Contrast-Induced Acute Kidney Injury: Specialty-Specific Protocols for Interventional Radiology, Diagnostic Computed Tomography Radiology, and Interventional Cardiology
2009; Elsevier BV; Volume: 84; Issue: 2 Linguagem: Inglês
10.4065/84.2.170
ISSN1942-5546
AutoresStanley Goldfarb, Peter A. McCullough, John McDermott, Spencer B. Gay,
Tópico(s)Traumatic Brain Injury and Neurovascular Disturbances
ResumoContrast-induced acute kidney injury (AKI) (also known as contrast-induced nephropathy) is an abrupt deterioration in renal function that can be associated with use of iodinated contrast medium. Although the increase in serum creatinine concentration is transient in most cases, contrast-induced AKI may lead to increased morbidity and mortality rates in selected at-risk populations. This review summarizes the findings of a multidisciplinary panel composed of computed tomography radiologists, interventional radiologists, cardiologists, and nephrologists convened to address the specialty-specific issues associated with minimizing the incidence of contrast-induced AKI. As part of this initiative, the panel developed specialty-specific protocols for preventing contrast-induced AKI, taking into account, for example, the variations in patient risk profile, inpatient or outpatient status, and staffing resources that characterize various clinical settings. The 3 protocols, each reflecting a consensus of expert opinion, address the prevention of contrast-induced AKI in interventional radiology, diagnostic computed tomography radiology, and interventional cardiology settings. The protocols are presented in the context of a review of recent guidelines and published reports of trials that discuss contrast-induced AKI and its prevention. The panel reviewed materials retrieved by a PubMed search covering the period January 1990 through January 2008 and used combinations of key words associated with the prevention and treatment of contrast-induced AKI. In addition, the panel reviewed the reference lists of selected articles and the tables of contents posted on the Web sites of selected journals for relevant publications not retrieved in the PubMed searches. Contrast-induced acute kidney injury (AKI) (also known as contrast-induced nephropathy) is an abrupt deterioration in renal function that can be associated with use of iodinated contrast medium. Although the increase in serum creatinine concentration is transient in most cases, contrast-induced AKI may lead to increased morbidity and mortality rates in selected at-risk populations. This review summarizes the findings of a multidisciplinary panel composed of computed tomography radiologists, interventional radiologists, cardiologists, and nephrologists convened to address the specialty-specific issues associated with minimizing the incidence of contrast-induced AKI. As part of this initiative, the panel developed specialty-specific protocols for preventing contrast-induced AKI, taking into account, for example, the variations in patient risk profile, inpatient or outpatient status, and staffing resources that characterize various clinical settings. The 3 protocols, each reflecting a consensus of expert opinion, address the prevention of contrast-induced AKI in interventional radiology, diagnostic computed tomography radiology, and interventional cardiology settings. The protocols are presented in the context of a review of recent guidelines and published reports of trials that discuss contrast-induced AKI and its prevention. The panel reviewed materials retrieved by a PubMed search covering the period January 1990 through January 2008 and used combinations of key words associated with the prevention and treatment of contrast-induced AKI. In addition, the panel reviewed the reference lists of selected articles and the tables of contents posted on the Web sites of selected journals for relevant publications not retrieved in the PubMed searches. Acute kidney injury (AKI) is a heterogeneous disorder with multiple etiologies, risk factors, and clinical presentations. Although patients with AKI are ultimately cared for by nephrologists, AKI occurs in various clinical settings and is associated with a specific etiology in each. The term contrast-induced AKI refers to the disorder as