Prefocal alignment improves stone comminution in shockwave lithotripsy

Dahlia L. Sokolov, Michael R. Bailey, Lawrence A. Crum, Philip M. Blomgren, Bret A. Connors, Andrew Evan

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Background: The Dornier HM-3 machine continues to be one of the most effective lithotripters in use. However, tissue damage occurs in most, if not all, shockwave lithotripsy (SWL) treatments. Cavitation appears to contribute to desired stone comminution as well as to undesired tissue damage. Studies of cavitation in electrohydraulic shockwave lithotripters indicate that the greatest cavitation activity occurs, not at the geometric focus, F2, but at a site proximal to F2 by 1 to 3 cm. In clinical practice, however, stones are aligned with F2. Materials and Methods: In vitro stone comminution, hemolysis, and free-radical production were assessed along the focal axis, and pig kidneys treated with SWL in vivo were sectioned to determine the extent of hemorrhagic injury along the focal axis. Model gypsum stones received 200 shockwaves in vitro at 18 kV. Results: At F2, the average number of fragments > 1.5 mm was 1.3 ± 0.5, and the weight loss was 11.3 ± 1.1%. At 2 cm from F2 (F2-2 cm), these values increased to 4 ± 2.8 and 16.1 ± 4.2%, respectively. Samples of 10% hematocrit blood were similarly exposed. Hemolysis was equivalent at F2-2 cm (14.7 ± 2.3%) and F2 (15.2 ± 3 %) but decreased significantly at all other positions. Samples of iodine solution received 1500 shockwaves at 20 kV. Hydroxyl radical production was greatest at F2-2 cm (0.384 ± 0.035 μM) and decreased significantly distal to this position. The volume of tissue injury in pig kidneys was greatest with prefocal shockwave exposure. Conclusion: Stone comminution may be achieved more rapidly without greater tissue damage by a simple shift in stone alignment to F2-2 cm.

Original languageEnglish
Pages (from-to)709-715
Number of pages7
JournalJournal of Endourology
Volume16
Issue number10
StatePublished - Dec 2002

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Lithotripsy
Hemolysis
Swine
Kidney
Calcium Sulfate
Wounds and Injuries
Hematocrit
Iodine
Hydroxyl Radical
Free Radicals
Weight Loss
In Vitro Techniques
Therapeutics

ASJC Scopus subject areas

  • Urology

Cite this

Sokolov, D. L., Bailey, M. R., Crum, L. A., Blomgren, P. M., Connors, B. A., & Evan, A. (2002). Prefocal alignment improves stone comminution in shockwave lithotripsy. Journal of Endourology, 16(10), 709-715.

Prefocal alignment improves stone comminution in shockwave lithotripsy. / Sokolov, Dahlia L.; Bailey, Michael R.; Crum, Lawrence A.; Blomgren, Philip M.; Connors, Bret A.; Evan, Andrew.

In: Journal of Endourology, Vol. 16, No. 10, 12.2002, p. 709-715.

Research output: Contribution to journalArticle

Sokolov, DL, Bailey, MR, Crum, LA, Blomgren, PM, Connors, BA & Evan, A 2002, 'Prefocal alignment improves stone comminution in shockwave lithotripsy', Journal of Endourology, vol. 16, no. 10, pp. 709-715.
Sokolov DL, Bailey MR, Crum LA, Blomgren PM, Connors BA, Evan A. Prefocal alignment improves stone comminution in shockwave lithotripsy. Journal of Endourology. 2002 Dec;16(10):709-715.
Sokolov, Dahlia L. ; Bailey, Michael R. ; Crum, Lawrence A. ; Blomgren, Philip M. ; Connors, Bret A. ; Evan, Andrew. / Prefocal alignment improves stone comminution in shockwave lithotripsy. In: Journal of Endourology. 2002 ; Vol. 16, No. 10. pp. 709-715.
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AU - Evan, Andrew

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N2 - Background: The Dornier HM-3 machine continues to be one of the most effective lithotripters in use. However, tissue damage occurs in most, if not all, shockwave lithotripsy (SWL) treatments. Cavitation appears to contribute to desired stone comminution as well as to undesired tissue damage. Studies of cavitation in electrohydraulic shockwave lithotripters indicate that the greatest cavitation activity occurs, not at the geometric focus, F2, but at a site proximal to F2 by 1 to 3 cm. In clinical practice, however, stones are aligned with F2. Materials and Methods: In vitro stone comminution, hemolysis, and free-radical production were assessed along the focal axis, and pig kidneys treated with SWL in vivo were sectioned to determine the extent of hemorrhagic injury along the focal axis. Model gypsum stones received 200 shockwaves in vitro at 18 kV. Results: At F2, the average number of fragments > 1.5 mm was 1.3 ± 0.5, and the weight loss was 11.3 ± 1.1%. At 2 cm from F2 (F2-2 cm), these values increased to 4 ± 2.8 and 16.1 ± 4.2%, respectively. Samples of 10% hematocrit blood were similarly exposed. Hemolysis was equivalent at F2-2 cm (14.7 ± 2.3%) and F2 (15.2 ± 3 %) but decreased significantly at all other positions. Samples of iodine solution received 1500 shockwaves at 20 kV. Hydroxyl radical production was greatest at F2-2 cm (0.384 ± 0.035 μM) and decreased significantly distal to this position. The volume of tissue injury in pig kidneys was greatest with prefocal shockwave exposure. Conclusion: Stone comminution may be achieved more rapidly without greater tissue damage by a simple shift in stone alignment to F2-2 cm.

AB - Background: The Dornier HM-3 machine continues to be one of the most effective lithotripters in use. However, tissue damage occurs in most, if not all, shockwave lithotripsy (SWL) treatments. Cavitation appears to contribute to desired stone comminution as well as to undesired tissue damage. Studies of cavitation in electrohydraulic shockwave lithotripters indicate that the greatest cavitation activity occurs, not at the geometric focus, F2, but at a site proximal to F2 by 1 to 3 cm. In clinical practice, however, stones are aligned with F2. Materials and Methods: In vitro stone comminution, hemolysis, and free-radical production were assessed along the focal axis, and pig kidneys treated with SWL in vivo were sectioned to determine the extent of hemorrhagic injury along the focal axis. Model gypsum stones received 200 shockwaves in vitro at 18 kV. Results: At F2, the average number of fragments > 1.5 mm was 1.3 ± 0.5, and the weight loss was 11.3 ± 1.1%. At 2 cm from F2 (F2-2 cm), these values increased to 4 ± 2.8 and 16.1 ± 4.2%, respectively. Samples of 10% hematocrit blood were similarly exposed. Hemolysis was equivalent at F2-2 cm (14.7 ± 2.3%) and F2 (15.2 ± 3 %) but decreased significantly at all other positions. Samples of iodine solution received 1500 shockwaves at 20 kV. Hydroxyl radical production was greatest at F2-2 cm (0.384 ± 0.035 μM) and decreased significantly distal to this position. The volume of tissue injury in pig kidneys was greatest with prefocal shockwave exposure. Conclusion: Stone comminution may be achieved more rapidly without greater tissue damage by a simple shift in stone alignment to F2-2 cm.

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