Dexmedetomidine Dose-Dependent Modulation of Lung Function and AQP1 Expression During One-Lung Ventilation in Adults Undergoing Thoracoscopic Surgery.

BACKGROUND This randomized controlled trial evaluated the dose-dependent effects of dexmedetomidine (DEX) on pulmonary function and aquaporin-1 (AQP1) expression during one-lung ventilation (OLV) in thoracoscopic surgery. MATERIAL AND METHODS Sixty patients were randomized into 3 groups in this single-center, double-blind trial: Control (Group C, saline), DEX 0.3 µg/kg/h (Group D1), and DEX 0.5 µg/kg/h (Group D2). Serum TNF-alpha/IL-8 levels were measured at 5 perioperative timepoints. Respiratory indices [respiratory index (RI), oxygenation index (OI), and dynamic lung compliance (Cdyn)] were calculated. Post-resection AQP1 expression in isolated lung tissue was assessed via semi-quantitative immunohistochemistry by 2 blinded pathologists (excellent agreement, kappa=0.82). Pearson correlation analysis was performed to assess relationships between AQP1 scores and TNF-alpha/IL-8 levels at OLV90 min. RESULTS Compared to Groups C and D1, Group D2 exhibited lower IL-8 and RI starting at OLV90 min and TNF-a at OLV120 min and 30 min after reinstitution of two-lung ventilation (ReTLV30 min), while OI improved after OLV60 min, and Cdyn increased at OLV90 min and OLV120 min (P<0.05). AQP1 expression in Group D2 exceeded Groups C and D1 (P<0.05). Pearson correlation analysis revealed negative correlations between AQP1 expression and both TNF-alpha (r=-0.672) and IL-8 (r=-0.744) levels at OLV90 min (P<0.001). CONCLUSIONS Dexmedetomidine dose-dependently attenuates OLV-induced lung injury and improves pulmonary function, concomitant with reduced inflammatory cytokines and preserved AQP1 expression. The 0.5 µg/kg/h dose demonstrated superior efficacy without increasing adverse events. This protection likely involves concurrent suppression of inflammation and modulation of alveolar fluid clearance pathways.