Pulmonary lesion induced by low and high positive end-expiratory pressure levels during protective ventilation in experimental acute lung injury

Abstract

In the present nonrecruited ALI model, protective mechanical ventilation with lower and higher PEEP levels than required for better oxygenation increased Est, L and DeltaP2, L, the amount of atelectasis, and PCIII mRNA expression. PEEP selection titrated for a minimum elastance and maximum oxygenation may prevent lung injury while deviation from these settings may be harmful.

Lung recruitment maneuver effects on respiratory mechanics and extravascular lung water index in patients with acute respiratory distress syndrome

“…Low-tidal-volume ventilation as a fundamental treatment of ARDS can reduce the mortality of severe ARDS and also lead to some alveolar hyperventilation, and even alveolar collapse. [5,6] Animal experiments showed that RM and protective ventilation of the lung in ARDS rabbits improved oxygenation and reduced extravascular lung water index. [7][8][9] Pulse contour continuous cardiac output (PICCO) is the only technology that can provide a quantitative indicator of EVLW at the bedside.…”

Effects of different tidal volumes in pulmonary and extrapulmonary lung injury with or without intraabdominal hypertension

“…Each electron microscopy image (15/animal) was analyzed for damage to the alveolar capillary membrane, type II pneumocyte, and endothelial cells. Pathological findings were graded according to a 5-point semi-quantitative severity-based scoring system as: 0 = normal lung parenchyma, 1 = 1-25%, 2 = 26-50%, 3 = 51-75%, and 4 = 76-100% of examined tissue [8,10,14].…”

“…IL-6, IL-1b, and caspase-3 mRNA expressions in lung were analyzed because of their role as mediators in the pathogenesis of ventilator induced lung injury [20]. The expression of PCIII mRNA was evaluated in lung tissue because it is the first collagen to be remodeled in the development/course of lung fibrogenesis [21], and also an early marker of lung parenchyma remodeling [13,14,22].…”

“…We cannot rule out that different results could have been obtained at higher PEEP levels and/or if recruitment maneuvers were applied; (5) respiratory rate was kept constant, since its increase has been reported to be associated with the release of inflammatory mediators [12]; (6) inflammatory mediators, apoptosis, and fibrogenetic response were measured in lung tissue but not in the blood; (7) anti-inflammatory responses were not evaluated; and (8) since the observation time was relatively short (1 h mechanical ventilation), the expression of mediators was quantified using RT-PCR instead of ELISA. In this line, it is well known that 1 h is sufficient time to produce changes in mRNA expression, but not to significantly change the level of protein [8,10,[12][13][14]22].…”

New and Conventional Strategies for Lung Recruitment in Acute Respiratory Distress Syndrome

“…However, the reduction in V T may result in alveolar derecruitment, cyclic opening and closing of atelectatic alveoli and distal small airways leading to ventilator-induced lung injury (VILI) if inadequate low positive end-expiratory pressure (PEEP) is applied [4]. On the other hand, high PEEP levels may be associated with excessive lung parenchyma stress and strain [5] and negative hemodynamic eff ects, resulting in systemic organ injury [6]. Th erefore, lung recruitment maneuvers have been proposed and used to open up collapsed lung, while PEEP counteracts alveolar derecruitment due to low V T ventilation [4].…”