Systemic and alveolar inflammatory response in the dependent and nondependent lung in patients undergoing lung resection surgery A prospective observational study

BACKGROUND Measurement of inflammatory mediators in bronchoalveolar lavage (BAL) during lung resection surgery with periods of one-lung ventilation (OLV) has revealed an intense local pulmonary response. The role of each lung in the inflammation that occurs during this procedure has never been investigated. OBJECTIVE(S) The primary objective of our study was to compare the inflammatory response in the dependent lung with that of the nondependent lung by measuring inflammatory markers in BAL. Our secondary objective was to assess the behaviour of these inflammatory mediators in patients with and without postoperative pulmonary complications (PPCs). DESIGN A prospective, observational study. SETTING Department of Anaesthesiology in a university hospital. PATIENTS Forty-six consecutive patients undergoing lung resection surgery. INTERVENTION(S) BAL samples were taken from dependent and nondependent lung 10 min before initiating OLV and at the end of OLV (once two-lung ventilation was established). All patients were followed up until 30 days after surgery. MAIN OUTCOME MEASURES The concentration of cytokines [interleukin (IL)-1, IL-2, IL-6, IL-10, tumour necrosis factor-alpha (TNF-alpha)], nitric oxide, carbon monoxide and matrix metalloproteinase 2 (MMP-2) was analysed in both lungs before and after OLV. PPCs were recorded. RESULTS In BAL fluid, all measured biomarkers, apart from IL-10, were significantly greater (P < 0.05) at the end of OLV than those obtained before OLV, both for the dependent and nondependent lung. The increase in measured biomarkers was similar in both lungs. Eight patients developed PPC. Patients who developed PPC had higher levels of TNF-alpha (P< 0.05) in BAL from the nondependent lung before and after OLV than patients who did not have PPC. Patients who developed PPC had a smaller increase in MMP-2 levels (P< 0.05) in the dependent lung than patients who did not have PPC. CONCLUSION In lung resection surgery, the inflammatory response is similar in both lungs. However, the greater increase in TNF-alpha levels in the nondependent lung and the smaller increase of MMP-2 concentration in the dependent lung may increase the susceptibility to develop PPC.