Hypoxia and reduced oxygen partial pressure is commonly occurring after abdominal surgery. This study aims to investigate whether similar changes also occur after orthopedic surgery in the form of upper limb surgery.

Inclusion: 60 patients undergoing orthopedic surgery in the form o knee-, hip-, shoulder- or elbow surgery.

Exclusion: Dementia or cognitive impairment that makes it impossible to participate in studies.

Arterial blood gas and lung function are undertaken before surgery, the day after surgery and at follow-up.

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 including obstructive sleep apnea. The cause of postoperative restrictive lung function and hypoxia is unknown. Previous studies report that PaO2 decreases by an average of 2 kPa after abdominal surgery, while PaCO2 is unchanged and vital capacity decreases by 35%. The effect of orthopedic surgery on oxygen and carbon dioxide partial pressure and lung function has previously not been investigated. This study aims to investigate possible changes in oxygen partial pressure and vital capacity after orthopedic surgery.

Design: Prospective cohort study

Inclusion: 60 patients undergoing orthopedic surgery in the form o knee-, hip-, shoulder- or elbow surgery..

Exclusion: Dementia or cognitive impairment that makes it impossible to 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 34 patients if the mean (SD) difference is 1 (2) kPa. Due to drop-outs the investigators calculate a need to include 60 patients.

Primary outcome measures:

• PaO2 from atrial blood gas

Secondary outcomes

• Vital capacity
• PaCO2 from atrial blood gas
• Forced expiratory volume in one second (FEV1)

Other variables examined: age, sex, height, weight, type of surgery, type of anesthesia, smoking status, length of surgery and previous diseases

Inclusion Criteria: Patients undergoing shoulder or elbow surgery -

Exclusion Criteria: Dementia or cognitive impairment that makes it impossible to participate in studies. Not willing to participate

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Patients undergoing shoulder or elbow surgery