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Keywords:

  • renal cell carcinoma;
  • renal ischemia;
  • laparoscopic partial nephrectomy;
  • ischaemia-reperfusion injury

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES

What's known on the subject? and What does the study add?

Off-clamp laparoscopic partial nephrectomy (LPN) is thought to preserve renal function by limiting warm ischaemia time (WIT) and consequently reperfusion injury. To date, studies using the off-clamp technique represent a heterogeneous group, with limited follow-up showing feasibility and safety in a restricted number of cases.

We report the largest experience of off-clamp vs on-clamp LPN with perioperative outcomes and intermediate follow-up of renal functional outcomes with stratification by WIT.

OBJECTIVE

  • • 
    To evaluate perioperative and 6-month renal functional outcomes of patients undergoing off-clamp vs complete hilar control laparoscopic partial nephrectomy (LPN).

PATIENTS AND METHODS

  • • 
    A retrospective review of 489 patients undergoing LPN was completed.
  • • 
    Preoperative imaging assessed tumour characteristics.
  • • 
    Patient demographics, perioperative parameters, and postoperative outcomes were documented.
  • • 
    Multivariable regression analysis was used to assess factors contributing to changes in postoperative renal function between off-clamp and clamped LPN.

RESULTS

  • • 
    In all, 289 LPNs were performed on-clamp and 150 were performed off-clamp.
  • • 
    Tumours in the on-clamp group were larger than those in the off-clamp group (mean [range] 3.3 [0.5–13.5] vs 2.7 [0.4–9] cm, P= 0.003).
  • • 
    Univariable analysis comparing off-clamp to on-clamp cohorts showed that estimated glomerular filtration rate (eGFR) was better preserved in the off-clamp cohort at 6 months (−5.8% vs –11.4%, P= 0.046). Multivariable analysis of the groups showed that estimate blood loss (P= 0.015) and warm ischaemia time (WIT, P< 0.001) were the only significant predictors of decreased eGFR in the postoperative period.
  • • 
    Difference in eGFR at 6 months was not significant when WIT was limited to 30 min. The complication rate was greater in the clamped cohort (10% vs 20%, P= 0.012).
  • • 
    There was no difference in transfusion rate or positive margin status.

CONCLUSIONS

  • • 
    LPN without hilar clamping is feasible, safe and associated with less renal injury as assessed by postoperative GFR in select patients.
  • • 
    With experience, it can be applied to complex renal lesions.

Abbreviations
EBL

estimated blood loss

eGFR

estimated GFR

LOS

length of stay

LPN

laparoscopic partial nephrectomy

WIT

warm ischaemia time.

INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES

Traditionally, laparoscopic partial nephrectomy (LPN) has replicated the open surgical technique in that the renal hilum is clamped [1]. Hilar control minimises blood loss and improves intraoperative visualisation, and thus may aid in achieving a more controlled resection and secure renorrhaphy. However, hilar control leads to the well-recognised complication of renal ischaemia-reperfusion injury translating to renal functional impairment, which may be irreversible [2]. Consequently, various modifications to surgical technique have been used to preserve renal function [3–5]. As renal ischaemia is an important consequence of hilar clamping, ischaemic time should be minimised or avoided when possible to maximise residual renal function.

One strategy to avoid ischaemic injury is to avoid ischaemia altogether by performing surgery completely off-clamp. The present study compares short-term perioperative and pathological outcomes of off-clamp (LPN without hilar clamping) and on-clamp LPN (standard LPN with both renal venous and arterial clamping) in patients undergoing LPN for renal masses. Both cohorts included patients with tumours >4 cm, thus expanding indications for LPN to include larger tumours, previously proven to be feasible and safe [6,7].

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES

LPN was performed in 439 patients between January 2006 and March 2010 by a single surgeon. With Institutional Review Board approval, patient demographic and clinical information was gathered into a prospectively maintained database. Preoperative imaging was reviewed before each case to assess tumour characteristics. Tumour characteristics including type (solid vs cystic), size, polar location (upper, central, lower), and growth pattern (exophytic, mesophytic, endophytic) was collected. Exophytic, mesophytic, and endophytic tumours were defined as tumours with < one third, one third to two thirds, and > two thirds of their volume within the renal parenchyma, respectively [8]. Tumours were classified as hilar if the tumour came in direct contact with the renal artery and/or vein on preoperative imaging. R.E.N.A.L. Nephrometry scores were tabulated for each tumour using the scoring system proposed by Kutikov et al. [9]. Patients with pathologically confirmed RCC were stratified by clinical T-stage using the 2002 American Joint Committee on Cancer TNM classification and separately analysed.

