ECMO: Emergencies and Complications

Medical Complications

  • Intracranial and other hemorrhage: The risk of bleeding in various areas during ECMO therapy.

  • Hemofiltration: A process often used in conjunction with ECMO to remove excess fluids and solutes from the blood.

  • Pneumothorax: The presence of air in the pleural space which can complicate respiration and ECMO functioning.

  • Cardiac arrest: A critical event where the heart stops functioning, necessitating immediate intervention.

  • Prolonged hypo/hypertension: Abnormally low or high blood pressure can lead to further complications; monitoring and management are crucial.

  • Severe coagulopathy: A severe alteration in the blood's ability to clot, frequently arising in patients on ECMO.

  • Seizures: Neurological events that may occur as a complication due to multiple factors in ECMO patients.

Additional Medical Complications

  • Cardiac stun: A phenomenon wherein myocardial function is temporarily impaired potentially due to perfusion changes.

  • Severe hypovolemia: When the blood volume is excessively low, affecting overall circulation and perfusion.

  • Tension pneumo and hemo-thorax: Conditions arising from air and blood accumulation in the pleural cavity that can cause respiratory distress.

Mechanical Complications

  • Circuit disruption: Any interruption in the ECMO circuit that affects flow and patient stability.

  • Raceway rupture: Breaking of the tubing that connects various components of the ECMO machine.

  • System or component failure: The breakdown of any ECMO component can compromise patient care.

  • Specific components affected:

    • Bladder: Used in the venous reservoir; any failure can affect fluid management.

    • Pump controller: Regulates blood flow; malfunctioning leads to inadequate circulation.

    • Oxygenator: Critical for gas exchange in the bloodstream; failure causes hypoxia.

    • Heater: Maintains blood temperature; malfunction can lead to hypothermia or hyperthermia.

Additional Mechanical Complications

  • Air embolus: Introduction of air into the circuit, which can lead to critical vascular occlusions.

  • Inadvertent decannulation: Accidental dislodging of the cannula from its vascular access site.

  • Clots: Formation within the circuit that impedes blood flow and increases pressure.

Safety Devices and Monitors

  • Air bubble detector: Identifies and alerts to the presence of air bubbles in the circuit.

  • Bladder box/servo-regulation: Maintains and regulates the pressure and fluid levels accordingly.

  • Blood flow-meter: Monitors the flow rate of blood through the system.

  • Pressure modulation: Ensures that pressures within the circuit are maintained within safe limits.

  • Venous Oxygenation Saturation and Routine ABG monitoring: Checks oxygen levels and acid-base status in the blood, aiding in patient assessment.

  • Temperature Monitoring: Important for maintaining the correct blood temperature during ECMO therapy.

  • Ventilation Gas Analyzer: Assesses the gases being delivered to the patient, crucial for ventilatory support management.

Assessment of the ECMO Circuit

  • Conduct a thorough evaluation at the beginning of each shift, focusing on:

    • Cannula to cannula connection

    • Venous cannula integrity

    • Venous reservoir/bladder functionality

    • Pump: Confirm that the EXT light is illuminated, indicating operational status.

    • Oxygenator: Ensure proper functioning and check for clots or blockages.

    • Heat exchanger: Check for adequate temperature regulation.

    • Arterial cannula: Inspect for patency and connections.

    • Environmental conditions: Ensure the surrounding operating conditions support effective ECMO function.

Pump-Related Complications

  • Pump failure: In the event of pump failure, immediate actions include:

    • Use of a hand crank to maintain circulation manually.

    • Call for assistance from the perfusion team.

    • Adjust speed control to zero to lessen flow until assistance arrives.

    • Confirm the correct direction of flow in the circuit.

    • Monitor circuit pressures continuously.

    • Conduct a visual inspection of the venous bladder to avoid cavitation.

    • Ensure the battery is functioning properly if using a battery-powered system.

  • Loss of occlusion: This occurs when membrane pressures decrease despite constant flow, leading to insufficient oxygenation. Key points include:

    • There will be increases in flow without corresponding increases in membrane pressures.

    • Utilization of an ultrasonic flow probe may be necessary to identify flow issues.

Oxygenator Complications

  • Pressure monitoring: Conduct pre and post checks, documented hourly to identify trends.

Definition: Pressure Drop

  • Defined as the resistance to blood flow created by the membrane oxygenator:

    • Pressure drop = pre-membrane pressure - post-membrane pressure.

Increase in Pressure Drop

  • Indicative of thrombus formation, leading to:

    • Elevated resistance to blood flow.

    • Decreased transfer of CO2 and O2.

    • Requires assessment of pre and post membrane blood gas levels.

