Real time noninvasive estimation of work of breathing using facemask leak-corrected tidal volume during noninvasive pressure support: validation study

  • Michael J. BannerEmail author
  • Carl G. Tams
  • Neil R. Euliano
  • Paul J. Stephan
  • Trevor J. Leavitt
  • A. Daniel Martin
  • Nawar Al-Rawas
  • Andrea Gabrielli
Original Research


We describe a real time, noninvasive method of estimating work of breathing (esophageal balloon not required) during noninvasive pressure support (PS) that uses an artificial neural network (ANN) combined with a leak correction (LC) algorithm, programmed to ignore asynchronous breaths, that corrects for differences in inhaled and exhaled tidal volume (VT) from facemask leaks (WOBANN,LC/min). Validation studies of WOBANN,LC/min were performed. Using a dedicated and popular noninvasive ventilation ventilator (V60, Philips), in vitro studies using PS (5 and 10 cm H2O) at various inspiratory flow rate demands were simulated with a lung model. WOBANN,LC/min was compared with the actual work of breathing, determined under conditions of no facemask leaks and estimated using an ANN (WOBANN/min). Using the same ventilator, an in vivo study of healthy adults (n = 8) receiving combinations of PS (3–10 cm H2O) and expiratory positive airway pressure was done. WOBANN,LC/min was compared with physiologic work of breathing/min (WOBPHYS/min), determined from changes in esophageal pressure and VT applied to a Campbell diagram. For the in vitro studies, WOBANN,LC/min and WOBANN/min ranged from 2.4 to 11.9 J/min and there was an excellent relationship between WOBANN,LC/breath and WOBANN/breath, r = 0.99, r2 = 0.98 (p < 0.01). There were essentially no differences between WOBANN,LC/min and WOBANN/min. For the in vivo study, WOBANN,LC/min and WOBPHYS/min ranged from 3 to 12 J/min and there was an excellent relationship between WOBANN,LC/breath and WOBPHYS/breath, r = 0.93, r2 = 0.86 (p < 0.01). An ANN combined with a facemask LC algorithm provides noninvasive and valid estimates of work of breathing during noninvasive PS. WOBANN,LC/min, automatically and continuously estimated, may be useful for assessing inspiratory muscle loads and guiding noninvasive PS settings as in a decision support system to appropriately unload inspiratory muscles.


Work of breathing Noninvasive Facemask Real-time corrections Tidal volume 



This work was supported by institutional/departmental funds and by Philips/Respironics, Inc.

Conflict of interest

Dr. Banner is a consultant for Convergent Engineering, developer of software used in the study. Dr. Euliano, President of Convergent Engineering, wrote software used in the study.


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Michael J. Banner
    • 1
    Email author
  • Carl G. Tams
    • 4
  • Neil R. Euliano
    • 4
  • Paul J. Stephan
    • 3
  • Trevor J. Leavitt
    • 4
  • A. Daniel Martin
    • 1
    • 2
  • Nawar Al-Rawas
    • 1
  • Andrea Gabrielli
    • 1
  1. 1.Department of AnesthesiologyUniversity of Florida College of MedicineGainesvilleUSA
  2. 2.Department of Physical Therapy, College of Public Health and Health ProfessionsUniversity of FloridaGainesvilleUSA
  3. 3.Santa Fe CollegeGainesvilleUSA
  4. 4.Convergent EngineeringNewberryUSA

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