Intraoperative data including renal warm ischaemia time (WIT), volume of i.v. fluid administered, estimated blood loss (EBL), operative duration, and intraoperative transfusions were recorded. Hospital charts were also reviewed to obtain the serum creatinine, haemoglobin, and haematocrit levels on postoperative day 1. Estimated GFR (eGFR) was calculated for each creatinine value based on the Cockcroft-Gault equation [10]. Charts were reviewed to obtain information about postoperative complications, transfusions, and length of stay (LOS). The modified Clavien classification system was used to report complications [11].

SURGICAL TECHNIQUE

The technique of standard transperitoneal LPN has been previously described [7]. A standard pneumoperitoneum of 15 mmHg was used. All masses were removed by cold excision and hilar vascular clamps were removed in reverse order after complete renorrhaphy. Cold excision was performed using a combination of laparoscopic scissors and blunt suction dissection to excise or enucleate the mass. The margin status was determined by obtaining a tissue biopsy of renal parenchyma from the base of the operative bed at the completion of the excision. Haemostasis was achieved by placement of titanium clips on visualised bleeding vessels, as well as argon-beam coagulation of the operative bed after biopsy. Off-clamp LPN was performed in select patients with ≤ cT1b tumours in the kidney, after careful evaluation of preoperative imaging and intraoperative findings when deemed feasible. Hilar tumours were enucleated with a similar technique as described. Off-clamp LPN was attempted on renal masses with varying degrees of complexity and evolved over time based on the surgeon's level of comfort. When excessive intraoperative bleeding was encountered, the renal hilum was clamped on demand.

The two cohorts were compared using the chi-squared test and Kolmogorov–Smirnov test to compare discrete categories and continuous variables, respectively. Continuous variables are reported with the mean (range); categorical variables are reported as frequencies. A P< 0.05 was considered to indicate statistical significance. Statistical adjustment for potential confounding factors was done with linear regression methodology to identify preoperative and intraoperative variables predictive of postoperative renal function.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES

In all, 439 patients underwent LPN with 289 performed on-clamp and 150 performed off-clamp. The patients' demographics, preoperative factors and baseline tumour characteristics and are shown in Tables 1 and 2. The off-clamp and on-clamp groups were comparable in age (59.2 vs 59.4 years), gender (65 vs 63% male), American Society of Anesthesiology (ASA) score (2.3 vs 2.3), Body mass index (29.8 vs 29.6 kg/m2), and preoperative eGFR (93.8 vs 97.5 mL/min), respectively. There was no association between clamp status (off-clamp vs on-clamp) and the patient characteristics listed above.

Table 1. The patients' characteristics (N= 439)
VariableOff-clamp (n= 150)On-clamp (n= 289) P
Mean (range) age, years59.2 (26–81)59.4 (21–93)NS
Gender, n (%):  NS
 Female52 (35)106 (37)
 Male98 (65)183 (63)
Mean (range):   
 ASA score2.3 (1–4)2.3 (1–4)NS
 BMI, kg/m229.8 (13.4–70.5)29.6 (18.5–62.6)NS
Preoperative eGFR, mL/min93.8 (28.1–292.6)97.5 (32.5–384.3)NS
Table 2. Tumour characteristics (N= 439)
VariableOff-clamp (n= 150)On-clamp (n= 289) P
Mean (range):   
 Tumour size, cm2.7 (0.4–9)3.3 (0.5–13.5)0.003
 Tumour volume, mL22.8 (1.6–364)33.6 (2.7–567)NS
N (%):   
 Tumour location:  NS
  Upper pole42 (36)89 (40)
  Mid pole33 (28)61 (28)
  Lower pole43 (36)70 (32)
  Unavailable3269
 Depth of penetration:  <0.001
  Endophytic19 (16)73 (31)
  Mesophytic29 (24)89 (38)
  Exophytic73 (60)74 (31)
  Unavailable2953
 Hilar tumour6 (4)17 (6)NS
 Histology:  NS
  Clear cell RCC66 (50)168 (60)
  Papillary RCC33 (25)45 (16)
  Chromophobe RCC6 (5)18 (6)
  Oncocytoma12 (9)25 (9)
  Angiomyolipomaother9 (6)6 (5)9 (3)14 (6)
  Unavailable1810

