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Manual ventilation and open suction procedures contribute to negative pressures in a mechanical lung model
  1. Espen Rostrup Nakstad1,2,
  2. Helge Opdahl1,
  3. Fridtjof Heyerdahl3,
  4. Fredrik Borchsenius2 and
  5. Ole Henning Skjønsberg2
  1. 1 Department of Acute Medicine, Oslo University Hospital, Ullevaal, Norway
  2. 2 Department of Pulmonary Medicine, Oslo University Hospital, Ullevaal, Norway
  3. 3 Department of Anesthesiology, Oslo University Hospital, Ullevaal, Norway
  1. Correspondence to Dr Espen Rostrup Nakstad; espen.nakstad{at}


Introduction Removal of pulmonary secretions in mechanically ventilated patients usually requires suction with closed catheter systems or flexible bronchoscopes. Manual ventilation is occasionally performed during such procedures if clinicians suspect inadequate ventilation. Suctioning can also be performed with the ventilator entirely disconnected from the endotracheal tube (ETT). The aim of this study was to investigate if these two procedures generate negative airway pressures, which may contribute to atelectasis.

Methods The effects of device insertion and suctioning in ETTs were examined in a mechanical lung model with a pressure transducer inserted distal to ETTs of 9 mm, 8 mm and 7 mm internal diameter (ID). A 16 Fr bronchoscope and 12, 14 and 16 Fr suction catheters were used at two different vacuum levels during manual ventilation and with the ETTs disconnected.

Results During manual ventilation with ETTs of 9 mm, 8 mm and 7 mm ID, and bronchoscopic suctioning at moderate suction level, peak pressure (PPEAK) dropped from 23, 22 and 24.5 cm H2O to 16, 16 and 15 cm H2O, respectively. Maximum suction reduced PPEAK to 20, 17 and 11 cm H2O, respectively, and the end-expiratory pressure fell from 5, 5.5 and 4.5 cm H2O to –2, –6 and –17 cm H2O. Suctioning through disconnected ETTs (open suction procedure) gave negative model airway pressures throughout the duration of the procedures.

Conclusions Manual ventilation and open suction procedures induce negative end-expiratory pressure during endotracheal suctioning, which may have clinical implications in patients who need high PEEP (positive end-expiratory pressure).

  • endotracheal suctioning
  • airway pressure
  • manual ventilation
  • Open suction procedure
  • bronchoscopy
  • closed catheter system
  • peak pressure
  • end-expiratory pressure

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  • Contributors HO helped design the study, participated in pretest measurements and worked extensively on manuscript and figure texts.

    FH participated in measurements and experimental procedures and did revision of the manuscript.

    FB helped design the study, was involved in the interpretation of pretest measurements and participated in the revision of the manuscript.

    OHS helped design the study, worked on the manuscript and did thorough revision of all text and figure legends.

    ERN (corresponding author) designed the study, made modifications to the lung model, did pretest measurements, carried out experimental procedures, drafted the manuscript and produced figures and legends.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Supplementary data files have been shared in a previous publication (reference 8).

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