Acute renal failure
BMJ 2006; 333 doi: https://doi.org/10.1136/bmj.38975.657639.AE (Published 12 October 2006) Cite this as: BMJ 2006;333:786
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We read with interest the clinical review[1] by Dr Hilton regarding
acute renal failure (ARF) in particular her references to the frequency of
and outcomes from acute renal failure[2,3]. We note that the Acute
Dialysis Quality Initiative (ADQI) group’s RIFLE classification is alluded
to[3]; however we feel the text would have benefited from a clear
description of this now validated classification of ARF as the myriad of
definitions using different criteria complicates understanding and
comparison of interventions and management strategies.
The ADQI group first published this consensus definition of renal
failure in 2004[4]. The use of criteria called RIFLE (Risk, Injury,
Failure, Loss, End-Stage) classifies changes in creatinine and/ or
glomerular filtration rate and urine output. Since its development it has
been validated in more than 20,000 patients seen at a large tertiary
centre, including 6,000 readmissions[5]. Hospital mortality increased
almost linearly through the Risk-Injury-Failure-End stage continuum.
It therefore seems appropriate to use the RIFLE criteria as a
standard definition for renal failure allowing for improved comparisons of
different patient groups around the world, and better assessment of the
management approach and therapies that Hilton describes1.
References
1. Acute Renal Failure. Hilton R. BMJ. 2006; 333: 786-90.
2. Feest TG, Round A, Hamad S. Incidence of severe acute renal
failure in adults: results of a community based study. BMJ 1993; 306: 481
-3.
3. Abosaif NY, Tolba YA, Heap m, Russell J, El Nahas AM. The outcome
of acute renal failure in the intensive care unit according to RIFLE:
model application, sensitivity and predictiability. Am J Kidney Dis 2005;
46: 1038-48.
4. Acute renal failure – definition, outcome measures, animal models,
fluid therapy and information technology needs: the Second International
Consensus Conference of the Acute Dialysis Quality Initiative (ADQI)
Group. Bellomo R, Ronco C, Kellum JA et al. Critical Care; 2004; 8: R202
-R212. Available online at http://ccforum.com/content/8/4/R204
5. An Assessment of the RIFLE Criteria for acute renal failure in
hospitalized patients. Uchino S, Bellomo R, Goldsmith D, et al. Crit Care
Med 2006; 34: 1913-17.
Competing interests:
None declared
Competing interests: No competing interests
We would like to thank the author for an erudite and insightful
review of such an important subject. One of the problems with describing
renal impairment in terms of its histopathology is that the exact nature
of the histological injury may not be evident for some time. In addition
to this, there is genuine debate surrounding the true histopathology of
acute tubular necrosis.
Therefore, we would like to describe and recommend a classification
based on function rather than pathology. The International Consensus
Classification of acute renal failure (ARF) has been produced by the Acute
Dialysis Quality Initiative group (www.ADQI.net). It is known as the
RILFE classification, which is an acronym: (R)isk of renal dysfunction,
(I)njury to the kidney, (F)ailure of kidney function, (L)oss of kidney
function and (E)nd-stage kidney disease.
RIFLE defines three grades of increasing severity of acute kidney
disease, based on changes in either serum creatinine (C) or urine output
(U) from baseline. It also includes two clinical outcomes: loss and end-
stage renal disease.
R = C x 1.5 or U < 0.5ml/kg/h for 6h
I = C x 2 or U < 0.5ml/kg/h for 12h
F = C x 3 or U < 0.3ml/kg/h for 24h or anuria for > 12h
L = persistent ARF, needing Renal Replacement Therapy(RRT) for > 4
weeks
E = needing RRT for > 3 months
A recent publication looked at over 5000 patients in general
intensive care unit beds. The study predictably showed that defined by
the RIFLE classification, the incidence of acute kidney injury is high
(67.2%), and that it is associated with an increased risk of hospital
mortality compared with those who never develop acure kidney injury. Over
50% of patients in class R progressed to more severe RIFLE classes, but
importantly, those who did not were not at risk of increased hospital
mortality.
In conclusion, the RIFLE classification is effective and pragmatic.
We would therefore ask for its use to be strongly considered.
References
1. Wan L, Bellomo R, et al. The pathogenesis of septic acute renal
failure. Current Opinion Critical Care 2003;9(6):496-502.
2. Bellomo R, Ronco C, et al. Acute renal failure – definition,
outcome measures, animal models, fluid therapy and information technology
needs: the Second International Consensus Conference of the Acute Dialysis
Quality Initiative (ADQI) Group. Critical Care 2004;8:R204-R212.
3. Hoste E, Clermont G, et al. RIFLE criteria for acute kidney
injury are associated with hospital mortality in critically ill patients:
a cohort analysis. Critical Care 2006;10:R73.
Competing interests:
None declared
Competing interests: No competing interests
The review by Hilton acknowledges that the immediate care of most
patients with acute renal failure in the UK is provided on Intensive care
units by Intensivists(1). Despite this there is an insufficient emphasis
placed on an effective clinical approach to the intensive care
resuscitation of these patients. In particular the article makes no
mention of ensuring an adequate renal perfusion pressure in patients who
have an elevated intra-abdominal pressure which can often prevent the need
for renal replacement therapy.