The mean tumour size in the off-clamp and on-clamp groups was 2.7 and 3.3 cm, respectively (Table 2). LPN was performed with hilar clamping in larger tumours (22.8 vs 33.6 cm, P= 0.003). Tumour location in the off-clamp group paralleled the on-clamp group with polar origin being the most common (36% vs 40% and 36% vs 32%, respectively). Depth of penetration was significantly greater in the on-clamp cohort with more exophytic tumours being performed without hilar clamping (P< 0.001). In all, 4% off-clamp and 6% of on-clamp procedures were hilar tumours. The proportion of histology types in off-clamp vs on-clamp was similar with clear cell carcinomas and papillary RCCs being the most common types in both groups (50% vs 60% and 25% vs 16%, respectively).

Tumour complexity by clamp type was analysed using the R.E.N.A.L scoring system (Table 3). The tumours were classified into low, moderate, and high complexity based on the sum of R.E.N.A.L sub-scores. In all, 62% of off clamp and 36% of on-clamp procedures were related to tumours in the low complexity category. There were a greater proportion of moderate complexity tumours in the on-clamp group as compared with the off-clamp group (48% vs 3%). Additionally, there were more high complexity score tumours in the on-clamp group (16% vs 7%).

Table 3. Comparison of tumour complexity using the R.E.N.A.L. scoring system
 Low complexityModerate complexityHigh complexity
Score 4–6Score 7–9Score 10–12
Off-clamp, %68284
On-clamp, %325117

PERIOPERATIVE CHARACTERISTICS

The mean operative duration was comparable for both clamp types (137.1 vs 141.3 min; Table 4). The EBL was larger in the off-clamp cohort, although there was no difference in transfusion rate between the groups (338.4 vs 276.8 mL; P= 0.021). The mean WIT in the on-clamp group was 25.5 min. The mean LOS was comparable between the off-clamp and on-clamp groups (2.5 days, all). The proportion of postoperative complications was significantly greater in the on-clamp group (11% vs 22%; P= 0.009). The change in creatinine, percentage change in creatinine and percentage change in eGFR 6 months after LPN were all significantly less in the off-clamp cohort (P= 0.175, P= 0.021 and P= 0.014 respectively). The EBL and WIT were associated with a change in eGFR in both univariate (P≤ 0.001 and P= 0.015) and multivariable analyses (both P≤ 0.001; Table 5). The tumour volume and operative duration did not translate to inferior postoperative renal function.

Table 4. Comparison of perioperative factors
VariableOff-clamp (n= 150)On-clamp (n= 289) P
Mean (range):   
 Operative duration, min137.1 (35–441)141.3 (31–400)NS
 EBL, mL338.4 (50–1700)276.8 (50–1300)0.023
 WIT, min025.5 (5–60)
 LOS, days2.5 (1–29)2.5 (1–15)NS
N (%):   
 Positive margin2 (1.3)4 (1.4)NS
 Transfusion5 (3)11 (4)NS
 Postoperative complications15 (10)58 (20)0.012
Mean (range):   
 Δ creatinine at 6 months, mg/dL+0.076 (−0.5 to 0.5)+0.167 (−0.4 to 1.7)0.019
 %Δ creatinine at 6 months8.7 (−55.6 to 66.7)16.9 (−36.4 to 101.9)0.024
 Δ eGFR at 6 months−3.9 (−80.2 to 181.5)−11.7 (−74.2 to 83.2)0.035
 %Δ eGFR at 6 months−5.8 (−40.0 to 125.0)−11.4 (−50.2 to 57.1)0.046
Table 5. Univariate and multivariable analysis of peri-operative parameters in predicting Δ eGFR
 UnivariateMultivariable
Operative durationNSNS
EBL<0.0010.015
On-clamp vs off-clamp0.0320.041
Tumour volumeNSNS
WIT<0.001<0.001

LPN was converted to radical nephrectomy in one patient with a mesophytic, hilar tumour in the off-clamp cohort and three patients in the on-clamp cohort. One patient in the on-clamp cohort required conversion to open surgery but was completed as a PN for a cT1a tumour. Only two (1.5%) of the off-clamp cases were converted to on-clamp secondary to intraoperative bleeding. The collecting system was entered in 12.4% of the patients in the off-clamp cohort and 34.4% of the patients in the on-clamp cohort necessitating pelvi-calyceal closure.

