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Critical Care

Open Access

Strain threshold for ventilator-induced lung injury

  • A Santini1,
  • A Protti1,
  • M Cressoni1,
  • T Langer1,
  • D Febres1,
  • G Conte2,
  • L Lombardi3,
  • M Lattuada3,
  • P Taccone3 and
  • L Gattinoni1
Critical Care201115(Suppl 1):P198

Published: 1 March 2011


Public HealthCompute TomographyEmergency MedicineLung InjuryWeight Change


Unphysiological lung strain (tidal volume/functional residual capacity, TV/FRC) may cause ventilator-induced lung injury (VILI) [1]. Whether VILI develops proportionally to the applied strain or only above a critical threshold remains unknown.


In 20 healthy, mechanically ventilated pigs, FRC and lung weight were measured by computed tomography. Animals were then ventilated for up to 54 hours with a TV set to produce a predetermined strain. At the end, lung weight was measured with a balance. VILI was defined as final lung weight exceeding the initial one.


Lung weight either did not increase at all (no-VILI group; lung weight change -73 ± 42 g, n = 9) or markedly augmented (VILI group; 264 ± 80 g, n = 11). In the two groups, strain was 1.38 ± 0.68 and 2.16 ± 0.50 (P < 0.01), respectively. VILI occurred only when lung strain reached or exceeded a critical threshold, between 1.5 and 2.1 (Figure 1).
Figure 1



In animals with healthy lungs VILI only occurs when lung strain exceeds a critical threshold.

Authors’ Affiliations

Dipartimento di Anestesiologia e Terapia Intensiva, Università degli Studi di Milano, Milan, Italy
Università degli Studi di Milano, Centro Ricerche Chirurgiche Precliniche, Milan, Italy
Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy


  1. Gattinoni L, Carlesso E, Cadringher P, et al.: Physical and biological triggers of ventilator-induced lung injury and its prevention [review]. Eur Respir J 2003,22(Suppl 47):15s-25s.View ArticleGoogle Scholar


© Santini et al. 2011

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.