Carbon Dioxide Retention

  • Occurs when fluid (water or blood) accumulates in the gas phase of the oxygenator:

    • Assessment of fluid from the gas exit port is fundamental; clear fluid allows for increased sweep gas, whereas blood-tinged fluid requires caution.

Failing Oxygenator

  • Symptoms indicating a failing oxygenator include:

    • Decreased oxygen or carbon dioxide transfer.

    • Rising pressure drop.

    • Increased hemolysis.

    • Development of consumptive coagulopathy.

    • Immediate consultation with a perfusionist and potential replacement of the oxygenator with a reprime kit.

Heat Exchanger Complications

  • Possible alterations to the heat exchanger include:

    • Structural changes.

    • Failure of the warming bath.

    • Water-to-blood leak leading to complications such as hemolysis, seizures, and potential sepsis.

  • Water to Blood leak: Requires immediate action:

    • Labs will show severe hemolysis and very low sodium levels.

    • Cut off the water bath and clamp lines, then call the perfusionist to prime a new circuit.

Tubing Complications

  • Tubing Rupture: This might be caused by:

    • Damage from a tubing clamp.

    • Piercing by a towel clamp.

    • Cracking from fatigue or traumatic tears in the raceway.

    • Recommended preventative measures include:

    • Using tie-bands on all high-pressure connections.

    • Utilizing Super Tygon tubing for the raceway.

    • Having a raceway change-out kit available comprising tubing, connectors, sterile scissors, and priming fluid.

  • Raceway Rupture: Response steps:

    • Disconnect the patient from ECMO.

    • Hand ventilate and initiate CPR if necessary.

    • Cut off gas flow and isolate the ruptured segment.

    • Use transfusions to maintain cardiac output and change the affected raceway segment, ensuring to prime it properly before reattaching the circuit.

Air Embolism Complications

  • Air embolism: Sources include:

    • Introduction via hitting the membrane or low-pressure environment.

    • Clamp obstruction on the venous side of the circuit.

    • Servo-regulation failure and gas-to-blood phase leaks.

    • It is critical to never obstruct the gas outlet; gas should only be off when there is no blood flow.

    • Fluid from the gas exit port must be observed diligently.

  • Management of Air Embolism:

    • Remove the patient from bypass and clamp the arterial line.

    • Unclamp the bridge, then clamp the venous line and stop gas flow.

    • Keep the patient's head lower than their body.

    • Aspirate accessible air from the arterial cannula if feasible.

  • Post-Event Management: Identify and repair the cause of the embolism; consider hyperbaric chamber treatment for decompression if air has entered the coronaries, and inotropic drugs may be needed.

Renal Failure Complications

  • Continuous hemofiltration: Used to remove plasma water and solutes, while retaining proteins.

  • Associated with increased plasma-free hemoglobin levels, necessitating close monitoring.

Hemolysis Complications

  • Caused by blood surface interactions and the utilization of roller pumps.

  • Clots within the circuit or membrane may promote coagulopathy, leading to red blood cells adhering to and lysing on fibrin strands.

Intracranial Hemorrhage

  • Occurs in approximately 13% of neonates on ECMO treatment. Risk factors include:

    • Systemic heparinization.

    • Systemic hypertension.

    • Gestational age of less than 35 weeks.

    • Weight of less than 2 kilograms.

  • Preventative strategies include avoiding thrombocytopenia and monitoring activated clotting times (ACTs) alongside heparin dosages.

Bleeding Complications

  • Cannula site bleeding: Essential to ensure hemostasis during cannulation; utilize hemostatic agents like Gelfoam, Surgicel, or topical thrombin.

    • The ACT may need to be lowered, and turning off heparin should only occur following consultation with a perfusionist.

    • Maintain a platelet count above 125,000; if blood loss exceeds 10 cc/hr for 2 hours, the wound requires exploration.

  • Other bleeding signs include decreasing hematocrit (HCT), rising heart rate (HR), falling blood pressure, and inadequate venous return.

Thrombocytopenia

  • Defined as a platelet count lower than 100,000. Possible causes include:

    • Decreased platelet production due to hypoxia.

    • Increased platelet consumption or removal to extravascular sites.

    • Dilution as a consequence of fluid management.

Platelet Transfusions

  • Indicated post-membrane, often necessitating a heparin bolus and more frequent ACT checks. Increasing the number of platelet transfusions beyond 4 per day may be required while assessing the circuit for clots and possibly changing the circuit or oxygenator if needed.

Hypertension Complications

  • May contribute to the increased incidence of intracranial hemorrhage (ICH). Causes to assess include pain, hypercarbia, and hypoxia.

  • Medical Management includes the use of:

    • Hydralazine, nitroglycerin, and captopril for blood pressure control.

Conclusion

  • Stay Calm and Positive: Essential mindset in managing ECMO treatments effectively and ensuring patient safety.