COMPLICATIONS

Two complications occurred intraoperatively in the off-clamp group, which were small bowel injuries associated with Veress needle insertion and electrocautery respectively. The serosal cautery injury was repaired laparoscopically with interrupted sutures, and Veress needle transgression was seen but not repaired. No intraoperative complications occurred in the on-clamp cohort.

In all, 15 complications were noted in the postoperative period in the off-clamp group compared with 59 in the on-clamp group (P= 0.019). Of the 15 postoperative complications in the off-clamp cohort, five were grade I complications (33%) consisting of superficial skin infections (two), urinary retention (one), fluid overload (one), and haematoma formation (one). Five patients had grade II complications (33%): one patient developed gastrointestinal bleeding requiring transfusion, one had acute urinary retention and subsequent UTI requiring antibiotics, one developed a wound infection that required antibiotics, one developed a pulmonary embolus, and another developed new-onset atrial fibrillation, the latter two required therapeutic anticoagulation. The remainder of the complications were grade IIIb complications (33%), including postoperative bleeding requiring angioembolisation in three patients, hydronephrosis requiring nephrostomy tube placement in one, and bladder rupture that required surgical intervention in one.

Of the 59 complications that occurred in the on-clamp group, 27 (46%) were grade I and included postoperative ileus (eight), atelectasis (seven), urine leak (three), urinary retention (three), recurrent haematuria (two), port site hernias (two), hyponatraemia (one), and port site haematoma (one). In all, 11 patients developed grade II complications (19%), which included superficial wound infections requiring antibiotics (four), C. difficile colitis (three), UTIs requiring antibiotics (two), pneumonia (one), and tachycardia requiring a β-blocker for rate control (one). In all, 21 patients developed grade III complications (36%), including postoperative bleeding requiring angioembolisation (16), gastrointestinal bleed requiring fulguration (two), clot retention and hydronephrosis necessitating nephrostomy tube placement (one), inferior vena cava filter to prevent clot migration (one), hydronephrosis requiring retrograde pyelography (one), and an incarcerated hernia necessitating small bowel resection (one).

PATHOLOGICAL OUTCOMES

The tumour histology for each cohort was encountered in statistically equivalent proportions as presented in Table 2. Tumours in the on-clamp group were bigger (in greatest dimension) than in the off-clamp group (3.3 vs 2.7 cm, P= 0.003), although not significantly larger in tumour volume (33.6 vs 22.8 mL, P= 0.176). There was a positive surgical margin in five patients in this cohort, one among the off-clamp group, and the remaining four from standard LPN with hilar control.

DEPTH OF PENETRATION

When tumours were stratified into endophytic, mesophytic and exophytic groups, there were no statistically significant differences in, patient demographics, tumour location, clinical T-stage, operative duration, or LOS, between off-clamp and on-clamp patients. The off-clamp cohort had a larger EBL than the on-clamp cohort in all three groups, but this difference was only significant in the mesophytic group (P= 0.02). Despite this, there were no statistically significant differences in transfusion rate or postoperative complications between the off-clamp and on-clamps cohorts in each of the three subgroups.

R.E.N.A.L. SCORING

We found no difference in the maximum radius of tumours, hilar location, anterior or posterior location, or location with respect to the polar line between cases performed off-clamp and on-clamp. However, notable differences were present in the proportion of endophytic vs exophytic tumours and nearness to the collecting system between the two cohorts, (P< 0.001). The off-clamp group consisted largely of tumours that were >50% exophytic (58.2%), followed by tumours that were <50% exophytic (33.0%) and tumours that were completely endophytic (8.8%). In contrast, the on-clamp group had similar rates of tumours that were >50% exophytic (37.7%) and <50% exophytic (39.8%), followed by endophytic tumours comprising 22.5% of on-clamp cases performed.

There was a significant difference in the nearness to the collecting system subscore between the off-clamp and on-clamp as well, with a 54.9% of off-clamp cases performed for tumours >7 mm from the collecting system compared with only 29.8% of on-clamp cases. A larger proportion of tumours <4 mm from the collecting system was performed in the on-clamp group (51.8%) compared with the off-clamp group (27.5%).

