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Keywords:

  • renal tumour;
  • laparoscopy;
  • partial nephrectomy;
  • renal function;
  • nephron-sparing surgery

Abstract

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

Authors from Cleveland assessed the impact of warm ischaemia on renal function, using their large database of laparoscopic partial nephrectomies for tumour. While agreeing that renal hilar clamping is essential for precise excision of the tumour, and other elements of the operation, the authors indicate that warm ischaemia may potentially damage the kidney. However, they found that there were virtually no clinical sequelae from warm ischaemic of up to 30 min. They also found that advancing age and pre-existing renal damage increased the risk of postoperative renal damage.

OBJECTIVE

To assess the effect of warm ischaemia on renal function after laparoscopic partial nephrectomy (LPN) for tumour, and to evaluate the influence of various risk factors on renal function.

PATIENTS AND METHODS

Data were analysed from 179 patients undergoing LPN for renal tumour under warm ischaemic conditions, with clamping of the renal artery and vein. Renal function was primarily evaluated in two groups of patients: 15 with tumour in a solitary kidney, who were evaluated by serial serum creatinine measurements; and 12 with two functioning kidneys undergoing unilateral LPN, and evaluated by renal scintigraphy before and 1 month after LPN to quantify differential renal function. Also, in all 179 patients, mean serum creatinine data at baseline, 1 day after LPN, at hospital discharge, and at the last follow-up were provided as supportive evidence. Logistic regression analyses were used to assess the effect of various risk factors on renal function after LPN, i.e. patient age, baseline serum creatinine, tumour size, solitary kidney status, duration of warm ischaemia, pelvicalyceal suture repair, urine output and intravenous fluids during LPN.

RESULTS

In the group of patients with a solitary kidney the mean warm ischaemia time was 29 min, kidney parenchyma excised 29%, and serum creatinine at baseline, discharge, the peak after LPN and at the last follow-up (mean 4.8 months) 1.3, 2.3, 2.8, and 1.8 mg/dL, respectively. One patient (6.6%) required temporary dialysis. In the second group, assessed by renal scintigraphy, the function of the operated kidney was reduced by a mean of 29%, commensurate with the amount of parenchyma excised. For all 179 patients, a combination of age ≥70 years and a serum creatinine level after LPN of ≥1.5 mg/dL correlated with a higher serum creatinine after LPN. On logistic regression, baseline serum creatinine and solitary kidney status were the only variables significant for serum creatinine status after LPN.

CONCLUSIONS

The bloodless field provided by renal hilar clamping is important for precise tumour excision, pelvicalyceal suture repair and securing parenchymal haemostasis during LPN. However, renal hilar clamping causes warm ischaemia. These data indicate that the clinical sequelae of warm ischaemic renal injury of ≈ 30 min are minimal. Advancing age and pre-existing azotaemia increase the risk of renal dysfunction after LPN, especially when the warm ischaemia exceeds 30 min.


Abbreviations
L(PN)

laparoscopic (partial nephrectomy)

WI

warm ischaemia.

INTRODUCTION

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

Laparoscopic partial nephrectomy (LPN) is gaining popularity as a promising minimally invasive nephron-sparing option for treating selected renal tumours [1–3]. Renal hilar clamping during LPN affords the near-bloodless operative field critical for achieving precise tumour excision, watertight pelvicalyceal suture repair and renal parenchymal haemostasis. However, renal hilar clamping causes warm ischaemia (WI), with its attendant potential for ischaemic renal injury.

In the present study we assessed the effect of renal hilar clamping-induced WI on renal function after LPN. Because the presence of a normal contralateral kidney will probably mask significant changes in serum creatinine levels after unilateral LPN, we specifically focused on two groups of patients, i.e. those undergoing LPN for tumour in a solitary kidney, and those with two functioning kidneys undergoing unilateral LPN but in whom radionuclide renal scans before and 1 month after LPN were available for objective documentation of differential renal function. We also examined the serum creatinine database for the entire cohort of 179 patients to identify the effect of various independent risk factors in causing ischaemic renal dysfunction.

