title: Preoperative Renal Resistive Index Predicts Risk of Acute Kidney Injury in Patients Undergoing Cardiac Surgery.
abstract: OBJECTIVE
  To investigate whether an elevated preoperative renal resistive index (RRI) predicts acute kidney injury (AKI) in patients undergoing cardiac surgery.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  Cohort of 96 adult cardiac surgical patients.
  
  
  METHODS
  Resistive index was measurement the day before surgery.
  
  
  RESULTS
  Renal Doppler was used to measure the resistive index in renal cortical or arcuate arteries the day before surgery. An elevated RRI was defined as≥0.7. AKI was defined as an absolute increase in postoperative compared with preoperative serum creatinine levels by≥26 µmol/L or a relative increase by≥50% or a postoperative urine output<0.5 mL/kg for 6 hours or longer. The relative risk of AKI in patients with an elevated RRI compared with those without an elevated RRI was analyzed using logistic regression. Among patients with an RRI<0.7, 6 (16%) developed AKI compared with 21 (36%) with an RRI≥0.7. The mean increases in postoperative serum creatinine levels were 12 μmol/L in those with an RRI<0.7 and 30 μmol/L in those with an RRI≥0.7. The crude odds ratio for AKI in patients with an RRI≥0.7 was 3.03 (1.09-8.42) compared with those with an RRI<0.7. After multivariable adjustment, the odds ratio was 2.95 (0.97-9.00).
  
  
  CONCLUSIONS
  Patients with an elevated preoperative RRI have an increased risk of developing AKI after cardiac surgery. In combination with other markers, the RRI might be a tool for identifying patients with an increased risk of developing AKI.
authors.affiliation: Department of Medicine, Karolinska Institutet, Solna, Sweden. Electronic address: daniel.hertzberg@ki.se.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hertzberg
authors.affiliation: Department of Emergency Medicine, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Simon L
authors.initials: SL
authors.lastname: Ceder
authors.affiliation: Section of Cardiothoracic Surgery, Karolinska University Hospital, Stockholm, Sweden; Department of Molecular Medicine and Surgery, Karolinska Institutet, Solna, Sweden.
authors.forename: Ulrik
authors.initials: U
authors.lastname: Sartipy
authors.affiliation: Department of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Kent
authors.initials: K
authors.lastname: Lund
authors.affiliation: Department of Medicine, Karolinska Institutet, Solna, Sweden; Department of Emergency Medicine, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Holzmann
mesh_terms: D058186:Acute Kidney Injury / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D000368:Aged; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000379:methods*; D011446:Prospective Studies; D012307:Risk Factors; D018617:Ultrasonography, Doppler, Pulsed / Q000379:methods
keywords: acute kidney injury; cardiac surgery; preoperative risk factors; renal resistive index