ECMO Weaning and Decannulation 4 — Questions and Answers
Question 1: In pediatric VA-ECMO for post-cardiac surgery myocardial stunning, which myocardial function marker on echocardiography is most commonly used to guide weaning readiness?
- Tissue Doppler E/e' ratio
- Left ventricular shortening fraction > 25–30% (Correct answer)
- Right ventricular systolic pressure gradient
- Tricuspid annular plane systolic excursion (TAPSE)
Correct answer: Left ventricular shortening fraction > 25–30%
An LV shortening fraction above 25–30% on echocardiography is a widely used pediatric benchmark indicating adequate myocardial recovery for VA-ECMO weaning.
Question 2: During a VV-ECMO weaning trial with sweep gas at zero, the patient's arterial blood gas shows pH 7.30, PaCO2 58 mmHg, PaO2 72 mmHg on FiO2 0.50. The correct interpretation is:
- Weaning is successful; proceed to decannulation
- Oxygenation is marginal and CO2 retention is unacceptable; defer decannulation (Correct answer)
- Only the hypercapnia is concerning; reduce ventilator rate to compensate
- Increase ECMO blood flow to improve oxygenation
Correct answer: Oxygenation is marginal and CO2 retention is unacceptable; defer decannulation
Both significant hypercapnia (PaCO2 58) and borderline oxygenation with respiratory acidosis indicate the native lungs are not yet ready to sustain gas exchange independently.
Question 3: Which of the following correctly describes the 'bridge-to-decision' scenario in which ECMO decannulation is deferred pending further evaluation?
- The patient has recovered myocardial function and wishes to stop ECMO
- ECMO supports a patient awaiting heart transplant listing or durable LVAD implantation (Correct answer)
- The patient is extubated and ambulatory on ECMO
- Decannulation site is infected, delaying the procedure
Correct answer: ECMO supports a patient awaiting heart transplant listing or durable LVAD implantation
Bridge-to-decision ECMO maintains perfusion while the team evaluates candidacy for definitive therapy such as transplant or durable mechanical support.
Question 4: When performing surgical decannulation of an arterial cannula in the femoral artery, the surgeon should routinely assess for:
- Adequate venous outflow from the contralateral femoral vein
- Distal limb perfusion by checking pedal pulses or Doppler signals after repair (Correct answer)
- Intraoperative EEG changes indicating cerebral hypoperfusion
- Hepatic artery patency via abdominal ultrasound
Correct answer: Distal limb perfusion by checking pedal pulses or Doppler signals after repair
Arterial decannulation carries risk of distal ischemia or embolism; confirming pedal pulses or Doppler flow after repair is essential before closure.
Question 5: A patient fails multiple VA-ECMO weaning trials over 14 days. The ECMO team should next consider:
- Indefinite continuation of ECMO support
- Evaluation for durable ventricular assist device implantation or heart transplantation (Correct answer)
- Switching to VV-ECMO to rest the heart further
- Increasing anticoagulation intensity to prevent circuit thrombosis
Correct answer: Evaluation for durable ventricular assist device implantation or heart transplantation
Repeated weaning failure after 2 weeks indicates the heart is unlikely to recover; escalation to a durable VAD or transplant evaluation is the appropriate next step.
Question 6: During decannulation of a right internal jugular VV-ECMO cannula, which maneuver most effectively prevents venous air embolism at the moment of cannula withdrawal?
- Having the patient perform a forced maximal inspiration
- Asking the patient to perform a Valsalva maneuver or holding breath at end-expiration (Correct answer)
- Placing the patient in reverse Trendelenburg (head up)
- Withdrawing the cannula at high speed to minimize exposure time
Correct answer: Asking the patient to perform a Valsalva maneuver or holding breath at end-expiration
Valsalva or breath-hold at end-expiration raises intrathoracic and central venous pressure, preventing air from entering the vein during cannula withdrawal.
Question 7: In ECMO weaning protocols, 'flow titration' refers to:
- Adjusting sweep gas FiO2 to control PaO2
- Systematically reducing pump blood flow in incremental steps while monitoring hemodynamic and gas exchange response (Correct answer)
- Titrating anticoagulation to maintain ACT within goal range
- Adjusting ventilator settings during the weaning process
Correct answer: Systematically reducing pump blood flow in incremental steps while monitoring hemodynamic and gas exchange response
Flow titration involves stepping down pump flow incrementally (e.g., 0.5 L/min decrements) to stress-test the patient's native cardiopulmonary function before decannulation.
ECMO Weaning and Decannulation 4
In pediatric VA-ECMO for post-cardiac surgery myocardial stunning, which myocardial function marker on echocardiography is most commonly used to guide weaning readiness?