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Periodic Fluctuation of Tidal Volumes Further Improves Variable Ventilation in Experimental Acute Respiratory Distress Syndrome.
- Source :
-
Frontiers in physiology [Front Physiol] 2018 Jul 12; Vol. 9, pp. 905. Date of Electronic Publication: 2018 Jul 12 (Print Publication: 2018). - Publication Year :
- 2018
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Abstract
- In experimental acute respiratory distress syndrome (ARDS), random variation of tidal volumes ( V <subscript> T </subscript> ) during volume controlled ventilation improves gas exchange and respiratory system mechanics (so-called stochastic resonance hypothesis). It is unknown whether those positive effects may be further enhanced by periodic V <subscript> T </subscript> fluctuation at distinct frequencies, also known as deterministic frequency resonance. We hypothesized that the positive effects of variable ventilation on lung function may be further amplified by periodic V <subscript> T </subscript> fluctuation at specific frequencies. In anesthetized and mechanically ventilated pigs, severe ARDS was induced by saline lung lavage and injurious V <subscript> T </subscript> (double-hit model). Animals were then randomly assigned to 6 h of protective ventilation with one of four V <subscript> T </subscript> patterns: (1) random variation of V <subscript> T </subscript> (WN); (2) P <subscript>04</subscript> , main V <subscript> T </subscript> frequency of 0.13 Hz; (3) P <subscript>10</subscript> , main V <subscript> T </subscript> frequency of 0.05 Hz; (4) VCV, conventional non-variable volume controlled ventilation. In groups with variable V <subscript> T </subscript> , the coefficient of variation was identical (30%). We assessed lung mechanics and gas exchange, and determined lung histology and inflammation. Compared to VCV, WN, P <subscript>04</subscript> , and P <subscript>10</subscript> resulted in lower respiratory system elastance (63 ± 13 cm H <subscript>2</subscript> O/L vs. 50 ± 14 cm H <subscript>2</subscript> O/L, 48.4 ± 21 cm H <subscript>2</subscript> O/L, and 45.1 ± 5.9 cm H <subscript>2</subscript> O/L respectively, P < 0.05 all), but only P <subscript>10</subscript> improved PaO <subscript>2</subscript> /F <subscript>I</subscript> O <subscript>2</subscript> after 6 h of ventilation (318 ± 96 vs. 445 ± 110 mm Hg, P < 0.05). Cycle-by-cycle analysis of lung mechanics suggested intertidal recruitment/de-recruitment in P <subscript>10</subscript> . Lung histologic damage and inflammation did not differ among groups. In this experimental model of severe ARDS, periodic V <subscript> T </subscript> fluctuation at a frequency of 0.05 Hz improved oxygenation during variable ventilation, suggesting that deterministic resonance adds further benefit to variable ventilation.
Details
- Language :
- English
- ISSN :
- 1664-042X
- Volume :
- 9
- Database :
- MEDLINE
- Journal :
- Frontiers in physiology
- Publication Type :
- Academic Journal
- Accession number :
- 30050467
- Full Text :
- https://doi.org/10.3389/fphys.2018.00905