Hypoxia and reduced oxygen partial pressure is commonly occurring after abdominal surgery. This study aims to investigate whether similar changes also occur after breast cancer surgery.

Inclusion: 60 women undergoing breast cancer surgery. Exclusion: Dementia or cognitive impairment that makes it impossible to participate in the study.

Arterial blood gas and lung function are undertaken before surgery and the day after surgery

Postoperative hypoxia complicates 30% - 50% of abdominal surgeries. People at particular risk for postoperative pulmonary complications including severe hypoxia are those who undergo abdominal surgery, emergency surgery or have a respiratory failure due to chronic lung disease. The cause of postoperative hypoxia and reduced lung function is unknown. Previous studies report that arterial partial pressure (PaO2) decreased by an average of 2 kilopascal after abdominal surgery, while carbon dioxide partial pressure (PaCO2) was unchanged and vital capacity decreased by 35%. The effect of breast cancer surgery on oxygen and carbon dioxide partial pressure and lung function has to the best of the investigators knowledge not been investigated. This study aims to investigate possible changes in oxygen partial pressure, carbon-dioxide partial pressure and vital capacity after breast cancer surgery.

Design: Prospective cohort study participate in studies. Method: Blood gas measurements and Lung function (Vital capacity and FEV1) The day before surgery, the day after surgery and at follow-up.

Power analysis: There is a need to investigate 27 patients if the mean (SD) difference is 0.5 (1) kilopascal. Due to drop-outs the investigators calculate a need to include up to 60 patients.

Inclusion Criteria:

• Women scheduled for surgery because of breast cancer.

Exclusion Criteria:

• Dementia or cognitive impairment that makes it impossible to participate in the study.

Women with breast cancer scheduled for surgery.