title: Open lung ventilation does not increase right ventricular outflow impedance: An echo-Doppler study.
abstract: OBJECTIVE
  Ventilation according to the open lung concept (OLC) consists of recruitment maneuvers, followed by low tidal volume and elevated positive end-expiratory pressure (PEEP). Elevated PEEP is associated with an increased right ventricular afterload. We investigated the effect of OLC ventilation on right ventricular outflow impedance during inspiration and expiration in patients after cardiac surgery using transesophageal echo-Doppler.
  
  
  METHODS
  A prospective, single-center, crossover, randomized, controlled clinical study.
  
  
  METHODS
  Cardiothoracic intensive care unit of a university hospital.
  
  
  METHODS
  Twenty-eight patients scheduled for elective cardiac surgery with cardiopulmonary bypass.
  
  
  METHODS
  In the intensive care unit, each patient was ventilated for approximately 30 mins according to both OLC and conventional ventilation. During OLC ventilation, recruitment maneuvers were applied until PaO2/FiO2 was >375 torr (50 kPa); during conventional ventilation no recruitment maneuvers were performed.
  
  
  RESULTS
  Transesophageal echo-Doppler measurements were performed at end-inspiration and end-expiration in a steady-state condition, 20 mins after initiation of a ventilation strategy. Mean acceleration of flow was determined in the long axis of the pulmonary artery in a transverse axis view. During OLC ventilation, a total PEEP of 14 +/- 4 cm H2O was applied vs. 5 cm H2O during conventional ventilation. Mean acceleration during expiration was comparable between groups. During inspiration, OLC ventilation did not cause a decrease of mean acceleration compared with expiration, whereas this did occur during conventional ventilation.
  
  
  CONCLUSIONS
  Despite the use of elevated PEEP levels, ventilation according to OLC does not change right ventricular outflow impedance during expiration and decreases right ventricular outflow impedance during inspiration.
authors.affiliation: Department of Anesthesiology, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Dinis
authors.initials: D
authors.lastname: Reis Miranda
authors.forename: Lennart
authors.initials: L
authors.lastname: Klompe
authors.forename: Joris
authors.initials: J
authors.lastname: Mekel
authors.forename: Ard
authors.initials: A
authors.lastname: Struijs
authors.forename: Jasper
authors.initials: J
authors.lastname: van Bommel
authors.forename: Burkhard
authors.initials: B
authors.lastname: Lachmann
authors.forename: Ad J J C
authors.initials: AJ
authors.lastname: Bogers
authors.forename: Diederik
authors.initials: D
authors.lastname: Gommers
mesh_terms: D001783:Blood Flow Velocity; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D018592:Cross-Over Studies; D015150:Echocardiography, Doppler; D017548:Echocardiography, Transesophageal; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000379:methods*; D011182:Postoperative Care / Q000379:methods*; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D015656:Respiratory Mechanics; D016278:Ventricular Function, Right