Is Peri-operative Hyperoxemia a Risk Factor for Postoperative Complications? A Randomised, Prospective Study in Patients Undergoing Vascular Surgery

Oxygen is probably one of the commonest "non-prescription" drug used in the hospital and its advantage in several situations including carbon monoxide poisoning, central hypoxia and prior to planned intubation in an acute situation are today well-established and commonly used. Oxygen has been frowned upon in the resuscitation of newborn babies because of the risk of retrolental hypoplasia, now well accepted and adopted in clinical practice. Oxygen has also been traditionally used to increase oxygen carrying capacity in patients presenting with an acute coronary syndrome (ACS), to reduce surgical site infections (SSI), to ensure adequate oxygen delivery to tissues in unconscious patients, during cardiac surgery and for postoperative management, specifically after major surgery. Thus, deliberate use of high inspiratory oxygen concentrations (e.g., 80% or above) is recommended in the treatment of specific intoxications, such as with carbon monoxide or cyanide, wherein hyperbaric oxygen should also be considered. In addition, a high oxygen fraction has been suggested to prevent adverse outcomes after surgery and anesthesia, including a reduction in wound infections and postoperative nausea and vomiting (PONV). In critically ill patients, oxygen delivery to the tissues is often compromised, and supplemental oxygen (e.g., face mask with 10 L oxygen per min) is commonly administered to patients with pneumonia, sepsis, acute coronary syndrome, or stroke - in fact, it is estimated that oxygen is given during transport in approximately one-third of all ambulance journeys.

Several reports published recently have questioned many of the "routine" uses of oxygen and some evidence even seems to point towards negative outcomes in some of these conditions. Specifically, excessive oxygen is likely to do more harm than good in the neonatal period, following cardio-pulmonary resuscitation and likely following acute myocardial infarction. Prospective, randomised studies on this important use of oxygen in the preoperative string are, however, lacking in the literature and in view of theoretical risks for hyperoxemia to several organs, the routine use of high oxygen fractions during the peri-operative phase can be questioned.

This study aims to assess peri-operative complications up to 1 year following vascular surgery in patients randomised to receive high inspired oxygen concentration (endpoint: SpO2 98 - 100%) or minimal inspired O2 concentration (endpoint: SpO2 > 90%).