The Use of Ultra-High Frequency Ultrasound for Vascular Access in Pediatric Patients

Introduction

Achieving vascular access in neonates and young children remains one of the more technically challenging aspects of pediatric care. Factors such as small vessel size, adiposity, and patient movement can complicate both arterial and venous cannulation, particularly in the NICU setting. While ultrasound guidance has become standard practice for central lines and regional blocks, conventional ultrasound systems often provide limited benefit for accessing very small, superficial vessels.

Recent advances in ultra-high frequency ultrasound (UHF) have introduced new possibilities for visualizing sub-millimeter vascular structures. A feasibility study conducted at Seattle Children’s Hospital aimed to assess the use of UHF for vascular access in patients under the age of six. The findings offer early insights into how this imaging modality may support procedural success in pediatric populations.¹

Limitations of Conventional Ultrasound in Pediatrics

Most portable ultrasound systems used in clinical settings operate in the 7–15 MHz range. These frequencies provide adequate depth penetration but lack the spatial resolution necessary to clearly image superficial vessels under 2 mm in diameter - common in infants and toddlers. As a result, ultrasound-guided cannulation of small arteries, particularly at the wrist, may be less effective.¹

Study Background and Methods

The High-frequency UltraSound in Kids study (HUSKY) investigated whether high-frequency ultrasound—operating at 15–50 MHz—could assist in the visualization and cannulation of peripheral arteries and central veins in children under six years of age. The Vevo 2100 system (VisualSonics, Fujifilm Sonosite) was used, with probes ranging up to 50 MHz and offering a resolution of 30 microns.

Forty patients were enrolled, and sixteen anesthesiologists with varying levels of experience in ultrasound-guided access participated. Probe selection (20, 30, 40, or 50 MHz) was determined by the operator based on patient anatomy and vessel depth. The primary endpoints were successful cannulation, time to cannulation, and operator-reported utility of the device.

Results and Observations

Arterial Cannulation:

• Successful arterial line placement using UHF was achieved in 33 of 40 patients.¹
• The UHF probe was selected in most cases due to its image resolution, particularly for radial and ulnar arteries.¹
• Median time to cannulation was 1 minute 26 seconds; the mean time was approximately 3 minutes 46 seconds.¹
• First-attempt success occurred in 13 cases; more than three attempts were required in four cases.¹ 

Venous Cannulation: 

• While UHF was less helpful for internal jugular vein cannulation because it was not always possible to view the carotid artery while cannulating the vein, it was used in 13 central venous access cases (all internal jugular), with no cases requiring abandonment of the technique during needle insertion.¹ 

Vessel Measurement:

• In patients where both radial and ulnar arteries were visualized, mean diameters were 1.71 mm and 1.53 mm respectively.¹ 

The study also explored changes in vessel size post-cannulation and noted occasional reductions in diameter, though these findings were limited to a small number of patients. 

Conclusion

The HUSKY study supports the feasibility of using ultra-high frequency ultrasound to assist with difficult vascular access in pediatric patients.¹

This article provides FUJIFILM Sonosite comments on the results from a single study. Results from case studies are not predictive of results in other cases. Results in other cases may vary.  At all times, it is the professional responsibility of the practitioner to exercise independent clinical judgment in each particular situation.