it occurs after exposure to iodinated contrast media, a disorder that has been more commonly known as contrast-induced nephropathy (CIN). The Acute Kidney Injury Network, recognizing the need for improving outcomes associated with the various forms of AKI, recently proposed using the following standardized diagnostic definition in all cases: an abrupt (within 48 hours) reduction in kidney function, evidenced by an increase in the serum creatinine concentration of at least 0.3 mg/dL (to convert to μmol/L, multiply by 88.4) or at least 50% from baseline or a reduction in urine output (documented oliguria of 6 hours).1Mehta RL Kellum JA Shah SV et al.Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury.Crit Care. 2007; 11: R31Crossref PubMed Scopus (5228) Google Scholar, 2Molitoris BA Levin A Warnock DG Acute Kidney Injury Network Working Group et al.Improving outcomes of acute kidney injury: report of an initiative.Nat Clin Pract Nephrol. 2007; 3: 439-442Crossref PubMed Scopus (124) Google Scholar The criterion of oliguria does not apply for many cases of contrast-induced AKI because patients are treated with intravenous fluids before and after the procedure with the goal of increasing periprocedural urine output. The most commonly used definition of CIN is an increase from the baseline serum creatinine concentration of at least 0.5 mg/dL or at least 25% within 48 to 72 hours after exposure to contrast media.3Morcos SK Contrast medium-induced nephrotoxicity.in: Dawson P Cosgrove DO Grainger RG Textbook of Contrast Media. Isis Medical Media Ltd, Oxford, England1999: 135-148Google Scholar, 4Nikolsky E Aymong ED Dangas G Mehran R Radiocontrast nephropathy: identifying the high-risk patient and the implications of exacerbating renal function.Rev Cardiovasc Med. 2003; 4: S7-S14PubMed Google Scholar, 5McCullough PA Adam A Becker CR CIN Consensus Working Panel et al.Epidemiology and prognostic implications of contrast-induced nephropathy.Am J Cardiol. 2006 Sep 16; 98 (Epub 2006 Feb 10.): 5K-13KAbstract Full Text Full Text PDF PubMed Scopus (352) Google Scholar Because the medical community is moving to adopt the concept and terminology of the American College of Radiology (ACR) in reference to studies of contrast-induced renal dysfunction and its prevention,6McCullough PA Multimodality prevention of contrast-induced acute kidney injury.Am J Kidney Dis. 2008; 51: 169-172Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar this report will do the same. However, we recognize that the clinical effect of the slightly different definitions of CIN and AKI has yet to be clarified. The incidence of contrast-induced AKI is low (2%) in the general population,4Nikolsky E Aymong ED Dangas G Mehran R Radiocontrast nephropathy: identifying the high-risk patient and the implications of exacerbating renal function.Rev Cardiovasc Med. 2003; 4: S7-S14PubMed Google Scholar but it is higher in certain at-risk groups of patients. Patients who have both chronic kidney disease (CKD) (defined as an estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m2)7Brosius III, FC Hostetter TH Kelepouris E et al.Detection of chronic kidney disease in patients with or at increased risk of cardiovascular disease: a science advisory from the American Heart Association Kidney and Cardiovascular Disease Council; the Councils on High Blood Pressure Research, Cardiovascular Disease in the Young, and Epidemiology and Prevention; and the Quality of Care and Outcomes Research Interdisciplinary Working Group developed in collaboration with the National Kidney Foundation.Circulation. 2006 Sep 5; 114 (Epub 2006 Aug 7.): 1083-1087Crossref PubMed Scopus (262) Google Scholar and diabetes mellitus are at highest risk8Rudnick MR Goldfarb S Wexler L Iohexol Cooperative Study et al.Nephrotoxicity of ionic and nonionic contrast media in 1196 patients: a randomized trial.Kidney Int. 1995; 47: 254-261Crossref PubMed Scopus (854) Google Scholar, 9Rihal CS Textor SC Grill DE et al.Incidence and prognostic importance of acute renal failure after percutaneous coronary intervention.Circulation. 2002; 105: 2259-2264Crossref PubMed Scopus (1456) Google Scholar, 10McCullough PA Adam A Becker CR CIN Consensus Working Panel et al.Risk prediction of contrast-induced nephropathy.Am J Cardiol. 