Lecture Summary: Monitoring Patients on VV ECMO
Learning Objectives
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Understand the goals of VV ECMO monitoring.
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Systematically assess the patient and ECMO circuit.
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Identify key parameters to monitor in both patient and machine.
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Recognize early signs of complications and readiness for weaning.
Principles of VV ECMO Monitoring
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Monitoring must be divided into three components:
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Patient – ICU assessment (organ function, hemodynamics, sedation, fluid balance).
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ECMO Circuit – ensuring correct function of pump, oxygenator, and cannulas.
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Interaction – harmony between patient’s cardiopulmonary system and ECMO.
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Multidisciplinary team (nurses, intensivists, perfusionists, surgeons, respiratory physicians) plays a critical role through daily rounds and checklists.
Patient Monitoring
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Respiratory System
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Clinical exam, chest imaging, ventilator settings.
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Key variables: tidal volume, compliance, gas exchange.
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Hemodynamics
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MAP, HR, fluid status (ultrasound, balance chart, exam).
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Volume overload → may delay ECMO weaning.
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Thermodilution is unreliable on ECMO.
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Neurological Status
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Vigilant monitoring for intracranial bleeding, sedation depth, pupillary reactions.
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Renal Monitoring
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Urine output, urine color, interaction with RRT.
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Drug Effects
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Pharmacokinetics altered by ECMO → focus on effect, not just dose.
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Hematology & Anticoagulation
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Daily targets for Hb, platelets, and anticoagulation adjusted to bleeding/thrombosis risk.
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ECMO Circuit Monitoring
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Cannulas: location (radiology + clinical), tip position, migration risks, infection/bleeding/DVT at site.
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Blood Gases:
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Pre-oxygenator: represents venous return/CvO₂ (consumption vs drainage adequacy).
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Post-oxygenator: represents oxygenator function (baseline reference after initiation).
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Pressures: Pre-pump and post-oxygenator pressures for circuit integrity.
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Alarms: Set high/low flow alarms early for safety.
Patient–ECMO Interaction
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Gas exchange depends on 3 components:
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Oxygenator performance.
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Native lung contribution (from full shunt → partial recovery).
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Proportion of undrained venous blood mixing with ECMO return.
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ABG monitoring:
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Arterial blood gas = final interaction of patient + ECMO.
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Compare with pre- and post-oxygenator gases to troubleshoot.
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Complications to Detect Early
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Cannula displacement or malposition.
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Bleeding (internal/external).
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Oxygenator dysfunction (falling post-oxygenator PaO₂).
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Infection or clot formation.
Key Takeaway Framework (ABC of Monitoring)
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A – Assess the patient.
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B – Assess the ECMO circuit.
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C – Assess their interaction.
Conclusion
Monitoring VV ECMO patients requires:
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Continuous vigilance,
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Structured assessment (patient, circuit, interaction),
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Multidisciplinary collaboration,
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Early recognition of complications and recovery to guide management and weaning.