Air vs contrast pyelogram for initial puncture access in percutaneous nephrolithotomy: a randomized controlled trial.

Percutaneous nephrolithotomy (PCNL) is a standard procedure for large renal stones. Contrast (traditionally) as well as air is being used to delineate pelvi-calyceal system (PCS) to perform initial puncture. Contrast, when used has certain disadvantages including poor differentiation of anterior and posterior calyces. In this interim analysis of 122 patients of a prospective study subjects were stratified in two groups: in group 1, contrast was used while in group 2, air was used to delineate PCS. Out of 122,103 patients underwent puncture by contrast or air exclusively while 19 patients required mix of contrast and air (14 patients failed puncture using contrast while 5 using air). Mean dosage of radiation exposure (8.43 vs. 14.26 mGy), duration of radiation exposure (0.66 vs. 1.02 min), access time (3.72 vs. 5.84 min), were less in group 2 as compared to group 1. 84.5% of patients underwent puncture in single attempt in group 2 as compared to 56.25% in group 1. Five patients had post-operative fever and one had trans-pleural tract dilation. Complete stone clearance was seen in 94.8% of patients using air to only 75% of patients using contrast. Conclusion: Air pyelogram is a feasible, safe, cost effective and efficient access alternative to contrast pyelogram and in difficult situation a mixture of both is better than using one.

Development of a computer assisted gantry system for gaining rapid and accurate calyceal access during percutaneous nephrolithotomy.

PURPOSE: To design a simple, cost-effective system for gaining rapid and accurate calyceal access during percutaneous nephrolithotomy (PCNL). MATERIALS AND METHODS: The design consists of a low-cost, light-weight, portable mechanical gantry with a needle guiding device. Using C-arm fluoroscopy, two images of the contrast-filled renal collecting system are obtained: at 0-degrees (perpendicular to the kidney) and 20-degrees. These images are relayed to a laptop computer containing the software and graphic user interface for selecting the targeted calyx. The software provides numerical settings for the 3 axes of the gantry, which are used to position the needle guiding device. The needle is advanced through the guide to the depth calculated by the software, thus puncturing the targeted calyx. Testing of the system was performed on 2 target types: 1) radiolucent plastic tubes the approximate size of a renal calyx (5 or 10 mm in diameter, 30 mm in length); and 2) foam-occluded, contrast-filled porcine kidneys. RESULTS: Tests using target type 1 with 10 mm diameter (n=14) and 5 mm diameter (n=7) tubes resulted in a 100% targeting success rate, with a mean procedure duration of 10 minutes. Tests using target type 2 (n=2) were both successful, with accurate puncturing of the selected renal calyx, and a mean procedure duration of 15 minutes. CONCLUSIONS: The mechanical gantry system described in this paper is low-cost, portable, light-weight, and simple to set up and operate. C-arm fluoroscopy is limited to two images, thus reducing radiation exposure significantly. Testing of the system showed an extremely high degree of accuracy in gaining precise access to a targeted renal calyx.

Development of a computer assisted gantry system for gaining rapid and accurate calyceal access during percutaneous nephrolithotomy

PURPOSE: To design a simple, cost-effective system for gaining rapid and accurate calyceal access during percutaneous nephrolithotomy (PCNL). MATERIALS AND METHODS: The design consists of a low-cost, light-weight, portable mechanical gantry with a needle guiding device. Using C-arm fluoroscopy, two images of the contrast-filled renal collecting system are obtained: at 0-degrees (perpendicular to the kidney) and 20-degrees. These images are relayed to a laptop computer containing the software and graphic user interface for selecting the targeted calyx. The software provides numerical settings for the 3 axes of the gantry, which are used to position the needle guiding device. The needle is advanced through the guide to the depth calculated by the software, thus puncturing the targeted calyx. Testing of the system was performed on 2 target types: 1) radiolucent plastic tubes the approximate size of a renal calyx (5 or 10 mm in diameter, 30 mm in length); and 2) foam-occluded, contrast-filled porcine kidneys. RESULTS: Tests using target type 1 with 10 mm diameter (n = 14) and 5 mm diameter (n = 7) tubes resulted in a 100 percent targeting success rate, with a mean procedure duration of 10 minutes. Tests using target type 2 (n = 2) were both successful, with accurate puncturing of the selected renal calyx, and a mean procedure duration of 15 minutes. CONCLUSIONS: The mechanical gantry system described in this paper is low-cost, portable, light-weight, and simple to set up and operate. C-arm fluoroscopy is limited to two images, thus reducing radiation exposure significantly. Testing of the system showed an extremely high degree of accuracy in gaining precise access to a targeted renal calyx.