Femoral cannulation is a widely used technique in cardiopulmonary bypass (CPB), especially in minimally invasive cardiac surgery (MICS) and reoperative procedures. This approach allows for an alternative arterial and venous access point, bypassing the need for direct aortic cannulation. However, it comes with its own set of challenges, requiring precise execution to ensure patient safety and optimal perfusion.
In this comprehensive guide, we will explore femoral cannulation in CPB, focusing on techniques, indications, complications, and best practices for perfusionists.
Table of Contents
1. Understanding Femoral Cannulation in CPB
1.1 What is Femoral Cannulation?
1.2 Indications for Femoral Cannulation
- Minimally invasive cardiac surgery (MICS) – Allows for small incisions and avoids median sternotomy.
- Reoperative cardiac surgeries – Prevents trauma to previous sternotomies and adhesions.
- Aortic disease (dissections, aneurysms, calcifications) – Avoids manipulation of the diseased aorta.
- Emergency situations (cardiac arrest, ECMO initiation) – Quick access for extracorporeal support.
- Obese patients or those with poor sternal access – Provides an alternative perfusion route.
1.3 Anatomical Considerations
The femoral artery and vein lie within the femoral sheath, along with the femoral nerve. Proper anatomical knowledge is crucial to prevent complications such as nerve injury or incorrect cannulation.
2. Techniques of Femoral Cannulation
Femoral cannulation involves the insertion of arterial and/or venous cannulas into the femoral artery and vein, facilitating extracorporeal circulation during cardiac surgery. This technique is particularly useful in cases where direct aortic access is challenging or contraindicated.
2.1 Surgical Techniques
A. Open Surgical Exposure
- Involves making an incision in the groin to expose the femoral artery and vein.
- Direct visualization ensures precise cannula placement.
- Common in reoperations and high-risk cases.
B. Percutaneous (Seldinger) Technique
- Ultrasound-guided needle insertion, followed by guidewire placement.
- Sequential dilatation of the vessel before inserting the cannula.
- Less invasive, faster recovery, and preferred in MICS.
2.2 Cannula Selection and Placement
- Arterial cannulas: Must be appropriately sized based on BSA and target flow rate.
- Venous cannulas: Larger sizes are preferred for optimal drainage.
- TEE and fluoroscopic guidance: Ensures accurate placement and prevents malpositioning.
2.3 Securing and Managing Cannulas
- Proper suturing and fixation to prevent dislodgment.
- Monitoring for kinking, occlusion, or positional shifts.
- Regular flow and pressure assessments.
3. Hemodynamic Management and Perfusion Considerations
3.1 Challenges of Retrograde Arterial Flow
Unlike aortic cannulation, femoral arterial flow is retrograde, meaning blood flows against the normal direction toward the aortic arch. This can:
- Increase afterload, leading to ventricular strain.
- Cause cerebral embolization if aortic plaques are dislodged.
- Require higher MAP settings to maintain adequate cerebral perfusion.
3.2 Limb Ischemia Prevention
One major concern with femoral cannulation is distal limb ischemia due to compromised blood flow. Prevention strategies include:
- Distal perfusion cannula – A side branch cannula to maintain flow to the lower limb.
- Near-Infrared Spectroscopy (NIRS) Monitoring – Ensures adequate perfusion.
- Frequent vascular assessments – Monitoring capillary refill and Doppler signals.
3.3 Venous Drainage Optimization
- Vacuum-Assisted Venous Drainage (VAVD) improves venous return.
- Bi-caval cannulation may be necessary for superior drainage.
- TEE confirmation prevents inadequate drainage or caval obstruction.
4. Complications and Risk Management
4.1 Arterial Complications
- Limb ischemia – Due to reduced distal flow; mitigated with distal cannulation.
- Aortic dissection – Can occur if the guidewire perforates the aortic wall.
- Stroke and embolism – Risk of retrograde embolization.
4.2 Venous Complications
- Venous hypertension – Occurs if drainage is inadequate.
- Caval occlusion – Can be caused by oversized venous cannulas.
4.3 Infection and Bleeding Risks
- Hematoma formation – Due to improper suturing or anticoagulation.
- Groin infections – More common in open techniques, requiring sterile field maintenance.
- Postoperative vascular compromise – Needs ongoing Doppler assessments.
5. Best Practices for Perfusionists
5.1 Preoperative Planning
- Doppler ultrasound or CTA assessment to evaluate vessel patency.
- Selecting the optimal cannulation technique based on patient anatomy.
5.2 Intraoperative Optimization
- Collaboration with the surgical team to ensure safe cannulation.
- Monitoring perfusion parameters (MAP, SvO2, NIRS, lactate levels).
- Adjusting flows and resistance for optimal organ perfusion.
5.3 Postoperative Care and Monitoring
- Continued limb perfusion assessment.
- Managing anticoagulation to prevent thrombotic complications.
- Early mobilization and wound care for open surgical cases.
6. Frequently Asked Questions (FAQs)
Why is femoral cannulation preferred over direct aortic cannulation in some cases?
Femoral cannulation is preferred in cases where direct aortic access is difficult or contraindicated, such as in reoperative cardiac surgery, severe aortic calcification, aortic dissections, and minimally invasive procedures.
How does TEE assist in femoral cannulation?
Transesophageal echocardiography (TEE) provides real-time visualization of the guidewire and cannula placement, ensuring correct positioning and preventing malpositioning or complications like retrograde dissection.
What are the best methods to prevent limb ischemia?
Using a distal perfusion cannula, monitoring limb perfusion with near-infrared spectroscopy (NIRS), and frequent vascular assessments help prevent limb ischemia.
How does retrograde flow impact perfusion dynamics?
Retrograde arterial flow can increase afterload, potentially leading to ventricular strain and increased cerebral embolization risk, requiring careful MAP regulation.
What are the risks of percutaneous femoral cannulation?
Risks include vascular injury, bleeding, limb ischemia, retroperitoneal hematoma, and aortic dissection if the guidewire or cannula is improperly positioned.
What are the signs of cannula malpositioning?
Signs include high resistance to flow, low perfusion pressures, inadequate venous drainage, and abnormal TEE or Doppler findings.
When should an alternative cannulation site be used?
An alternative site should be used if there is femoral artery disease, poor vessel patency, severe peripheral vascular disease, or complications arise during insertion.
Conclusion
Femoral cannulation remains a vital technique in CPB, offering advantages in minimally invasive procedures, reoperations, and aortic pathologies. However, it requires careful planning, real-time monitoring, and post-op vigilance to mitigate complications.
Perfusionists play a critical role in optimizing flow, managing hemodynamic challenges, and preventing complications. Adopting best practices such as TEE guidance, distal perfusion cannulas, and VAVD can significantly enhance patient outcomes.
As advancements in cannulation technology and perfusion monitoring continue to evolve, femoral access is becoming safer and more effective than ever before.
🔹 Stay informed, stay precise, and elevate your perfusion practice! 🔹
