In November 2016 the WHO produced guidelines on the prevention of surgical site infection. Along with some very sensible recommendations about when to give antibiotics and whether patients should have a bath before surgery there was a section on how much oxygen we anaesthetists should administer to patients during and immediately after an operation. (Section 4.12 in the guidelines below).
http://www.who.int/gpsc/global-guidelines-web.pdf?ua=1
The guidelines state that the group looked at the evidence and then performed their own meta-analysis, and a further subgroup analysis. Some of you may already know that meta-analyses are one of my personal hobby horses. Every trial has its own biases and then we bunch a load of them together in order to concentrate and distill these biases, then do a subgroup analysis to focus on the areas where those biases may have taken the trial results to statistical significance. I can name you many subjects where a meta-analysis has changed our practice only to be disproven a few years later by a well conducted trial.
I sent these guidelines out to my consultant colleagues and not one supported it. In fact one of my colleagues who is also a medical statistician produced an excellent piece of work summarised here:
They answered the wrong question, looking only at infection rates and ignoring overall benefit or harm to the patient. In a Cochrane analysis Here the chance of high oxygen concentrations reducing surgical site infection was described as low, and in addition there could be a 20% increase in mortality for those patients with high oxygen concentrations.
So essentially high oxygen concentration may reduce SSIs a little, or it might cause a 20% increase in mortality. Or neither. In any case the evidence is far too flimsy to put this into international guidelines, and there is a chance they may actually cause harm to the patients we’re treating. I won’t be changing my practice based on these guidelines, it’s a shame it’s been included at all as it reduces the impact of the rest of the document.