What are the considerations for axillary artery cannulation in pediatric bypass cases?

Axillary Artery Cannulation in Pediatric Bypass Cases

Axillary artery cannulation in pediatric cardiac bypass cases is associated with significantly lower complication rates compared to femoral arterial access and should be considered the preferred approach when peripheral arterial cannulation is not feasible. 1

Advantages of Axillary Artery Cannulation

• Axillary artery cannulation permits antegrade flow in the arch vessels and is usually free from atherosclerosis with rich collateral vessels to the distal arm 2
• It provides a lower risk of atheroemboli compared to other cannulation sites 3
• Particularly beneficial in cases involving aortic dissection by reducing the risk of malperfusion 3
• Facilitates selective antegrade cerebral perfusion during hypothermic circulatory arrest 3
• Associated with significantly lower rates of vascular compromise (6.2% vs 19.9%) and pulse loss (2.1% vs 9.5%) compared to femoral arterial lines in pediatric patients 1

Technical Considerations

Cannulation Techniques

• Two main approaches exist for axillary artery cannulation:
  • Direct cannulation technique 4
  • Side-graft technique (anastomosing a graft to the axillary artery) 4
• The side-graft technique may reduce the risk of arterial damage or dissection compared to direct cannulation, though this hasn't shown statistical significance in all studies 4
• Ultrasound guidance is strongly recommended for arterial cannulation in pediatric patients to improve success rates and reduce complications 2

Anatomical Considerations

• Special attention must be paid to the brachial plexus during cannulation, particularly in small children and neonates, by visualizing it and avoiding a too lateral approach 2
• The axillary artery size must be evaluated pre-procedurally, as inadequate vessel size is a common reason for abandoning planned axillary cannulation (reported in approximately 4% of cases) 5
• The external diameter of the catheter should not exceed 1/3 of the internal diameter of the vessel to avoid the risk of venous thrombosis 2

Complications and Risk Factors

• Overall complication rates from axillary artery cannulation are relatively low (3.3-14%) 4, 5
• Potential complications include:
  • Local issues: seroma, hematoma, chronic pain, pectoralis major muscle atrophy 5
  • Vascular complications: arterial damage, dissection, thrombosis 4
  • Neurological: brachial plexus injury (though rare with proper technique) 4
• Risk factors for complications in pediatric central arterial cannulation include:
  • Neonatal and infant age groups 1
  • Presence of genetic syndromes 1
  • Prematurity 1
  • Longer anesthesia time 1
  • Larger catheter size relative to vessel diameter 1

Monitoring and Safety Measures

• Ultrasound equipment should remain easily accessible at the patient's bedside after central venous catheter placement to detect early life-threatening catheter-related complications 2
• Transesophageal echocardiography (TEE) is valuable for detecting potential complications like aortic dissection during the procedure 6
• Pre-procedural ultrasound evaluation of all possible vascular options allows for rational choice of the most appropriate vessels to cannulate 2

Special Considerations for Pediatric Patients

• There is no ideal site for cannulation in children; the best site should be determined after ultrasound examination 2
• Ultrasound-guided arterial catheterization improves first-pass success and should be used routinely in children and neonates 2
• The experience gained by using ultrasound routinely will be beneficial in difficult or extreme cases 2
• In recent research, axillary arterial access was associated with significantly fewer complications than femoral access in pediatric cardiac surgery patients 1

Pitfalls and Caveats

• Cannulation into an axillary artery is not always safe; rare but serious complications like aortic dissection can occur 6
• Malperfusion in aortic dissections has been reported in up to 20% of cases using the side-graft technique 4
• Inadequate vessel size is the most common reason for abandoning planned axillary cannulation 5
• While generally safer than femoral cannulation, serious complications can still occur and require vigilant monitoring 1, 4