Radial Dilation of Nephrostomy Balloons : A Comparative Analysis

Purpose: The dynamics of percutaneous balloon expansion may differ with increasing extrinsic compressive forces and Materials and Methods: Results: All balloons were unable to reach 90% of their expected diameter with larger constrictive loads (122g) at low (4 Conclusions: The Bard X-Force and Cook Ultraxx percutaneous nephrostomy balloons achieved the most reliable radial


INTRODUCTION
Percutaneous renal access is an important component of many complex procedures including stone extraction, antegrade endopyelotomy, and resection of transitional cell carcinoma of the upper of complications such as blood loss and perforation ous nephrostomy tract dilation have included serially introduced, progressive fascial dilators, Amplatz dilator sets, metal coaxial dilators and high pressure Clinical Urology Clinical Urology the instrument of choice as they allow for one-step time, and reduced risk of hemorrhage in comparison proposed that the lateral compressive forces produced by the balloons are less traumatic and thereby minimize complications in comparison to the angular shearing forces exerted by successive dilation meth-The dynamics of percutaneous balloon expansion may differ with increasing extrinsic compressive compares the ability of several percutaneous balloons

MATERIALS AND METHODS
Three 30 Fr nephrostomy balloons were tested: Bard X-Force™ (Bard, Covington, GA) Bosmethods used were the same as those used to test complace, the balloon tip was secured by elevated vise plastic bag for adding radial load was attached to a string, which was wrapped around the balloon once and then secured so that the bag was hanging between measuring 1/100 th of an inch was secured vertically balloon circumference was recorded at pressures of tested three times consecutively for each radial load to evaluate balloon performance through a range forces have previously been demonstrated to be effective at eliciting differences in balloon performance -

RESULTS
All balloons were unable to reach 90% of their expected diameter with larger constrictive loads -X-Force™ and Cook Ultraxx™ balloons reached at    All balloons performed well under low constriction forces and reached at least 80% of the balloons for each pressure and load were not statistimanufacturer, all balloons performed radial dilation notably less than expected for all constrictive loads at - diameter for all constrictive forces at burst pressure,

COMMENTS
The ability to obtain optimal percutaneous access is critical with respect to percutaneous neph-percutaneous neph- shown to be higher with fewer complications when access is obtained by a urologist versus an interventional pelviocalyceal tears can lead to excessive bleeding Clinical and animal studies have shown similar blood loss, renal damage, and chronic renal function changes when comparing Amplatz and balloon dilation systems under a single puncture setting acute and chronic effects on the renal parenchyma suggest that the choice of dilatation can be based rately placed minimizing the risk of creating a false passage, are quick to use, and provide compressive ered to be the safest method of percutaneous tract from the surgeon compared to longitudinal shearing the pressure tamponade effect of the balloon may overall, including a 25% risk of failure in patients with a history of prior renal surgery compared to 8% of of pyelonephritis were not shown to be predictors for trolled incremental changes in pressure; yet, this does not correlate with proportional changes in dilate a nephrostomy tract in patients with no prior renal surgery while higher pressures are necessary to achieve full dilation in those with a history of During balloon inflation, a characteristic "waist" will appear in areas of high resistance such as the amount of force required to eliminate the waist will vary according to the degree of resistance and nature of the applied force during balloon inflation maximizes the net force in the direction of radial dilation in comparison to other dilator systems where dispersion of forces limit effectiveness under the same net force and are also subject to a fascial dilators tend to be more effective than high developed balloon dilators with a burst pressure of potential downsides to using balloon dilation include During our previous years of experience with that in approximately 5-10% of procedures, we would need to convert to use of an Amplatz dilator set due to Since completing this study, we have successfully

CONCLUSIONS
From the individual percutaneous balloons tested, the Bard X-Force™ and Cook Ultraxx™ percutaneous balloons were found to be superior to with regards to radial dilation consistently closer to the able to achieve reliable radial dilation against large constrictive forces simulating fascial or retroperito--

EDITORIAL COMMENT
The authors compare the characteristics of three balloon dilators used to achieve tract dilation in percutaneous nephrostolithotomy from three different used to check the variation in balloon circumference with different pressures against constrictive loads that shown that balloon fascial dilation is less time consuming and results in less renal parenchyma damage and bleeding when compared to mechanical dilators include high cost, failure in performing access in obese patients and in those who have undergone previall of the balloon dilators were unable to reach 90% of their expected diameters with larger constrictive loads sures and two of them reached 90% of the expected ing corroborates the idea that urologists may select a balloon with a higher pressure rating when treating expensive and a 25% failure rate to create adequate renal access in patients with a history of prior renal surgery has been reported (3); probably in such cases using mechanical dilators can be more cost effective

EDITORIAL COMMENT
Choice of nephrostomy tract dilation tech-plications such as blood loss and perforation of the Among other choices, Balloon systems have typically been the instrument of choice for many surgeons as they allow for one-step dilation, minimized risk of hemorrhage in comparison to other methods compressive forces produced by the balloons are less traumatic and thereby minimize complications in comparison to the angular shearing forces exerted The potential downsides to using balloon effectiveness in the face of dysmorphic body habitus The ideal site of percutaneous puncture should be selected to maximize the use of rigid instruments, minimize the risk of complications and obtain This study compares the ability of several percutaneous balloons to expand under different radial All balloons were unable to reach 90% of their expected diameter with larger constrictive loads minimizing the risk of creating a false passage, are REFERENCES AA, Smith AD: Comparative study of degree of renal trauma between Amplatz sequential fascial dilation and balloon dilation during percutaneous renal surgery in

Division of Urology Federal University of Rio Janeiro State, UNIRIO
Rio de Janeiro, RJ, Brazil E-mail: mrubins74@hotmail.com

EDITORIAL COMMENT
The balloon dilation used in percutaneous access for kidney surgery represents a very effective and less traumatic than other kinds of dilators as disspace in the urinary tract for the tip of the balloon dilator, in order to dilate all the way from the skin to posterior one, otherwise during the dilation the bal-The balloon should be dilated uniformly to permit the smoothly introduction of the Amplatz sheet over it to able when an irregularity of the balloon occurs (as a Then, the urologist has to dispose off his balloon analyses the third condition above with practical application for surgeons at the moment of choosing importance to choose the reliable dilators that will
of percutaneous tract creation on incidence of renal tors affecting blood loss during percutaneous nephrodilation using a balloon dilator in percutaneous renal surgery: experience with 95 cases and comparison with assessment of renal damage associated with semi-rigid AA, Smith AD: Comparative study of degree of renal trauma between Amplatz sequential fascial dilation and balloon dilation during percutaneous renal surgery in loss and transfusion rates associated with percutaneous poreal shock-wave lithotripsy and percutaneous neph-AD: Percutaneous Approaches to the Upper Urinary -Accepted after revision: June 3, 2008