Skip to main content
SpringerLink
Log in

The zero ischemia index (ZII): a novel criterion for predicting complexity and outcomes of off-clamp partial nephrectomy

  • Original Article
  • Published:
World Journal of Urology Aims and scope Submit manuscript

Abstract

Purposes

Although several anatomical classification systems that aimed to standardize the description of renal tumors were previously reported, a special classification system is required to help predict the complexity and perioperative outcomes of off-clamp nephron-sparing surgery (NSS). We developed a novel criterion—zero ischemia index (ZII), aiming to help predict the perioperative outcomes after off-clamp NSS and guide patient selection.

Methods

We retrospectively evaluated 149 patients between June 2009 and July 2014 in our institution who underwent off-clamp NSS with available computed tomography images. ZII was defined as the product of the tumor diameter and depth within renal parenchyma. ZII was then analyzed to investigate its association with perioperative outcomes. A specific ZII score was further selected to best guide patient selection in off-clamp NSS.

Results

ZII was significantly associated with estimated blood loss >500 mL (OR 1.270, 95% CI 1.036–1.557, p = 0.021), operative time >2 h (OR 1.286, 95% CI 1.051–1.573, p = 0.014), surgical complications (OR 1.251, 95% CI 1.035–1.511, p = 0.020), overall complications (OR 1.208, 95% CI 1.016–1.436, p = 0.032), and >10% decrease in estimated glomerular filtration rate (OR 1.362, 95% CI 1.045–1.776, p = 0.022). Patients with ZII > 6 may bear a higher risk of hemorrhage, perioperative complications, and a longer operative time, if they underwent an off-clamp NSS, compared to those with ZII ≤ 6.

Conclusions

The ZII is a novel and readily measurable criterion which can help predict renal complexity of tumor and risk of perioperative outcomes after off-clamp NSS. ZII = 6 is established as a preliminary threshold for patient selection of off-clamp NSS. A more robust criterion is to be validated with more samples in a prospective study.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1

Similar content being viewed by others

Abbreviations

ASA:

American Society of Anesthesiologists score

BMI:

Body mass index

CSA:

Contact surface area

CT:

Computed tomography

EBL:

Estimated blood loss

eGFR:

Estimated glomerular filtration rate

Hi:

Length between midpoint of imaginary line and the deepest point of tumor

LPN:

Laparoscopic partial nephrectomy

NSS:

Nephron-sparing surgery

OT:

Operative time

OPN:

Open partial nephrectomy

PADUA:

Preoperative aspects and dimensions used for an anatomical classification

RAPN:

Robot-assisted partial nephrectomy

RENAL:

Radius exophytic/endophytic nearness anterior/posterior location

Ri:

Maximum tumor diameter within renal parenchyma

ROC:

Receiver operating characteristic

ZII:

Zero ischemia index

ZS:

Zhongshan

References

  1. Campbell SC et al (2009) Guideline for management of the clinical T1 renal mass. J Urol 182(4):1271–1279

    Article  PubMed  Google Scholar 

  2. Van Poppel H et al (2011) Treatment of localised renal cell carcinoma. Eur Urol 60(4):662–672

    Article  PubMed  Google Scholar 

  3. Thompson RH et al (2007) The impact of ischemia time during open nephron sparing surgery on solitary kidneys: a multi-institutional study. J Urol 177(2):471–476

    Article  PubMed  Google Scholar 

  4. Simmons MN, Fergany AF, Campbell SC (2011) Effect of parenchymal volume preservation on kidney function after partial nephrectomy. J Urol 186(2):405–410

    Article  PubMed  Google Scholar 

  5. Thompson RH et al (2010) Every minute counts when the renal hilum is clamped during partial nephrectomy. Eur Urol 58(3):340–345

    Article  PubMed  Google Scholar 

  6. Godoy G et al (2009) Effect of warm ischemia time during laparoscopic partial nephrectomy on early postoperative glomerular filtration rate. J Urol 181(6):2438–2443 (discussion 2443–2445)