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

Data were retrospectively analysed from 179 patients undergoing LPN for tumour since August 1999 (mean age 62 years, sd 13, range 23–87); the mean (sd, range) American Society of Anesthesiology score was 2.6 (0.6, 1–4), the body mass index 30.1 (7.9, 18–74) kg/m2 and tumour size 2.9 (1.3, 1–10) cm. The technique of LPN was detailed elsewhere [1]. Specifically, LPN routinely used WI, with the renal artery and vein clamped in all 179 patients. The mean WI time was 31 (10, 4–55) min (Fig. 1), the operative duration 198 (90–345) min, and the estimated blood loss 216 (25–1500) mL. Immediately on concluding the operation, after consultation with the assistants, the operating surgeon documented the consensus subjective impression of the percentage of kidney parenchyma excised during the LPN. Baseline and perioperative data were collected and entered prospectively into a computerized database. Follow-up serum creatinine and MAG3 renal scan data were collected by telephone contact with the patient and/or local physician.

image

Figure 1. Scatter plot showing that in most cases the warm ischaemia time was ≈ 30 min.

Download figure to PowerPoint

Fifteen patients had a LPN for tumour in a solitary kidney; their serum creatinine levels (normal 0.7–1.4 mg/dL) were available serially before LPN, at hospital discharge, at the peak recorded after LPN, and at the last follow-up. In 12 further patients undergoing unilateral LPN with both kidneys functioning, 99mTc-MAG3 renal scintigrams were available before and 1 month after LPN, to quantify any change in differential renal function. These two subgroups were used as the primary determinants for assessing renal function after LPN.

Also, for the entire study population of 179 patients, serum creatinine levels at baseline (before LPN), 1 day after LPN, at discharge and at the last follow-up were assessed as supporting evidence of renal functional status. For further analysis, all 179 patients were stratified in three different ways. First, based on WI time, patients were divided into two groups (group 1, WI < 30 min, group 2, ≥ 30 min); second, based on WI and age, patients were divided into four groups (group A1, WI < 30 min and <70 years old, group A2, WI < 30 min and age ≥ 70; group B1, WI ≥ 30 min and age < 70; and group B2, WI ≥ 30 min and age ≥ 70). Third, based on WI and baseline serum creatinine level, patients were divided into four groups (group C1, WI < 30 min and serum creatinine <1.5 mg/dL; group C2, WI < 30 min and creatinine ≥1.5 mg/dL; group D1, WI ≥30 min and creatinine <1.5 mg/dL; and group D2, WI ≥  30 min and creatinine ≥ 1.5 mg/dL).

The statistical significance between various groups was assessed using the t-test, Wilcoxon rank-sum test, anova, or Kruskal-Wallis test for continuous variables, and the chi-square test for categorical variables. All data are reported as the mean/median (sd/range), with P < 0.05 considered to indicate statistically significant differences. Multiple linear regression analysis was used to assess the effect of various independent variables on serum creatinine after surgery, i.e. patient age, WI time, pelvicalyceal suture repair, tumour size, baseline serum creatinine, solitary kidney status, and intravenous fluid administration and urine output during LPN.

RESULTS

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

No kidney was lost because of ischaemic sequelae. The details for the 15 patients undergoing LPN for tumour in a solitary kidney are shown in Table 1; one patient with a 6.5-cm tumour in the solitary kidney had a 60% heminephrectomy and then required temporary haemodialysis. No other patient required haemodialysis after LPN.

Table 1.  LPN in a solitary kidney; the effect of WI on serum creatinine levels
Patient no.Age, yearsTumour size, cmWI time, min% kidney excisedSerum creatinine, mg/dL Follow-up months
Before1 dayAt dischargeMaxFinal
  • *

    Delayed nephrectomy for bleeding; NA, not available;

  • †This patient required temporary dialysis after LPN; as such, his serum creatinine levels after LPN were excluded from the calculations for means in two columns, i.e. serum creatinine at discharge and maximum serum creatinine.

  1622.519NA1.22.12.0NA* 10
 2514.534NA0.82.22.02.21.1 7
 3622.718NA0.91.11.11.11.1 2
 478 1.419NA0.91.21.21.21.2 7
 5622.5NANA1.11.62.33.41.9 6
 6675.028502.12.82.33.42.3 3
 7418.342NA1.52.33.23.41.5 9
 8742.531 151.52.43.43.61.5  1
 9726.555651.42.86.28.73.3 6
10822.235201.51.61.61.91.9  1
11423.9NA301.42.62.73.42.8 3
1258 1.533 101.22.42.41.61.6  1
13722.834 151.21.61.51.61.3  1
14872.814NA1.51.72.02.31.9  1
15443.517NA1.11.11.01.11.1 14
Mean643.529291.31.92.32.31.6 4.8

The details of the 12 patients who had MAG3 renal scintigraphy before and after LPN to assess differential renal function are shown in Table 2. The mean differential function of the target kidney was 45% before and 32% 1 month after LPN; as such, the calculated reduction of function of the operated kidney from baseline was 29%.

