To the Editor:
We read with great interest the results of the multicenter randomized controlled trial by Beck-Schimmer et al.1 We congratulate the authors on performing the first study with sufficient statistical power to detect differences in outcomes between two anesthetic techniques in lung resection surgery. The authors used a recognized anesthetic agent (desflurane) with protective (antiinflammatory) lung effects during one-lung ventilation (OLV), although they did not measure perioperative biomarkers of inflammatory response. Most previous hypotheses proposed that this lung-protective role must affect postoperative outcome; however, the surprising results of the study by Beck-Schimmer et al.1 lead us to think that it is perhaps time to reevaluate these hypotheses.
We would like to point out a series of issues that might strengthen the conclusions of this study and could be beneficial for future studies. First, we believe that it is important to report the amount of fluids administered during surgery and the airway pressures during OLV in both groups because an association between these variables and postoperative lung injury has been demonstrated. Second, the authors did not provide data about the depth of anesthesia. Did they use the bispectral index to maintain a similar grade of hypnosis in both groups? The study sample comprised mainly cancer patients, in whom the minimum alveolar concentration of inhaled anesthetics is lower than in noncancer patients. The percentage of desflurane needed to maintain suitable hypnosis could be different. Furthermore, the authors did not show hemodynamic parameters. Can the authors ensure that the triple low (recognized variable that could affect outcome) values were similar between groups? Third, in parts of the article, the authors base their findings on volatile anesthesia. We think that they should specify which volatile agent was used. The effects of volatile agents differ, and the differences could have an impact on outcome. We believe that the authors should have avoided the general term volatile anesthesia and stated that their results were obtained with desflurane. The bronchodilator effects of volatile anesthetics differ from one drug to another and provide the anesthetist with useful information, especially in the case of patients with hyperreactivity. However, several investigations show that with desflurane, bronchodilator effects could disappear when the minimal alveolar concentration is greater than 1, whereas with other volatile agents, such as sevoflurane, bronchodilator properties are not dose-dependent.2,3 This observation could prove to be very important in chronic obstructive pulmonary disease and smokers. Second, experimental and clinical studies have shown that desflurane has less antioxidant power4–6 than other inhaled agents; the role of oxidative stress in postoperative lung injury during OLV is well known. The same research group previously showed better postoperative outcome after lung resection surgery when they compared sevoflurane with propofol.7
The authors declare no competing interests.