title: Intraoperative positive end-expiratory pressure evaluation using the intratidal compliance-volume profile.
abstract: BACKGROUND
  Lung-protective mechanical ventilation during general surgery including the application of PEEP can reduce postoperative pulmonary complications. In a prospective clinical observation study, we evaluated volume-dependent respiratory system compliance in adult patients undergoing ear-nose-throat surgery with ventilation settings chosen empirically by the attending anaesthetist.
  
  
  METHODS
  In 40 patients, we measured the respiratory variables during intraoperative mechanical ventilation. All measurements were subdivided into 5 min intervals. Dynamic compliance (CRS) and the intratidal volume-dependent CRS curve was calculated for each interval and classified into one of the six specific compliance profiles indicating intratidal recruitment/derecruitment, overdistension or all. We retrospectively compared the occurrences of the respective compliance profiles at PEEP levels of 5 cm H2O and at higher levels.
  
  
  RESULTS
  The attending anaesthetists set the PEEP level initially to 5 cm H2O in 29 patients (83%), to 7 cm H2O in 5 patients (14%), and to 8 cm H2O in 2 patients (6%). Across all measurements the mean CRS was 61 (11) ml cm H2O(-1) (40-86 ml cm H2O(-1)) and decreased continuously during the procedure. At PEEP of 5 cm H2O the compliance profile indicating strong intratidal recruitment/derecruitment occurred more often (18.6%) compared with higher PEEP levels (5.5%, P<0.01). Overdistension was practically never observed.
  
  
  CONCLUSIONS
  In most patients, a PEEP of 5 cm H2O during intraoperative mechanical ventilation is too low to prevent intratidal recruitment/derecruitment. The analysis of the intratidal compliance profile provides the rationale to individually titrate a PEEP level that stabilizes the alveolar recruitment status of the lung during intraoperative mechanical ventilation.
  
  
  BACKGROUND
  DRKS00004286.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Straße 55, Freiburg D-79106, Germany steffen.wirth@uniklinik-freiburg.de.
authors.forename: S
authors.initials: S
authors.lastname: Wirth
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Straße 55, Freiburg D-79106, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Baur
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Straße 55, Freiburg D-79106, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Spaeth
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Straße 55, Freiburg D-79106, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Guttmann
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Medical Center Freiburg, Hugstetter Straße 55, Freiburg D-79106, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schumann
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008168:Lung / Q000502:physiology*; D008170:Lung Compliance / Q000502:physiology*; D008176:Lung Volume Measurements / Q000379:methods; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D011175:Positive-Pressure Respiration / Q000379:methods*; D011446:Prospective Studies; D013990:Tidal Volume / Q000502:physiology; D055815:Young Adult
keywords: compliance–volume curve; elective surgery; lung compliance mechanical ventilation; respiratory system mechanics