Table 2.  The effect of WI on differential renal function as determined by MAG3 renal scintigraphy
Patient no.Age, yearsWI time, min% kidney excisedSerum creatinine, mg/dLRenal scan*, %
Before1 monthBefore1 month % reduction*
  • *

    The ‘before’ and ‘1 month’ differential renal function represents the contribution of the target kidney of a total of 100% for both kidneys, and thus the ‘% reduction describes that from the baseline ipsilateral preoperative value (= 100%) calculated as inline image

  • ×

    ×100. NA, not available.

  16342300.91.0503824
 26528302.43.04437 16
 35430NA0.80.9453033
 46135101.01.236.935 5
 55642 52.52.55043 14
 65842350.91.5483038
 74445250.81.0502452
 87531300.91.0564520
 94445600.81.0502452
 105441401.21.33531 10
 113736200.90.93838 0
 126948300.71.0422833
Mean5739291.21.4453229

Patients in group 1 (WI < 30 min) had a shorter operating time, less blood loss, a lower incidence of pelvicalyceal entry and a shorter hospital stay than those in group 2 (WI ≥ 30 min; Table 3). Nevertheless, groups 1 and 2 were comparable in terms of serum creatinine 1 day after LPN, at discharge, and at the latest follow-up. The mean follow-up in group 1 was longer than in group 2 (Table 3).

Table 3.  The effect of WI; the overall demographic data, information during and after LPN, and the serum creatinine levels
VariableGroup
1 (WI < 30 min)2 (WI ≥ 30 min)POverall
  • *

    Student's t-test;

  • †chi-square test;

  • ‡Wilcoxon rank-sum test;

  • ¶% of preoperative value. ASA, American Society of Anesthesiology.

No. of patients 74105NA179
Male, n (%) 40 (54) 65 (62) 0.29105 (59)
Mean (sd, range):
age, years 64 (13, 23–87) 60 (13, 30–86) 0.1* 62 (13, 23–87)
ASA class  2.7 (0.6, 2–4)  2.5 (0.6, 1–4) 0.15  2.6 (0.6, 1–4)
body mass index, kg/m2 29.8 (8.0, 18–59) 30.2 (7.8, 18–74) 0.77* 30.1 (7.9, 18–74)
tumour size, cm  2.8 (1.4, 0.9–10)  3.1 (1.3, 1.0–8.3) 0.13*  2.9 (1.3, 0.9–10)
Central tumours, n (%)  18 (31) 26 (33) 0.73 44 (32)
Calyceal entry and repair, n (%) 37 (51) 97 (93)<0.001134 (76)
Mean (sd, range):
WI time, min 22 (6, 4–29) 37 (6, 30–55)<0.001* 31 (10, 4–55)
operative time, min176 (51, 90–345)211 (48, 129–315)<0.001*196 (52, 90–345)
blood loss, mL194 (258, 10–1500)230 (229, 30–1500) 0.005215 (241, 10–1500)
Complications during LPN, n (%)  3 (4) 10 (9.5) 0.16 13 (7.3)
Mean (sd, range):
hospital stay, h 56 (40, 23–229) 79 (78, 23–768)<0.001 69 (65, 23–768)
Serum creatinine, mg/dL
before LPN  1.2 (0.5, 0.6–3.4)  1.1 (0.5, 0.4–3.1) 0.19*  1.1 (0.5, 0.4–3.4)
1 day after  1.2 (0.5, 0.6–2.9)  1.4 (0.5, 0.5–3.7) 0.21*  1.3 (0.5, 0.5–3.7)
at discharge  1.3 (0.7, 0.6–4.2)  1.4 (0.6, 0.5–4.0) 0.48*  1.4 (0.6, 0.5–4.2)
at last follow-up  1.3 (0.6, 0.5–4.2)  1.3 (0.6, 0.5–3.7) 0.88*  1.3 (0.6, 0.5–4.2)
maximum  1.5 (0.7, 0.6–4.2)  1.6 (1.0, 0.7–8.7) 0.34*  0.5 (0.7, 0.0–7.3)
Duration to last estimate, months  6.1 (7.7, 0.03–27)  2.6 (3.8, 0.03–18)<0.001*  4.1 (6.0, 0.03–27)
% increase at last follow-up 13.2 (21.4, 0–50) 15.5 (32, 0–170) 0.4* 14.4 (0–170)
No. patients requiring dialysis  0  1NA  1

