Intensive Care Medicine

, Volume 36, Issue 4, pp 648–655

Estimation of inspiratory muscle pressure in critically ill patients

  • Eumorfia Kondili
  • Christina Alexopoulou
  • Nectaria Xirouchaki
  • Katerina Vaporidi
  • Dimitris Georgopoulos



Recently, a new technology has been introduced aiming to monitor and improve patient ventilator interaction (PVI monitor). With the PVI monitor, a signal representing an estimation of the patient’s total inspiratory muscle pressure (PmusPVI) is calculated from the equation of motion, utilizing estimated values of resistance and elastance of the respiratory system.


The aim of the study was to prospectively examine the accuracy of PmusPVI to quantify inspiratory muscle pressure.

Methods and interventions

Eleven critically ill patients mechanically ventilated on proportional assist ventilation with load-adjustable gain factors were studied at three levels of assist (30, 50 and 70%). Airway, esophageal, gastric and transdiaphragmatic (Pdi) pressures, volume and flow were measured breath by breath, whereas the total inspiratory muscle pressure (Pmus) was calculated using the Campbell diagram.


For a given assist, PmusPVI throughout inspiration did not differ from the corresponding values calculated using the Pdi and Pmus signals. Inspiratory and expiratory time did not differ among the various methods of calculation. Inspiratory muscle pressure decreased with increasing assist, and the magnitude of this decrease did not differ among the various methods of pressure calculation.


A signal generated from flow, volume and airway pressure may be used to provide breath-by-breath quantitative information of inspiratory muscle pressure.


Transdiaphragmatic pressure Resistance Elastance Mechanical ventilation 

Supplementary material

134_2010_1753_MOESM1_ESM.doc (70 kb)
Supplementary material (DOC 70 kb)
134_2010_1753_MOESM2_ESM.ppt (542 kb)
Supplementary material (PPT 541 kb)


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Copyright information

© Copyright jointly hold by Springer and ESICM 2010

Authors and Affiliations

  • Eumorfia Kondili
    • 1
  • Christina Alexopoulou
    • 1
  • Nectaria Xirouchaki
    • 1
  • Katerina Vaporidi
    • 1
  • Dimitris Georgopoulos
    • 1
  1. 1.Intensive Care Medicine DepartmentUniversity Hospital of Heraklion, Medical School, University of CreteCreteGreece

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