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For patients who need temporary mechanical circulatory support, the placement and management of the devices play critical roles in treatment. Careful technique and continued monitoring help reduce potential complications associated with vascular access.
In her presentation, “The Cannula Is the Culprit,” Dr. Allison Dupont, an interventional cardiologist with Northside Hospital Heart Institute and director of the cardiac intensive care unit and ECMO programs for Northside Hospital System, outlines practical approaches to safe cannula placement and management. Many mechanical circulatory support complications can be avoided through meticulous attention to detail.
The presentation focuses on percutaneous venoarterial extracorporeal membrane oxygenation, or VA ECMO, which supports patients with severe circulatory failure. Cannulas connect the patient’s blood vessels to the support system. Dupont emphasizes that safe access, appropriate equipment selection, and post-placement care are essential.
Safer access begins with imaging
Dupont recommends ultrasound to guide access to the femoral vessels. Her presentation encourages clinicians to build ultrasound proficiency during routine procedures so the technique is familiar when emergency support becomes necessary.
When circumstances allow, imaging through a small initial sheath can help assess access to the common femoral artery before clinicians insert larger equipment.
She also recommends placing a distal perfusion sheath to supply blood farther down the leg before inserting the arterial ECMO cannula, when time permits. This step addresses the risk of inadequate limb perfusion.
Equipment and positioning matter
Creating a path for an ECMO cannula requires adequate guidewire support and careful dilation. Dupont highlights the importance of choosing a supportive wire and preparing the surrounding tissue to allow cannula advancement.
Cannula selection should reflect the patient and the circumstances. Dupont discusses differences in cannula lengths and diameters for bedside placement, resuscitation, and escalation of support for cardiogenic shock. Her central message is to select appropriate equipment for the individual patient needs.
Protecting the limbs
After cannulation, the care team shifts its attention to maintaining safe, effective support.
Dupont identifies reduced blood flow to the leg, known as limb ischemia, as a complication that requires close attention. Equipment used to maintain blood flow must remain free of kinks that could obstruct circulation.
Securing cannulas is another priority. Dupont emphasizes firm suturing, particularly because some patients may eventually walk while receiving support. Reliable fixation helps limit the risk of movement or dislodgment.
Monitoring continues after the procedure
For patients undergoing cannulation in the cardiac catheterization laboratory, Dupont recommends placing a pulmonary artery catheter and a right radial arterial line before transfer, if they are not already present.
She also highlights checking oxygenation in the right radial artery before leaving the laboratory to assess for Harlequin syndrome, a potential oxygenation concern during VA ECMO support.
When venous pressure alarms occur, her presentation recommends first assessing whether additional volume is needed while simultaneously assessing for ECMO circuit related issues, such as kinking of tubing.
Throughout the presentation, Dupont stresses consistent attention to methodical details. Safe vascular access, imaging when available, appropriate cannula selection, and stable placement establish the foundation for the care of these incredibly sick patients.
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