Background: Acute lung injury after thoracic surgery relates to alveolar inflammation induced by one-lung ventilation (OLV) and surgical manipulation. However, alveolar recruitment manoeuvres (ARM), conventional ventilation, and airway manipulation may increase alveolar trauma. This study evaluates pulmonary immune effects of these co-factors in a porcine model.
Methods: Twenty-two piglets (27.3 kg) were randomised to spontaneous breathing (N.=4), two-lung ventilation (TLV, N.=6), OLV with propofol (6 mg/kg/h, N.=6) or desflurane anesthesia (1MAC, N.=6). Mechanical ventilation settings were constant throughout the experiment: VT=10 mL/kg, FIO2=0.4, PEEP=5 cmH2O. OLV was performed by left-sided bronchial blockade. Thoracic surgery was simulated for 60 min. ARM (airway pressure of 40 mbar for 10 s) was applied before and after each airway manipulation. Cytokines and mRNA-expression were assessed by immunoassays and semi-quantitative RT-PCR in alveolar lavage fluids, serum and tissue samples prior to and after OLV (TLV in controls).
Results: Repetitive ARM and TLV induced no significant proinflammatory effects. OLV enhanced cytokine release but less with desflurane inhalation than propofol infusion (median (IQR) [pg/mL], dependent lung): Interleukin-8: TLV 44 (17) to 68 (35), propofol 82 (17) to 494 (231), desflurane 89 (30) to 282 (44). Likewise, serum cytokines were different: tumour necrosis factor-a: TLV 37 (13) to 62 (7), propofol 55 (39) to 94 (60), desflurane 43 (33) to 41 (25). Expression of interleukin-8-mRNA increased after OLV, but mRNA expression was not modulated by anesthetics.
Conclusion: ARM, standard TLV and repetitive BAL do not additionally contribute to lung injury resulting from OLV for thoracic surgery in healthy porcine lungs. OLV induces expression of interleukin-8-mRNA in alveolar cells, which is not modulated by different anesthetic drugs.