Compared with group A1 (WI < 30 min and age <70 years) patients in group A2 (WI <30 min and age ≥ 70 years) had a higher serum creatinine 1 day after LPN, at discharge and at the latest follow-up (Table 4). Similarly, compared with group A1, patients in B2 had a higher serum creatinine 1 day after LPN, at discharge, and at the last follow-up, and a higher percentage increase from baseline.

Table 4.  LPN; the effect of WI and age on serum creatinine levels
VariableGroupP*
A (WI < 30 min) B (WI ≥ 30 min) 
  1. P values: for subgroups A,B: A, A1 vs A2; B, A1 vs B1; C, A1 vs B2; D, A2 vs B1; E, A2 vs B2; F, B1 vs B2. For subgroups C and D, A, C1 vs C2; B, C1 vs D1; C, C1 vs D2; D, C2 vs D1; E, C2 vs D2; F, D1 vs D2. †% of preoperative value. ‡Baseline serum creatinine befor LPN.

Subgroup (age, years)A1 (<70)A2 (≥70)B1 (<70)B2 (≥70) 
No. of patients47277233NA
Mean (range):
WI time, min22 (4–29)22 (10–29)37 (30–55)37 (30–52)<0.001 B,C,D,E
age, years56 (23–69)76 (70–87)53 (30–69)75 (70–86)<0.001 A,C,D,F
Serum creatinine, mg/dL
before LPN‡ 1.1 (0.6–2.6) 1.3 (0.6–3.4) 1.0 (0.4–2.6) 1.2 (0.6–3.1)0.003 D
1 day after 1.1 (0.6–2.8) 1.5 (0.6–2.9) 1.3 (0.5–3.2) 1.4 (0.7–3.7)0.01 A, 0.02 C
at discharge 1.2 (0.6–3.6) 1.6 (0.6–4.2) 1.4 (0.5–3.4) 1.4 (0.6–4.0)0.007 A, 0.02 C
at last follow-up 1.2 (0.6–2.9) 1.5 (0.5–4.2) 1.2 (0.5–2.8) 1.5 (0.8–3.7)0.012 A, 0.006 C, 0.018 D
time to last follow-up, months 6.2 (0.03–27) 6.0 (0.03–24) 2.3 (0.03–18) 3.2 (0.03–18)<0.001 B, 0.02 C, 0.005 D
% increase at last follow-up 11.4 (0–50)16.3 (0–50)22.9 (0–100)31 (0–170)0.002 C
Subgroup (creatinine, mg/dL)C1 (<1.5)C2 (≥1.5)D1 (<1.5)D2 (≥1.5) 
No. of patients60 1493 12NA
Mean (range):
WI time, min22 (4–29)23 (10–29)37 (30–55)38 (31–52)<0.001 B,C,D,E
age, years62 (23–86)70 (50–87)60 (30–86)66 (41–82)0.005 D
Serum creatinine, mg/dL
before LPN‡ 0.9 (0.6–1.4) 2.0 (1.5–3.4) 1.0 (0.4–1.4) 1.9 (1.5–3.1)<0.001 A,C,D,F
1 day after 1.1 (0.6–2.4) 1.9 (1.2–2.9) 1.2 (0.5–2.5) 2.0 (0.7–3.7)<0.001 A,C,D,F
at discharge 1.1 (0.6–3.6) 2.1 (0.9–4.2) 1.2 (0.5–3.4) 2.2 (0.6–4.0)<0.001, A,C,D,F
at last follow-up 1.1 (0.5–1.9) 2.3 (1.4–4.2) 1.2 (0.5–3.3) 2.1 (1.5–3.7)<0.001, A,C,D,F
time to last follow-up, months 6.0 (0.03–27) 6.6 (0.03–20) 2.5 (0.03–18) 3.4 (0.03–12)0.003 B
% increase at last follow-up 13 (0–50) 14.1 (0–44.4)26.9 (0–170) 14.1 (0–62.5)0.013 B
No. patients requiring dialysis 0  1 0 0NA

Both groups with a higher baseline serum creatinine (Groups C2 and D2) had a significantly higher serum creatinine level than the groups C1 and D1 (normal baseline creatinine) at each time assessed. However, there was no difference in serum creatinine between groups C2 and D2 1 day after LPN, at discharge or at the latest follow-up (Table 4).

