Changes in oxygen saturation in the 72 hours after hip surgery: the effect of oxygen therapy

The aim of this study was to investigate changes in oxygen saturation (SpO2) occurring during the three days following hip surgery in patients in this hospital and to determine to what extent SpO2 might be improved by oxygen therapy for 24 or 72 hours. Eighty-three patients (aged 43-96 years) scheduled for elective total hip replacement or emergency surgery for hip fractures were studied. Forty-four patients had 24 hour postoperative oxygen prescribed by their anaesthetist or surgeon; we randomized these to either continue oxygen for a total of three days (Group 1) or to discontinue oxygen after Day 1 (Group 2). Patients not prescribed oxygen by the surgeon or anaesthetist (n = 39) were randomly assigned either to receive oxygen for three days (Group 3) or not to receive oxygen (Group 4). Oxygen was administered through nasal cannulae at a flow of 2 l.min-1. SpO2 was measured every 10 seconds for three days and stored on computer disc. Percentage of time spent with SpO2 below 90% was used as an index of desaturation. Patients receiving oxygen had significantly improved SpO2. In patients not receiving oxygen, desaturation was most severe on Days 1 and 2, improving somewhat on Day 3. On Day 2 desaturation was similar in Groups 2 and 4. When oxygen was not being administered males were significantly more desaturated than females. Our investigations indicate that following hip surgery poor saturation continues for at least two days and can be improved by oxygen therapy.