From the Research
For most urinary stones, I recommend using 3000 shocks at appropriate power settings to maximize stone clearance rates, as this provides better stone fragmentation than 2500 shocks. The treatment should be delivered at a frequency of 60-90 shocks per minute, as slower rates improve fragmentation efficiency 1. While using 3000 shocks may extend the procedure time by a few minutes compared to 2500 shocks, the improved stone clearance often reduces the need for repeat procedures. However, the shock number should be adjusted based on real-time visualization of stone fragmentation, patient tolerance, and stone composition. Patients with harder stones (like calcium oxalate monohydrate or cystine stones) particularly benefit from the higher shock number. Be aware that increasing shock numbers also increases the risk of renal parenchymal damage and hematoma formation, so proper coupling, accurate targeting, and appropriate power ramping remain essential regardless of total shock count.
Some key considerations when deciding on the number of shocks include:
- Stone size and location: larger stones or those in certain locations may require more shocks to achieve adequate fragmentation 2, 3
- Stone composition: harder stones may require more shocks to break up effectively 1
- Patient factors: patient tolerance and overall health should be taken into account when determining the optimal number of shocks
It's also important to note that the effectiveness of ESWL can vary depending on the specific lithotripsy device and technique used, as well as the experience of the operator 4. Therefore, it's essential to consider these factors when making treatment decisions.
In terms of specific studies, a prospective randomized trial found that an escalating voltage treatment strategy produced better stone comminution than a fixed strategy, with 81% of patients in the escalating group achieving stone-free status compared to 48% in the fixed group 1. Another study found that stone size was a significant predictor of treatment outcome, with larger stones requiring more shocks to achieve adequate fragmentation 2.
Overall, while the optimal number of shocks for ESWL may vary depending on individual patient factors, using 3000 shocks at appropriate power settings is generally recommended to maximize stone clearance rates.