Abstract

TREJO, Humberto et al. Effect of using several levels of Positive End-Expiratory Pressure over barotrauma’s induced lung injury in a model of isolated and perfused rabbit lungs.. Invest. clín [online]. 2006, vol.47, n.1, pp.49-64. ISSN 0535-5133.

The use of Positive end-expiratory pressure (PEEP) as a strategy of mechanical ventilation offers its advantages, such as improved oxygenation, without causing alveolar overstretching and barotrauma. We aim to investigate the effect of several levels of PEEP on barotrauma and, whether an optimal level of PEEP exists. Forty-eight New Zealand rabbits (2.5-3.5 kg) were divided into four groups with PEEP settings of 0, 4, 8 and 12 cmH₂O, at increasing levels of inspiratory volume (IV). This was done in blood perfused rabbit lungs and in lungs perfused with a Buffer-Albumin Solution. We observed that lungs ventilated with PEEP 0 cmH₂O suffered pulmonary rupture at high IV (300cc), with significant increases of Pap (Pulmonary artery pressure) and FFR (Fluid filtration rate). Lungs ventilated with PEEP 8 and 12 suffered pulmonary rupture at lower IV (200cc and 150cc vs. 300cc respectively) On the other hand, lungs ventilated with PEEP 4 cmH₂O reached the highest IV (400cc), in addition, they showed the lowest elevations of Pap and FFR. The acellular lungs ventilated with PEEP 4, 8 and 12 showed pulmonary rupture at lower IV when compared with cellular ones (300cc vs. 400cc: 100cc vs. 200cc and 100cc vs. 150cc respectively). We concluded that an optimal PEEP exists, which protects against barotrauma, however, excess of PEEP could enhance its development. The blood could contain some mediators which attenuate the damage induced by barotrauma

Keywords : Positive end-expiratory pressure (PEEP); ventilatory induced lung injury (VILI); inspiratory volume (IV); barotrauma; acute respiratory distress syndrome (ARDS); lung edema..