title: Can ventilator settings reduce the negative effects of endotracheal suctioning? Investigations in a mechanical lung model.
abstract: The insertion of suction devices through endotracheal tubes (ETTs) increases airway resistance and the subsequent suctioning may reduce airway pressures and facilitate atelectasis. The aim of this study was to investigate how airway pressures and tidal volumes change when different combinations of suction equipment and ETT sizes are used, and to what extent unfavorable effects can be ameliorated by choice of ventilator settings.
  
  
  
  A mechanical ventilator was connected to a lung model by ETTs of 9 mm, 8 mm or 7 mm internal diameter (ID) with a pressure transducer inserted distal to the ETT. The effects of suction procedures with bronchoscope and closed catheter systems were investigated during pressure controlled ventilation (PCV) and volume controlled ventilation (VCV). In each mode, the effects of changes in inspiration:expiration (I:E) ratio, trigger sensitivity and suction pressure were examined.
  
  
  
  The variables that contributed most to negative model airway pressures and loss of tidal volume during suctioning were (in descending order); 1) Small-size ETTs (7-8 mm ID) combined with large diameter suction devices (14-16 Fr); 2) inverse I:E ratio ventilation (in VCV); 3) negative ventilator trigger sensitivity; and 4) strong suction pressure. The pressure changes observed distal to the ETTs were not identical to those detected by the ventilator.
  
  
  
  Negative model airway pressure was induced by suctioning through small-size ETTs. The most extreme pressure and volume changes were ameliorated when conventional ventilator settings were used, such as PCV mode with short inspiration time and a trigger function sensitive to flow changes.
authors.affiliation: Department of Acute Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway. espen.nakstad@gmail.com.|Department of Pulmonary Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway. espen.nakstad@gmail.com.
authors.forename: Espen R
authors.initials: ER
authors.lastname: Nakstad
authors.affiliation: Department of Acute Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway.
authors.forename: Helge
authors.initials: H
authors.lastname: Opdahl
authors.affiliation: Department of Acute Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway.
authors.forename: Fridtjof
authors.initials: F
authors.lastname: Heyerdahl
authors.affiliation: Department of Pulmonary Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Borchsenius
authors.affiliation: Department of Pulmonary Medicine, Oslo University Hospital, Ullevaal, Oslo, Norway.|University of Oslo, Oslo, Norway.
authors.forename: Ole H
authors.initials: OH
authors.lastname: Skjønsberg
mesh_terms: D000403:Airway Resistance; D006801:Humans; D007442:Intubation, Intratracheal / Q000009:adverse effects* / Q000379:methods; D008954:Models, Biological; D012121:Respiration, Artificial / Q000379:methods*; D013396:Suction / Q000009:adverse effects* / Q000379:methods*; D013990:Tidal Volume; D012122:Ventilators, Mechanical
keywords: Airway pressure; AutoPEEP; Bronchoscopic suctioning; Closed Catheter System; End-expiratory pressure; Endotracheal suctioning; High frequency trigging; Peak pressure; Pressure Controlled Ventilation; Ventilator; Volume Controlled Ventilation