Effect of different tidal volumes and PEEP levels on gas exchange and FRC

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The effect of PEEP on improving oxygenation and FRC is well known [1], not so the effects of PEEP and tidal volumes on gas exchange and FRC.

The aim of this study was to evaluate the effect of three different levels of tidal volume (300, 600, 900 ml) and PEEP (5, 10, 15 cmH₂O) on gas exchange and FRC. We studied nine intubated sedated and paralyzed patients (5 males) in controlled volume ventilation with respiratory failure in the early phase of the disease. Baseline clinical characteristics: age 60± 19 years, weight 72± 10 kg, PaO₂/FiO₂ 240± 101, PEEP level of 10 cmH₂O. FRC was measured with the Helium dilution technique during an end-expiratory pause. Data are expressed as mean ± sd.

Moreover, we found a significant correlation between PaO₂ and FRC in every considered conditions (r =0.61, P<0.05).

Our results showed that both the level of PEEP and the level of tidal volume, but not their interaction, have a significant effect on improving FRC and gas exchange.

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