Abstract
IntroductionMechanical ventilation with high positive end-expiratory pressure (PEEP) has been used in patients with acute respiratory distress syndrome (ARDS) and intra-abdominal hypertension (IAH), but the role of PEEP in minimizing lung injury remains controversial. We hypothesized that in the presence of acute lung injury (ALI) with IAH: 1) higher PEEP levels improve pulmonary morphofunction and minimize lung injury; and 2) the biological effects of higher PEEP are more effective in extrapulmonary (exp) than pulmonary (p) ALI.MethodsIn 48 adult male Wistar rats, ALIp and ALIexp were induced by Escherichia coli lipopolysaccharide intratracheally and intraperitoneally, respectively. After 24 hours, animals were anesthetized and mechanically ventilated (tidal volume of 6 mL/kg). IAH (15 mmHg) was induced and rats randomly assigned to PEEP of 5 (PEEP5), 7 (PEEP7) or 10 (PEEP10) cmH2O for 1 hour.ResultsIn both ALIp and ALIexp, higher PEEP levels improved oxygenation. PEEP10 increased alveolar hyperinflation and epithelial cell damage compared to PEEP5, independent of ALI etiology. In ALIp, PEEP7 and PEEP10 increased lung elastance compared to PEEP5 (4.3 ± 0.7 and 4.3 ± 0.9 versus 3.1 ± 0.3 cmH2O/mL, respectively, P <0.01), without changes in alveolar collapse, interleukin-6, caspase-3, type III procollagen, receptor for advanced glycation end-products, and vascular cell adhesion molecule-1 expressions. Moreover, PEEP10 increased diaphragmatic injury compared to PEEP5. In ALIexp, PEEP7 decreased lung elastance and alveolar collapse compared to PEEP5 (2.3 ± 0.5 versus 3.6 ± 0.7 cmH2O/mL, P <0.02, and 27.2 (24.7 to 36.8) versus 44.2 (39.7 to 56.9)%, P <0.05, respectively), while PEEP7 and PEEP10 increased interleukin-6 and type III procollagen expressions, as well as type II epithelial cell damage compared to PEEP5.ConclusionsIn the current models of ALI with IAH, in contrast to our primary hypothesis, higher PEEP is more effective in ALIp than ALIexp as demonstrated by the activation of biological markers. Therefore, higher PEEP should be used cautiously in the presence of IAH and ALI, mainly in ALIexp.
Highlights
Mechanical ventilation with high positive end-expiratory pressure (PEEP) has been used in patients with acute respiratory distress syndrome (ARDS) and intra-abdominal hypertension (IAH), but the role of PEEP in minimizing lung injury remains controversial
High PEEP used to keep lungs open may overdistend certain lung regions, resulting in increased lung injury. In view of these facts, we aimed to investigate the effects of different PEEP levels on arterial blood gases, lung mechanics and histology, as well as to identify biological markers associated with inflammation, apoptosis, fibrogenesis and damage inflicted to alveolar epithelial and endothelial cells in models of pulmonary acute lung injury (ALIp) and extrapulmonary acute lung injury (ALIexp) with IAH in rats
partial pressure of arterial oxygen (PaO2) and Est,L were comparable among groups at Baseline-zero end-expiratory pressure (ZEEP), regardless of ALI etiology (Table 1)
Summary
Mechanical ventilation with high positive end-expiratory pressure (PEEP) has been used in patients with acute respiratory distress syndrome (ARDS) and intra-abdominal hypertension (IAH), but the role of PEEP in minimizing lung injury remains controversial. The optimization of positive end-expiratory pressure (PEEP) plays a relevant role in preventing the development of ventilator-induced acute lung injury (VALI) in patients with acute respiratory distress syndrome (ARDS) [1]. Experimental and clinical studies have suggested that the etiology of ARDS (pulmonary and extra-pulmonary, ALIp and ALIexp, respectively) may affect the response to PEEP. According to those studies, in ALIp alveolar edema and tissue consolidation predominate, whereas ALIexp is associated with potentially recruitable alveolar collapse [2]. High PEEP used to keep lungs open may overdistend certain lung regions, resulting in increased lung injury
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
