People with sleep apnoea (shortness of breath) experience a greater risk of complications after elective knee or hip replacement. In sleep apnoea - which is most common in obese people - the muscles of the back of the throat relax during sleep and so obstruct the airways. The person stops breathing, momentarily, many times during the night and levels of oxygen in the blood fall.
Researchers have studied 80 patients with sleep apnoea, and 70 with normal sleep breathing patterns, all of whom were having hip or knee replacements. They found that 20% in the sleep apnoea group had complications after the operation, compared to nine per cent in the control group.he anaesthetics, sedatives and painkillers used around surgery aggravate sleep apnoea, as does the need to lie on the back after the operation. The researchers say sleep apnoea should, if possible, be treated before this kind of surgery to improve the outcome.