Abstract Rationale Mechanical chest compressions during cardiopulmonary resuscitation (CPR) generate hydrostatic lung edema described as cardiopulmonary resuscitation-associated lung edema (CRALE), but whether molecular injury pathways are activated concurrently remains uncertain. We hypothesized that proteomic signatures of epithelial–endothelial barrier stress emerge early after CPR, compounding rapid hydrostatic edema, providing a mechanistic link that may help understand the high incidence of acute respiratory distress syndrome (ARDS) in post-CPR survivors. Methods Bronchoalveolar lavage fluid (BALF) was collected from the right and left lungs of eight pigs before and immediately after return of spontaneous circulation (or a maximum of 45 minutes of CPR) following experimental cardiac arrest and CPR (IACUC #2022-0135). Proteins were digested, tandem-mass-tag labeled (TMT-18plex), and analyzed by high-resolution LC–MS/MS. Differentially abundant proteins (DAPs) were defined by fold change 1.5 or 0.67 and P 0.05. Pathway enrichment was performed using STRING and DAVID. Representative sections from three pigs from the caudal right and left caudal lung lobes were stained with H&E and Phosphotungstic Acid Hematoxylin (PTAH, fibrin staining) to correlate molecular and histologic changes. Selected protein (PAI-1) was validated by Western blot. Results Over 1,000 proteins were identified per lung. Seventy-four and seventy-five DAPs distinguished pre- and post-CPR BALF from left and right lungs, respectively. Scatter (Fig. 1A) and Volcano plots (Fig. 1B) revealed numerous up- and downregulated proteins, reflecting distinct but overlapping proteomic responses between lungs. Within the most upregulated species were Serpin family E member 1 (SERPINE1/PAI-1), Apolipoprotein A1 (APOA1), several members of the Inter-alpha-trypsin inhibitor heavy chain family (ITIH), vitronectin (VTN), and soluble receptor for advanced glycation end products (sRAGE), with variations across both lungs. Pathway enrichment indicated early activation of complement and coagulation cascades, platelet degranulation, lipid metabolism, and extracellular matrix–receptor interaction networks. Histology revealed preserved parenchymal architecture with mild septal and vascular neutrophil expansion, interstitial edema, and patchy fibrin deposition, findings consistent with early pneumocyte injury and mild inflammation. Densitometric analysis showed that PAI-1 intensity increased by approximately two-to three-fold post-CPR in both left and right lung BALF pools. Conclusions Unbiased BALF proteomics identified relevant molecular responses to CPR characterized by antifibrinolytic activation, complement upregulation, and epithelial–endothelial barrier stress. These findings suggest that the hydrostatic edema described with CRALE may coexist with an early coupled mechanical–molecular phase of injury. Recognition of this phase may help develop early interventions to limit post-resuscitation lung injury and optimize ventilatory management. This abstract is funded by: Cornell University Multi-investigator seed grant
Araos et al. (Fri,) studied this question.