title: High positive end-expiratory pressure levels promote bacterial translocation in experimental pneumonia.
abstract: OBJECTIVE
  A previous study in piglets with experimental pneumonia showed that reducing atelectasis by means of open lung ventilation attenuated bacterial translocation compared to conventional ventilation settings. This study examined the effect of open lung ventilation with higher than necessary positive end-expiratory pressures (PEEP) on bacterial translocation.
  
  
  METHODS
  Prospective animal study in a university-affiliated research laboratory.
  
  
  METHODS
  Thirty piglets.
  
  
  METHODS
  Animals were surfactant-depleted by whole-lung lavage and infected with group B streptococci. Thereafter the animals were ventilated for 5 h according to either a conventional ventilation strategy, open lung strategy, or open lung/high-PEEP strategy. Blood samples for blood gas analysis and blood bacterial counts were taken every hour. After 5 h of ventilation surviving animals were killed, and lung colony forming units and lung mechanics parameters were determined.
  
  
  RESULTS
  All animals in both open lung groups survived but only 30% of those in the conventional ventilation group. Open lung ventilation resulted in significantly less bacterial translocation than either conventional or high-PEEP ventilation. Lung function in the conventional ventilated group was significantly less than in the two open lung groups.
  
  
  CONCLUSIONS
  The lowest level of bacterial translocation was observed during optimal ventilation (open lung) which was achieved by using individually tailored settings. Deviation to either side can be harmful, as shown by the increased bacterial translocation during conventional and high-PEEP ventilation.
authors.affiliation: Department of Anesthesiology, Erasmus Medical Center, P.O. Box 2040, 3000 CA, Rotterdam, The Netherlands. mbwana@gmail.com
authors.forename: Robert A
authors.initials: RA
authors.lastname: Lachmann
authors.forename: Anton H
authors.initials: AH
authors.lastname: van Kaam
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Haitsma
authors.forename: Burkhard
authors.initials: B
authors.lastname: Lachmann
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D018988:Bacterial Translocation; D015169:Colony Count, Microbial; D008168:Lung / Q000382:microbiology / Q000503:physiopathology; D018410:Pneumonia, Bacterial / Q000382:microbiology* / Q000503:physiopathology; D011175:Positive-Pressure Respiration; D013552:Swine