On logistic linear regression analysis, only the baseline serum creatinine and solitary kidney status were predictive of serum creatinine levels after LPN (Table 5). A high baseline serum creatinine was predictive of creatinine at 1 day after LPN, at discharge and at the last follow-up (all P < 0.001; Table 5). Although solitary kidney status correlated with maximum serum creatinine (P < 0.001), it did not correlate with serum creatinine at the last follow-up. All other evaluated factors did not correlate with postoperative serum creatinine levels at any time (Table 5).

Table 5.  Factors affecting serum creatinine: multivariate analysis
FactorP for serum creatinine
1 day after LPNat dischargeMaximum increaseLatest% increase at last follow-up
  • *

    statistically significant.

WI0.510.560.050.070.06
Age0.390.760.460.090.30
Serum creatinine before LPN<0.001*<0.001*0.89<0.001*0.02
Solitary kidney status0.670.90<0.001*0.830.74
Presence of calyceal entry0.470.850.940.370.46
Tumour size0.380.890.10.490.48
Intraoperative
urine output0.160.430.890.190.59
intravenous fluids0.500.080.160.02*0.23

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 gaining popularity as a viable minimally invasive treatment option for selected patients with a renal tumour [1–3]. We attempted to simulate the time-tested surgical principles of open PN in our technique of LPN [1,4], central to which is the routine clamping of the renal artery and vein. The near-bloodless field with clear visibility offered by renal hilar clamping provides an optimal surgical environment for precise tumour excision, watertight suture repair of the pelvicalyceal system, and haemostatic suture repair of the soft unperfused renal parenchyma. Obviously, renal hilar control is of even greater significance for excising larger central tumours abutting or infiltrating the renal sinus. However, clamping the renal hilum is associated with the potential for ischaemic renal damage; it is therefore important to evaluate the impact of WI on renal function.

Canine studies show that recovery of the unprotected kidney depends on the period of WI [5,6]. Recovery of renal function is complete within minutes after 10 min of WI, complete within hours after 20 min, complete within 3–9 days after 30 min, usually complete within weeks after 60 min, and incomplete (30–50%) after 120 min [5,6]. As such, current clinical practice is to limit the WI time to ≈ 30 min. At our institute, renal hypothermia is necessary infrequently, in only ≈ 5% of patients, even during open PN [4].

The mean (range) WI time in the present study was 31 (4–55) min; the data show the technical feasibility of reliably performing all the critical steps of precise tumour excision and haemostatic renal reconstruction in a time-sensitive fashion, using a purely laparoscopic technique. In our recent comparison of open and LPN in 200 patients [4], the mean WI time was significantly longer in the laparoscopic than in the open group (28 vs 18 min, P < 0.001) but the median serum creatinine before (both 1.0 mg/dL) and after surgery (1.0 vs 1.1 mg/dL) was similar in the two groups.

Measuring serum creatinine in patients with a solitary kidney provides an accurate assessment of postoperative renal function in the clinical setting. Serial serum creatinine data were analysed in 15 patients undergoing LPN for tumour in a solitary kidney; the mean tumour size was 3.5 cm, WI time 29 min and percentage kidney excised 29%. There was a significant rise in serum creatinine immediately after LPN, reflecting some acute tubular necrosis from the WI, but it reverted to baseline with time. Thus, in these 15 patients, within the confines of the WI (29 min), the nadir serum creatinine was commensurate with the approximate amount of renal parenchyma excised.

The 12 patients assessed by renal scans (Table 2) had a mean 29% reduction in differential renal function (45% before and 32% after LPN), which generally corresponded to the percentage of kidney parenchyma excised (29%).

As expected, in the presence of both functioning kidneys, unilateral LPN did not significantly affect serum creatinine levels. Specifically comparing group 1 and group 2, there was no significant difference in serum creatinine level at any time (Table 3). The significance of these data may be somewhat diminished by the presence of a functioning contralateral kidney, status of hydration, exposure to nephrotoxins and muscle mass.

