Volume recruitment and oxygenation in pulmonary edema: A comparison between HFOV and CMV

Jacob Iasha Sznajder*, Avi Nahum, David E. Hansen, G. Richard Long, Lawrence D H Wood

*Corresponding author for this work

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Purpose: In acute lung injury, edema floods alveoli decreasing mean lung volume (MLV) and increasing pulmonary venous admixture (Qva/Qt). We reasoned that a ventilatory strategy that uses large tidal volumes (VT) might recruit volume differently than a strategy that uses very small VT (high-frequency oscillatory ventilation, HFOV) which may require an inflation maneuver to total lung capacity (TLC) for full recruitment. Materials and Methods: We studied six dogs with pulmonary edema induced by oleic acid injury and compared HFOV with conventional mechanical ventilation (CMV). Increasing mean airway opening pressure (Pao) from 6 to 14 cm H2O raised MLV from 932 ± 162 to 1550 ± 210 mL and from 872 ± 145 to 1242 ± 192 mL during CMV and HFOV, respectively, whereas Qva/Qt decreased from 24.1 ± 8.5 to 9.3 ± 4.3% and from 42.2 ± 6.8 to 30.4 ± 9.3%. We repeated our measurements at a Pao of 14 cm H2O after an inflation maneuver to TLC. Results: Intlation to TLC recruited additional lung volume and decreased Qva/Qt further only during HFOV. After an inflation to TLC, we observed a rapid isobaric volume loss from the deflation limb of the pressure-volume curve during both CMV and HFOV. Conclusions: We conclude that after oleic acid injury in dogs pressure-volume hysteresis has two components: a recruitable portion associated with gas exchange improvement and a nonrecruitable portion. At the level of PEEP used in this study (8.5 cm H2O), full lung recruitment during HFOV required inflation to TLC, whereas during CMV it was accomplished by the relatively large VT.

Original languageEnglish (US)
Pages (from-to)126-135
Number of pages10
JournalJournal of Critical Care
Volume13
Issue number3
DOIs
StatePublished - Sep 1998

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine

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