes a conformational change in antithrombin, increasing its activity by over 1000-fold, leading to the rapid inactivation of key clotting factors, primarily thrombin (Factor IIa) and Factor Xa.

Question 69: 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 proportionally
PaCO2 decreases, potentially causing hypocapnia (Correct answer)
PaCO2 increases due to back-diffusion

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.

Question 70: After successful decannulation from VA-ECMO, anticoagulation management typically involves:

High-dose heparin infusion for 48 hours to prevent rebound thrombosis
Transition to antiplatelet therapy only, regardless of underlying condition
Continuation of therapeutic anticoagulation per underlying cardiac condition and thromboembolic risk (Correct answer)
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 71: Which coagulation factor is most significantly consumed during ECMO due to continuous contact with the circuit surface?

Factor XIII
Factor VIII
Factor V
Fibrinogen (Correct answer)

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 72: What is the primary function of ECMO in respiratory failure?

To stimulate lung function
To increase heart rate
To provide oxygenation and remove carbon dioxide (Correct answer)
To regulate blood pressure

Correct answer: To provide oxygenation and remove carbon dioxide

Explanation: The primary function of ECMO in respiratory failure is to act as an artificial lung, providing oxygen to the blood and removing carbon dioxide.

Question 73: Why is systemic anticoagulation required during ECMO, and what is the most common agent used?

To prevent air embolism by lowering blood viscosity; aspirin is routinely used
To maintain laminar blood flow through the oxygenator; bivalirudin is standard
To prevent arterial vasospasm at cannulation sites; warfarin is standard
To prevent circuit thrombosis from blood-surface contact activation; unfractionated heparin is most common (Correct answer)

Correct answer: To prevent circuit thrombosis from blood-surface contact activation; unfractionated heparin is most common

Blood contact with the artificial circuit surfaces activates the coagulation cascade; unfractionated heparin is the most widely used anticoagulant to prevent life-threatening circuit thrombosis.

Question 74: 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 75: Air is detected in the ECMO circuit approaching the patient. The immediate response is to:

Administer 100% FiO2 to absorb the air
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

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: Which complication is specifically associated with VA ECMO but NOT VV ECMO?

Systemic arterial embolism (Correct answer)
Circuit clot formation
Oxygenator failure
Hemolysis from pump

Correct answer: Systemic arterial embolism

Systemic arterial embolism is unique to VA ECMO because air or thrombus entering the arterial circuit is delivered directly into the systemic circulation, unlike VV ECMO.

Question 77: What is the primary hemodynamic difference between VA-ECMO and VV-ECMO?

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

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

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

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 79: In a centrifugal ECMO pump, what is the effect of an acute increase in afterload (e.g., arterial hypertension) on pump flow?

Flow remains constant as centrifugal pumps are flow-controlled
Flow oscillates due to pressure-flow coupling
Flow decreases as the pump is sensitive to pressure changes (Correct answer)
Flow increases due to increased driving pressure

Correct answer: Flow decreases as the pump is sensitive to pressure changes

Unlike roller pumps, centrifugal pumps are not occlusive and their flow decreases when afterload increases, making continuous flow monitoring essential.

Question 80: What is the recommended strategy when air is detected in the ECMO circuit?

Clamp the circuit, stop the pump, and remove air before restarting (Correct answer)
Increase pump speed to push air through quickly
Administer IV heparin bolus immediately
Switch from VA to VV ECMO mode

Correct answer: Clamp the circuit, stop the pump, and remove air before restarting

Air entry requires immediate circuit clamping and pump stoppage to prevent air embolism, followed by controlled de-airing before circuit restart.

Question 81: During ECMO, urine output less than 0.5 mL/kg/hr for more than 2 hours suggests:

Appropriate diuresis
Therapeutic fluid balance
Acute kidney injury or inadequate perfusion (Correct answer)
Excessive anticoagulation

Correct answer: Acute kidney injury or inadequate perfusion

Oliguria below 0.5 mL/kg/hr is a standard marker of inadequate renal perfusion or acute kidney injury requiring prompt assessment of ECMO flows and hemodynamics.

Question 82: How does ECMO-induced hemolysis contribute to renal injury?

Hemolysis triggers a cytokine storm that damages renal endothelium
Free hemoglobin causes renal tubular toxicity and vasoconstriction of the renal microvasculature (Correct answer)
Hemolysis reduces oxygen delivery to the kidneys by decreasing hematocrit
Hemolyzed red cells cause glomerular mechanical obstruction

Correct answer: Free hemoglobin causes renal tubular toxicity and vasoconstriction of the renal microvasculature

Free plasma hemoglobin released during hemolysis is directly nephrotoxic, causing oxidative tubular injury and scavenging nitric oxide to produce renal vasoconstriction and ischemia.

