Much has been written about radiocontrast induced nephropathy and
the appropriate measures to avoid it. As far as I am informed the latest
evidence underscores the importance of hydration, questions the value of
calcium antagonists and even discourages the use of mannitol or furosemide.
Since the consequence of suboptimal treatment before, during and after
angiography in the worst case may be a permanent need of dialysis, a
practice of prophylactic dialysis immediately after the angiographic
procedure has evolved in many centers. This has now reached the point where
angiologists prescribe dialysis "just in case".
I have been unable to find any good studies in the area. Therefore I have
some questions:
1) Diabetics with decreased renal function are one group of patients
especially prone to develop problems. Is there any level of renal function,
in diabetics or other high risk patients, below which one can safely abstain
from dialysis, provided that adequate measures have otherwise been taken?
2) Is there any amount of contrast media (for example measured in grams of
iodine), below which one can safely say that the risk is minimal?
3) Is there any information regarding within what time span after the
angiographic procedure one needs to dialyse? Intuitively my feeling is that
the optimal management would be simultaneous dialysis and angiography!
4) If you do dialyse - how effective does that dialysis has to be in order
to work? Is it enough with a standard procedure, i.e., one treatment
corresponding to a Kt/V (urea) of more than 1.2?
Karl G. Prütz, MD (Department of Medicine, Helsingborg, Sweden)
Response by George R. Aronoff, M.D., University of Louisville, KY
Although much has been written about contrast induced
acute renal failure, questions remain about its pathogenesis
and treatment. The absence of reliable animal models that
closely parallel the human response to contrast dye and the
relative infrequency of the syndrome limit our ability to
definitively answer many of these questions. Studies of the
time honored use of intravenous hydration, loop diuretics,
and mannitol are conflicting. Estimates of the incidence of
contrast induced renal insufficiency vary widely.
Consequently, we are faced with making clinical decisions
based on few randomized, controlled clinical trials and
weighing the probability of an adverse effect of the contrast
and the risk and cost of preventive measures. Excellent
reviews of these issues summarize the available information.
(1-3)
There are no data to support the use of dialysis in preventing
contrast induced renal injury. In fact, one randomized study
published as an abstract, showed no effect of prophylactic
hemodialysis in patients with chronic renal failure receiving
low osmolality contrast.(4) Since no benefit of prophylactic
dialysis has been demonstrated, the risks of temporary
access, anticoagulation, and the dialysis procedure
obviously outweigh the benefit.
References
1. Barrett BJ. Contrast nephrotoxicity. J Am Soc Nephrol
1994;5:125-136.
2. Idee JM, Beaufils H, Bonnemain B. Iodinated contrast
media-induced nephropathy: pathophysiology, clinical
aspects and prevention. Fundam Clin Pharmacol
1994;8:193-206.
3. Solomon R, Werner C, Mann D, et al. Effects of saline,
mannitol, and furosemide on acute decreases in renal
function induced by radiocontrast agents. N Engl J Med
1994;331:1416-1420.
4. Lehnert T, Gondolf K, Schaffner T, et al. Effect of
hemodialysis after contrast media application in adults with
renal insufficiency. J Am Soc Nephrol 1995;6:469.
(July, 1996)
There is at least one study on radiocontrast clearance
during hemodialysis:
Moon SS; Bäck SE; Kurkus J; Nilsson-Ehle P. Hemodialysis for
elimination of the nonionic contrast medium iohexol after
angiography in patients with impaired renal function.
Nephron, 70: 4, 1995, 430-7. The study shows that elimination
occurs (clearance about 70 ml/min). The authors suggest
clinical benefit from the procedure.
Karl G Prütz (kg.prutz@helsingborg.se)
Helsingborg, Sweden-Tuesday, August 06, 1996 at 11:20:47 (CDT)