WI is incrementally deleterious to renal function [5,6]; moreover, these deleterious effects may be compounded by increasing age and high baseline serum creatinine level. As such, we have always tried to minimize the duration of WI during LPN. We interpret the influence of WI stratified by age or baseline serum creatinine (Table 4) as follows. There was no difference in mean serum creatinine at various times after LPN between groups A1 and B1, or between A2 and B2; similarly there was no difference between C1 and D1, and C2 and D2. Taken together, these group comparisons essentially compare patients of similar age (A1 vs B1, A2 vs B2), or similar baseline serum creatinine (C1 vs D1, C2 vs D2), separated by an arbitrary WI threshold of 30 min. Given that most of the WI times were ≈ 30 min, and that 92% of the patients had two functioning kidneys, it is not surprising that there were no significant differences in mean serum creatinine levels. However, there were significant differences in serum creatinine after LPN when comparing the extreme groups, i.e. A1 vs B2 and C1 vs D2. Thus, patients with a WI of <30 min and aged <70 years or a baseline serum creatinine of < 1.5 mg/dL had significantly lower mean serum creatinine levels at all times than had patients with a WI of ≥ 30 min and aged ≥70 years or a baseline serum creatinine of ≥1.5 mg/dL. This rise in serum creatinine was more pronounced soon after LPN and typically tended towards baseline at the subsequent follow-up. More telling is that these differences in serum creatinine were significant despite the presence of a functioning contralateral kidney. We interpret these findings to suggest that prolonged WI is not tolerated well by the compromised kidney. Indeed, had these calculations been for a sufficiently large series of patients with a solitary kidney, or using more sensitive indicators of renal injury, we think it is likely that the differences would have been more significant.

Logistic linear regression analysis showed that only the baseline serum creatinine level was predictive of a high level after LPN. Solitary kidney status was predictive of a higher maximum recorded serum creatinine, but not of serum creatinine at the last follow-up. All other factors did not correlate significantly with postoperative serum creatinine.

In selected patients in whom an extended period of renal hilar clamping is anticipated to complete the LPN, renal hypothermia can now be achieved by minimally invasive means. Recently, three different techniques of laparoscopic renal hypothermia were described; surface hypothermia with ice slush [7], retrograde cooling of the collecting system with cold perfusion [8], and intra-arterial cooling through a percutaneously placed angiocatheter [9]. In these limited initial clinical experiences described, the core renal temperatures achieved by these various techniques were as follows 5–19 °C (surface-contact ice-slush), 24 °C (transureteric cold perfusion) and 25 °C (intra-arterial). Further refinement of and experience with these techniques is necessary before wider clinical use.

Renal hilar clamping during LPN is not used universally; recently, Guillonneau et al.[10] retrospectively compared LPN with (12 patients) or without (16) renal hilar clamping. The tumours were larger in the first group (1.9 vs 2.5 cm). LPN with no renal hilar clamping was associated with a significantly greater blood loss (708 vs 270 mL, P = 0.014), and longer surgery (179 vs 121 min, P = 0.004) than with renal hilar control. There was no significant difference in postoperative serum creatinine level (1.3 vs 1.45 mg/dL, P = 0.075) between the groups.

The drawbacks of the present study include its retrospective design; there were also relatively few patients with a solitary kidney or with renal scan data before and after LPN. Although the amount of parenchyma excised was determined prospectively by consensus among the surgeons during LPN, it remains inherently a subjective estimate. Finally, serum creatinine is a relatively less sensitive indicator of renal functional compromise. Future studies should include creatinine clearance data accrued prospectively.

In conclusion, a substantive LPN typically requires renal hilar control; its many technical advantages notwithstanding, renal hilar clamping causes some WI. In patients with a solitary kidney, within the confines of the present WI, there was no significant renal damage and the nadir serum creatinine after surgery appeared commensurate with the approximate amount of kidney parenchyma excised. These findings were objectively corroborated by differential renal function on MAG3 scans before and 1 month after LPN. The present data suggest that the clinical sequelae of WI injury of ≈ 30 min are minimal. Advancing age and pre-existing renal insufficiency appear to be associated with greater ischaemic renal dysfunction, especially when the duration of WI is > 30 min.

CONFLICT OF INTEREST

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

Inderbir Gill is a speaker for Pfizer and an investigator for Baxter.

REFERENCES

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