2006 Sep 18; 98 (Epub 2006 Feb 23.): 27K-36KAbstract Full Text Full Text PDF PubMed Scopus (327) Google Scholar; the incidence of contrast-induced AKI is as high as 50% for patients with multiple risk factors.11Manske CL Sprafka JM Strony JT Wang Y Contrast nephropathy in azotemic diabetic patients undergoing coronary angiography.Am J Med. 1990; 89: 615-620Abstract Full Text PDF PubMed Scopus (468) Google Scholar Contrast-induced AKI has serious prognostic implications; it is linked to increases in length of hospital stay and to higher rates of in-hospital cardiovascular events, in-hospital mortality, and 1-year and 5-year mortality rates.5McCullough PA Adam A Becker CR CIN Consensus Working Panel et al.Epidemiology and prognostic implications of contrast-induced nephropathy.Am J Cardiol. 2006 Sep 16; 98 (Epub 2006 Feb 10.): 5K-13KAbstract Full Text Full Text PDF PubMed Scopus (352) Google Scholar, 9Rihal CS Textor SC Grill DE et al.Incidence and prognostic importance of acute renal failure after percutaneous coronary intervention.Circulation. 2002; 105: 2259-2264Crossref PubMed Scopus (1456) Google Scholar, 12McCullough PA Wolyn R Rocher LL Levin RN O'Neill WW Acute renal failure after coronary intervention: incidence, risk factors, and relationship to mortality.Am J Med. 1997; 103: 368-375Abstract Full Text Full Text PDF PubMed Scopus (1471) Google Scholar, 13Gruberg L Mintz GS Mehran R et al.The prognostic implications of further renal function deterioration within 48 h of interventional coronary procedures in patients with pre-existent chronic renal insufficiency.J Am Coll Cardiol. 2000; 36: 1542-1548Abstract Full Text Full Text PDF PubMed Scopus (659) Google Scholar, 14Weisbord SD Chen H Stone RA et al.Associations of increases in serum creatinine with mortality and length of hospital stay after coronary angiography.J Am Soc Nephrol. 2006 Oct; 17 (Epub 2006 Aug 23.): 2871-2877Crossref PubMed Scopus (192) Google Scholar Even relatively small changes in renal function after administration of contrast medium are associated with substantial increases in mortality rates14Weisbord SD Chen H Stone RA et al.Associations of increases in serum creatinine with mortality and length of hospital stay after coronary angiography.J Am Soc Nephrol. 2006 Oct; 17 (Epub 2006 Aug 23.): 2871-2877Crossref PubMed Scopus (192) Google Scholar; this finding suggests that renal insufficiency is a sensitive marker of poor outcomes for patients at risk or perhaps that transient episodes of renal ischemia may produce secondary hemodynamic or vascular changes in other organs.15Hassoun HT Grigoryev DN Lie ML et al.Ischemic acute kidney injury induces a distant organ functional and genomic response distinguishable from bilateral nephrectomy.Am J Physiol Renal Physiol. 2007 Jul; 293 (Epub 2007 Feb 27.): F30-F40Crossref PubMed Scopus (171) Google Scholar The materials cited in this review include recent guidelines and published reports of clinical trials of contrast-induced AKI and its prevention. These materials were retrieved by a PubMed search covering the period January 1990 through January 2008. The search used combinations of the following key words: contrast agent, nephrotoxicity, hydration, N-acetylcysteine, sodium bicarbonate nephropathy, and acute kidney injury. In addition, we reviewed the reference lists of published articles and the tables of contents posted on the Web sites of selected journals for relevant publications not retrieved by the PubMed search. Several official organizations representing the disciplines of cardiology, nephrology, and radiology have recognized the importance of addressing the management of contrast-induced renal complications in their formal practice guidelines. The extent to which preventive measures for contrast-induced AKI are addressed varies across guidelines. The most recent American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for the management of patients with unstable angina or non-ST elevation myocardial infarction and for percutaneous coronary intervention (PCI) highlight the importance of using iso-osmolar contrast media as a preventive measure for patients with CKD who require coronary intervention: “In chronic kidney disease patients undergoing angiography, isosmolar contrast agents are indicated and are preferred.”16King III, SB Smith Jr, SC Hirshfeld Jr, JW et al.2007 focused update of the ACC/AHA/SCAI 2005 guideline update for percutaneous coronary intervention: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines: 2007 Writing Group to Review New Evidence and Update the ACC/AHA/SCAI 2005 Guideline Update for Percutaneous Coronary Intervention, Writing on Behalf of the 2005 Writing Committee [published correction appears in Circulation. 