What are the recommended power injector settings for an Endovascular Aneurysm Repair (EVAR) procedure?

Power Injector Settings for EVAR

For EVAR procedures, use a power injector set to deliver 50-100 mL of non-ionic iodinated contrast agent (≥350 mg/mL concentration) at a flow rate of ≥4 mL/sec. 1

Recommended Settings

Flow Rate and Volume

• Flow rate: ≥4 mL/sec is the standard recommendation from the European Society of Cardiology for CT angiography of large vessels including aortic imaging 1
• Volume: 50-100 mL of contrast medium is appropriate for adequate vessel opacification 1
• Higher flow rates (4-6 mL/sec) may be used for coronary and large vessel imaging, with volumes ranging from 50-160 mL depending on scan duration 1

Contrast Agent Specifications

• Use non-ionic iodinated contrast media with concentration ≥350 mg/mL 1
• Non-ionic agents are preferred over high-osmolar agents to reduce adverse reactions 2
• For patients with renal impairment (eGFR <60 mL/min/1.73m²), consider using the minimum effective concentration (200-300 mg I/mL) 2

Technical Requirements

• Power injector capability: The injector must be flow-rate controlled and capable of delivering up to 50 mL/sec for cardiac and large vessel angiography 1
• Pressure monitoring: Automatic detection and termination of over-pressure situations is essential 1
• Syringe heating: Maintain contrast material at approximately 37°C using a syringe heater 1

Timing Considerations

Scan Delay

• Standard delay: 15 seconds between contrast injection and image acquisition for most patients 1
• Extended delay: 15-30 seconds for patients with pulmonary arterial hypertension, right ventricular failure, or cardiac failure 1
• Use bolus-tracking method with threshold of 100 HU for arterial phase imaging 1

Vascular Access Requirements

Catheter Specifications

• Use an 18-gauge or larger cannula designed for power injection rates, typically placed in an antecubital vein 1
• Ensure the catheter is rated for the intended injection pressure and flow rate 3
• The syringe should be electrically isolated with independent ground cable attached to patient support 1

Safety Protocols

Pre-Procedure Assessment

• Assess renal function before selecting contrast concentration and volume 2
• For patients with eGFR <30 mL/min/1.73m², use extremely low doses or consider alternative imaging 2
• Ensure proper hydration before and after the procedure 2

Monitoring

• Monitor for extravasation: Power injector use has a low complication rate (0.1%) when proper protocols are followed 4
• The injector should have audible signals indicating current flow >20 mA 1
• Trigger and remote controls should automatically terminate injection when released 1

Post-Procedure Care

• Monitor renal function within 48-72 hours after contrast administration in high-risk patients 2
• Watch for signs of contrast-induced acute kidney injury in patients with pre-existing chronic kidney disease 2

Common Pitfalls to Avoid

• Insufficient flow rate: Using rates <4 mL/sec may result in inadequate vessel opacification for proper EVAR planning 1
• Inappropriate catheter size: Using catheters smaller than 18-gauge limits achievable flow rates and increases risk of catheter damage 1
• Ignoring renal function: Failing to adjust contrast concentration and volume for patients with impaired renal function increases risk of contrast-induced nephropathy 2
• Inadequate contrast warming: Cold contrast increases viscosity and may require higher injection pressures 1