Laser Doppler flowmetric determination of ureteral blood flow after ureteral access sheath placement

Costas D. Lallas, Brian K. Auge, Ganesh V. Raj, Robert Santa-Cruz, John F. Madden, Glenn M. Preminger

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

Background and Purpose: The ureteral access sheath has positively impacted ureteroscopy by decreasing operative times and increasing success rates. However, as previous studies have suggested that large-caliber endoscopes may cause ureteral ischemia, concern has been raised about the impact of access sheath insertion on ureteral blood flow. We sought to determine whether the access sheath compromises ureteral blood supply and, if so, causes ischemic damage to the ureter during ureteroscopic procedures. Materials and Methods: Using a swine animal model, ureteral blood flow was measured with a laser Doppler flowmeter. Eleven ureteral units were randomized into four study groups: those dilated with 10F-12F, 12F-14F, and 14F-16F access sheaths (N = 3 per group) and an undilated control group (N = 2). Blood flow measurements were obtained from the proximal ureter via laser Doppler flowmetry for 70 minutes at 5-minute intervals. Hemodynamic variability was controlled for through intraoperative heart rate and oxygen saturation monitoring, as well as a second Doppler probe that was placed on the animal's skin, from which readings were also taken every 5 minutes. Results were correlated with histopathologic findings. Results: The control group demonstrated little ureteral blood flow variability over the course of 70 minutes. The study groups that were dilated with sheaths, however, all showed a decrease in ureteral blood flow after access sheath insertion, with the flow in animals dilated with 12F-14F and 14F-16F sheaths dropping below 50% of baseline. This initial drop in blood flow was followed by a gradual increase from nadir toward baseline values over the course of the study. On average, the 14F-16F group reached nadir more quickly and took longer to restore its ureteral blood flow. All animals remained hemodynamically stable throughout the study, showing only minimal variability in heart rate, oxygen saturation, and skin blood flow over the 70-minute experiment. Histologically, there was no evidence of ischemic damage in any of the study groups at 72 hours. Conclusions: In this animal model, the access sheath does cause a transient decrease in ureteral blood flow. Nonetheless, compensatory mechanisms of the ureteral wall restore blood flow to near-baseline rates and preserve urothelial integrity, suggesting that use of the ureteral access sheath remains a safe adjunct to flexible ureteroscopy. Because the chronic effects of the access sheath have yet to be elucidated, care must be taken in selecting an appropriate-size sheath for each individual case. Preventive measures may be available to help avoid sheath-related ureteral injury in those patients identified as high risk.

Original languageEnglish (US)
Pages (from-to)583-590
Number of pages8
JournalJournal of Endourology
Volume16
Issue number8
StatePublished - Oct 2002

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Lasers
Ureteroscopy
Ureter
Animal Models
Heart Rate
Oxygen
Flowmeters
Control Groups
Skin
Laser-Doppler Flowmetry
Endoscopes
Operative Time
Reading
Swine
Ischemia
Hemodynamics
Wounds and Injuries

ASJC Scopus subject areas

  • Urology

Cite this

Lallas, C. D., Auge, B. K., Raj, G. V., Santa-Cruz, R., Madden, J. F., & Preminger, G. M. (2002). Laser Doppler flowmetric determination of ureteral blood flow after ureteral access sheath placement. Journal of Endourology, 16(8), 583-590.

Laser Doppler flowmetric determination of ureteral blood flow after ureteral access sheath placement. / Lallas, Costas D.; Auge, Brian K.; Raj, Ganesh V.; Santa-Cruz, Robert; Madden, John F.; Preminger, Glenn M.

In: Journal of Endourology, Vol. 16, No. 8, 10.2002, p. 583-590.

Research output: Contribution to journalArticle

Lallas, CD, Auge, BK, Raj, GV, Santa-Cruz, R, Madden, JF & Preminger, GM 2002, 'Laser Doppler flowmetric determination of ureteral blood flow after ureteral access sheath placement', Journal of Endourology, vol. 16, no. 8, pp. 583-590.
Lallas, Costas D. ; Auge, Brian K. ; Raj, Ganesh V. ; Santa-Cruz, Robert ; Madden, John F. ; Preminger, Glenn M. / Laser Doppler flowmetric determination of ureteral blood flow after ureteral access sheath placement. In: Journal of Endourology. 2002 ; Vol. 16, No. 8. pp. 583-590.
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AU - Preminger, Glenn M.

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N2 - Background and Purpose: The ureteral access sheath has positively impacted ureteroscopy by decreasing operative times and increasing success rates. However, as previous studies have suggested that large-caliber endoscopes may cause ureteral ischemia, concern has been raised about the impact of access sheath insertion on ureteral blood flow. We sought to determine whether the access sheath compromises ureteral blood supply and, if so, causes ischemic damage to the ureter during ureteroscopic procedures. Materials and Methods: Using a swine animal model, ureteral blood flow was measured with a laser Doppler flowmeter. Eleven ureteral units were randomized into four study groups: those dilated with 10F-12F, 12F-14F, and 14F-16F access sheaths (N = 3 per group) and an undilated control group (N = 2). Blood flow measurements were obtained from the proximal ureter via laser Doppler flowmetry for 70 minutes at 5-minute intervals. Hemodynamic variability was controlled for through intraoperative heart rate and oxygen saturation monitoring, as well as a second Doppler probe that was placed on the animal's skin, from which readings were also taken every 5 minutes. Results were correlated with histopathologic findings. Results: The control group demonstrated little ureteral blood flow variability over the course of 70 minutes. The study groups that were dilated with sheaths, however, all showed a decrease in ureteral blood flow after access sheath insertion, with the flow in animals dilated with 12F-14F and 14F-16F sheaths dropping below 50% of baseline. This initial drop in blood flow was followed by a gradual increase from nadir toward baseline values over the course of the study. On average, the 14F-16F group reached nadir more quickly and took longer to restore its ureteral blood flow. All animals remained hemodynamically stable throughout the study, showing only minimal variability in heart rate, oxygen saturation, and skin blood flow over the 70-minute experiment. Histologically, there was no evidence of ischemic damage in any of the study groups at 72 hours. Conclusions: In this animal model, the access sheath does cause a transient decrease in ureteral blood flow. Nonetheless, compensatory mechanisms of the ureteral wall restore blood flow to near-baseline rates and preserve urothelial integrity, suggesting that use of the ureteral access sheath remains a safe adjunct to flexible ureteroscopy. Because the chronic effects of the access sheath have yet to be elucidated, care must be taken in selecting an appropriate-size sheath for each individual case. Preventive measures may be available to help avoid sheath-related ureteral injury in those patients identified as high risk.

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