Short time effects of compliance guided flow-controlled ventilation versus standard of care pressure-controlled ventilation: a prospective porcine trial.

Background: Flow-controlled ventilation (FCV) represents a novel ventilation method, which guarantees a continuous gas flow during inspiration and expiration. Long term comparison to volume- and pressure-controlled ventilation (PCV) after five- and ten hours have shown improved gas exchange parameters and lung tissue aeration. Aim of this porcine trial was to compare gas exchange parameters and lung tissue aeration in short time application of FCV compared to PCV to determine effects which will most probably pertain in short lasting procedures under general anesthesia.
Methods: After induction of general anesthesia nine pigs were randomly ventilated either with compliance guided FCV settings or standard of PCV with compliance titrated positive end-expiratory pressure and peak pressure set to achieve a tidal volume of 7 mL/kg. Subsequently an arterial blood gas sample was obtained, and a computed tomography scan was performed. Afterwards, each animal was extubated and on the following day the same protocol was performed again with the alternative ventilation method.
Results: Primary analysis of 18 datasets from nine animals (with paired comparison) revealed a significantly improved oxygenation with FCV compared to control (paO<inf>2</inf> 118 vs. 109, 95% CI 2 to 16 mm Hg; P=0.042). The required respiratory minute volume was significantly lower with FCV (7.4 vs. 10.8, 95% CI -4.0 to -2.9 L/min; P<0.001) to achieve similar levels of normocapnia. However, lung tissue aeration did not significantly differ between ventilation methods.
Conclusions: In this short-term ventilation comparison FCV improved gas exchange parameters without differences in lung tissue aeration compared to PCV.