title: Does PEEP impair the hepatic outflow in patients following liver transplantation?
abstract: OBJECTIVE
  Evaluation of the impact of end-expiratory pressure (PEEP) ventilation on venous liver outflow, portal vein, and hepatic artery flows as well as systemic hemodynamics in patients following liver transplantation (LT).
  
  
  METHODS
  Prospective, interventional patient study.
  
  
  METHODS
  University hospital intensive care unit.
  
  
  METHODS
  65 consecutive patients after LT.
  
  
  METHODS
  All patients were intubated and mechanically ventilated with biphasic positive airway pressure (BIPAP). The effects of three levels of PEEP (0, 5, and 10 mbar) applied at random order on hepatic inflow and outflow were studied in the immediate postoperative period.
  
  
  RESULTS
  Central venous-, arterial pressure, and cardiac index was recorded from every patient at three different PEEP levels (0, 5, and 10 mbar). Simultaneously, flow velocities in the hepatic-, portal vein, and hepatic artery were determined by Doppler ultrasound. PEEP of 10 mbar significantly increased central venous pressure in comparison with zero PEEP. Mean arterial pressure and cardiac index was not influenced. Hepatic inflow and outflow of the transplanted livers were not impaired by any of the used PEEP levels.
  
  
  CONCLUSIONS
  BIPAP ventilation with PEEP levels up to 10 mbar does not affect systemic hemodynamics. Furthermore, neither venous outflow nor portal venous or hepatic artery inflow of the liver are impaired at PEEP levels up to 10 mbar immediately following liver transplantation. Although these results suggest that PEEP ventilation up to 10 mbar does not affect liver hemodynamics, further studies are needed to determine whether these findings could be confirmed for a longer ventilation period with PEEP.
authors.affiliation: University Clinic Essen, Department of General-, Visceral-, and Transplant Surgery, Hufelandstrasse 55, 45122 Essen, Germany. fuat.saner@uni-essen.de
authors.forename: Fuat H
authors.initials: FH
authors.lastname: Saner
authors.forename: Goran
authors.initials: G
authors.lastname: Pavlaković
authors.forename: Yanli
authors.initials: Y
authors.lastname: Gu
authors.forename: Nils R
authors.initials: NR
authors.lastname: Fruhauf
authors.forename: Andreas
authors.initials: A
authors.lastname: Paul
authors.forename: Arnold
authors.initials: A
authors.lastname: Radtke
authors.forename: Silvio
authors.initials: S
authors.lastname: Nadalin
authors.forename: Massimo
authors.initials: M
authors.lastname: Malagó
authors.forename: Christoph E
authors.initials: CE
authors.lastname: Broelsch
mesh_terms: D000704:Analysis of Variance; D001783:Blood Flow Velocity; D016009:Chi-Square Distribution; D005260:Female; D006499:Hepatic Artery / Q000000981:diagnostic imaging; D006801:Humans; D007362:Intensive Care Units; D008099:Liver / Q000098:blood supply* / Q000000981:diagnostic imaging; D016031:Liver Transplantation; D008297:Male; D008875:Middle Aged; D011169:Portal Vein / Q000000981:diagnostic imaging; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D018615:Ultrasonography, Doppler, Color