title: Perioperative optimal blood pressure as determined by ultrasound tagged near infrared spectroscopy and its association with postoperative acute kidney injury in cardiac surgery patients.
abstract: OBJECTIVE
  Perioperative blood pressure management by targeting individualized optimal blood pressure, determined by cerebral blood flow autoregulation monitoring, may ensure sufficient renal perfusion. The purpose of this study was to evaluate changes in the optimal blood pressure for individual patients, determined during cardiopulmonary bypass (CPB) and during early postoperative period in intensive care unit (ICU). A secondary aim was to examine if excursions below optimal blood pressure in the ICU are associated with risk of cardiac surgery-associated acute kidney injury (CSA-AKI).
  
  
  METHODS
  One hundred and ten patients undergoing cardiac surgery had cerebral blood flow monitored with a novel technology using ultrasound tagged near infrared spectroscopy (UT-NIRS) during CPB and in the first 3 h after surgery in the ICU. The correlation flow index (CFx) was calculated as a moving, linear correlation coefficient between cerebral flow index measured using UT-NIRS and mean arterial pressure (MAP). Optimal blood pressure was defined as the MAP with the lowest CFx. Changes in optimal blood pressure in the perioperative period were observed and the association of blood pressure excursions (magnitude and duration) below the optimal blood pressure [area under the curve (AUC) < OptMAP mmHgxh] with incidence of CSA-AKI (defined using Kidney Disease: Improving Global Outcomes criteria) was examined.
  
  
  RESULTS
  Optimal blood pressure during early ICU stay and CPB was correlated (r = 0.46, P < 0.0001), but was significantly higher in the ICU compared with during CPB (75 ± 8.7 vs 71 ± 10.3 mmHg, P = 0.0002). Thirty patients (27.3%) developed CSA-AKI within 48 h after the surgery. AUC < OptMAP was associated with CSA-AKI during CPB [median, 13.27 mmHgxh, interquartile range (IQR), 4.63-20.14 vs median, 6.05 mmHgxh, IQR 3.03-12.40, P = 0.008], and in the ICU (13.72 mmHgxh, IQR 5.09-25.54 vs 5.65 mmHgxh, IQR 1.71-13.07, P = 0.022).
  
  
  CONCLUSIONS
  Optimal blood pressure during CPB and in the ICU was correlated. Excursions below optimal blood pressure (AUC < OptMAP mmHgXh) during perioperative period are associated with CSA-AKI. Individualized blood pressure management based on cerebral autoregulation monitoring during the perioperative period may help improve CSA-AKI-related outcomes.
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Daijiro
authors.initials: D
authors.lastname: Hori
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Hogue
authors.affiliation: Department of Cardiovascular Surgery, Saitama Medical Center, Jichi Medical University, Saitama, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Adachi
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Max
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Joel
authors.initials: J
authors.lastname: Price
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Sciortino
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Kenton
authors.initials: K
authors.lastname: Zehr
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: John
authors.initials: J
authors.lastname: Conte
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Duke
authors.initials: D
authors.lastname: Cameron
authors.affiliation: Division of Cardiac Surgery, Department of Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA kmandal2@jhmi.edu.
authors.forename: Kaushik
authors.initials: K
authors.lastname: Mandal
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D000368:Aged; D062186:Arterial Pressure; D001795:Blood Pressure Determination / Q000379:methods*; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D002560:Cerebrovascular Circulation; D005260:Female; D006706:Homeostasis; D006801:Humans; D007022:Hypotension / Q000209:etiology / Q000503:physiopathology; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D011182:Postoperative Care / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012079:Renal Circulation; D012307:Risk Factors; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors; D016896:Treatment Outcome; D014463:Ultrasonography
keywords: Acute kidney injury; Cerebral autoregulation; Haemodynamic management; Perioperative care