2008;117 (6):e161].Circulation. 2008 Jan 15; 117 (Epub 2007 Dec 13.): 261-295Crossref PubMed Scopus (626) Google Scholar, 17Anderson JL Adams CD Antman EM et al.ACC/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction—executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 2002 Guidelines for the Management of Patients With Unstable Angina/Non-ST-Elevation Myocardial Infarction) developed in collaboration with the American College of Emergency Physicians, the Society for Cardiovascular Angiography and Interventions, and the Society of Thoracic Surgeons; endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation and the Society for Academic Emergency Medicine.J Am Coll Cardiol. 2007; 50: 652-726Abstract Full Text Full Text PDF Scopus (240) Google Scholar This is a class I recommendation at level of evidence A and is based on the findings of clinical trials and meta-analyses.18Jo SH Youn TJ Koo BK et al.Renal toxicity evaluation and comparison between visipaque (iodixanol) and hexabrix (ioxaglate) in patients with renal insufficiency undergoing coronary angiography: the RECOVER study: a randomized controlled trial.J Am Coll Cardiol. 2006 Sep 5; 48 (Epub 2006 Aug 17.): 924-930Abstract Full Text Full Text PDF PubMed Scopus (256) Google Scholar, 19McCullough PA Bertrand ME Brinker JA Stacul F A meta-analysis of the renal safety of isosmolar iodixanol compared to low-osmolar contrast media.J Am Coll Cardiol. 2006 Aug 16; 48 (Epub 2006 Jul 24.): 692-699Abstract Full Text Full Text PDF PubMed Scopus (276) Google Scholar The guidelines advise that patients with cardiovascular disease should be screened for CKD according to the AHA/National Kidney Foundation (NKF) recommendations7Brosius III, FC Hostetter TH Kelepouris E et al.Detection of chronic kidney disease in patients with or at increased risk of cardiovascular disease: a science advisory from the American Heart Association Kidney and Cardiovascular Disease Council; the Councils on High Blood Pressure Research, Cardiovascular Disease in the Young, and Epidemiology and Prevention; and the Quality of Care and Outcomes Research Interdisciplinary Working Group developed in collaboration with the National Kidney Foundation.Circulation. 2006 Sep 5; 114 (Epub 2006 Aug 7.): 1083-1087Crossref PubMed Scopus (262) Google Scholar and that use of iso-osmolar contrast media should be guided by the results of such screening. The latest ACR formal practice guidelines for using iodinated contrast media focus on determining which patients have an increased overall risk of adverse effects because such patients are likely to benefit from the use of low-osmolar rather than high-osmolar contrast media.20Segal A Ellis JH Baumgartner BR et al.Manual on Contrast Media: Version 6; 2008. ACR Am Coll Radiol.http://www.acr.org/SecondaryMainMenuCategories/quality_safety/contrast_manual.aspxGoogle Scholar Specific ACR recommendations (as they appear in the updated ACR Manual on Contrast Media) for preventing contrast-induced AKI include the following: initiating intravenous volume expansion with saline both before and after CM administration, administering the antioxidant N-acetylcysteine (NAC) to patients at risk, measuring the serum creatinine concentration of patients with suspected renal dysfunction, and using either low-osmolar or iso-osmolar contrast media for all patients with renal insufficiency.20Segal A Ellis JH Baumgartner BR et al.Manual on Contrast Media: Version 6; 2008. ACR Am Coll Radiol.http://www.acr.org/SecondaryMainMenuCategories/quality_safety/contrast_manual.aspxGoogle Scholar The NKF has issued clinical practice guidelines for evaluating and managing cardiovascular disease in patients undergoing dialysis: use of iso-osmolar contrast media and administration of NAC are appropriate