title: Doppler renal resistive index for early detection of acute kidney injury after major orthopaedic surgery: a prospective observational study.
abstract: BACKGROUND
  Postoperative acute kidney injury (AKI) is a cause of morbidity and mortality. Its diagnosis requires better markers than variations in diuresis or postoperative serum creatinine.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the accuracy of Doppler renal resistive index for early detection of AKI after hip or knee arthroplasty.
  
  
  METHODS
  A prospective observational study.
  
  
  METHODS
  A single-centre study in a university hospital.
  
  
  METHODS
  Fifty men and women older than 65 years, requiring hip or knee replacement with at least two perioperative AKI risk factors, including diabetes, arteritis, chronic heart or renal dysfunction, and prescription of angiotensin-converting enzyme (ACE) inhibitors. Exclusion criteria were poor abdominal echogenicity, arrhythmia, respiratory failure or agitation.
  
  
  METHODS
  Renal resistive index was measured preoperatively and in the postanaesthesia care unit.
  
  
  RESULTS
  Sixteen patients presented with AKI in the postoperative period. Resistive index was increased in this group in both the preoperative [0.72 (0.69 to 0.73) vs. 0.66 (0.58 to 0.71); P = 0.01] and postoperative periods [0.75 (0.71 to 0.75) vs. 0.67 (0.62 to 0.72); P = 0.0001]. Resistive index evaluated by ROC curves and AUC to detect AKI was 0.862 [95% confidence interval (95% CI) 0.735 to 0.943]. The most accurate cut-off value was a postoperative resistive index of 0.705 (sensitivity = 94%, specificity = 71%, LR+ = 3.19 and LR- = 0.09). The grey area between 0.705 and 0.73, corresponding to the inconclusive zone, included 26% (13/50) of all the patients.
  
  
  CONCLUSIONS
  Postoperative resistive index appears to be effective for early detection of AKI after major orthopaedic surgery. Resistive index can be measured in the postoperative care unit in patients at risk of AKI.
  
  
  BACKGROUND
  29-0512.
authors.affiliation: From the Département Anesthésie-Réanimation, CHU Toulouse, Université Toulouse III Paul Sabatier, Faculté de Médecine Toulouse-Rangueil, EA 4564-MATN, Institut Louis Bugnard (IFR 150), Toulouse, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Marty
authors.forename: Simon
authors.initials: S
authors.lastname: Szatjnic
authors.forename: Fabrice
authors.initials: F
authors.lastname: Ferre
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Conil
authors.forename: Nicolas
authors.initials: N
authors.lastname: Mayeur
authors.forename: Olivier
authors.initials: O
authors.lastname: Fourcade
authors.forename: Stein
authors.initials: S
authors.lastname: Silva
authors.forename: Vincent
authors.initials: V
authors.lastname: Minville
mesh_terms: D058186:Acute Kidney Injury / Q000000981:diagnostic imaging* / Q000209:etiology*; D000368:Aged; D000369:Aged, 80 and over; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008297:Male; D019637:Orthopedic Procedures / Q000009:adverse effects*; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000209:etiology*; D011446:Prospective Studies; D018608:Ultrasonography, Doppler / Q000379:methods