title: Repeated open endotracheal suctioning causes gradual desaturation but does not exacerbate lung injury compared to closed endotracheal suctioning in a rabbit model of ARDS.
abstract: BACKGROUND
  Although endotracheal suctioning induces alveolar derecruitment during mechanical ventilation, it is not clear whether repeated endotracheal suctioning exacerbates lung injuries. The present study aimed to determine whether repeated open endotracheal suctioning (OS) exacerbates lung injury compared to closed endotracheal suctioning (CS) during mechanical ventilation in an animal model of acute respiratory distress syndrome (ARDS).
  
  
  METHODS
  Briefly, thirty six Japanese white rabbits were initially ventilated in pressure-controlled mode with a constant tidal volume (6 mL/kg). Then, lung injury was induced by repeated saline lavage. The rabbits were divided into four groups, namely: a) OS; b) CS; c) control with ARDS only; d) and healthy control (HC) without ARDS. Animals in all the groups were then ventilated with positive end expiratory pressure (PEEP) at 10 cm H2O. CS was performed using 6 French-closed suctioning catheters connected to endotracheal tube under the following conditions: a) a suctioning time and pressure of 10 sec and 140 mm Hg, respectively; and b) a suction depth of 2 cm (length of adapter) plus tracheal tube. OS was performed using the same conditions described for CS, except the ventilator was disconnected from the animals. Each endotracheal suctioning was performed at an interval of 30 min.
  
  
  RESULTS
  PaO2/FIO2 (P/F) ratio for CS, control and HC groups remained at >400 for 6 hours, whereas that of the OS group progressively declined to 300 (p < 0.05), with each suctioning. However, no difference was observed either in lung injury score (histology) or in the expression pattern of inflammatory cytokines (tumor necrosis factor-α and interleukin-6) after 6 hours between the OS and CS groups in the circulatory as well as the pulmonary tissues.
  
  
  CONCLUSIONS
  Progressive arterial desaturation under conditions of repeated endotracheal suctioning is greater in OS than in CS time-dependently. However, OS does not exacerbate lung injury during mechanical ventilation when observed over a longer time span (6 hours) of repeated endotracheal suctioning, based on morphological and molecular analysis.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Sakuramoto
authors.forename: Nobutake
authors.initials: N
authors.lastname: Shimojo
authors.forename: Subrina
authors.initials: S
authors.lastname: Jesmin
authors.forename: Takeshi
authors.initials: T
authors.lastname: Unoki
authors.forename: Junko
authors.initials: J
authors.lastname: Kamiyama
authors.forename: Masami
authors.initials: M
authors.lastname: Oki
authors.forename: Ken
authors.initials: K
authors.lastname: Miya
authors.forename: Satoru
authors.initials: S
authors.lastname: Kawano
authors.affiliation: Department of Emergency and Critical Care Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan. mizutani@md.tsukuba.ac.jp.
authors.forename: Taro
authors.initials: T
authors.lastname: Mizutani