TABLE 1

The groups and subgroups of the present study

Group descriptionGroup abbreviation
Critically ill MV patients; active humidificationGroup P
 Active humidification turned on prior to and during EBC collection
  • +H

 Active humidification turned off
  • –H pooled

  … 10 min prior to and during EBC collection
  • –H10

  … 60 min prior to and during EBC collection
  • –H60

  … 60 min prior to and during EBC collection, and replacement of ventilator tubing prior to EBC collection
  • –H60T

  … 60 min prior to and during EBC collection, and replacement of ventilator tubing and humidifier chamber prior to EBC collection
  • –H60TH

MV surgical patients; passive humidificationGroup S, +Passive
Artificial lungs ventilated with V500 ventilators; active humidificationV500

The conditions of air humidification prior to and during EBC collection are described in the left-hand column, and the abbreviations for the groups in the right-hand column. The numbers and letters used in the abbreviations are underscored in their respective descriptions. Each EBC sample belongs in only one group, but some patients had EBC collected under more than one condition. EBC: exhaled breath condensate; MV: mechanically ventilated.