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  • Poster presentation
  • 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