Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access
Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc
Journal website https://jocmr.elmerjournals.com

Original Article

Volume 16, Number 7-8, August 2024, pages 375-380


Risk Factors and Outcomes of Acute Kidney Injury After Cardiac Surgery: A Retrospective Observational Single-Center Study

Tables

Table 1. KDIGO Severity Staging for AKI
 
StageeGFR/serum creatinine criteriaUrine output criteria
eGFR: estimated glomerular filtration rate; KDIGO: Kidney Disease: Improving Global Outcomes.
Stage 11.5 - 1.9 times baseline
OR
≥ 26.5 µmol/L increase within 48 h
≤ 0.5 mL/kg/h for 6 - 12 h
Stage 22 - 2.9 times baseline≤ 0.5 mL/kg/h ≥ 12 h
Stage 3Three times baseline
OR
Increase in serum creatinine ≥ 354 µmol/L
OR
Initiation of renal replacement therapy (e.g., dialysis)
≤ 0.3 mL/kg/h ≥ 24 h
OR
Anuria for ≥ 12 h

 

Table 2. Pre-Operative Patient Characteristics
 
Patient characteristicsData (% or IQR)
BMI: body mass index; CVI: cerebrovascular insult; IQR: interquartile range.
Gender (male)142 (85.0)
Age (years)57 (44 - 64)
BMI26.3 (23.5 - 30.2)
Diabetes88 (52.7)
Hypertension94 (56.3)
Ischemic heart disease119 (71.3)
Smoking (active or ex-smoker)54 (32.3)
Previous CVI11 (6.6)
Congestive heart failure8 (4.8)
Creatinine (µmol/L)81 (68 - 102)
Urea (mmol/L)5.5 (4.3 - 7.4)
Hemoglobin (g/dL)11.7 (10.0 - 13.2)

 

Table 3. Intra- and Post-Operative Patient Characteristics
 
Patient characteristicsData (% or IQR)
AKI: acute kidney injury; CABG: coronary artery bypass grafting; CCU: cardiac care unit; CRRT: continuous renal replacement therapy; ICU: intensive care unit; IQR: interquartile range.
Type of surgery
  CABG114 (68.3)
  Valve replacement43 (25.7)
  Both10 (6.0)
Cardiopulmonary bypass duration (min.)80 (67 - 105)
Cross-clamping time (min.)55 (42 - 69)
Blood products transfused?69 (41.3)
AKI post-operatively46 (27.5)
  CRRT/dialysis4 (2.4)
ICU or CCU stay?128 (76.6)
  Duration (days)5 (3 - 8)
Post-operative inotropic support72 (43.1)
Death5 (3.0)
  30-day mortality4 (2.4)

 

Table 4. Univariate Comparison Between AKI Versus Non-AKI Patients
 
Factor predisposing for AKIAKI (N = 46)Non-AKI (N = 121)P-value
AKI: acute kidney injury.
Hemoglobin (g/dL)9.9 (8.9 - 11.9)12.0 (10.8 - 13.9)< 0.0001
Age (years)65 (40 - 72)56 (44 - 62)0.003
Diabetes21 (45.7)67 (55.4)0.300
Hypertension24 (52.2)70 (57.9)0.601
Pre-operative creatinine (µmol/L)97.5 (77.2 - 127)77.0 (67.0 - 93.5)< 0.0001
Pre-operative urea (mmol/L)7.2 (5.4 - 9.4)5.2 (4.2 - 6.3)< 0.0001
Type of surgery< 0.0001
  CABG25 (54.3)89 (73.6)
  Valve12 (26.1)31 (25.6)
  Both9 (19.6)1 (0.8)
Post-operative inotropes43 (93.5)29 (24.0)< 0.0001
Intra-operative blood products transfused?32 (69.9)37 (30.6)< 0.0001
Cross-clamp time (min)68.5 (57.3 - 98.0)47.0 (38.0 - 61.0)< 0.0001
Cardiopulmonary bypass time (min)100.5 (80.5 - 119.5)72.5 (63.0 - 90.0)< 0.0001

 

Table 5. Logistic Regression Analysis for the Development of Post-Operative AKI Based on Significant Results Obtained in Univariate Analysis Detailed in Table 4
 
Factor predisposing for AKIOR (95% confidence interval)P-value
aType of surgery: CABG, valve repair or both in increasing level of complexity. bPost-operative inotropes: odds ratio for NO inotropic support. If YES inotropic support then OR 46.08 (4.136 - 513.3), P = 0.002. *Continuous variables in the analysis. AKI: acute kidney injury; OR: odds ratio.
Hemoglobin (g/dL)*0.480 (0.279 - 0.826)0.008
Age (years)*1.101 (1.021 - 1.186)0.012
Pre-operative creatinine (µmol/L)*1.037 (1.000 - 1.076)0.048
Pre-operative urea (mmol/L)*0.986 (0.752 - 1.293)0.921
Type of surgerya4.387 (0.797 - 24.149)0.089
Post-operative inotropesb0.022 (0.002 - 0.242)0.002
Intra-operative blood products transfused?0.459 (0.069 - 3.047)0.420
Cross-clamp time (min)*1.099 (1.009 - 1.197)0.030
Cardiopulmonary bypass time (min)*1.039 (0.987 - 1.094)0.142