title: Variable lung protective mechanical ventilation decreases incidence of postoperative delirium and cognitive dysfunction during open abdominal surgery.
abstract: BACKGROUND
  Postoperative cognitive dysfunction (POCD) is a subtle impairment of cognitive abilities and can manifest on different neuropsychological features in the early postoperative period. It has been proved that the use of mechanical ventilation (MV) increased the development of delirium and POCD. However, the impact of variable and conventional lung protective mechanical ventilation on the incidence of POCD still remains unknown, which was the aim of this study.
  
  
  METHODS
  162 patients scheduled to undergo elective gastrointestinal tumor resection via laparotomy in Ningbo No. 2 hospital with expected duration >2 h from June, 2013 to June, 2015 were enrolled in this study. Patients included were divided into two groups according to the scheme of lung protective MV, variable ventilation group (VV group, n=79) and conventional ventilation group (CV group, n=83) by randomization performed by random block randomization. The plasma levels of inflammatory cytokines, characteristics of the surgical procedure, incidence of delirium and POCD were collected and compared.
  
  
  RESULTS
  Postoperative delirium was detected in 36 of 162 patients (22.2%) and 12 patients of these (16.5%) belonged to the VV group while 24 patients (28.9%) were in the CV group (P=0.036). POCD on the seventh postoperative day in CV group (26/83, 31.3%) was increased in comparison with the VV group (14/79, 17.7%) with significant statistical difference (P=0.045). The levels of inflammatory cytokines were all significantly higher in CV group than those in VV group on the 1st postoperative day (P<0.05). On 7th postoperative day, the levels of IL-6 and TNF-α in CV group remained much higher compared with VV group (P<0.05).
  
  
  CONCLUSIONS
  Variable vs conventional lung protective MV decreased the incidence of postoperative delirium and POCD by reducing the systemic proinflammatory response.
authors.affiliation: Department of Anesthesiology, Ningbo No. 2 Hospital No. 41 Xibei Street, Ningbo 315000, Zhejiang Province, China.
authors.forename: Ruichun
authors.initials: R
authors.lastname: Wang
authors.affiliation: Department of Anesthesiology, Ningbo No. 2 Hospital No. 41 Xibei Street, Ningbo 315000, Zhejiang Province, China.
authors.forename: Junping
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Anesthesiology, Ningbo No. 2 Hospital No. 41 Xibei Street, Ningbo 315000, Zhejiang Province, China.
authors.forename: Guorong
authors.initials: G
authors.lastname: Wu
keywords: Postoperative cognitive dysfunction; conventional ventilation; mechanical ventilation; open abdominal surgery; variable ventilation