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Volume 3 Supplement 1

ESICM LIVES 2015

  • Poster presentation
  • Open Access

Elevation of serum phosphorus, an early biomarker of acute kidney injury after cardiac sugery?

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  • 1
Intensive Care Medicine Experimental20153 (Suppl 1) :A465

https://doi.org/10.1186/2197-425X-3-S1-A465

  • Published:

Keywords

  • Positive Predictive Value
  • Cardiopulmonary Bypass
  • Renal Replacement Therapy
  • Negative Predictive Value
  • Acute Kidney Injury

Introduction

Acute kidney injury (AKI) is common after cardiac surgery and is a strong predictor of morbidity and mortality [1]. Hyperphosphatemia following AKI, by renal excretion defect, has never been studied in this context and could be a simple marker of AKI.

Objectives

The aim of this study was to assess the predictability of serum phosphorus (Ph) for AKI monitoring after cardiac surgery.

Methods

In this retrospective diagnostic validation study of 547 patients admitted in our institute between January 2012 and December 2012, we excluded patients with end stage renal disease (clearance < 15mL / min / 1.73m2) or dialyzed, solitary kidney or nephrectomy, lack of data. Serum creatinine (Cr) and Ph were measured preoperatively and postoperatively specifically (H0, H12, H24, H48, H72). The percentage of maximum elevation of Ph (%EPh = [(maximum -minimum) / minimum] * 100) was calculated. AKI was defined as an increase Cr more than 26.5 mmol / L in 48 hours according to KDIGO criteria [2].The diagnostic performance of postoperative Ph thresholds were analysed by elaborating area under the receiver operating characteristic curves (AUC-ROC) with sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV).

Results

From the 386 patients included, the mean Euroscore II was 4.2 ± 6.3%, SAPS II score, 26.4 ± 10.8. Among them, 21.2% developed AKI (grade 1: 13.2%, grade 2: 4.1%, grade 3: 3.1%) and 2.6% required renal replacement therapy (RRT). Patients with AKI had Euroscore II, duration of cardiopulmonary bypass, transfusion needing and mortality higher than those without AKI (p < 0.001). The %EPh and the Ph at 48 hours (Ph48H) were significantly higher in AKI patients than in no AKI patients: 81 ± 79% and 1.47 ± 0.46 mmol/l vs 25 ± 23% and 0.99 ± 0.2 mmol/L, respectively (p < 0.001). A value of Ph48H > 1.19 mmol/L ( Se 72% (60-82), Sp 84% (71-92), PPV 84%, NPV 72%) and a %EPh > 49 % (Se 73% (61-81), Sp 83% (76-88), PPV 66%, NPV 86%) were predictive of AKI. In AKI patients, the %EPh and Ph48H significantly increased with the severity of AKI (Table 1). In these patients, a Ph48H < 1.53 mmol/L and a %EPh < 77% predicted the non use of RRT (Se 100% (62-100), Sp 85% (77-91), PPV 35% NPV 100%), respectively (Table 2).

Table 1

AKI severity

%EPh

Ph48H (mmol/L)

Grade 1

60 ± 45

1.25 ± 0.4

Grade 2

74 ± 58

1.73 ± 0.4

Grade 3

159 ± 132

1.80 ± 0.5

Table 2

 

Thresholds

AUC (IC95% )

p value

AKI diagnostic

Ph48H

1.19 mmol/L

0.813 (0.735-0.890)

< 0.0001

%EPh

49%

0.830 (0.772-0.889)

< 0.0001

RRT requiring

Ph48H

1.53 mmol/L

0.924 (0.879-0.970)

< 0.0001

%EPh

77%

0.818 (0.683-0.952)

< 0.0001

Conclusions

After cardiac surgery, serum phosphorus seems to be a simple, reliable and inexpensive biomarker at bedside for AKI monitoring. A value less than 1.53 mmol/L at 48h may predict the no-initiation of RRT in case of AKI and may guide the clinician to a non-invasive-AKI therapeutic. Obviously, these results should be interpreted with caution regarding the retrospective nature of the study.

Authors’ Affiliations

(1)
Arnaud de Villeneuve University Hospital, Department of Anesthesiology and Intensive Care, Montpellier, France

References

  1. Lassnigg A, Schmidlin D, Mouhieddine M, Bachmann LM, Druml W, Bauer P, et al: Minimal changes of serum creatinine predict prognosis in patients after cardiothoracic surgery: a prospective cohort study. J Am Soc Nephrol. 2004, 15: 1597-1605. 10.1097/01.ASN.0000130340.93930.DD.PubMedView ArticleGoogle Scholar
  2. Kidney Disease: Improving Global Outcomes (KDIGO) Acute Kidney Injury Work Group. KDIGO Clinical Practice Guideline for Acute Kidney Injury. Kidney Inter. 2012, Suppl 2: 1-138.Google Scholar

Copyright

© Ridolfo et al.; 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.

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