Tumours were further subclassified into low, moderate, and high complexity based on the sum of R.E.N.A.L subscores (Table 5). There was a significant difference in the complexity of tumours performed off-clamp and on-clamp (P< 0.001). Tumours of moderate or high complexity were more likely to have been selected for inclusion in the on-clamp cohort than tumours of low complexity

WIT SUBGROUP ANALYSIS

In the on-clamp cohort, 180 patients had <30 min WIT, and 109 patients had a WIT of >30 min. There was a linear relationship with the amount of WIT compared with tumour size and tumour volume across the three groups. When compared with patients with <30 min WIT, procedures performed off-clamp had a greater EBL (338.4 vs 250.8 mL, P< 0.001; Table 6). However, the lack of warm ischemia did not yield a difference in renal functional outcomes when the WIT was limited to 30 min. There were no differences in the overall operative duration and LOS, although the rate of complications remained significant.

Table 6. The effect of WIT on perioperative factors
 Off-clampOn-clamp P
WIT 0 minWIT <30 min
No. of patients150180
Mean (range):   
 Age, years59.2 (26–81)59.2 (21.4–80.6)NS
 Tumour size, cm2.7 (0.4–9)3.1 (0.5–13.5)NS
 Tumour volume, mL22.8 (1.6–364)28.9 (1–567)NS
 Operative duration, min137.1 (35–441)137.6 (31–400)NS
 EBL, mL338.4 (50–1700)250.8 (5–1300)<0.001
 LOS, days2.5 (1–29)2.51 (1–29)NS
 Δ eGFR at 6 months−3.9 (−80.2 to 181.5)−8.6 (−59.5 to 83.2)NS
 % Δ eGFR at 6 months−5.8 (−40 to 125)−8.9 (−50.2 to 57.1)NS
Postoperative complications, n (%)12 (8)39 (22)<0.001

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES

LPN is a well-established approach for the treatment of small renal tumours. As long-term oncological outcomes have become available in recent years and shown equivalence to open PN, considerable focus has been given to minimising morbidity associated with the procedure [12,13]. This includes maintenance of long-term renal function.

Several authors have described techniques to decrease renal ischaemic injury and contemporary series are presented in Table 7[14–21]. Early unclamping after starting a running suture on the tumour bed has been shown to significantly decrease WIT [3,22]. The vascularised renal parenchyma is subsequently closed over a surgical bolster. This technique reduces WIT by ≈50%, without increasing intraoperative bleeding or postoperative complications. Additionally, vascular control provided during microdissection of renal vessels and selective arterial clamping of tumour vasculature has been described and represents regional ischaemia with the potential of collateral damage to adjacent nephrons rather than true ‘zero-ischaemia’. An alternative method of reducing ischaemia time is ‘on-demand’ clamping of the hilum [23]. In this technique, the hilum is dissected but clamped only in the case of excessive bleeding. Of 39 patients in the present study, 31 required ‘on-demand’ clamping with a mean WIT of 9 min. Of note, there was a high rate of blood transfusions (21%) and two patients required open conversion due to excessive bleeding.

Table 7. Contemporary series of off-clamp LPN
Reference N TechniqueMean (sd or range) tumour size, cmMean (sd or range) EBL, mLMean (sd or range) operative duration, minPositive margin, nMean (sd or range) preoperative GFR, mL/minMean (sd or range) postoperative GFR, mL/min
  • *

    Selective transarterial embolisation.

Tanagho et al. 2012 [15]42Off-clamp2.7 (1.4)138 (50–1500)143 (59)078.5 (28.9)76.2 (27.6)
Gill et al. 2012 [16]58Micro-bulldog clamps3.2 (0.9–13.0)206 (25–1000)264 (126–480)079.6 (29.3–147)61.5
Novak et al. 2012 [17]28Off-clamp2.1 (0.8–4.9)274 (50–1500)183 (77–404)089.886.5
Gill et al. 2011 [18]15Micro-bulldog clamps2.5 (1–4)150 (20–400)180 (78–360)075.372.9
Simone et al. 2011 [19]311Off-clamp (101) STE* (210)2.14 (1.5–4)100 (20–240)60 (45–160)096 (60–120)97.5 (65–120)
Koo et al. 2010 [20]11Off-clamp2.62 (1.4)159 (153)174 (55)0N/AN/A
White et al. 2010 [21]8Off-clamp2.4 (1.1–3.5)569 (250–2000)167 (118–215)0N/AN/A
Guillonneau et al. 2003 [14]12Off-clamp2.0 (1.2–3)708 (200–1800)179.1 (90–390)0N/AN/A
Present Study150Off-clamp2.7 (0.4–9)338 (50–1700)137 (35–441)2106 (28–258)99 (22–201)

Janetschek et al. [24] described an early series of off-clamp LPN on small (<2 cm) exophytic lesions in 25 patients. Bipolar coagulation forceps were used for both simultaneous dissection and haemostasis with an mean (range) blood loss of 287 (20–800) mL. Guilloneau et al.[14] also reported a comparative series of off-clamp vs on-clamp PN for small renal tumours in 28 patients. Margins were negative in all patients, but increased bleeding and longer operative duration was reported in the off-clamp group.

