Very Transient Cases of Acute Kidney Injury in the Early Postoperative Period After Cardiac Surgery: The Relevance of More Frequent Serum Creatinine Assessment and Concomitant Urinary Biochemistry Evaluation

doi:10.1053/j.jvca.2015.04.020

Journal of Cardiothoracic and Vascular Anesthesia

Volume 30, Issue 1, January 2016, Pages 56-63

https://doi.org/10.1053/j.jvca.2015.04.020 Get rights and content

Objective

To evaluate if more frequent serum creatinine (sCr) measurements in the early postoperative period (first 48 hours) after cardiac surgery would help in early diagnosis of acute kidney injury (AKI), as well as reveal cases of AKI duration of fewer than 24 hours (vtAKI). The sequential blood and urinary biochemical profile of patients who developed vtAKI was compared with that of the patients who did not develop AKI or who developed AKI for more than 48 hours (pAKI).

Design

A retrospective analysis of prospectively collected data.

Setting

Two intensive care units of 2 private hospitals.

Participants

Twenty-nine patients who underwent cardiac surgery who had 6 values of serum creatinine (sCr) measured within the first 48 hours after surgery and concomitant spot urine samples for urine biochemistry assessment.

Interventions

None.

Measurements and Main Results

Eighteen patients (62%) developed Acute Kidney Injury Network (AKIN) sCr-based AKI, half of them for fewer than 24 hours. Most AKI patients had the sCr increase diagnosed 6 to 12 hours after surgery. When comparing the sequential alterations of blood and urinary parameters among patients with no AKI, vtAKI, and pAKI, the authors found that most of them were similar among groups, differing only in magnitude and duration.

Conclusions

More frequent sCr measurements in the early postoperative period, together with urine biochemistry assessment, have the potential to anticipate AKI diagnosis after cardiac surgery and reveal cases of very transient AKI usually not diagnosed in current practice. The clinical relevance of these findings must be evaluated in larger, prospective studies.

Section snippets

Materials and methods

The study was approved by the local ethics committee. The authors retrospectively retrieved the data from all consecutive patients who were admitted in the immediate postoperative period after cardiac surgery between October 2012 and December 2013 in 2 ICUs in São Paulo, Brazil. Most of the data were obtained using electronic medical records. Results of the blood and urinary laboratory examinations were retrieved from the Internet (local laboratory site), with access protected by individual

Statistical Analysis

Normality of the data distribution was made using the Shapiro-Wilk test. Values were presented as median and 25th and 75th percentiles or mean±standard deviation (SD) according to nonparametric or parametric distribution, respectively. Multiple pairwise comparison of the general characteristics among no-AKI, vtAKI, and pAKI patients were made using the Student t-test or Rank Sum Mann-Whitney test for continuous variables, or Chi-square/Fisher exact test for categoric variables as appropriate.

Results

A total of 29 cardiac surgery patients were admitted in the 2 ICUs during the study period, 24 in ICU1 and 5 in ICU2. None of these patients had an exclusion criterion, so all 29 cases were evaluated. Eighteen out of the 29 patients (62%) developed AKI within the first 48 hours after surgery. Of these, 9 patients (50%) developed vtAKI, 2 patients (11%) developed tAKI, and 7 patients (39%) developed pAKI. The 2 patients with tAKI were excluded from the analyses for 2 reasons: (1) As a separate

Discussion

In the present study, the authors observed that vtAKI was very frequent in the early postoperative period after cardiac surgery and that most diagnoses of postoperative AKI were made very soon after ICU admission, independently of their subsequent duration. Although vtAKI duration was a priori defined as being less than 24 hours, most cases resolved within the first 12 hours after diagnosis. Urinary biochemical profile had similarities among the 3 groups, such as significant evolutional

Conclusions

AKI is a serious consequence of cardiac surgery, and its occurrence still is underestimated or late in diagnosis. AKI seems to be triggered in the very early postoperative period. The combination of more frequent sCr assessment as well as simultaneous urine biochemistry evaluation, at least in the first 12 hours after surgery, may help reveal these cases. Some blood physicochemical and urinary biochemical changes occur after cardiac surgery independently of AKI development, but their magnitude

Acknowledgments

The authors would like to thank Aline Ramacciotti and Vanessa Melo for their cooperation in the acquisition of the data.

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Urine biochemistry in the early postoperative period after cardiac surgery: Role in acute kidney injury monitoring
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In other words, we would expect a higher creatinine excretion for this rate of UO. In postoperative patients, an increased FEK is frequent at ICU admission as a surrogate of surgery-induced renal microcirculatory stress [24,25]. Most of these patients have normal sCr and sK, and thus the increased FEK is a function of a high KU/CrU ratio.
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However, the low incidence of AKI in this study questions the influence of priming with starches on the development of AKI in this study’s patients. Finally, AKI after cardiac surgery with CPB is most frequently mild5 and transient.6 Therefore, this type of transient AKI may have been missed because frequent creatinine measurements were not performed during the early postoperative period.
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Original ArticleVery Transient Cases of Acute Kidney Injury in the Early Postoperative Period After Cardiac Surgery: The Relevance of More Frequent Serum Creatinine Assessment and Concomitant Urinary Biochemistry Evaluation

Objective

Design

Setting

Participants

Interventions

Measurements and Main Results

Conclusions

Section snippets

Materials and methods

Statistical Analysis

Results

Discussion

Conclusions

Acknowledgments

Kidney Int

Kidney Int

J Card Fail

J Crit Care

Crit Care Resusc

Epidemiology of acute kidney injury

Contrib Nephrol

Acute kidney injury in patients undergoing cardiac surgery

J Nephrol

Physicochemical analysis of blood and urine in the course of acute kidney injury in critically ill patients: A prospective, observational study

BMC Anesthesiol

Fractional excretion of potassium in the course of acute kidney injury in critically ill patients: Potential monitoring tool?

Rev Bras Ter Intensiva

Urine biochemistry in the early postoperative period after cardiac surgery: Role in acute kidney injury monitoring

Case Rep Crit Care

Original Article
Very Transient Cases of Acute Kidney Injury in the Early Postoperative Period After Cardiac Surgery: The Relevance of More Frequent Serum Creatinine Assessment and Concomitant Urinary Biochemistry Evaluation