Question 83: A 48-year-old patient on VV ECMO for ARDS for the past week develops a sudden drop in platelet count from 160,000/µL to 55,000/µL. Simultaneously, new thrombus is visualized in the oxygenator. This clinical presentation is most suspicious for which of the following complications?

Disseminated Intravascular Coagulation (DIC)
Sepsis-induced thrombocytopenia
Hemodilution from fluid overload
Heparin-Induced Thrombocytopenia (HIT) (Correct answer)

Correct answer: Heparin-Induced Thrombocytopenia (HIT)

The classic presentation of Heparin-Induced Thrombocytopenia (HIT) involves a significant drop in platelet count (typically >50%) occurring 5-10 days after heparin exposure, combined with a paradoxical prothrombotic state leading to new or worsening thrombosis. While DIC and sepsis can cause thrombocytopenia, the combination with a new thrombotic event strongly points towards HIT.

Question 84: In ECMO management, 'chatter' of the venous drainage cannula or tubing typically indicates:

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

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

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

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

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

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

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

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 88: 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?

Prothrombin time/INR
Anti-Xa level
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 89: In ECMO patients with both active bleeding and circuit clot, which viscoelastic TEG parameter guides the decision to use antifibrinolytic therapy?

LY30 (percent lysis at 30 minutes) (Correct answer)
Maximum amplitude (MA)
R time (reaction time)
K time (clot kinetics time)

Correct answer: LY30 (percent lysis at 30 minutes)

LY30 greater than 3% on TEG indicates significant fibrinolysis, guiding use of antifibrinolytics like tranexamic acid to reduce ongoing clot dissolution and bleeding.

Question 90: Which anticoagulation monitoring strategy is most commonly used during VV ECMO in adults?

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

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 91: A centrifugal pump used in modern ECMO circuits generates flow primarily through:

Piston-driven positive displacement
Roller compression of the tubing
Impeller or cone rotation creating centrifugal force (Correct answer)
Electromagnetic induction creating a rotating magnetic field

Correct answer: Impeller or cone rotation creating centrifugal force

Centrifugal ECMO pumps use a rapidly spinning impeller or cone that imparts kinetic energy to blood through centrifugal force, generating flow.

Question 92: During ECMO priming, the circuit is typically filled with which solution to remove air before patient connection?

5% dextrose water
Albumin 5% alone
Fresh frozen plasma
Heparinized normal saline or balanced crystalloid (Correct answer)

Correct answer: Heparinized normal saline or balanced crystalloid

Heparinized normal saline or balanced crystalloid (e.g., Plasma-Lyte) is the standard prime solution used to displace air and prepare the circuit before connection to the patient.

Question 93: A 50-year-old patient on VV ECMO for ARDS has a PaCO2 that has risen from 45 mmHg to 60 mmHg over four hours. The ECMO pump flow is stable, and the patient's metabolic state is unchanged. Which parameter on the ECMO circuit should be adjusted first to directly address the hypercapnia?

Increase the pump RPM to increase blood flow.
Increase the sweep gas flow rate. (Correct answer)
Decrease the patient's ventilator respiratory rate.
Increase the FiO2 on the gas blender.

Correct answer: Increase the sweep gas flow rate.

In an ECMO circuit, carbon dioxide removal is almost entirely dependent on the sweep gas flow rate. Increasing the flow of gas (the 'sweep') across the membrane creates a steeper concentration gradient for CO2, facilitating more efficient diffusion from the blood into the gas phase. Increasing pump flow or FiO2 primarily affects oxygenation. Decreasing the ventilator rate would worsen hypercapnia.

Question 94: A major concern with high-dose propofol infusions in ECMO patients is development of:

Hepatic encephalopathy
Adrenal insufficiency
Propofol infusion syndrome (PRIS) (Correct answer)
Neuroleptic malignant syndrome

Correct answer: Propofol infusion syndrome (PRIS)

Propofol infusion syndrome, characterized by metabolic acidosis, rhabdomyolysis, and cardiac failure, is a rare but life-threatening complication at high doses.

Question 95: Why is systemic anticoagulation typically administered before the first dilator is placed during ECMO cannulation?