because of their potential benefit in preserving renal function. The NKF guidelines caution against routine use of sodium bicarbonate and volume expansion for these patients.21National Kidney Foundation DOQI K/DOQI clinical practice guidelines for cardiovascular disease in dialysis patients.http://www.kidney.org/professionals/KDOQI/guidelines_cvd/guide2.htmGoogle Scholar The European Society of Urogenital Radiology (ESUR) has issued guidelines for using contrast media. These guidelines incorporate risk factors for CIN, recommendations for identifying patients at risk, and strategies for reducing risk, such as using either low-osmolar or iso-osmolar contrast media, initiating intravenous volume expansion, and discontinuing administration of nephrotoxic drugs.22European Society of Urogenital Radiology ESUR Guidelines on Contrast Media, Version 6.0.http://www.esur.org/ESUR_Guidelines_NEW.6.0.htmlGoogle Scholar The existing guidelines often lack detail and do not cover all aspects of patient management. In particular, they often fail to address specialty-specific issues. Such issues may be associated with variation in risk-benefit ratios across different patient populations or with practical aspects of implementing risk assessment and prophylactic strategies for contrast-induced AKI in certain settings, such as a busy computed tomography (CT) unit with a large number of patients, limited space, and limited nursing resources or an interventional cardiology setting for patients undergoing elective PCI. Specialty-specific technical and procedural factors may also dictate management choices. In studies of peripheral vessels, particularly runoff studies, the choice of contrast media is dictated by patient tolerability because image quality is easily reduced by motion artifacts driven by patient discomfort. Local pain associated with injection of contrast media has been correlated with osmolality.23Holder JC Dalrymple GV Pain and aortofemoral arteriography: the importance of chemical structure and osmolality of contrast agents.Invest Radiol. 1981; 16: 508-512Crossref PubMed Scopus (11) Google Scholar, 24Manke C Marcus C Page A Puey J Batakis O Fog A Pain in femoral arteriography: a double-blind, randomized, clinical study comparing safety and efficacy of the iso-osmolar iodixanol 270 mgI/ml and the low-osmolar iomeprol 300 mgI/ml in 9 European centers.Acta Radiol. 2003; 44: 590-596PubMed Google Scholar Several studies that have compared the tolerability of the iso-osmolar contrast medium iodixanol with that of low-osmolar contrast medium report that iso-osmolar contrast medium is associated with a decrease in the intensity of discomfort (heat sensations) and pain.24Manke C Marcus C Page A Puey J Batakis O Fog A Pain in femoral arteriography: a double-blind, randomized, clinical study comparing safety and efficacy of the iso-osmolar iodixanol 270 mgI/ml and the low-osmolar iomeprol 300 mgI/ml in 9 European centers.Acta Radiol. 2003; 44: 590-596PubMed Google Scholar, 25Kløw NE Levorstad K Berg KJ et al.Iodixanol in cardioangiography in patients with coronary artery disease: tolerability, cardiac and renal effects.Acta Radiol. 1993; 34: 72-77PubMed Google Scholar, 26Tveit K Bolz KD Bolstad B et al.Iodixanol in cardioangiography: a double-blind parallel comparison between iodixanol 320 mg I/ml and ioxaglate 320 mg I/ml.Acta Radiol. 1994; 35: 614-618PubMed Google Scholar, 27Palmers Y De Greef D Grynne BH Smits J Put E A double-blind study comparing safety, tolerability and efficacy of iodixanol 320 mgI/ml and ioxaglate 320 mgI/ml in cerebral arteriography.Eur J Radiol. 1993; 17: 203-209Abstract Full Text PDF PubMed Scopus (27) Google Scholar, 28Pugh ND Sissons GR Ruttley MS Berg KJ Nossen JO Eide H Iodixanol in femoral arteriography (phase III): a comparative double-blind parallel trial between iodixanol and iopromide.Clin Radiol. 1993; 47: 96-99Abstract Full Text PDF PubMed Scopus (2) Google Scholar, 29Verow P Nossen JO Sheppick A Kjaersgaard P A comparison of iodixanol with iopamidol in aorto-femoral angiography.Br J Radiol. 1995; 68: 973-978Crossref PubMed Scopus (36) Google Scholar, 30Justesen P Downes M Grynne BH Lang H Rasch W Seim E Injection-associated pain in femoral arteriography: a European multicenter study comparing safety, tolerability, and efficacy of iodixanol and iopromide.Cardiovasc Intervent Radiol. 