    Article  PubMed  Google Scholar 

  7. Thompson RH et al (2010) Comparison of warm ischemia versus no ischemia during partial nephrectomy on a solitary kidney. Eur Urol 58(3):331–336

    Article  PubMed  Google Scholar 

  8. Smith GL et al (2011) Non-clamped partial nephrectomy: techniques and surgical outcomes. BJU Int 107(7):1054–1058

    Article  PubMed  Google Scholar 

  9. Gill IS et al (2012) Zero ischemia anatomical partial nephrectomy: a novel approach. J Urol 187(3):807–814

    Article  PubMed  Google Scholar 

  10. Kutikov A, Uzzo RG (2009) The R.E.N.A.L. nephrometry score: a comprehensive standardized system for quantitating renal tumor size, location and depth. J Urol 182(3):844–853

    Article  PubMed  Google Scholar 

  11. Ficarra V et al (2009) Preoperative aspects and dimensions used for an anatomical (PADUA) classification of renal tumours in patients who are candidates for nephron-sparing surgery. Eur Urol 56(5):786–793

    Article  PubMed  Google Scholar 

  12. Simmons MN et al (2012) Diameter-axial-polar nephrometry: integration and optimization of R.E.N.A.L. and centrality index scoring systems. J Urol 188(2):384–390

    Article  PubMed  Google Scholar 

  13. Nisen H et al (2014) Renal tumour invasion index as a novel anatomical classification predicting urological complications after partial nephrectomy. Scand J Urol 48(1):41–51

    Article  PubMed  Google Scholar 

  14. Hakky TS et al (2014) Zonal NePhRO scoring system: a superior renal tumor complexity classification model. Clin Genitourin Cancer 12(1):e13–e18

    Article  PubMed  Google Scholar 

  15. Zhou L et al (2015) The Zhongshan score: a novel and simple anatomic classification system to predict perioperative outcomes of nephron-sparing surgery. Medicine 94(5):e506

    Article  PubMed  PubMed Central  Google Scholar 

  16. Leslie S et al (2014) Renal tumor contact surface area: a novel parameter for predicting complexity and outcomes of partial nephrectomy. Eur Urol 66(5):884–893

    Article  PubMed  Google Scholar 

  17. Zhou L et al (2015) Number of renal columns invaded by tumor: a novel parameter for predicting complexity and outcomes of off-clamp open partial nephrectomy. J Am Coll Surg 221(2):539.e1–549.e1

  18. Levey AS et al (2009) A new equation to estimate glomerular filtration rate. Ann Intern Med 150(9):604–612

    Article  PubMed  PubMed Central  Google Scholar 

  19. Dindo D, Demartines N, Clavien PA (2004) Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg 240(2):205–213

    Article  PubMed  PubMed Central  Google Scholar 

  20. R Core Team (2016) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. http://www.R-project.org/

  21. Faul F et al (2007) G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods 39(2):175–191

    Article  PubMed  Google Scholar 

  22. Faul F et al (2009) Statistical power analyses using G*Power 3.1: tests for correlation and regression analyses. Behav Res Methods 41(4):1149–1160

    Article  PubMed  Google Scholar 

  23. White WM et al (2010) Robotic partial nephrectomy without renal hilar occlusion. BJU Int 105(11):1580–1584

    Article  PubMed  Google Scholar 

  24. Okhunov Z et al (2011) The comparison of three renal tumor scoring systems: C-Index, P.A.D.U.A., and R.E.N.A.L. nephrometry scores. J Endourol 25(12):1921–1924

    Article  PubMed  Google Scholar 

  25. Kreshover JE, Kavoussi LR, Richstone L (2013) Hilar clamping versus off-clamp laparoscopic partial nephrectomy for T1b tumors. Curr Opin Urol 23(5):399–402

    Article  PubMed  Google Scholar 

  26. Simone G et al (2015) Indications, techniques, outcomes, and limitations for minimally ischemic and off-clamp partial nephrectomy: a systematic review of the literature. Eur Urol 68(4):632–640

    Article  PubMed  Google Scholar 

  27. Porpiglia F et al (2015) Evaluation of functional outcomes after laparoscopic partial nephrectomy using renal scintigraphy: clamped vs clampless technique. BJU Int 115(4):606–612

    Article  PubMed  Google Scholar 

  28. Kaczmarek BF et al (2013) Off-clamp robot-assisted partial nephrectomy preserves renal function: a multi-institutional propensity score analysis. Eur Urol 64(6):988–993

    Article  PubMed  Google Scholar 

Download references

Acknowledgements

The authors thank Hongsheng Xu for his supporting of mathematics.

