Presented by: Zhamshid Okhunov MD
Loma Linda University Health

Introduction

During percutaneous nephrolithotomy (PCNL), access is most frequently achieved using continuous fluoroscopy, subjecting both patients and surgeons to radiation. Recently, pulsed fluoroscopy and low dose settings have been applied to endourologic procedures but may make establishing renal access challenging. The purpose of this study was to compare two different techniques for establishing renal access using ultra-low dose pulsed fluoroscopy settings in a benchtop model. 

Materials

A renal access model was created with a 12th rib and a target positioned in the upper calyx (Figure 1A). Ten urology attendings/trainees and ten medical students participated in a prospective, randomized, cross-over, benchtop study using two ultra-low dose fluoroscopy techniques. In all trials, the low dose button was selected and combined with pulsed fluoroscopy at 1 pulse per second. In the first technique (Figure 1B), an 18-gauge needle was held using a metal clamp and inserted using a conventional bull’s-eye method. In the second technique (Figure 1C & 1D), a laser beam from the image intensifier was used to guide insertion of a specialized needle, using a low-density handle. Fluoroscopy time, radiation dose, renal access time, and total number of attempts were recorded. Participants then rated the difficulty (1-10) and satisfaction with each technique. Paired comparisons were conducted using Wilcoxon signed-rank test, with p-value <0.05 considered significant. 

Results

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Both ultra-low dose techniques had a high success rate with 95% for laser-guided and 85% for conventional after 3 trials (p=0.29). The mean fluoroscopy time for the laser technique (4.1 sec) was 44% lower than the conventional needle (7.3 sec; p=0.043). Even at the lowest fluoroscopy settings, the average radiation used was significantly higher when using the conventional needle (1.5 mGy) compared to the laser-guided needle (0.81 mGy; p=0.04). Access was significantly easier using the laser-guided technique (4.6/10) vs the conventional needle (6.6/10; p=0.021). 80% preferred using the laser-guided technique to establish renal access. 

Conclusion

Although challenging, pulsed and low dose fluoroscopy can be used for establishing renal access during PCNL. Addition of a specialized laser-guided needle further reduces fluoroscopy time and simplifies the procedure. 

Funding

None

Lead Authors

Tyler Humphries,
Loma Linda University Health

Co-Authors

Ala'a Farkouh, MD
Loma Linda University Health

Matthew I. Buell, MD
Loma Linda University Health

Akin S. Amasyali, MD
Loma Linda University Health

Rose Leu, MD
Loma Linda University Health

Kanha Shete, DO
Loma Linda University Health

Katya Hanessian,
Loma Linda University Health

Zhamshid Okhunov, MD
Loma Linda University Health

D. Duane Baldwin, MD
Loma Linda University Health