During anesthesia and surgery, oxygen is routinely administered to all patients. Inspired oxygen concentrations, however, vary between 30% - 100% and oxygen is often administered in a seemingly random manner.

During anesthesia and surgery, oxygen is routinely administered to all patients. Inspired oxygen concentrations, however, vary between 30% - 100% and oxygen is often administered in a seemingly random manner.A striking conundrum is evident immediately when one review studies on the effects of oxygen on cytokines synthesis. Most investigators have found that hyperoxia enhances proinflammtory cytokines transcription and translations (11). In contrast, hyperparic oxygen has generally been shown to suppress stimulus induced porinflammtory cytokine production (12). Other studies have demonstrated that supplemental oxygen improves inflammatory and immune function (13), and it is not associated with clinically important side effect (14). We therefor undertook the current prospective randomized study to investigate whether perioperative supplemental oxygen (30% versus 80%) on pro and anti-inflammatory response in patients undergoing major abdominal cancer surgeries as our primary outcome.

Inclusion Criteria:

• candidates for abdominal cancer surgeries

Exclusion Criteria:

• Patients with chronic diseases, such as chronic obstructive pulmonary disease or pneumonia,
• body mass index (BMI) >35 kg/m2,
• severe malnutrition (albumin <3),
• leukopenia (white blood cell <4,000 g/dL),
• surgery within the previous 30 days and
• O2 saturation < 90%, as measured using a pulse oximeter