If the intra-abdominal pressure is greater
than 20mmHg and associated with organ dysfunction such as oliguria this
condition is known as abdominal compartment syndrome (2). If unrecognised
or untreated a persistently elevated intra-abdominal pressure can result
in acute renal failure. This condition is well recognised by Intensivists
with 76% of Intensive Care Units measuring intra-abdominal pressure via
the intravesical route(3). If abdominal compartment syndrome is developing
acute renal failure can be prevented by continued fluid resuscitation, use
of vasopressors and decompression of the abdomen. Improved recognition of
this condition both by Surgeons and Physicians would benefit patient care.
1. Hilton R. Acute renal failure. British Medical Journal 333; 786-790
2. Sugrue M. Intra-abdominal pressure : time for clinical practice
guidelines. Intensive Care Medicine 2002;28:389-391.
3.Ravishankar N and Hunter J . Measurement of intra-abdominal pressure in
intensive care units in the United Kingdom; a national postal
questionnaire study. British Journal of Anaesthesia 2005; 94 : 763-766
Competing interests:
None declared
Competing interests: No competing interests
This is an excellently written review addressing a commonly seen
problem. It is now increasingly recognised that measures such as
administration of Loop diuretics and Dopamine do not improve outcomes and
may sometimes cause undesirable side effects. Despite this, management of
Acute Renal Failure very often has involved administration of loop
diuretics and Dopamine more by way of tradition and desperation rather
than based on evidence base. The main focus as outlined in this review
should be to optimise fluid balance and hemodynamics while withdrawing
offending drugs and treating infections and obstruction if any. It will be
now useful to develop nationally acceptable and auditable guidelines.
Guidelines when coming from a nationally recognised body will effectively
change practise from convention to that based on evidence.
Competing interests:
None declared
Competing interests: No competing interests
Editor –
Hilton’s review of the management of acute renal failure1 highlights
the key issue of prevention of this common and costly in-hospital
complication particularly since supportive care rather than definitive
treatment is the most commonly available therapeutic strategy.
I propose that the estimated glomerular filtration rate (eGFR) should
be clearly highlighted on all hospital drug charts in the same way that
drug allergies are documented. With the advent of the routine reporting
of the eGFR there is now an opportunity to highlight those at risk of
acute renal failure from an early stage in their admission. High-risk
groups include elderly patients, in whom a normal serum creatinine may
represent significantly impaired renal function, and patients with
established chronic renal failure.
Clear documentation of the eGFR would give medical, nursing and
pharmacy staff every opportunity to avoid prescribing potentially
nephrotoxic drugs to patients with impaired renal function and would also
allow correct and prompt dose adjustment of commonly prescribed drugs such
as anti-biotics.
This would be a cheap and simple method to help reduce the clinical
and cost burden of acute renal failure, a condition in which prevention is
far easier than cure.
Gavin Dreyer
specialist registrar
Department of nephrology,
North Middlesex University Hospital, London, UK
Gavin.Dreyer@nmh.nhs.uk
1. Hilton R. Acute renal failure BMJ 2006 333:786-790 (14 October)
I declare no conflict of interest.
Competing interests:
None declared
Competing interests: No competing interests
Traynor et al (1) are correct in pointing out that approximately 5%
of UK patients have National Kidney Foundation-Kidney Disease Outcomes
Quality Initiative (NKF-K/DOQI) stages 3-5, however, the number of
patients will vary a lot for several reasons. Firstly, the version of the
4-variable Modification of Diet in Renal Disease Study Group (MDRD)
equation employed is very important (2). Secondly, the 4-variable MDRD
equation is far from ideal for several reasons including the fact that the
study contained few patients with NKF-K/DOQI stages 1 and 2 (3) such that
a negative bias of 29% has been reported in healthy persons (4) and that
mathematical issues also exist regarding the derivation of the equation
(5). It is important to realise that the 95% confidence interval for an
estimated glomerular filtration rate (eGFR) of 60 ml/min is ±26 ml/min (6)
and accordingly, repeat measurement is essential for values <60 ml/min.
Finally, while Traynor et al (1) believe that iohexol is a superior
radiocontrast agent the MDRD study employed iothalamate as the reference
method despite the fact that it is positively biased (3 – 5 ml/min at low
levels of GFR and 15 – 25 ml/min in healthy subjects) when compared to
inulin which is seen as the gold standard GFR method (7 – 10). These
issues will play an important part in determining the renal workload of
every UK general practice.
References
1.Traynor J, MactierR, Geddes CC and Fox JG. How to measure renal
function in clinical practice. BMJ 2006; 33: 733-7.
2.Reynolds TM and Twomey PJ. Implications of method specific
creatinine adjustments on GMS chronic kidney disease classification.JCP.
In press.
