In the last decade, several attempts have been made to minimize ischemia time, which is the only modifiable factor affecting RF. This has led to the development of different surgical techniques4. PN modalities, whether open, laparoscopic, or robotic, typically involve hilar clamping, which allows precise tumor resection and closure of the renal defect in a bloodless field. However, the temporary ischemic injury potentially worsens the RF. The effect of optimal warm ischemia time (WIT) during clamped PN on long term renal functional outcomes is still a matter of debate. In a recent systematic review on the role of ischemia, the authors suggested that limited WIT periods (<20-25 min) may have a negligible effect on RF5.
However, as ischemia is the only surgical modifiable parameter, the negative effect of WIT led surgeons to develop techniques to minimize renal hypoperfusion, such as preoperative super-selective transarterial embolization (P-STE)6, parenchymal clamping7, early unclamping8, selective clamping9 , and zero-ischemia procedure10. These techniques were recently described as “minimally ischemic” in order to distinguish them by a pure unclamped approach4. In patients with normal baseline RF the adoption of these techniques remain controversial, especially due to the need for advanced surgical skills. Compared with clamped PN, where the tumor bed is virtually bloodless, during minimally ischemic or pure unclamped PN, constant suction irrigation and excellent technical suturing ability for bleeding control are crucial to obtain proper control of resection margins, and to ensure a satisfactory hemostasis.
With increased experience and with the availability of robotic platform, Zero Ischemia PN10, and subsequently by a pure unclamped approach can be utilized. Zero Ischemia PN is a complex procedure, requiring about 3 hrs (range: 1.3-6 hrs) in expert hands10, advanced skills in the intraoperative use of ultrasound/Doppler imaging and a meticulous microdissection of multiple arterial branches. This technique is not exempt from risks, including ischemic (temporary occlusion and reperfusion) and hemorrhagic ones (related to a microdissection of hilar vessels and branches). This technique is certainly best suited for hilar and medially located renal tumors, while a hilar microdissection for laterally located tumors would require a large nephrotomy with consequent ischemic risks.
The pure unclamped technique is essentially based on a straight access to the tumor, without renal hilum dissection, the development of an enucleation plane and a stepwise identification of tertiary and quaternary arterial branches feeding the tumor. For this technique meticulous dissection of margins is required and a simultaneous use of two irrigation and suction devices to improve visualization of the resection bed. Identified feeding vessels are selectively coagulated or clip ligated and transected. Finally, clips can be safely removed during the renorrhaphy.
Due to the lack of prospective randomized trials comparing clamped PN with unclamped PN, definitive conclusions on the superiority of one approach over the others regarding long-term RF outcome are not possible. A retrospective comparison of minimally ischemic PN and clamped PN by Desai et al.11 showed that minimally ischemic PN was associated with a lower decrease in eGFR at discharge (0% vs 11%, p = 0.01) and at last follow-up (11% vs 17%, p = 0.03).
The robot-assisted approach helps to simplify some of the technical difficulties of this complex technique. Dr. Gallucci concluded that his experience supports pure unclamped PN as a feasible and safe surgical approach in tertiary referral centers, providing excellent oncologic and functional outcomes.
Speaker: Michele Gallucci, MDProfessor at the University La Sapienza and the free University Biomedical Campus of Rome, as well as President Italian Association of Urologists, Rome, Italy
Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre @GoldbergHanan at The 15th Meeting of the EAU Section of Oncological Urology ESOU18 - January 26-28, 2018 - Amsterdam, The Netherlands
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