Intensive Care Medicine

, 33:2109

Measurement of functional residual capacity by helium dilution during partial support ventilation: in vitro accuracy and in vivo precision of the method

  • Fabiano Di Marco
  • Lidia Rota Sperti
  • Barbara Milan
  • Riccardo Stucchi
  • Stefano Centanni
  • Laurent Brochard
  • Roberto Fumagalli
Original

DOI: 10.1007/s00134-007-0833-6

Cite this article as:
Di Marco, F., Rota Sperti, L., Milan, B. et al. Intensive Care Med (2007) 33: 2109. doi:10.1007/s00134-007-0833-6

Abstract

Objective

Measurement of functional residual capacity (FRC) during controlled and especially during assisted ventilation remains a challenge in the physiological evaluation of ventilated patients. To validate a bag-in-box closed helium dilution technique allowing measurements both during pressure-controlled (PCV) and pressure-support ventilation (PSV).

Design and setting

Experimental study on lung models containing different volumes, and measurements in patients in the intensive care unit of a university hospital. In patients measurements were performed in duplicate during controlled and assisted ventilation.

Patients

Thirty-three patients (aged 57 ± 17 years) mechanically ventilated with PCV and PSV.

Measurements and results

In the lung model assessment of accuracy showed an overall mean difference between FRC measurements and lung model volume of 0.5% (2 SD 5.7%). In patients assessment of repeatability showed a bias between duplicate FRC measurements of −1 ± 70 ml (95% CI −141 to +139 ml). The coefficient of variation was of 3.2% for all measurements with a comparable repeatability in PSV and PCV mode (coefficient of variation of 3.4 and 3.2%, respectively). During the rebreathing period a small reduction in tidal volume (−8.5 ± 5.4%) and mean airway pressure (−2.3 ± 4.7%) was observed with only a 0.3 cmH2O mean increase in PEEP and no change in respiratory rate and I/E ratio.

Conclusions

This specifically designed closed helium dilution bag-in-box technique allows accurate FRC measurement with good repeatability during both partial PSV and PVC without exposing patients to disconnection and changes in PEEP.

Keywords

Functional residual capacityMechanical ventilationPartial support ventilation

Supplementary material

134_2007_833_MOESM1_ESM.doc (122 kb)
Electronic Supplementary Material (DOC 123K)

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Fabiano Di Marco
    • 1
  • Lidia Rota Sperti
    • 2
  • Barbara Milan
    • 2
  • Riccardo Stucchi
    • 2
  • Stefano Centanni
    • 1
  • Laurent Brochard
    • 3
  • Roberto Fumagalli
    • 2
  1. 1.II Clinica di Malattie dell’Apparato Respiratorio, Ospedale San PaoloUniversità degli Studi di MilanoMilanItaly
  2. 2.Unità di Anestesia e Rianimazione, Azienda Ospedale S. Gerardo Monza, and Dipartimento di Medicina SperimentaleUniversità degli Studi Milano-BicoccaMilanItaly
  3. 3.Réanimation MédicaleHôpital Henri Mondor, AP-HPCréteilFrance