Hadji-Moussa M et al, 2013: Effect of High Shock Number on Acute Complication Development After Extracorporeal Shockwave Lithotripsy
Hadj-Moussa M, Brown JA
Section of Urology, Georgia Health Sciences University , Augusta, Georgia
ABSTRACT PURPOSE: We assessed whether high shock number is associated with higher rates of acute complication development after extracorporeal shockwave lithotripsy (SWL).
PATIENTS AND METHODS: A retrospective chart review of 372 patients who underwent 436 SWL procedures at 24 kV using a Medstone STS-T lithotripter (Medstone International Inc., Aliso Viejo, CA) was conducted. Complications occurred within 4 weeks of SWL. Treatments were split into three cohorts based on shock number (4000). Postoperative sequelae of patients who were stone free and those with residual stone were studied separately. Chi-square tests were used to evaluate the relationship between shock number cohort and postoperative complication development.
RESULTS: SWL treatments recorded for each cohort were 158 (37.4%), 145 (34.4%), and 119 (28.2%), respectively. The short-term complication rate when SWL was successful was 8.3% overall. Complication rate for each cohort was 9.5% (11), 7.8% (5), and 7.2% (7), respectively. When SWL was successful, statistical analysis revealed no significant difference between complication rates and shock number cohort (P=0.63). Complications in patients with a residual stone occurred after 41.4% of treatments and trended upward with shock number cohort, but did not reach statistical significance (P=0.84).
CONCLUSIONS: At high voltage, high shock number was not shown to cause higher rates of short-term postoperative complications, as experienced by patients, when SWL was successful or resulted in a residual stone, yet complication rates associated with residual stone burden were approximately five times as common. Forgoing a higher shock number in the presence of a residual stone may therefore increase the risks of sequelae immediately after SWL.
J Endourol. 2013 Jun 13. [Epub ahead of print]
PMID:23537270 [PubMed - as supplied by publisher]. FREE ARTICLE
Safe treatment of patients with non-invasive stone disintegration should exclude damage to the renal tissue, ureters and other organs and anatomical structures along the shock wave path. These important aspects were not addressed in this retrospective review of 372 patients treated with various numbers of shock waves in the range 600 -8200 (!).
The complications recorded were all related to unsatisfactory disintegration of stones, thus with the risk of getting both pain and other symptoms caused by obstruction. The two conclusions drawn were that the overall complications of this kind did not increase statistically with the number of shock waves and when such a trend was demonstrated, the patients had residual stones for which they were treated with the largest number of shock waves.
Although a larger number of shock waves most certainly had been administered with the ambition to disintegrate stones that responded poorly to the treatment, the important question is: For stone that apparently disintegrate less efficiently than expected; is it meaningful to give an excessive number of shock waves? It is my own experience that when a reasonable number of shock waves does not result in successful disintegration, a search should be made for other explanations of the poor disintegration than insufficient shock wave power.