Authors’ contribution

YL was involved in data collection, manuscript writing, data analysis; LZ collected data and wrote the manuscript; TB, ZX, XH, YZ, SJ, and YX collected data; ; JG and HW were involved in project development and data collection.

Author information

Author notes

    Authors and Affiliations

    1. Department of Urology, Zhongshan Hospital, Fudan University, 180th Fengling Rd, Xuhui District, Shanghai, 200032, China

      Yaohui Li, Lin Zhou, Tingchang Bian, Zhuoyi Xiang, Yeqing Xu, Yanjun Zhu, Xiaoyi Hu, Shuai Jiang, Jianming Guo & Hang Wang

    Authors
    1. Yaohui Li
      View author publications

      You can also search for this author in PubMed Google Scholar

    2. Lin Zhou
      View author publications

      You can also search for this author in PubMed Google Scholar

    3. Tingchang Bian
      View author publications

      You can also search for this author in PubMed Google Scholar

    4. Zhuoyi Xiang
      View author publications

      You can also search for this author in PubMed Google Scholar

    5. Yeqing Xu
      View author publications

      You can also search for this author in PubMed Google Scholar

    6. Yanjun Zhu
      View author publications

      You can also search for this author in PubMed Google Scholar

    7. Xiaoyi Hu
      View author publications

      You can also search for this author in PubMed Google Scholar

    8. Shuai Jiang
      View author publications

      You can also search for this author in PubMed Google Scholar

    9. Jianming Guo
      View author publications

      You can also search for this author in PubMed Google Scholar

    10. Hang Wang
      View author publications

      You can also search for this author in PubMed Google Scholar

    Corresponding authors

    Correspondence to Jianming Guo or Hang Wang.

    Ethics declarations

    Conflict of interest

    The authors declare that they have no conflict of interest.

    Ethical standards

    All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study, formal consent is not required.

    Additional information

    Yaohui Li and Lin Zhou have contributed equally to this article.

    Electronic supplementary material

    Below is the link to the electronic supplementary material.

    Supplement Figure 1

    Simplified nomogram for predicting perioperative outcomes. To use the nomogram, draw a line downwards from ZII axis to axes below ZII axis to determine the risk of perioperative outcomes. ZII: zero ischemia index, EBL: estimated blood loss OC: overall complications, SC: surgical complications, OT: operative time (TIFF 215 kb)

    Supplement Figure 2

    Calibration plot of perioperative outcomes: A) estimated blood loss ≥500 mL; B) overall complications; C) operative time >2 h; D) risk criteria; E) surgical complications; EBL: estimated blood loss; OC: overall complications, SC: surgical complications, OT: operative time (TIFF 6827 kb)

    Supplementary material 3 (DOCX 14 kb)

    Supplementary material 4 (DOCX 14 kb)

    Supplementary material 5 (DOCX 15 kb)

    Supplementary material 6 (DOCX 15 kb)

    Rights and permissions

    Reprints and permissions

    About this article

    Check for updates. Verify currency and authenticity via CrossMark

    Cite this article

    Li, Y., Zhou, L., Bian, T. et al. The zero ischemia index (ZII): a novel criterion for predicting complexity and outcomes of off-clamp partial nephrectomy. World J Urol 35, 1095–1102 (2017). https://doi.org/10.1007/s00345-016-1975-3

    Download citation

    • Received:

    • Accepted:

    • Published:

    • Issue Date:

    • DOI: https://doi.org/10.1007/s00345-016-1975-3

    Keywords

    Search

    Navigation