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

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 96: In a patient undergoing right internal jugular VV-ECMO cannulation, the drainage cannula tip should ideally rest at:

The right atrium-IVC junction (Correct answer)
The hepatic vein ostium
The right ventricle
The right atrium-SVC junction (cavoatrial junction)

Correct answer: The right atrium-IVC junction

The drainage tip at the IVC-RA junction maximizes venous return from both the IVC and RA while avoiding right ventricular irritation.

Question 97: During ECMO decannulation, protamine is administered to reverse heparin. What is the most feared complication of protamine administration?

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

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 98: What does a sudden drop in the ECMO sweep gas FiO2 setting achieve during management?

Increases CO2 removal
Improves circuit priming
Reduces oxygenation to test native lung function (Correct answer)
Decreases oxygen delivery to the patient

Correct answer: Reduces oxygenation to test native lung function

Reducing sweep gas FiO2 (a 'sweep trial') tests the native lung's ability to oxygenate blood, used during VV ECMO weaning assessments.

Question 99: Recirculation during VV-ECMO is best defined as:

Oxygenated blood from the return cannula re-entering the drainage cannula (Correct answer)
Air entrainment into the ECMO circuit
Retrograde flow from the return cannula to the heart
Backflow of blood through the oxygenator membrane

Correct answer: Oxygenated blood from the return cannula re-entering the drainage cannula

Recirculation occurs when oxygenated blood exiting the return cannula is immediately aspirated back into the drainage cannula before reaching the systemic circulation.

Question 100: What is the significance of a widening arteriovenous CO2 difference (AVCO2 gap) in an ECMO patient?

Excessive sweep gas flow
Membrane oxygenator failure
Improved lung recovery
Inadequate tissue perfusion and anaerobic metabolism (Correct answer)

Correct answer: Inadequate tissue perfusion and anaerobic metabolism

A widening AVCO2 gap (>6 mmHg) suggests poor cardiac output and tissue hypoperfusion with anaerobic CO2 production.

Question 101: The ECMO specialist notes that the post-membrane PO2 has dropped from 450 to 180 mmHg despite unchanged sweep gas settings. The most likely explanation is:

Pump speed has inadvertently increased
Patient's native lung function has improved
Oxygenator clotting reducing functional membrane surface area (Correct answer)
Arterial cannula has migrated into the left ventricle

Correct answer: Oxygenator clotting reducing functional membrane surface area

Clot accumulation within the fiber bundle reduces available gas exchange surface, causing a fall in post-oxygenator PO2 even with maintained sweep gas flow.

Question 102: 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?

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

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 103: Which coagulation abnormality is uniquely associated with ECMO and results from destruction of high-molecular-weight von Willebrand factor multimers?

Disseminated intravascular coagulation (DIC)
Heparin-induced thrombocytopenia (HIT)
Fibrinolysis shutdown syndrome
Acquired von Willebrand syndrome (AVWS) (Correct answer)

Correct answer: Acquired von Willebrand syndrome (AVWS)

High shear stress generated by the ECMO pump cleaves large vWF multimers via ADAMTS-13, producing an acquired von Willebrand syndrome that impairs primary hemostasis and contributes to bleeding complications.

Question 104: In the context of ECMO weaning, what does the term 'circuit holiday' refer to?

Reduction in sweep gas to the minimum possible level for 24 hours
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

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 105: During VA-ECMO weaning, pump speed is reduced to minimum and the patient's mean arterial pressure drops to 50 mmHg with a CVP of 22 mmHg. This hemodynamic pattern suggests:

Inability to tolerate reduced ECMO support indicating failed wean (Correct answer)
Vasodilatory shock requiring vasopressors only
Volume depletion requiring fluid resuscitation
Cardiac recovery adequate for decannulation

Correct answer: Inability to tolerate reduced ECMO support indicating failed wean

Hypotension with elevated CVP during ECMO wean indicates the native heart cannot maintain adequate output independently, meaning the patient has failed the wean trial.

Question 106: What does a persistently elevated pulmonary artery pressure on VA ECMO most likely indicate?

Pulmonary embolism unrelated to ECMO
LV distension due to insufficient venting (Correct answer)
Circuit recirculation
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 107: A VA-ECMO patient on full support suddenly develops pulsatile arterial waveforms with increased mean arterial pressure. This most likely indicates:

Aortic valve regurgitation worsening
Circuit malfunction reducing flow
Systemic hypertension crisis
Recovery of native cardiac function (Correct answer)

Correct answer: Recovery of native cardiac function

Return of pulsatility on VA-ECMO signifies improved native cardiac contractility, which is a positive sign of cardiac recovery.

Question 108: What is the most common cannulation site for peripheral VA ECMO in adults?

