© 2006 American Thoracic Society DOI: 10.1165/rcmb.F321
Clinical Use of Normobaric HyperoxiaInsititute of Physiology, Charite-Universitatsmedizin Berlin, Berlin, Germany From the Authors: Dr. Tornero-Campello is correct in that the use of supplemental perioperative oxygen to reduce the risk of surgical wound infections is currently a matter of intense controversy. Since our manuscript (1) focuses on early cellular responses of lung endothelial cells to hyperoxia, we cited the respective studies (2, 3) to point out the fact that normobaric hyperoxia is not solely administered to hypoxemic, but frequently also to normoxemic patients. Yet, Dr. Tornero-Campello's comment gives us the opportunity to revisit the effects of supplemental perioperative oxygen in greater detail. Whereas the two large randomized studies by Greif and coworkers (2) and Belda and colleagues (3) showed a relative risk reduction for postoperative surgical-wound infections of 54% and 39% when patients were perioperatively ventilated with 80% as compared with 30% O2, respectively, the randomized trial by Pryor and coworkers (4) and the smaller study by Mayzler and colleagues (5) failed to show a benefit of perioperative supplemental oxygen. Potential reasons underlying these divergent results such as different inclusion criteria or methodologic limitations have been discussed intensely, but remain speculative. As pointed out by Dellinger (6), if the results of the three large trials are pooled, supplemental perioperative oxygen is still associated with an absolute risk reduction of 3.7% and a relative risk reduction of 24% for surgical site infections (P = 0.10). An individual benefit in 3.7% of patients (or even in 9.5% of patients, as reported by Belda and coworkers) can probably not be expected to reflect in clinical outcome parameters of the whole patient population. Yet, the study by Greif and colleagues shows that absence of infection signficantly affected outcome—for example, by reducing hospitalization days by 39% (3). Hence, perioperative supplemental oxygen is likely to prevent not only surgical wound infections, but also to improve outcome parameters in the small percentage of patients ultimately profiting from this therapy. Based on the promising data by Greif and coworkers and Belda and colleagues, recent reviews have emphasized the advantages of supplemental oxygen (7) and proposed its implementation in integrated care pathways (8). Yet, since normobaric hyperoxia can cause pulmonary absorption atelectasis (9) and, as shown in our study (1), results in rapid cellular responses and oxygen radical formation in lung microvessels, caution should be taken not to compromise pulmonary structural and functional integrity for potential systemic benefits in a small percentage of patients. Footnotes Conflict of Interest Statement: The author does not have a financial relationship with a commercial entity that has an interest in the subject of this manuscript. References
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