Alveolar preservation with high inflation pressure and intermediate oxygen concentration reduces ischemia-reperfusion injury of the lung

Background: This study investigated the optimal alveolar oxygen concentration and inflation pressure during ischemia that reduces lung ischemia-reperfusion injury (LIRI). Methods: Male Sprague-Dawley rats (n = 66) underwent 150 minutes of left lung ischemia by hilar clamping at an airway inflation pressure (P) of 5 or 30 cm H 2O and an oxygen (O) concentration of 0%, 30%, or 100% (P 5O 0, P 5O 30, P 5O 100, P 30O 0, P 30O 30 and P 30O 100 groups). Lungs preserved with 0% oxygen were inflated with 100% nitrogen. Measurements of arterial blood gas values, pulmonary compliance, histology, flow cytometry of bronchoalveolar lavage fluid were performed on day 2 postoperatively. Results: Inflation with 30 cm H 2O resulted in increased partial pressure of arterial oxygen (Pao 2) and lung compliance, decreased diffuse alveolar damage, and less infiltration of CD4 + and CD8 + lymphocytes and major histocompatibility complex class II-positive (MHCII +) antigen-presenting cells (APCs) in the left lung on day 2 compared with clamping at an airway inflation pressure of 5 cm H 2O. The 100% oxygen groups demonstrated a lower Pao 2 and a decreased pulmonary compliance than 30% oxygen groups. More CD8 + lymphocytes and MHCII + APCs were found in the P 5O 100 group than in the P 5O 0 and P 5O 30 groups. Conclusion: Alveolar inflation with a pressure of 30 cm H 2O and an oxygen concentration of 30% decreases the severity of LIRI. The protective effect is mainly due to hyperinflation and, to a lesser extent, through oxygen concentration.

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