Femoral vein and radial artery
Right internal jugular vein and subclavian artery
Femoral vein and femoral artery (Correct answer)
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 109: A patient has been successfully weaned from peripheral Veno-Venous (VV) ECMO. The team is preparing for decannulation at the bedside. Which of the following is a critical preparatory step to minimize the risk of bleeding complications?

Administering a bolus of unfractionated heparin to prevent thrombus dislodgement.
Ensuring anticoagulation has been held and coagulation parameters are in a safe range. (Correct answer)
Maximizing ECMO blood flow just prior to cannula removal.
Placing the patient in a steep Trendelenburg position to prevent air embolism.

Correct answer: Ensuring anticoagulation has been held and coagulation parameters are in a safe range.

Decannulation involves removing large-bore cannulas from major vessels, posing a significant risk of hemorrhage. To ensure effective hemostasis via manual pressure or surgical repair, systemic anticoagulation must be discontinued and its effects must be verified to have diminished (e.g., via aPTT or ACT) before proceeding with cannula removal.

Question 110: After ECPR for drug-induced cardiac arrest, weaning should be attempted when which criterion is met?

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

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 111: What are the risks associated with ECMO?

ECMO is not resource-intensive or expensive.
Bleeding is the only risk associated with ECMO.
There are no risks associated with ECMO.
Bleeding, trauma to vessels, needle sticks, and resource intensity are risks associated with ECMO. (Correct answer)

Correct answer: Bleeding, trauma to vessels, needle sticks, and resource intensity are risks associated with ECMO.

Explanation: There are some concerning risks and downsides associated with ECMO and eCPR: Bleeding Trauma to vessels Needle sticks and exposures to healthcare workers during cannulation Can be confusing and overwhelming to the patient’s family Very resource intensive and expensive But there are benefits as well: Increased neurologically intact survival from cardiac arrest

Question 112: During management of a patient on VA ECMO with a centrifugal pump, you observe that the measured circuit blood flow has suddenly decreased from 4.5 LPM to 2.5 LPM, while the pump RPM has been increased from 3500 to 4000 in an attempt to compensate. Which of the following is the most likely cause for this change?

Inadequate venous drainage due to hypovolemia
An obstruction in the arterial (return) line (Correct answer)
Sudden improvement in native cardiac function
Air embolism in the venous drainage line

Correct answer: An obstruction in the arterial (return) line

Centrifugal pumps are afterload-sensitive. A sudden obstruction in the arterial line (e.g., cannula thrombus, kinked tubing, or dissection) increases the resistance (afterload) the pump must work against. This increased resistance directly causes a drop in flow. The combination of a falling flow despite an increasing RPM is a classic sign of a post-pump obstruction.

Question 113: 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?

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

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 114: 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?

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

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 115: A centrifugal pump is the most common type used in adult ECMO circuits. A key characteristic of a centrifugal pump is that its flow is:

Insensitive to afterload but dependent on preload
Preload dependent and afterload sensitive (Correct answer)
Dependent on afterload but insensitive to preload
Independent of afterload and preload

Correct answer: Preload dependent and afterload sensitive

Centrifugal pumps are non-occlusive pumps. Their output (flow) is dependent on the amount of blood available to enter the pump (preload) and sensitive to the resistance it has to pump against (afterload). For example, if afterload increases (e.g., due to a kink in the return line), the flow will decrease at the same RPM setting.

Question 116: What is the preferred route of nutritional support for hemodynamically stable ECMO patients?

Total parenteral nutrition via central line
Oral feeding once sedation is reduced
Peripheral parenteral nutrition
Enteral nutrition via nasogastric or nasoenteric tube (Correct answer)

Correct answer: Enteral nutrition via nasogastric or nasoenteric tube

Enteral nutrition is preferred in stable ECMO patients because it preserves gut integrity, reduces infection risk, and is associated with better outcomes compared to parenteral routes.

Question 117: 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.
Asystole often indicates non-cardiogenic causes of arrest. (Correct answer)
ECPR is only effective for shockable rhythms like V-fib and V-tach.
Asystole is a less common cause of cardiac arrest.

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

Explanation: 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 118: Cerebral regional oxygen saturation (rSO2) measured by NIRS falls below 50% in an ECMO patient. The first intervention should be:

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

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

Right ventricular free wall akinesis
Left ventricular ejection fraction of 15%
LVEF ≥ 35% with no severe valvular abnormality (Correct answer)
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 120: What is the most common cause of heparin resistance in ECMO patients?

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

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.

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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