Radial dilation of nephrostomy balloons: a comparative analysis

Abstract

PURPOSE: The dynamics of percutaneous balloon expansion may differ with increasing extrinsic compressive forces and increasing inflation pressures. This study compares the ability of percutaneous balloons to expand under different radial constrictive forces. MATERIALS AND METHODS: Three 30F nephrostomy balloons were tested: Bard X-Force™, Boston Scientific Microvasive Amplatz Tractmaster™, and Cook Ultraxx™. With a super stiff guidewire in place, the balloon tip was secured by elevated vice grips on either side of the balloon. A string was wrapped around the balloon center once, and incremental increases in load were added (2g, 42g, 82g, and 122g) to represent increasing extrinsic compression. The balloon was inflated with a contrast agent and circumference changes were measured at increments of 4 ATM, 10 ATM, and burst pressure. Balloons were tested in triplicate for each load. RESULTS: All balloons were unable to reach 90% of their expected diameter with larger constrictive loads (122g) at low (4 ATM) and nominal (10 ATM) inflation pressures. Only the Bard and Cook balloons reached at least 90% of the expected diameter with a coefficient of variance (CV) less than 10% at burst pressure under the larger constrictive load (122g), 94.3% ± 6.7%, CV 7.1% and 96.3% ± 2.9%, CV 3.0% respectively. All balloons performed well under low constriction forces and reached at least 80% of the expected diameter by 10 ATM under all constrictive loads. CONCLUSIONS: The Bard X-Force and Cook Ultraxx percutaneous nephrostomy balloons achieved the most reliable radial dilation against large constrictive forces simulating fascial or retroperitoneal scar tissue.

Keywords

• balloon dilation
• percutaneous nephrolithotomy
• renal calculi