3.Level AS, Bosch JP, Lewis JB, Greene T, Rogers N, Roth D, for the
MDRD Study Group. A more accurate method to estimate glomerular filtration
rate from serum creatinine: a new prediction equation. Ann Int Med 1999;
130: 461-70
4.Rule AD, Larson TS, Bergstralh EJ, Slezak JM, Jacobsen SJ and Coslo
FG. Using serum creatinine to estimate glomerular filtration rate:
Accuracy in good health and in chronic kidney disease. Ann Intern Med
2004; 141:929-937.
5.Twomey PJ and Reynolds TM. The MDRD formula is not as well-
validated as one would hope for. QJM 2006. In press.
6.Deacon A. Limitations of estimating kidney function in adults using
formulae. Ann Clin Biochem 2006; 43:85.
7.Perrone RD, Steinman TI, Beck GJ et al. Utility of radioisotopic
filtratration markers in chronic renal insufficiency: Simultaneous
comparison of 125I-iothalmate, 169Yb-DTPA, 99mTc-DTPA and inulin. The
Modification of Diet in Renal Disease Study. Am J Kidney Dis 1990;16:224 –
235.
8.Odlind B, Hallgren R, Sohtell M and Lindstrom B: Is 125I-iothalmate
an ideal marker for glomerular filtration? Kidney Int 1985; 27:9 – 16.
9.Back SE, Krutzen E and Nilsson-Ehle P: Contrast media and
glomerular filtration: Dose dependence of clearance for three agents. J
Pharma Sci 1988; 48:765 - 767.
10.Petri M, Bockenstedt L, Colman J et al. Serial assessment of
glomerular filtration rate in lupus nephropathy. Kidney Int 1988; 34:832 –
839.
Competing interests:
None declared
Competing interests: No competing interests
To this well written article we will like to add the following points
1. Causes of Pre Renal Failure can also include pulmonary
hypertension,pulmonary embolus, pancreatitis, peritonitis,and some rare
causes like hyperviscosity syndrome in multiple myeloma and polycythemia
and also in patients on positive pressure mechanical ventilation.
2. Causes of Intrinsic Renal Failure can also include toxemia of
pregnanacy, hemolytic uremia syndrome, renal allograft rejection.
3. Causes of Post Renal Failure can also include neurogenic bladder ,
phimosis, congenital valves.
4. In managing the ARF complicatons in addition to hyperkalemia ,
acidosis , we also have to correct hyponatremia(restriction of water
intake), hyperphosphatemia(restriction of dietary phosphate) ,
hypocalcemia( calcium gluconate, calcium carbonate) ,hypermagnesemia(
disconitue any antacids)and hyperuricemia( allopurinol, forced alkaline
diuresis).
5. In investigations we can also calculate Urine Diagnostic Indices
like ( Fractional Excretion of Sodium(Na), Urine Na concentration, Urine
creatinine to plasma creatinine ratio, Urine speific gravity, Urine
osmolality, Renal failure index, Plasma Blood Urea Nitrogen/ creatinine
ratio) . They can help differentiate between pre-renal and intrinsic renal
failure.
6.Renal Biopsy is indicated when pre-renal and post renal have been
excluded and cause of intrinsic renal failure is other then ischemic or
nephrotoxic injury.
Competing interests:
None declared
Competing interests: No competing interests
Which specialist?
Editor
I urge caution in the apparent suggestion in the review by Hilton (1) that
nephrology represents the only source of a specialist opinion for the
management of acute renal failure (ARF). Different referral
patterns/triage options may be more appropriate in some institutions. In
Northern Ireland, the importance of this was recognised in the Department
of Health (DHSSPSNI) Review of Renal Services (2).
The experience of delayed referral of ARF is not unique to
nephrologists. As Dr Hilton points out, ARF commonly presents in hospital
patients as one of several organ dysfunctions. The appropriate specialists
to look after such patients are those whose training and expertise is in
the management of multiple organ dysfunction ie intensivists. Dr Hilton
recognises the availability of continuous renal replacement equipment in
the ICU setting but apparently not the specialists who manage and
prescribe the therapy in this setting, and who treat the underlying
condition.
Referral of all patients with ARF (rather than those with isolated
ARF) to a nephrologist, may result in delayed appropriate therapy. In my
institution we enjoy collaboration with our sole nephrology colleague in a
fashion analogous to our collaboration with respiratory medicine. The fact
that we manage the acute episode does not preclude involvement of other
specialists at some point subsequently. There is an onus on us to identify
promptly patients who are referred inappropriately to us and whom we
should not manage eg those presenting with vasculitic aetiology or
glomerulonephritis. Perhaps unintentionally, it appears from the review
that Dr Hilton does not recognise the converse situation. This is somewhat
surprising in that the definitive study which she quotes (but does not
reference) demonstrating the lack of value of dopamine in this situation
was carried out by intensivists (3).
1. Hilton R. Acute Renal failure. BMJ 2006;333:786-790. (14 October.)
2. http://www.dhsspsni.gov.uk/renal_chpt7_13.pdf
3. Bellomo R, Chapman M, Finfer S, Hickling K, Myburgh J. Lancet
2000;356(9248):2139-43.
Competing interests:
None declared
Competing interests: No competing interests