The aims of the research is to determine whether a Hyperoxic intermittent stimuli protocol can increase reticulocyte counts, signififying a rise in EPO production, in patients undergoing abdominal surgery

For anemia treatment in cancer patients, human recombinant erythropoietin is often used. However, its application is constrained due to high costs, side effects, and limited availability in some regions. This research and clinical exploration aim to identify an tool alternative to transfusion.

Randomization was conducted post-surgery in a 1:1 ratio across groups: Normobaric Oxygen Paradox (NOP) group, and a control (CTR) group. The NOP group received 60% oxygen for two hours on days 1, 3, and 5 post-surgery using a venti-mask. The CTR group did not receive oxygen therapy during the post-operatory period starting from day 1. All patients could receive oxygen during the surgery and the first 24 hours post-surgery (day 0) as needed. The belonging to one group or the other was blinded to the laboratory staff.

Pre-surgery, all patients were administered an oral benzodiazepine. General anesthesia was employed, potentially combined with epidural techniques and standard anesthesia monitors were used. The choice of anesthesia technique was at the discretion of the anesthetist. During surgery, patients received 40-50% FiO2 ventilation and were extubated at the surgery's end. Post-surgery, patients were admitted to the ICU for at least 24 hours, receiving oxygen if saturation dropped below 98%. The oxygen protocol commenced 24 hours after ICU admission (day 1). The transfusion threshold was set at 8 g/dl with clinical signs.

Inclusion Criteria:

• patients undergoing abdominal oncological surgery

Exclusion Criteria:

• GFR<60 ml/minute and/ or creatinine serum level > 2mg/dl
• Transfusion of red blood cells per or postoperatively
• Bleeding requiring repeated transfusions during or after surgery
• Severe respiratory syndrome necessitating continuous oxygen
• Intolerance to oxygen mask

The belonging to one group or the other was blinded to the laboratory staff.