Alveolar fluid clearance in healthy pigs and influence of positive end-expiratory pressure

Abstract

IntroductionThe objectives were to characterize alveolar fluid clearance (AFC) in pigs with normal lungs and to analyze the effect of immediate application of positive end-expiratory pressure (PEEP).MethodsAnimals (n = 25) were mechanically ventilated and divided into four groups: small edema (SE) group, producing pulmonary edema (PE) by intratracheal instillation of 4 ml/kg of saline solution; small edema with PEEP (SE + PEEP) group, same as previous but applying PEEP of 10 cmH2O; large edema (LE) group, producing PE by instillation of 10 ml/kg of saline solution; and large edema with PEEP (LE + PEEP) group, same as LE group but applying PEEP of 10 cmH2O. AFC was estimated from differences in extravascular lung water values obtained by transpulmonary thermodilution method.ResultsAt one hour, AFC was 19.4% in SE group and 18.0% in LE group. In the SE + PEEP group, the AFC rate was higher at one hour than at subsequent time points and higher than in the SE group (45.4% vs. 19.4% at one hour, P < 0.05). The AFC rate was also significantly higher in the LE + PEEP than in the LE group at three hours and four hours.ConclusionsIn this pig model, the AFC rate is around 20% at one hour and around 50% at four hours, regardless of the amount of edema, and is increased by the application of PEEP.

Transpulmonary Thermodilution Enables to Detect Small Short-Term Changes in Extravascular Lung Water Induced by a Bronchoalveolar Lavage

“…Using transpulmonary thermodilution in pigs, Garcia-Delgado et al (21) found a slightly higher rate of decrease in EVLWI under levels of positive end-expiratory pressure similar to the ones we used. Using transpulmonary thermodilution in pigs, Garcia-Delgado et al (21) found a slightly higher rate of decrease in EVLWI under levels of positive end-expiratory pressure similar to the ones we used.…”

TIP peptide inhalation in experimental acute lung injury: effect of repetitive dosage and different synthetic variants

“…Patients suffering from a high-grade AFC impairment in early ARDS have significantly higher mortality rates [4]. The present model implies a sustained effect of the TIP peptide on the initial alveolar flooding, which, in the absence of recruitment or PEEP [18], is consistent with a resolution of oedema fluid. Hence, an early enhancement of the alveolar fluid clearance may not only reduce the lung water content but also lead to more homogenous lung tissue.…”

Prediction of pulmonary edema by plasma protein levels in patients with sepsis

“…Mechanical ventilation and the applied PEEP are also presumed to play an important role in pulmonary edema formation, but the empirical results are conflicting. Some studies show that the application of high PEEP causes more pulmonary edema formation and lung damage [27][28][29], whereas others show that higher PEEP results in less pulmonary edema by increasing alveolar fluid clearance [30]. These conflicting results reflect the complexity of the mechanisms underlying pulmonary edema formation.…”