61 148
whom had a solitary kidney. With mean eGFRs of 89 ml/
min/1.73m
2
and 86 ml/min/1.73m
2
in the placebo and
treatment arms, respectively, both cohorts were at low
baseline risk for significant deterioration in postoperative
renal function. This may obscure any potential benefit of
mannitol that could have been realized in patients with a
solitary kidney or preoperative CKD. Also of note, no patient
received intraoperative furosemide. This deserves mention
as there is evidence that mannitol may actually worsen
eGFR through increased renal oxygen consumption unless
given concurrently with furosemide
[10].
We therefore question if the data is enough to discourage
the use of routine mannitol administration. We believe
these results should encourage us to consider what is
perhaps a more timely question of whether transient renal
ischemia remains a relevant concern for patients with
normal preoperative renal function in the modern-day era
of PN, where clamp times are generally less than 30 min. In
the present study, it should be noted for both treatment and
placebo groups that a mean clamp time of 27 min translated
to absolute reductions in filtration that averaged less than
10 ml/min/1.73 m
2
at 6 mo with corresponding mean
endpoint eGFRs of 80 ml/min/1.73 m
2
and 78 ml/min/
1.73m
2
, respectively
—
values well away from critical states
of renal insufficiency. Therefore, a criticism of this trial
relates to the potential for selection bias where enrolled
patients may have possessed an inherent resilience to
treatment effect. As such, it remains unknown whether
mannitol can be beneficial for cohorts with more tenuous
renal function.
The premise behind nephron-sparing surgery is to
mitigate risk of progression to advanced stages of CKD. The
high-quality evidence presented here enables us to
confidently abandon the empirical administration of
mannitol during elective PN in patients with normal
preoperative renal function, as its use offered no benefit to
postoperative renal function following PN with hilar
vascular occlusion. However, several important questions
remain: might mannitol confer benefit for patients with
higher risk of postoperative renal injury, namely
those with lower preoperative eGFR, larger tumors, or
solitary kidneys? Could a different dosing regimen, or
coadministration with furosemide, potentially show a
benefit? Proponents of mannitol, noting its relative
inexpense, may cite these gaps in knowledge to justify
its continued use until further prospective studies can
better arbitrate this debate.
Conflicts of interest:
All authors certify that they have no con
fl
icts of
interest to disclose.
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