MObILE study - Midodrine effect on Orthostatic IntoLErance after hip and knee replacements

After a hip or knee joint replacement it is important to mobilise (get out of bed and move) early to recover faster, and reduce the risk of complications after surgery. Mobilisation can be hindered by orthostatic intolerance, described as the development of symptoms (dizziness, nausea, vomiting, blurred vision, feeling of heat, and fainting) when standing upright. Orthostatic intolerance has been reported to happen in up to 60% of patients after surgery. Reasons include an inability of the peripheral blood vessels to constrict (tighten) properly in response to standing. Midodrine is a drug that works by constricting the peripheral blood vessels, thereby improving blood pressure. This study aims to investigate if midodrine can reduce the occurrence of orthostatic intolerance after hip and knee joint replacements. One-hundred and seventy patients will be randomised to receive either midodrine or placebo in the early postoperative period. Orthostatic intolerance will be assessed on the day of surgery (approx 6 hours after surgery), and on the first day after surgery (approx 24 hours after surgery).