Overview
Definition:
Ultrasound-guided peripheral intravenous (IV) cannulation is a technique that utilizes real-time ultrasonography to visualize veins and guide the insertion of an IV catheter, particularly in patients with difficult venous access
This method enhances the success rate and reduces complications compared to traditional blind insertion.
Epidemiology:
Difficult venous access affects an estimated 5-10% of patients in the general population, increasing to up to 40% in specific groups like elderly patients, individuals with obesity, those with dark skin, and frequent IV drug users
USG-guided PIV can reduce cannulation attempts by up to 50% in these populations.
Clinical Significance:
Effective peripheral IV access is crucial for administering fluids, medications, blood products, and for hemodynamic monitoring
USG-guided cannulation improves patient comfort, reduces the need for multiple venipunctures, minimizes tissue trauma and hematoma formation, and shortens the time to treatment initiation, especially in emergency and critical care settings
It is a vital skill for surgical residents preparing for DNB and NEET SS examinations.
Indications
Patient Factors:
History of difficult venous access
Obesity
Dark skin pigmentation
Previous failed cannulation attempts
Presence of edema or scarring
Young children and elderly patients.
Clinical Situations:
Emergency department settings
Intensive care units
Operating rooms
Oncology patients undergoing chemotherapy
Patients requiring prolonged IV therapy
When accurate central venous access is not immediately indicated or feasible.
Vein Characteristics:
Small, fragile, or deeply located veins
Varicose veins
Tortuous venous pathways
Patients with chronic venous insufficiency
Absence of palpable veins despite thorough examination.
Equipment And Setup
Ultrasound Machine:
High-frequency linear transducer (typically 10-15 MHz)
Ultrasound gel
Sterile probe cover and sterile gel
Appropriate sterile drapes and sterile gloves.
Cannulation Supplies:
Peripheral IV catheters of appropriate size (e.g., 20-24G)
Antiseptic solution (e.g., chlorhexidine or povidone-iodine)
Tourniquet
Dressing supplies (transparent semipermeable dressing, tape)
Saline flush syringes.
Patient Preparation:
Explain the procedure to the patient and obtain informed consent
Position the patient comfortably, ensuring adequate limb support and venous distension (e.g., arm dependent)
Cleanse the venipuncture site with antiseptic solution and allow it to dry completely.
Technique Ultrasound Guided
Probe Placement And Imaging:
Apply ultrasound gel to the skin over the target area
Place the sterile transducer in a sterile sleeve with gel in a long-axis (sagittal) or short-axis (transverse) view
Identify a suitable, clearly visualized vein that is compressible and free from thrombus.
Vein Assessment:
In long-axis view, observe the vein’s depth, diameter, and course
Assess for pulsatility (to distinguish from arteries)
In short-axis view, the vein appears as a anechoic, circular or oval structure that collapses when slight pressure is applied by the transducer
Ideally, target a vein that is >3mm in diameter and <2cm in depth.
Cannulation Approach:
The needle can be advanced in-plane (parallel to the long axis of the transducer) or out-of-plane (perpendicular to the long axis)
The in-plane approach provides a continuous view of the entire needle shaft as it advances into the vein and is generally preferred for better visualization and control of the needle tip.
Catheter Insertion And Securing:
Advance the needle/catheter assembly slowly under direct ultrasound visualization, aiming for the center of the vein
A flash of blood (venous flashback) in the catheter hub confirms venous entry
Advance the catheter off the needle, remove the needle, and secure the catheter with a dressing
Flush the catheter with saline to confirm patency.
Advantages
Increased Success Rate:
Significantly higher success rates, especially in patients with difficult venous access, reducing the number of insertion attempts.
Reduced Complications:
Lower incidence of nerve injury, arterial puncture, hematoma formation, and phlebitis compared to landmark-based techniques.
Improved Patient Experience:
Less patient discomfort and anxiety due to fewer painful venipunctures and faster access.
Time Efficiency:
Quicker establishment of IV access in emergent situations, leading to faster administration of life-saving treatments.
Complications
Local Complications:
Hematoma formation
Bleeding
Local infection
Infiltration of infusate
Nerve injury (rare)
Arterial puncture (if not carefully differentiated)
Phlebitis.
Systemic Complications:
Catheter embolism (rare)
Sepsis (rare)
Air embolism (rare)
Thrombophlebitis.
Prevention Strategies:
Strict sterile technique
Proper vein selection and assessment using ultrasound
Gentle insertion to avoid intimal damage
Securement of the catheter to prevent dislodgement
Regular monitoring of the IV site for signs of inflammation or infection
Using the smallest effective catheter size.
Key Points
Exam Focus:
Understanding indications for USG-guided PIV
Key equipment and sterile precautions
Differentiating artery vs
vein on ultrasound (pulsatility, shape)
In-plane vs
out-of-plane needle insertion techniques
Recognizing and managing potential complications.
Clinical Pearls:
Always use sterile technique and a sterile probe cover for USG-guided procedures
Practice recognizing venous structures in various anatomical locations
Consider vein depth and compressibility for optimal cannulation
If unsure, always re-assess with ultrasound before advancing the needle.
Common Mistakes:
Failure to use sterile technique or probe cover
Incorrect identification of arteries as veins
Attempting cannulation without clear visualization of the needle tip
Advancing the needle too aggressively
Inadequate securing of the IV catheter.