Letters Section Editor: Stephen J. Lurie,
MD, PhD, Senior Editor.
In Reply: Dr Hopf and colleagues note that
our protocol permitted management variability. Our "real world" design allowed
us to evaluate the effect of oxygen as it would be used in practice—if
the benefit of hyperoxia depends upon an unrealistically tight set of cofactors,
then its usefulness as a routine intervention is questionable. We acknowledged
the potential biases involved. However, given that the issue faced by anesthesiologists
and surgeons was whether hyperoxia should become standard practice, the practical
question of our study is whether any inequalities between the groups were
so large as to have concealed a significantly beneficial effect of hyperoxia.
We strongly doubt this to be true. In comparing our results with those of
Greif et al,1 it is imperative to note critical
differences in the patients studied. For example, 30% of their patients were
transfused with an average of 3 units of blood, compared with 3% receiving
an average of 1.4 units in our study. Transfusion affects oxygen physiology
and causes immunomodulation.2 It is unclear
what role this might have as a cofactor with respect to hyperoxia. Thus, our
conclusion was not that hyperoxia has no usefulness, but that it was premature
to use it as a routine measure until important limitations are identified.
We agree that we did not disprove that oxygen can be useful. But we did show
that simply "dialing up" the oxygen for every patient—as Hopf and colleagues
describe it, "oxygen used without reference to its properties"—is not
Pryor KO, Fahey III TJ, Lien CA, Goldstein PA. Supplemental Oxygen and Risk of Surgical Site Infection—Reply. JAMA. 2004;291(16):1956. doi:10.1001/jama.291.16.1958-b