Evaluation of pressure/volume loops based on intratracheal pressure measurements during dynamic conditions

Sigurbergur Kárason*, S. SØndergaard, S. Lundin, J. Wlklund, O. Stenqvist

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


Background: The aim of this study was to evaluate and compare information about lung mechanics obtained by dynamic pressure/volume loops based on Y-piece and intratracheal airway pressure. Methods: Airway pressure was measured simultaneously at the Y-piece and trachea. Flow/tidal volume was measured by sidestream spirometry at the Y-piece. The effect of an intraluminal catheter in the tube was evaluated in a lung model. Ten adults with acute lung injury and mechanical ventilation were studied. Measurements were performed during volume-(VC) and pressure-controlled (PC) ventilation at different ventilator settings. Results: Lung model: There was a statistically significant difference (P<0.001) between trachea and Y-piece pressure/volume loop areas during both VC and PC ventilation. The ratio trachea area/Y-piece area decreased with increased endotracheal tube resistance (r=0.96). Patients: The difference between trachea and Y-piece P/V-loops was statistically significant at all 21 ventilatory settings (P<0.05-0.001). The tracheal loop revealed clearly intrinsic PEEP and lowered compliance during overinflation, which was difficult or impossible to see in the Y-piece pressure/volume loop. Conclusion: By measuring airway pressure at the trachea the effect of endotracheal tube resistance during inspiration is excluded while it is included during expiration, yielding correct end-points of inspiration and expiration. This makes it possible to calculate accurately total compliance of the respiratory system during dynamic conditions. By monitoring of airway pressure in the trachea, respiratory mechanics can be assessed more accurately and ventilatory settings adjusted to attenuate ventilator induced lung injury. (C) Acta Anaesthesiologica Scandinavica 44 (2000).

Original languageEnglish
Pages (from-to)571-577
Number of pages7
JournalActa Anaesthesiologica Scandinavica
Issue number5
Publication statusPublished - 2000

Other keywords

  • Airway pressure
  • Endotracheal tube resistance
  • Lung mechanics
  • Mechanical ventilation
  • Monitoring techniques
  • Pressure-volume curves


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