The effect of WIT has been extensively studied both clinically and in the laboratory setting. Off-clamp LPN patients have been compared with on-clamp LPN with WITs of <30 vs >30 min [25]. There was no significant change in the median postoperative serum creatinine levels. None of the 118 patients, including one patient with 55 min of clamping, required dialysis. Porpiglia et al. [26] also reported no significant difference between preoperative eGFR and at 3 months after LPN in 18 patients with WITs of >30 min. These findings are in contrast with the results of the present study, which shows equilibration of serum creatinine levels and eGFR at 6 months postoperatively in those with WITs of <30 min, but not a protective effect of off-clamp status compared with the overall on-clamp cohort. However, in the Porpiglia et al.[26] study, renal scintigraphy showed the contribution of the affected kidney decreased from 48% to 36% on postoperative day 5, then increased to 40% at 3 months and 43% at 1 year postoperatively. In this limited retrospective study, despite decreasing contribution of the affected renal moiety, the overall GFR was maintained and no patient required dialysis postoperatively in the presence of a normal contralateral kidney.

Godoy et al. [27] used interval analysis to show no significant difference in the GFR for WITs of <40 min in a cohort of 101 patients. However, there was a significantly greater decrease in GFR and lower GFR postoperatively in patients who had WITs of >40 min. In all, 10 patients in the present on-clamp cohort had a WIT of ≥40 min and subgroup analysis of these patients did not show a significant difference in the postoperative GFR when compared with the rest of the on-clamp cohort (P= 0.492).

Off-clamp LPN has been shown to have equivalent oncological outcomes as standard LPN [28]. In the present study, the use of hilar vessel clamps, clamp time, and EBL were the only factors on multivariate linear regression models predicting a decreased eGFR. The effect of greater blood loss in both groups may be a consequence of a more complex procedure requiring a more comprehensive renorrhaphy, potentially compromising a greater area of functioning renal parenchyma. The tumour volume and operative duration did not lead to differences in eGFR, suggesting that off-clamp LPN can be used for carefully selected large, complex renal masses and thus minimising renal ischaemic injury, and optimising postoperative renal function. There was no difference in positive surgical margin rates between the groups, suggesting that off-clamp surgery allows for a complete resection, with adequate visualisation, without compromising oncological control.

In the present study, we compared the perioperative characteristics of 150 patients undergoing off-clamp LPN with 289 patients undergoing on-clamp LPN. We found statistically significant differences in the serum creatinine levels 6 months postoperatively, and postoperative complication rates. The differences in renal function, although statistically significant, were relatively small, and may not have a substantial impact on overall long-term renal function. We also found no difference in operative duration, EBL, and transfusion rates between patients undergoing off-clamp and on-clamp LPN.

The present study was limited to a single very experienced surgeon, allowing for more uniform comparisons of outcomes across the two operative techniques compared. The greatest limitation of the present study was selection bias, as off-clamp procedures early in the series were performed on exophytic tumours that permitted relatively easy repair of the renorrhaphy, with no strict criteria determining clamp status but rather preoperative imaging and intraoperative findings (Table 5). Additionally, creatinine-based estimations of renal function can show variability associated with muscle mass, hydration status, and nutritional status. Longer follow-up is needed to determine the true impact of off-clamp LPN on the ultimate eGFR rendered in patients postoperatively and the clinical significance, compared with matched patients who undergo LPN with complete hilar control.

In conclusion, nephron-sparing surgery is the preferred surgical approach for amenable renal tumours. Recently, attention has been increasingly focused toward strategies aimed at maximising function in remaining renal units by minimising ischaemia time. LPN can be performed off-clamp in selected patients with organ-confined renal tumours without compromising operative duration, blood loss, or LOS. Rates of positive margins, blood transfusion, intraoperative and postoperative complications, and conversion to open surgery were low and limited to patients with cT1a disease in this series. Off-clamp LPN allows for the traditional benefits of minimally invasive surgery and completely avoids ischaemia time, providing the ultimate strategy for renal protection. Further studies with longer follow-up are needed to elucidate the impact of limited ischaemia on long-term renal function.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. CONFLICT OF INTEREST
  8. REFERENCES