Volume 19 Supplement 1

35th International Symposium on Intensive Care and Emergency Medicine

Open Access

Continuous infusion of low-dose iohexol confirms 1-hour creatinine clearance is more accurate in acute kidney injury than 4-hour creatinine clearance: preliminary data

  • J Dixon1,
  • K Lane1,
  • R Dalton2,
  • I MacPhee1 and
  • B Philips1
Critical Care201519(Suppl 1):P292

https://doi.org/10.1186/cc14372

Published: 16 March 2015

Introduction

There is currently no accurate method of measuring the glomerular filtration rate (GFR) during acute kidney injury (AKI). Four-hour creatinine clearance (4-CrCl) is often used. We have previously validated a method of measuring the GFR using a continuous infusion of low-dose iohexol (CILDI) in patients with stable renal function (GFR from normal to <30 ml/minute/1.73 m2). Steady state was achieved in <10 hours in all subjects and we calculate that variations >10.3% suggest an AKI. In this study we compare GFR measured by CILDI with 4-CrCl and 1-hour creatinine clearance (1-CrCl).

Methods

Critically ill patients with evolving AKI and patients following nephrectomy were recruited. Demographics were compared using the t test. CIDLI was connected for up to 72 hours. Plasma and renal iohexol and creatinine concentrations were measured by tandem mass spectrometry four times daily. Iohexol renal clearance (IRC) and 1-CrCl and 4-CrCl were calculated and compared using Bland-Altman analysis.

Results

Baseline estimated GFR was similar in the postnephrectomy (88 ± 28) to the evolving AKI group (92 ± 23), P = 0.70. The evolving AKI group had a higher APACHE score (17.8 ± 5.1 vs. 10.6 ± 3.9; P < 0.001). When 1-CrCl was compared with IRC, a bias of 0.8% (SD 26%, limits of agreement -52 to 50%; Pearson's r = 0.90) was observed in the evolving AKI group, whereas bias was -3.3% (SD 16, limits of agreement -35 to 29%; Pearson's r = 0.95) in the postnephrectomy group. When 4-CrCl was compared with IRC, bias was 5.1% (SD 54, limits of agreement -102 to 112%, Pearson's r = 0.45) in the established AKI group and bias was -4.5% (SD 38, limits of agreement -79 to 70%; Pearson's r = 0.78) in the postnephrectomy group.

Conclusion

Our data suggest that 4-CrCl is not as accurate and precise as 1-CrCl in patients with AKI and following nephrectomy. IRC appears to be more accurate and precise in patients with a predicted AKI risk and outcome (post nephrectomy) than in patients with evolving AKI. We hypothesise that IRC will be useful alternative to creatinine-based measures of AKI.

Authors’ Affiliations

(1)
St George's Hospital and University of London
(2)
King's College

Copyright

© Dixon et al.; licensee BioMed Central Ltd. 2015

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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