Amplatz versus Balloon for Tract Dilation in Ultrasonographically Guided Percutaneous Nephrolithotomy: A Randomized Clinical Trial
Table 1
Definition of some important variables.
variable
definition
Glomerular Filtration Rate
For adult patients, Modified Diet for Renal Disease (MDRD) equation: GFR (ml/min/1.73 m2) = 175 × (Cr in mg/dl) × (Age) × (0.742 if female)
For children under 18 years, Bedside Schwartz equation: GFR (ml/min/1.73 m2) = (0.41 × Height in cm) / Cr in mg/dl
Stone Surface Area
Length (mm) wide(mm) 0.25 ( = 3.14159)
Needle Puncture Time
The time to get access to the desired calyx under ultrasonography guide using Chiba needle to inserting the guide wire
Tract Dilation Time
The time spent to complete dilation using either Amplatz dilator or balloon including inserting the Working sheath
Access Time
Total of Needle puncture time and Tract dilation time
Total Nephroscopy Time
All the time from the beginning of the nephroscopy, lithotripsy and stone extraction to the moment that the nephrostomy site is closed or the nephrostomy tube is secured
Overall Operating Time
All duration of the operation including the time spent for patient preparation and ureteral catheter placemen and repositioning to the end of operation
Significant Fever
An oral temperature higher than 38.5°C
Urine Leakage
The presence of urine draining on the flank more than 48 hours after removal of the ureteral catheter or nephrostomy tube
Stone Free Rate (SFR)
The absence of any residual stone fragment bigger than four millimeters in the ultrasonography or plain radiographic imaging on the first postoperative day
Cost
sum of devices, surgical supplies and bed costs from admission to discharge including readmissions
