Background Long-term postoperative cognitive dysfunction
may occur in the elderly. Age may be a risk factor and
hypoxaemia and arterial hypotension causative factors.
We investigated these hypotheses in an international
Methods 1218 patients aged at least 60 years completed
neuropsychological tests before and 1 week and 3 months
after major non-cardiac surgery. We measured oxygen
saturation by continuous pulse oximetry before surgery and
throughout the day of and the first 3 nights after surgery.
We recorded blood pressure every 3 min by oscillometry
during the operation and every 15–30 min for the rest of
that day and night. We identified postoperative cognitive
dysfunction with neuropsychological tests compared with
controls recruited from the UK (n=176) and the same
countries as study centres (n=145).
Findings Postoperative cognitive dysfunction was present in
266 (25·8% [95% CI 23·1–28·5]) of patients 1 week after
surgery and in 94 (9·9% [8·1–12·0]) 3 months after
surgery, compared with 3·4% and 2·8%, respectively, of
UK controls (p