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Article of the Week: Renal Function is the same regardless of clamp technique 6 months after RAPN

June 10, 2015/by admin Z.9

Every Week the Editor-in-Chief selects the Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an accompanying editorial written by a prominent member of the urological community. This blog is intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation.

Finally, the third post under the Article of the Week heading on the homepage will consist of additional material or media. This week we feature a video from Prof. Rha, discussing his paper.

If you only have time to read one article this week, it should be this one.

Renal Function is the same regardless of clamp technique 6 months after Robot-assisted Partial Nephrectomy: Analysis of Off-Clamp, Selective Arterial Clamp and Main Artery Clamp with minimum of 1 year follow-up.

Christos Komninos*‡, Tae Young Shin†, Patrick Tuliao*, Woong Kyu Han*, Byung Ha Chung*, Young Deuk Choi* and Koon Ho Rha*

*Department of Urology and Urological Science Institute, Yonsei University College of Medicine, Seoul, †Department of Urology, Chuncheon Sacred Hospital, Hallym Medical College, Chuncheon, Korea, and ‡Department of Urology, General Hospital of Nikaia ‘St. Panteleimon’, Athens, Greece

Read the full article

OBJECTIVE

To compare the renal functional outcomes, with >1 year of follow-up, of patients who underwent robot-assisted partial nephrectomy (RAPN) performed with different clamping techniques.

PATIENTS AND METHODS

The peri-operative data of patients undergoing RAPN performed with different clamping techniques were retrospectively analysed (group 1: off-clamp, n = 23; group 2: selective clamp, n = 25; group 3: main artery clamp, n = 114). The main outcome measures were postoperative serum creatinine level, estimated glomerular filtration rate (eGFR) and percentage change in eGFR, the data for which were collected at periodic intervals during the first 12 months and annually thereafter, in addition to late eGFR value. Only patients with >1 year of follow-up were included in the analysis.

RESULTS

The baseline characteristics of groups 2 and 3 were similar, while patients in group 1 had smaller sized tumours and lower tumour complexity. The median follow-up periods were 45 (group 1), 20 (group 2) and 47 (group 3) months. The median clamping times were 24.8 min in the main artery clamp and 18 min in the selective artery clamp groups. Group 2 had greater median blood loss volume (100 vs 500 vs 200 mL for groups 1, 2 and 3, respectively; P < 0.01) and a longer length of hospital stay (3 vs 4 vs 3 days for groups 1, 2 and 3, respectively; P = 0.02). No significant differences were found among the groups with regard to transfusion rates, positive surgical margin rates, complications, recurrence or mortality rates. Groups 1 and 2 had significantly less deterioration of postoperative renal function during the first 3 months after surgery (P = 0.04; percent change in eGFR −1.5, −2 and −8% for groups 1, 2 and 3, respectively), but this beneficial outcome was not observed after 6 months or for the latest eGFR measurement (P = 0.48; latest percent change in eGFR −3, −6 and −3.5% for groups 1, 2 and 3, respectively). In regression analysis, baseline eGFR, type of clamp procedure and tumour complexity score were predictive of normal renal function 7 days after surgery, while only baseline eGFR and age could predict it 1 year postoperatively.

CONCLUSIONS

Off-clamp and selective artery clamp techniques result in superior short-term renal functional outcomes compared with the main artery clamp approach; however, after the 6th postoperative month, there were no significant differences regarding the functional outcome among the above surgical techniques, as long as the warm ischaemia time was 20–30 min.

Editorial: To clamp or not to clamp in robotic partial nephrectomy?

June 10, 2015/by Ben Challacombe

The article by Komninos et al. [1], in this issue of the BJUI has looked into the importance of warm ischaemia techniques in robot-assisted partial nephrectomy (RAPN) on the deterioration in short- and longer-term renal function. A case series of 162 procedures undertaken by a single surgeon over a 7-year period was analysed. Within this cohort, 114 patients underwent main artery clamping, whilst 23 and 25 patients underwent off-clamp and selective artery clamping methods, respectively.

Segmental artery clamping and off-clamp techniques have been recently developed to minimize the warm ischaemia time (WIT), which, if prolonged, can result in loss of normal functioning parenchyma, potentially causing renal impairment [2]. This paper has correctly identified that many studies on RAPN within the literature have a limited 6-month follow-up regarding postoperative renal function, and the authors sought to evaluate this further. They have shown that significantly less deterioration in renal function over the first 3 months is seen in the off-clamp and selective artery clamp techniques compared with main artery clamping. Importantly, however, this reduction seems transient and was not seen at 6 months and 1 year after surgery.