1997; 20: 251-256Crossref PubMed Scopus (29) Google Scholar Overall, the key issue that becomes important to define for each specialty is the degree of risk that makes the effort needed to screen patients, identify those at risk, and then implement prevention strategies, a requirement despite any impracticality. Should all patients be screened for CKD, or should screening be reserved for a select group? Routinely performing serum creatinine assays for all patients may be costly, cumbersome, and inconvenient.31Thomsen HS How to avoid CIN: guidelines from the European Society of Urogenital Radiology.Nephrol Dial Transplant. 2005; 20: i18-i22Crossref PubMed Scopus (63) Google Scholar In most cases, the clinical history provides enough information to allow determination of which patients are likely to have CKD and therefore the risk of contrast-induced AKI. In outpatient and emergency settings, a basic questionnaire that addresses the patient's history of renal disorders and additional risk factors may be simpler and more cost-effective than universal serum creatinine screening.31Thomsen HS How to avoid CIN: guidelines from the European Society of Urogenital Radiology.Nephrol Dial Transplant. 2005; 20: i18-i22Crossref PubMed Scopus (63) Google Scholar, 32Choyke PL Cady J DePollar SL Austin H Determination of serum creatinine prior to iodinated contrast media: is it necessary in all patients?.Tech Urol. 1998; 4: 65-69PubMed Google Scholar Another approach, developed and validated for patients undergoing PCI, is to assess a patient's degree of risk by using a scoring system based on risk factors for contrast-induced AKI.33Mehran R Aymong ED Nikolsky E et al.A simple risk score for prediction of contrast-induced nephropathy after percutaneous coronary intervention: development and initial validation.J Am Coll Cardiol. 2004; 44: 1393-1399Abstract Full Text Full Text PDF PubMed Scopus (1864) Google Scholar What measurement should be used? Serum creatinine concentration alone is an insensitive indicator of kidney function. The commonly used cutoff, a serum creatinine concentration of 1.5 mg/dL or higher, fails to detect 40% of patients at risk of contrast-induced AKI.34Band RA Gaieski DF Mills AM et al.Discordance between serum creatinine and creatinine clearance for identification of ED patients with abdominal pain at risk for contrast-induced nephropathy.Am J Emerg Med. 2007; 25: 268-272Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar The GFR is thought to provide the best overall index of renal function, but measuring it may be impractical. Instead, estimates of renal function, either the eGFR or the calculated creatinine clearance (CrCl) rate, are determined by empirically derived formulas based on the serum creatinine concentration. The eGFR is calculated by using the Modification of Diet in Renal Disease (MDRD) formula; the CrCl rate, by using the Cockcroft-Gault formula.35Levey AS Bosch JP Lewis JB Greene T Rogers N Roth D Modification of Diet in Renal Disease Study Group A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation.Ann Intern Med. 1999; 130: 461-470Crossref PubMed Scopus (13009) Google Scholar, 36Lameire N Adam A Becker CR CIN Consensus Working Panel et al.Baseline renal function screening.Am J Cardiol. 2006 Sep 18; 98 (Epub 2006 Feb 20.): 21K-26KAbstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar Although both methods have limitations,37Froissart M Rossert J Jacquot C Paillard M Houillier P Predictive performance of the modification of diet in renal disease and Cockcroft-Gault equations for estimating renal function.J Am Soc Nephrol. 2005 Mar; 16 (Epub 2005 Jan 19.): 763-773Crossref PubMed Scopus (705) Google Scholar estimating the GFR from the serum creatinine concentration is recommended because it provides a more sensitive and specific measure of renal function than does the serum creatinine concentration alone. The 4-variable MDRD formula, which uses the serum creatinine concentration and the patient's age, with adjustments for sex and race, is preferable to the Cockcroft-Gault formula,37Froissart M Rossert J Jacquot C Paillard M Houillier P Predictive performance of the modification of diet in renal disease and Cockcroft-Gault equations for estimating renal function.J Am Soc Nephrol. 