title: Impact of cardiopulmonary bypass management on postcardiac surgery renal function.
abstract: OBJECTIVE
  Cardiac surgery on cardiopulmonary bypass (CPB) is associated with postoperative renal dysfunction and up to 4% of patients with normal preoperative renal function develop acute renal failure (ARF) requiring dialysis. According to recent investigations, CPB management is not evidence-based and, thus, current clinical CPB practice may favor renal dysfunction. The purpose of our study was to investigate if postcardiac surgery renal dysfunction is influenced by CPB management.
  
  
  METHODS
  We selected three groups of patients with normal preoperative renal function who had been subjected to cardiac surgical procedures on CPB: 44 patients with postoperative ARF requiring hemofiltration/dialysis (ARF group), 51 patients with postoperative renal dysfunction not requiring hemofiltration/dialysis (serum creatinine increase > 0.5 mg/dl within 48 h postsurgery: CREA group), and 48 patients with normal postoperative renal function (Control group). The patients' on-line CPB records were analyzed for CPB duration, CPB perfusion pressure, CPB flow, and periods on CPB at a perfusion pressure <60 mmHg. On-CPB diuretic and vasoconstrictor medication was recorded.
  
  
  RESULTS
  Patient demographics were similar for the three groups. In the ARF group, CPB duration was longer (166 +/- 77 [standard deviation, SD] min) compared to CREA (115 +/- 41 min; p < 0.001) and to Control groups (107 +/- 40 min; p < 0.001), and mean CPB flow was lower (2.35 +/- 0.36 l/min/m2) compared to CREA (2.61 +/- 0.35 l/min/m2; p = 0.0015) and to Control groups (2.51 +/- 0.33 l/min/m2; p = 0.09). Mean arterial pressure on CPB (ARF: 61 +/- 10; CREA: 60 +/- 7;
  
  
  METHODS
  63 +/- 9 mmHg; p = 0.19) as well as furosemide and norepinephrine medication on CPB were similar for the groups. Compared to Control (46 +/- 26 min), CPB duration at arterial pressures <60 mmHg was longer in ARF (78 +/- 60 min; p = 0.034) and in CREA (62 +/- 36 min;p = 0.048).
  
  
  CONCLUSIONS
  Our data suggest that current clinical CPB management impacts postoperative renal function. We found that patients with normal preoperative renal function who developed postoperative ARF had longer CPB duration, lower CPB perfusion flow, and longer periods on CPB at pressures < 60 mmHg compared to patients with no post CPB ARF. However, our data do not allow us to separate these CPB-related factors from the potential influence of perioperative low cardiac output syndrome as a cause for postoperative ARF. Thus, future clinical studies are required to elucidate CPB-induced ARF and to optimize CPB management for ARF prevention.
authors.affiliation: Clinic for Cardiothoracic Surgery, University of Cologne, Cologne, Germany. uwe.mehlhorn@medizin.uni-koeln.de
authors.forename: Uwe M
authors.initials: UM
authors.lastname: Fischer
authors.forename: Wilko K
authors.initials: WK
authors.lastname: Weissenberger
authors.forename: R David
authors.initials: RD
authors.lastname: Warters
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Geissler
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Allen
authors.forename: Uwe
authors.initials: U
authors.lastname: Mehlhorn
mesh_terms: D058186:Acute Kidney Injury / Q000209:etiology* / Q000628:therapy; D000368:Aged; D001794:Blood Pressure; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D003404:Creatinine / Q000097:blood; D003422:Critical Care; D005260:Female; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D013997:Time Factors
chemical_list: D003404:Creatinine