Overview
Definition:
Umbilical arterial catheter (UAC) placement is a procedure to insert a catheter into the umbilical artery, typically for monitoring arterial blood pressure, sampling arterial blood for gas analysis, and administering fluids or medications in neonates.
Epidemiology:
UACs are commonly used in critically ill neonates, particularly premature infants and those requiring mechanical ventilation or vasoactive support
The incidence varies based on the acuity of neonatal intensive care units (NICUs) and the patient population served.
Clinical Significance:
UACs provide continuous hemodynamic monitoring and access for frequent blood sampling, which is crucial for timely diagnosis and management of conditions like respiratory distress syndrome, asphyxia, sepsis, and congenital heart disease in neonates
However, they are associated with significant complications, requiring careful consideration of risks and benefits.
Indications
Hemodynamic Monitoring:
Continuous direct arterial blood pressure monitoring is essential in unstable neonates, including those with shock, severe illness, or requiring vasoactive support
This allows for real-time assessment of perfusion and response to interventions.
Frequent Blood Sampling:
Regular arterial blood gas (ABG) analysis is vital for managing respiratory failure, metabolic acidosis, and monitoring oxygenation
UACs minimize the need for repeated heel-pricks or peripheral arterial punctures.
Fluid And Medication Administration:
Provides reliable access for administering essential fluids, medications (e.g., inotropes, vasopressors, antibiotics), and blood products to critically ill neonates, especially when peripheral venous access is challenging.
Exchange Transfusion:
While less common now, UACs can be used for exchange transfusions in neonates with severe hyperbilirubinemia or hemolytic disease.
Procedure Technique
Preparation:
Sterile technique is paramount
Ensure proper patient positioning, identification of the umbilical stump, and availability of all necessary equipment including a UAC, saline flush, antiseptic solution, and appropriate lighting
The umbilical cord should be cleansed thoroughly.
Catheter Insertion:
The umbilical artery is cannulated, typically after ligation of the cord, leaving a small stump for traction
The catheter is advanced into the umbilical artery, and its position is confirmed radiographically to ensure it is above the diaphragm and below the renal arteries (ideally at T6-T10 level).
Securing And Management:
Once correctly positioned, the catheter is secured to the abdominal wall to prevent dislodgement
Regular flushing with sterile saline (usually 1-2 mL/kg every 4-8 hours) is performed to maintain patency and prevent thrombus formation
Continuous monitoring of the catheter site for signs of infection or ischemia is crucial.
Complications
Early Complications:
Hemorrhage from the umbilical stump or catheter site
Vasospasm of the umbilical artery
Thrombosis and embolism leading to ischemia of lower extremities, kidneys, or intestines
Infection (local or systemic, e.g., omphalitis, sepsis)
Catheter knotting or avulsion
Arrhythmias during insertion
Accidental over-advancement into the aortic arch.
Late Complications:
Ischemic injury to distal organs (e.g., bowel necrosis, renal infarction, limb ischemia)
Persistent hypertension in pulmonary circulation
Atherosclerotic changes in the aorta later in life
Infection leading to osteomyelitis or endocarditis (rare)
Catheter-related thrombus formation.
Prevention Strategies:
Adherence to sterile technique
Proper catheter sizing and selection
Accurate radiographic confirmation of catheter tip position
Regular flushing to maintain patency
Close monitoring of peripheral perfusion and signs of ischemia
Prompt removal of the catheter once no longer indicated
Avoiding excessive manipulation of the catheter
Careful aseptic technique during all manipulations.
Management Of Complications
Hemorrhage:
Immediate removal of the catheter
Direct pressure on the site
If severe, ligation of the umbilical vessels may be necessary.
Thrombosis And Embolism:
Immediate catheter removal
Assessment of distal perfusion
Anticoagulation therapy may be considered in select cases, balancing risk of bleeding with embolic event
Surgical intervention is rarely indicated.
Infection:
Prompt catheter removal
Blood cultures and inflammatory markers
Empiric antibiotics are initiated based on local protocols
If sepsis is confirmed, treatment is continued based on sensitivities.
Ischemic Injury:
Aggressive management to restore perfusion if possible
Supportive care
Monitoring for organ-specific complications (e.g., bowel rest for NEC, renal support for renal compromise)
Long-term follow-up for sequelae.
Key Points
Exam Focus:
Understand the specific anatomical landmarks for correct UAC tip placement (e.g., above diaphragm, below renal arteries, ideally T6-T10)
Differentiate between early and late complications
Know the critical role of UACs in hemodynamic management of sick neonates.
Clinical Pearls:
Always confirm UAC tip position with X-ray before infusing medications or vasoactive agents
Maintain meticulous sterile technique and regular flushing to minimize complications
Promptly remove the UAC as soon as it is no longer clinically indicated.
Common Mistakes:
Incorrect catheter tip positioning leading to serious complications like aortic arch thrombosis or mesenteric ischemia
Failure to maintain aseptic technique
Not flushing the catheter regularly, leading to occlusion
Delaying catheter removal when no longer indicated.