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Volume 3 Supplement 1


  • Oral presentation
  • Open Access

Impact of The Assist Ventilation Mode On Work of Breathing (Wob): Neurally Adjusted Ventilatory Assist (Nava) Versus Pressure Support Ventilation (Psv) Versus Proportional Assist Ventilation Plus (Pav+)

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Intensive Care Medicine Experimental20153 (Suppl 1) :A9

  • Published:


  • Pressure Support Ventilation
  • Ventilation Mode
  • Mode Algorithm
  • Airway Opening
  • Ventilation Duration


During assisted mechanical ventilation, appropriate WOB prevents diaphragm atrophy and fastens weaning. During PSV the ventilator support is fixed, irrespective of the patient's effort. On the contrary, both the NAVA and PAV + algorithms are designed to amplify patient's spontaneous effort. [1], [2]


To test if the assist ventilation mode algorithm has an impact on patient's WOB.


In 12 patients NAVA, PSV and PAV+ were randomly applied in a crossover fashion, for 4 hours each. The electrical diaphragmatic activity (EAdi) was continuously recorded during all the modes. WOB per breath (WOBBREATH) was estimated by converting the EAdi pressure time product (PTP)/breath in muscular PTP/breath (PTPBREATH). The conversion factor was the ratio between EAdi peak and airway opening pressure negative peak during an end-expiratory occlusion.


See figure 1
Figure 1
Figure 1

PTP,breath vs time in the three ventilatory modes . Red lines: range of physiological PTP BREATH


PTPBREATH was in the physiological range during NAVA and PAV + whereas during PSV remained constantly below it. We speculate that, as compared to PSV, NAVA and PAV+ favored a correct matching between diaphragm contraction and ventilator assistance. Further studies are required to test if the WOB pattern during assisted ventilation has an impact on mechanical ventilation duration and other clinically meaningful outcome parameters.

Authors’ Affiliations

Università degli Studi di Bari 'Aldo Moro', Dipartimento dell'Emergenza e dei Trapianti d'Organo, Bari, Italy
Università di Ferrara, Department of Morphology, Surgery and Experimental Medicine, Ferrara, Italy


  1. Sinderby C, Navalesi P, Beck J, Skrobik Y, Comtois N, Friberg S, Gottfried SB, Lindström L: Neural control of mechanical ventilation in respiratory failure. Nat Med. 1999, 5 (12): 1433-6. 10.1038/71012. DecPubMedView ArticleGoogle Scholar
  2. Younes M: Proportional assist ventilation, a new approach to ventilatory support. Theory Am Rev Respir Dis. 1992, 145 (1): 114-20. 10.1164/ajrccm/145.1.114. JanPubMedView ArticleGoogle Scholar
  3. Bellani G, Mauri T, Coppadoro A, Grasselli G, Patroniti N, Spadaro S, Sala V, Foti G, Pesenti A: Estimation of patient´s inspiratory effort from the electrical activity of the diaphragm. Crit Care Med. 2013, 41 (6): 1483-91. 10.1097/CCM.0b013e31827caba0. JunPubMedView ArticleGoogle Scholar


© Di Mussi et al.; 2015

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.