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Critical Care

, 4:P123 | Cite as

Influence of different PEEP levels and tidal volumes on the regional nonaerated tissue: experimental study

  • N Bottino
  • G Eccher
  • P Pelosi
  • A McKibben
  • A Adams
  • M Goldner
  • JJ Marini
  • L Gattinoni
Meeting abstract

Keywords

Oleic Acid Hydrostatic Pressure Tidal Volume Acute Respiratory Distress Syndrome Lower Region 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Full text

Introduction

In the Acute Respiratory Distress Syndrome (ARDS), although the edema is homogeneously distributed, a hydrostatic pressure gradient squeezes the gas out from the alveoli, causing a lung density increase along a gravity gradient. We studied by CT scan, in an oleic acid induced ARDS experimental model, the influence of different VT and PEEP levels on the regional nonaerated tissue during volume-controlled ventilation.

Methods

ARDS was induced in six sedated, paralyzed and mechanically-ventilated dogs by an oleic acid dose (0.075 mg/kg) injected into the pulmonary circulation. After ARDS induction, the volume-controlled ventilation was maintained, changing three tidal volumes (VT) (12, 24 and 36 ml/kg) and two PEEP levels (5 and 15 cmH2O).During each of the six randomized steps a CT scan section has been taken, at end-expiration and end-inspiration, 5 cm above the diaphragm. For data analysis, we divided the CT scan section into an upper and a lower part. The nonaerated tissue mass of the upper or lower region was calculated from the densities (ρ) (-200 H <CT <+100 H) and the volume (V), according to the formula m=ρ×V [1]; then it was standardized for the area of each lung region. To evaluate the effect of VT, PEEP level and lung region (upper/lower) on the amount of nonaerated tissue, we performed analysis of variance, in condition of end-expiration and end-inspiration, respectively.

Results

The behavior of nonaerated tissue (g/cm2) is shown in the table (data expressed as mean ± SD).

The amount of nonaerated tissue is greater in the lower region than in the upper one, in both end-expiration and end-inspiration (P<0.01). In both regions PEEP and VT independently affect the amount of nonaerated tissue (P<0.01). There is interaction between PEEP and VT only at end-inspiration (end-expiration: P=n.s.; end-inspiration: P<0.01).

Conclusion

The effects of PEEP level and VT on lung recruitment are greater in dependent lung regions and at end-inspiration.

Table

  

5, low VT

5, normal VT

5, high VT

15, low VT

15, normal VT

15, high VT

upper

end-exp.

0.14± 0.08

0.12± 0.07

0.17± 0.14

0.06± 0.02

0.05± 0.03

0.06± 0.02

 

end-insp.

0.06± 0.03

0.05± 0.03

0.05± 0.03

0.05± 0.02

0.05± 0.03

0.04± 0.02

lower

end-exp.

0.81± 0.05

0.70± 0.11

0.55± 0.19

0.29± 0.14

0.20± 0.10

0.12± 0.04

 

end-insp.

0.68± 0.05

0.42± 0.07

0.21± 0.17

0.24± 0.12

0.10± 0.05

0.05± 0.03

References

  1. 1.
    Pelosi P, et al.: . Am J Respir Crit Care Med 1994, 149: 8.PubMedCrossRefGoogle Scholar

Copyright information

© Current Science Ltd 2000

Authors and Affiliations

  • N Bottino
    • 1
  • G Eccher
    • 1
  • P Pelosi
    • 3
  • A McKibben
    • 2
  • A Adams
    • 2
  • M Goldner
    • 2
  • JJ Marini
    • 2
  • L Gattinoni
    • 1
  1. 1.1st. Anestesia e RianimazioneOsp. Maggiore Policlinico-IRCCSMilanoItaly
  2. 2.University of MinnesotaSt PaulUSA
  3. 3.Dip. Scienze Cliniche e BiologicheUniv. dell'InsubriaSt VareseItaly

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