2005 Mar; 16 (Epub 2005 Jan 19.): 763-773Crossref PubMed Scopus (705) Google Scholar particularly for patients with diabetes.38Rigalleau V Lasseur C Perlemoine C et al.Estimation of glomerular filtration rate in diabetic subjects: Cockcroft formula or Modification of Diet in Renal Disease study equation?.Diabetes Care. 2005; 28: 838-843Crossref PubMed Scopus (179) Google Scholar, 39Beauvieux MC Le Moigne F Lasseur C et al.New predictive equations improve monitoring of kidney function in patients with diabetes.Diabetes Care. 2007 Aug; 30 (Epub 2007 May 29.): 1988-1994Crossref PubMed Scopus (59) Google Scholar Should the eGFR be assessed immediately before the procedure? If not, how recent should the assessment be? For many inpatients, a current serum creatinine measurement should be available. In outpatient settings, should the referring physician be expected to provide results of a recent assay? For high-risk patients, should the procedure be deferred until results of a recent assessment of kidney function are available? Point-of-care testing, which can provide the serum creatinine concentration within minutes, is likely to be useful in such situations.40Firestone D Wos A Killeen JP et al.Can urine dipstick be used as a surrogate for serum creatinine in emergency department patients who undergo contrast studies?.J Emerg Med. 2007 Aug; 33 (Epub 2007 Jun 13.): 119-122Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar With regard to timing the serum creatinine assay, it is important to establish the baseline serum creatinine concentration before intravenous volume expansion is initiated (discussed subsequently). Otherwise, estimates of renal function may be misleading because of the decrease in the serum creatinine concentration that is induced by increased extracellular fluid volume. In an emergency situation, the importance of a procedure using contrast medium and the risk of delaying that procedure must be balanced against the risk of kidney injury. Because specialties that use contrast-enhanced procedures differ in the extent to which inpatient or outpatient populations and emergency or nonemergency procedures are represented, the issues raised by the preceding questions are probably best addressed by specialty-specific, rather than general, protocols. The risk of contrast-induced AKI is considered increased and clinically important when the eGFR is lower than 60 mL/min/1.73 m2.36Lameire N Adam A Becker CR CIN Consensus Working Panel et al.Baseline renal function screening.Am J Cardiol. 2006 Sep 18; 98 (Epub 2006 Feb 20.): 21K-26KAbstract Full Text Full Text PDF PubMed Scopus (100) Google Scholar However, this threshold probably includes too many patients to allow a focus on those who are truly at high risk. For example, patients with an eGFR of 30 mL/min/1.73 m2 have a 30% to 40% risk of contrast-induced AKI and a 2% to 8% risk of requiring dialysis.41McCullough PA Sandberg KR Epidemiology of contrast-induced nephropathy.Rev Cardiovasc Med. 2003; 4: S3-S9Google Scholar Furthermore, because an eGFR cutoff of less than 60 mL/min/1.73 m2 places a large number of patients in the at-risk group, the practicality and implementation of guidelines may be reduced. Also, a moderate reduction in eGFR is common among elderly patients, for whom eGFR levels of 50 to 59 mL/min/1.73 m2 may not have the same clinical importance as similar values in younger patients with underlying specific forms of CKD.42O'Hare AM Bertenthal D Covinsky KE et al.Mortality risk stratification in chronic kidney disease: one size for all ages?.J Am Soc Nephrol. 2006 Mar; 17 (Epub 2006 Feb 1.): 846-853Crossref PubMed Scopus (318) Google Scholar Therefore, using a lower eGFR threshold (<30, 45, or 50 mL/min/1.73 m2) to define contrast-induced AKI risk may be more appropriate in some situations. Volume Expansion. Extracellular volume expansion plays a well-established role in reducing the risk of contrast-induced AKI, although few trials have directly addressed the ideal protocol.43Stacul F Adam A Becker C CIN Consensus Working Panel et al.Strategies to reduce the risk of contrast-induced nephrop
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