The authors comment on the median clamping times used in the two separate clamping techniques, with 24.8 and 18 min in the main artery and selective artery clamping groups, respectively; however, no specific analysis was provided of the significance of these times on renal function outcome. Elsewhere Abreu et al. [3], have reported that ‘zero ischaemia time’, with no hilar clamping, preserves renal function with a median decrease of 0 mg/dL in creatinine and a 5 mL/min/1.73 m² reduction in estimated GFR (eGFR) rate at hospital discharge in a robotic surgery series. Similarly, George et al. [4] have shown that, at 6 months, less renal injury is sustained, as demonstrated by eGFR, when an off-clamp laparoscopic technique was used compared with an on-clamp technique, and that WIT was a significant predictor of decreased eGFR in the postoperative period.

Warm ischaemia time is a topic of much debate in the literature and remains a controversial area of significant interest. As most predictors of eGFR, such as age, comorbidity and pre-existing renal function, are unmodifiable, the attractive challenge with WIT is that it is a surgically modifiable variable. Reassuringly, RAPN clamp time is typically shorter than in pure laparoscopic partial nephrectomy, and usually shorter than the generally accepted limit of 30 min that has been associated with good preservation of postoperative renal function [5]. More recently, Wiener et al. [6] were able to establish that WIT ≤ 22 min prevented a statistically significant decline in renal function at 6–12 months.

In light of this evidence, another technique of ‘early unclamping’ is being increasingly considered, especially in RPN, but several considerations, including increased blood loss and potential increased difficulty with the renorrhaphy, have limited its application [5]. The paper by Komninos et al. is supported by another study that analysed 95 consecutive RAPN cases, in which a variety of clamping techniques was used (artery and vein, artery alone and unclamp), showing that GFR and overall percentage decrease in GFR was similar for all three methods at a median follow-up of 6 months and suggesting that intermediate-term renal function outcome is irrespective of clamping technique [7].

Clearly there are limitations to the present study, including its non-randomized, retrospective nature and the low sample sizes of the off-clamp and selective artery groups and the authors have recognized this. The entire population also had a low body mass index and comorbidity status compared with many RAPN series. The off-clamp tumours were all relatively exophytic, significantly smaller than the other groups (1.7 vs 3.5 and 3.3 cm), and far less complex, with PADUA scores of 7 compared with 10 and 9. Despite this, the study has shown, with a respectable follow-up period, that although there is a significant initial deterioration in renal function with the main artery clamping technique at 3 months compared with the selective artery and off-clamp methods, there was no significant difference in renal deterioration between the three groups at 6 months and at 1 year.

It is also interesting to see that, even though patients in the main artery clamping group had larger and more complex tumours, inevitably resulting in a greater resected volume of normal-functioning nephrons, renal function deterioration was no different from the off-clamp group by 6 months. The authors have contributed to the evidence for main artery clamping in RPN, particularly in complex tumours in healthy younger patients with bilateral functioning renal units. Techniques to minimize warm ischaemia are likely to continue to have a role in higher risk and imperative indications for partial nephrectomy.

Read the full article

Buket N. Ertansel, Norbert Doeuk and Ben Challacombe

Guy’s & St Thomas’s Hospital, London, UK

References

1 Komninos C, Shin TY, Tuliao P et al. Renal Function is the same regardless of clamp technique 6 months after Robot-assisted Partial Nephrectomy: analysis of Off-Clamp, Selective Arterial Clamp and Main Artery Clamp with minimum of 1 year follow-up. BJU Int 2014; doi: 10.1111/bju.12975. [Epub ahead of print]

2 Thompson RH, Lane BR, Lohse CM et al. Every minute counts when the renal hilum is clamped during partial nephrectomy. Eur Urol 2010; 58: 340–5

3 Abreu AL, Gill IS, Desai MM. Zero-ischaemia robotic partial nephrectomy (RPN) for hilar tumours. BJU Int 2011; 108 (Pt 2): 948–54

4 George AK, Herati AS, Srinivasan AK et al. Perioperative outcomes of offclamp vs complete hilar control laparoscopic partial nephrectomy. BJU Int 2013; 111 (Pt B): E235–41

5 Cawley O, Roman A, Brown M, Challacombe B. Exploring the evidence for early unclamping during robot-assisted partial nephrectomy: is it worth the time and effort? BJU Int 2014; doi: 10.1111/bju.12836. [Epub ahead of print]

6 Wiener S, Kiziloz H, Dorin RP, Finnegan K, Shichman SS, Meraney A. Predictors of postoperative decline in estimated glomerular ﬁltration rate in patients undergoing robotic partialnephrectomy. J Endourol 2014; 28: 807–13

7 Krane LS, Mufarrij PW, Manny TB, Hemal AK. Comparison of clamping technique in robotic partial nephrectomy: does unclamped partial nephrectomy improve perioperative outcomes and renal function? Can J Urol 2013; 20: 6662–7

Video: 6 months after RAPN – Renal Function is the same regardless of clamp technique

June 10, 2015/by admin Z.9