We appreciate the interest of Dr. Tornero-Campello in the anesthesiologist's role in the prevention of surgical site infections (SSIs). Further, we note his repeated contention that the duration of hospitalization is a more appropriate outcome measure than the incidence of infection is been published in letters to multiple journals.1–3
Our objectives in preparing this article4were to produce an evidence-based, timely, concise, and clinically relevant document to educate practicing anesthesiologists regarding the best approaches to reducing surgical site infections. We believe that there is sufficient evidence to suggest that normobaric hyperoxia reduces the incidence of SSI in colorectal surgery.5,6Nevertheless, Dr. Tornero-Campello's focus on hospital duration of stay as an outcome measure allows us to reexamine these data in greater detail.
Dr. Tornero-Campello notes that one study7that included a heterogenous population of patients undergoing major abdominal surgery did not show a benefit of hyperoxia and may have been associated with an increase in morbidity and in the duration of hospitalization. It is extremely important to note that criticism of this study has been significant. For example, variables such as anesthetic technique, fluid management, and pain management were not controlled.8,9Information on blood glucose control, strongly associated with the incidence of SSI, was not included.10The small sample size and statistical analysis has not held up to rigorous post hoc examination.11Although patients were prospectively randomized to their perioperative oxygen group, the presence of SSI was determined by retrospective chart review,8,9as we note in our article. It is imperative that we consider these methodologic flaws when we weigh the results of this study. Last, it would seem intuitive that if hyperoxia did confer an increase risk of “clinically significant harm,” some hint of this risk would have been evident in the two larger studies by Grief et al. 5and Belda et al. 6
Faults with the above study aside, we concede that the use of hyperoxia was not associated with a decrease in the duration of hospitalization in either of the two studies cited in our review.5,6Nevertheless, we reject Dr. Tornero-Campello's assertion that the prevention of SSI is only significant if it results in a tenable “difference in days of hospitalization, time to solid food intake, or staples removed.” Indeed, it is difficult for us to imagine any SSI that is not clinically significant: Even an infection that may be easily treated in the outpatient setting results in the use of antibiotics, which may further increase the prevalence of antibiotic-resistant organisms and leads to an increased cost of care.4,12
Although we may debate the clinical significance of hyperoxia in the prevention of SSIs, we hope Dr. Tornero-Campello will agree that the prevention of any infection, even if it not associated with an increase in duration of hospitalization, is a clinically relevant outcome and a substantial improvement in patient care.
*University of Virginia Health System, Charlottesville, Virginia. firstname.lastname@example.org