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  • Open Access

Oxygenation correlates with lung aeration during unsupported spontaneous breathing in porcine lung collapse model

  • 1,
  • 1,
  • 1 and
  • 1
Critical Care201216 (Suppl 1) :P121

  • Published:


  • Mechanical Ventilation
  • Respiratory Rate
  • Lung Tissue
  • Rank Correlation
  • Tidal Volume


We investigated whether oxygenation correlates with lung aeration during unsupported spontaneous breathing (SB) and mechanical ventilation (MV) in a porcine lung collapse model.


In 14 anesthetized supine piglets, lung collapse was induced by negative pressure application (NPA) to the endotracheal tube. Eight animals resumed SB 5 minutes after NPA, six animals were kept on MV at a respiratory rate and tidal volume corresponding to SB. Thoracic CTs and arterial blood gases were taken 2.5 and 30 minutes after NPA. Spearman rank correlation was used for testing; values are given as mean (95% CI).


Thirty minutes after NPA the amount of lung tissue in collapsed regions was similar in both groups (MV: 40% (36 to 44), SB: 35% (26 to 43); P = 0.22). Resuming SB, PaO2/FiO2 improved significantly more with less amount of collapsed lung tissue 2.5 minutes after NPA (r = -0.87, P = 0.033). During SB a significant negative correlation between PaO2/FiO2 and the amount of collapsed lung tissue (r = -0.76, P = 0.038) was observed; no such correlation could be seen during MV (r = -0.3, P = 0.2) (Figure 1).
Figure 1
Figure 1

PaO 2 /FiO 2 plotted against the proportion of atelectatic lung tissue. Open circles, SB; solid circles, MV.


In porcine lung collapse PaO2/FiO2 correlates with lung aeration during unsupported SB, but not during MV at a similar breathing pattern. The less lung collapse the animals have, the more PaO2/FiO2 improves resuming SB.

Authors’ Affiliations

Uppsala University, Uppsala, Sweden


  1. Cressoni M, Caironi P, Polli F, et al.: Anatomical and functional intrapulmonary shunt in acute respiratory distress syndrome. Crit Care Med 2008, 36: 669-675. 10.1097/01.CCM.0000300276.12074.E1View ArticlePubMedGoogle Scholar


© Vimlati et al.; licensee BioMed Central Ltd. 2012

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.