The study of incidence of post operative delirium in geriatric patients with hyponatremia undergoing coronary artery bypass grafting procedure in a tertiary care hospital

Delirium, defined as an acute disorder of attention and global cognitive function is a common, serious and potentially preventable source of morbidity and mortality in hospitalized elderly patients. Different studies have shown that existence of hyponatremia in perioperative period can contribute to delirium.To assess the incidence of post operative delirium in elderly patients with peri operative hyponatremia undergoing coronary artery bypass grafting (a major cardiac surgery).Prospective cohort study, Study Period: 1 ½ years. Using a prepared questionnaire after obtaining fully informed written consent. 3 visits for each patient: 1) before surgery, 2) in the ICU: 48 hours after surgery, 3) In ward after shifting out from ICU. Details from patients, care givers and nursing staff regarding features of delirium are obtained. Patients were classified into two groups, one group included patients with normal/mild hyponatremia (serum sodium>/= 130 mEq/L) and other group with moderate to severe hyponatremia (serum sodium</=129.9) for convenience of analysis.Out of total 250 patients included in the study, 43 (17.2%) patients developed post operative delirium. Patients with moderate- severe hyponatremia had more chance for development of post operative delirium. Out of 146 patients with moderate- severe hyponatremia 37 (25.34%) patients developed post operative delirium compared to 6 (5.77%) patients with normal or mild hyponatremia (p:<0.001). Hyponatremia in peri operative period is a risk factor contributing to post operative delirium and patient’s sodium levels should be closely monitored in peri operative period.