title: Renal resistive index by transesophageal and transparietal echo-doppler imaging for the prediction of acute kidney injury in patients undergoing major heart surgery.
abstract: BACKGROUND
  Acute kidney injury (AKI) following major heart surgery (MHS) is associated with early decrease in renal blood flow and worsened prognosis. Doppler-derived renal resistive index (RRI), which reflects renal vascular resistance, may predict the development of AKI in patients undergoing MHS.
  
  
  METHODS
  We studied 60 consecutive patients (mean age 69.5 years, range 30-88, 41 males) undergoing MHS. We measured RRI, both at the renal sinus and intraparenchymally, by transesophageal echo-Doppler ultrasound (TE-EDus) at anesthesia induction and at the end of surgery in all patients. Additionally, we measured RRI by external transparietal echo-Doppler ultrasound (TP-EDus) at the following time points: anesthesia induction, end of surgery, 4 and 24 h from cardiopulmonary bypass (CPB) start. We also measured serum neutrophil gelatinase associated lipocalin (NGAL) at the same time points.
  
  
  RESULTS
  AKI [serum creatinine (sCr) increase ≥0.3 mg/dl vs. baseline within 72 h] developed in 23/60 (38.3 %) patients, with two requiring dialysis. Systemic hemodynamic parameters were similar in the patients who developed AKI (AKI+) and in those who did not (AKI-). Intraparenchymal RRI at end-surgery was significantly higher in AKI+ compared to AKI- patients, both at TE-EDusand TP-EDus(TE-EDusmean difference, p = 0.004; TP-EDusmean difference, p = 0.013; difference between TE-EDusand TP-EDusresults, p = 0.066), although the predictive performance was limited with both methods (area under the curve [AUC] of the receiver-operator characteristics: 0.71 and 0.70 for TE-EDusand TP-EDus, respectively). Serum NGAL values were higher in AKI + than in AKI- patients (anesthesia induction, p = 0.037; end-surgery, p = 0.007; 4 h from CPB start, p = 0.093; 24 h from CPB start, p = 0.024. However, combining RRI with serum NGAL at end-surgery did not provide a clear-cut advantage in predicting AKI.
  
  
  CONCLUSIONS
  In patients undergoing MHS, increased echo-Doppler ultrasound-derived RRI at end-surgery is significantly associated with the risk of AKI, but has limited practical utility for identifying the patients who will develop AKI.
authors.affiliation: Renal Failure Unit, Department of Clinical and Experimental Medicine, University of Parma, Via Gramsci, 14, 43100, Parma, Italy. giuregolisti@gmail.com.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Regolisti
authors.affiliation: Renal Failure Unit, Department of Clinical and Experimental Medicine, University of Parma, Via Gramsci, 14, 43100, Parma, Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Maggiore
authors.affiliation: Renal Failure Unit, Department of Clinical and Experimental Medicine, University of Parma, Via Gramsci, 14, 43100, Parma, Italy.
authors.forename: Carola
authors.initials: C
authors.lastname: Cademartiri
authors.affiliation: Heart Surgery Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Loredana
authors.initials: L
authors.lastname: Belli
authors.affiliation: Heart Surgery Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Tiziano
authors.initials: T
authors.lastname: Gherli
authors.affiliation: Renal Failure Unit, Department of Clinical and Experimental Medicine, University of Parma, Via Gramsci, 14, 43100, Parma, Italy.
authors.forename: Aderville
authors.initials: A
authors.lastname: Cabassi
authors.affiliation: Nephrology and Dialysis Unit, Policlinico Umberto I, University of Rome "La Sapienza", Rome, Italy.
authors.forename: Santo
authors.initials: S
authors.lastname: Morabito
authors.affiliation: Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Castellano
authors.affiliation: Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy.
authors.forename: Loreto
authors.initials: L
authors.lastname: Gesualdo
authors.affiliation: Renal Failure Unit, Department of Clinical and Experimental Medicine, University of Parma, Via Gramsci, 14, 43100, Parma, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Fiaccadori
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D003404:Creatinine / Q000097:blood; D005260:Female; D006801:Humans; D007668:Kidney / Q000098:blood supply*; D000071068:Lipocalin-2 / Q000097:blood; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012077:Renal Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012079:Renal Circulation; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D018608:Ultrasonography, Doppler / Q000379:methods*; D014655:Vascular Resistance
chemical_list: D015415:Biomarkers; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D003404:Creatinine
keywords: Acute kidney injury; Doppler ultrasound imaging; Echocardiography, transesophageal; Heart surgery; Resistance, vascular