Metabolic and Biochemical Responses of the Healthy Human Lung to Nonthoracic Surgery

The objective of this study was to evaluate and assign numbers to biochemical or cellular entities in lung-healthy patients that change immediately postsurgery compared with the same parameters immediately presurgery, with the hypothesis that biochemical markers with significant change could be the basis of tests to predict postoperative respiratory complications. Thirty lung-healthy adults who were to undergo elective surgical procedures requiring general anesthesia participated. The population included sequential persons that met inclusion criteria and gave consent. At intubation and before surgery, a bonchoalveolar lavage (BAL) was performed. Before extubation but after completion of surgical procedures, a second 100-ml BAL was performed in the contralateral lung. Serum from both time periods was also collected. Total cell counts were elevated postsurgery in smokers and subjects claiming childhood but not current asthma, who also showed increased postsurgical BAL IL-1 but not increased TNFα. LDH and its isoenzymes, measured in both BAL and serum, showed no correlation with time on surgical ventilation, average FiO₂, or average peak pressure during surgical ventilation. BAL LDH isoenzyme 4 showed a significant elevation pattern pre-to-post surgery when the entire subject population was considered irrespective of surgery type or time on ventilation. Presurgery versus postsurgery variation was best measured in BAL rather than in serum. The pulmonary, biochemical, and cellular parameters measured in the pre- and postsurgical BALs of lung-healthy subjects undergoing nonthoracic surgery show subtle modulations of pulmonary defense markers, defined by significantly increased proinflammatory cytokines and cell counts postsurgery compared to the same patient presurgery.