Efficacy of Midodrine for the Prevention of Orthostatic Hypotension During Early Mobilization After Fast-track Hip Arthroplasty

Inclusion Criteria: * Scheduled for primary unilateral hip arthroplasty * Age \>= 18 years * Able to give informed consent Exclusion Criteria: * General anaesthesia for the current procedure * Digoxin treatment. * history of renal or hepatic failure * history of glaucoma * history chronic urinary retention requiring treatment * history of orthostatic intolerance / hypotension * other autonomous nervous system disease * alcohol or drug abuse * current malignant disease * females in the fertile age (possible pregnancy or breast feeding) * Treatment with anticoagulants * BMI \> 40 kg/m2 * Dementia or cognitive dysfunction (investigators evaluation)