Post-operative electrolyte imbalance: its incidence and prognostic implications for elderly orthopaedic patients

In order to assess incidence and prognostic implications of post-operative electrolyte disorders for elderly patients, 180 patients aged 79.5 +/- 6.8 years, range 70-96 years, admitted to a geriatric-orthopaedic liaison service were prospectively followed from admission to discharge or death. The association of age, basic medical conditions, type of anaesthesia and perioperative complications with post-operative sodium/potassium imbalance and fatality was assessed by logistic regression analysis. The incidence of post-operative electrolyte imbalance and fatality was 15% and 8.8%, respectively. Electrolyte imbalance was independently predicted by spinal anaesthesia [odds ratio (OR) = 2, confidence limits (CL) = 1.24-3.19], multiple pathology (OR = 2, CL = 1.1-3.58), use of cathartics (OR = 1.76, CL = 1.05-2.91) and intra-operative complications (OR = 1.7, CL = 1.03-2.88). Death was predicted by electrolyte imbalance (OR = 2.32, CL = 1.21-4.43), post-operative noninfective complications (OR = 2.3, CL = 1.09-4.84) and age greater than 79 years (OR = 1.17, CL = 1.06-1.3). Post-operative electrolyte imbalance is a marker of very frail medical status and a risk factor for death among elderly orthopaedic patients.