Advertisement

Deciding When to Start Renal Replacement Therapy After Cardiac Surgery in Real Life

Published:December 25, 2022DOI:https://doi.org/10.1053/j.jvca.2022.12.021
      To the Editor:
      Acute kidney injury (AKI) is a frequent complication of cardiac surgery that contributes to postoperative morbidity and mortality. The timing of renal replacement therapy (RRT) remains unclear.
      • Corredor C
      • Thomson R
      • Al-Subaie N.
      Long-term consequences of acute kidney injury after cardiac surgery: A systematic review and meta-analysis.
      ,
      • Chew STH
      • Hwang NC.
      Acute kidney injury after cardiac surgery: A narrative review of the literature.
      The Artificial Kidney Initiation in Kidney Injury (AKIKI) trial and the Standard versus Accelerated Initiation of Renal-Replacement Therapy in Acute Kidney Injury (STARRT-AKI) trial, 2 randomized clinical trials conducted in the intensive care unit (ICU), showed no difference in mortality between an early or delayed strategy of initiation of RRT.
      • Gaudry S
      • Hajage D
      • Schortgen F
      • et al.
      Initiation strategies for renal-replacement therapy in the intensive care unit.
      ,
      STARRT-AKI InvestigatorsCanadian Critical Care Trials GroupAustralian and New Zealand Intensive Care Society Clinical Trials Group
      Timing of initiation of renal-replacement therapy in acute kidney injury.
      However, these studies mainly included patients with sepsis. The Early versus deLAyed Initiation (ELAIN) of RRT in critically ill patients with AKI study, which mostly included postoperative cardiac surgery patients in its population, showed a decrease in mortality for early initiation of RRT.
      • Zarbock A
      • Kellum JA
      • Schmidt C
      • et al.
      Effect of early vs delayed initiation of renal replacement therapy on mortality in critically ill patients with acute kidney injury: The ELAIN randomized clinical trial.
      We note that STARRT-AKI and AKIKI found a decrease in RRT rate of 35% and 51%, respectively, in the delayed strategy group. On the contrary, there was no such decrease in ELAIN, with a 92% RRT rate in this group. In our cardiothoracic ICU, the physicians' practice is to start RRT late.
      We performed a retrospective, observational, single-center study of patients in the cardiothoracic ICU of the University Hospital of Limoges to compare the proportion of RRT if the early criteria of the ELAIN, AKIKI, and STARRT-AKI studies had been chosen. All patients who developed AKI at least stage 2 according to the Kidney Disease Improving Global Outcomes (KDIGO) classification based on creatinine levels within a week after cardiac surgery were included. Patients with a history of renal transplantation or chronic kidney disease were excluded.
      Of 978 patients who had been treated in our institution, 65 patients met the inclusion criteria. Demographics are provided in Table 1. Of these patients, 32 (49%) did not progress to KDIGO Stage 3 and did not require RRT, 13 (20%) progressed to KDIGO Stage 3 without RRT, and 20 (31%) progressed to KDIGO Stage 3 and required RRT. However, if we had applied the criteria for early RTT of the ELAIN and STARRT-AKI studies, all 65 patients would have required RRT. Therefore, we were able to avoid treating 45 patients (69%) with RRT (Fig 1, A). Similarly, with the early strategy criteria of the AKIKI study (KDIGO 3 patients), 33 (51%) patients would have received RRT, whereas this intervention has been avoided in 13 patients (39%) (Fig 1, A). These results were similar to those of the STARRT-AKI and AKIKI studies but not to ELAIN. Survival among patients with and without RRT was similar (Fig 1, B).
      Table 1Demographics
      CharacteristicsOverall N = 65RRT N = 20Without RRT N = 45p
      Age, y69 (64-75)71.5 (63-73.5)68 (64-75)0.77
      Emergency29 (45)9 (45)20 (44)0.99
      Previous cardiac surgery7 (10)2 (10)5 (11)0.99
      CPB duration, min100 (60-182)148 (80-199)122 (79-194)0.83
      Cross-clamp duration, min45 (72-110)90 (57-115)84 (48-126)0.98
      Hemolysis18 (28)10 (50)8 (18)0.015
      Surgical revision8 (12)2 (10)6 (13)0.99
      History of high blood pressure36 (55)10 (50)26 (58)0.60
      History of diabetes18 (28)5 (25)13 (28)0.99
      Preoperative LVEF, %55 (48-62)55 (48-69)55 (46-61)0.51
      Creatinine before surgery, µmol/L85 (70-95)90 (78-102)84 (68-93)0.08
      Higher creatinine, µmol/L247 (186-417)469 (385-604)210 (173-248)< 0.0001
      Urea nitrogen, mmol/L19.5 (15-25.6)25 (20-33)17 (13-24)0.0004
      Creatinine at day 7, µmol/L175 (109-267)268 (180-392)140 (99-215)0.0003
      Creatinine at discharge of ICU, µmol/L135 (100-232)220 (141-289)117 (88-152)0.002
      KDIGO 333 (51)20 (100)13 (29)< 0.0001
      Duration of RRT, dNA4.5 (3.75-6.25)0NA
      Potassium, mEq/L5.5 (5-6)5.75 (5.5-6.1)5.4 (4.9-5.9)0.1
      Postoperative pH7.26 (7.19-7.3)7.2 (7.17-7.26)7.28 (7.21-7.32)0.014
      Postoperative base deficit4 (3-6)5 (4-6)3.5 (1.9-5.3)0.025
      Mechanical ventilation >48 h30 (46)15 (75)15 (33)0.003
      Postoperative length of stay in ICU and intermediate care unit, d14 (9-22)23.5 (17-34)11 (8-16)< 0.0001
      Mortality12 (18)6 (30)6 (13)0.17
      NOTE. The continuous variables are presented as median and IQR (Q1-Q3). The categorical variables are presented as number (proportion). The 2 groups were compared using Mann-Whitney U test for continuous variables and the chi-square test or Fisher exact test for the categorical variables.
      Abbreviations: CPB, cardiopulmonary bypass; ICU, intensive care unit; KDIGO, Kidney Disease Improving Global Outcomes; LVEF, left ventricular ejection fraction; RRT, renal replacement therapy.

      Conflict of Interest

      None.

      References

        • Corredor C
        • Thomson R
        • Al-Subaie N.
        Long-term consequences of acute kidney injury after cardiac surgery: A systematic review and meta-analysis.
        J Cardiothorac Vasc Anesth. 2016; 30: 69-75
        • Chew STH
        • Hwang NC.
        Acute kidney injury after cardiac surgery: A narrative review of the literature.
        J Cardiothorac Vasc Anesth. 2019; 33: 1122-1138
        • Gaudry S
        • Hajage D
        • Schortgen F
        • et al.
        Initiation strategies for renal-replacement therapy in the intensive care unit.
        N Engl J Med. 2016; 375: 122-133
        • STARRT-AKI Investigators
        • Canadian Critical Care Trials Group
        • Australian and New Zealand Intensive Care Society Clinical Trials Group
        Timing of initiation of renal-replacement therapy in acute kidney injury.
        N Engl J Med. 2020; 383: 240-251
        • Zarbock A
        • Kellum JA
        • Schmidt C
        • et al.
        Effect of early vs delayed initiation of renal replacement therapy on mortality in critically ill patients with acute kidney injury: The ELAIN randomized clinical trial.
        JAMA. 2016; 315: 2190-2199