Postoperative delirium in patients aged 75 and more undergoing elective non-cardiac surger

Introduction: An increasing number of very old patients undergo surgical procedures. Nevertheless, few data are available about postoperative delirium in this population. Aims: To assess the incidence of delirium in a population of patients aged 75 years and more undergoing elective non-cardiac surgery under general anesthesia and to evaluate pre-operative characteristics and perioperative events associated with delirium occurrence. Methods: In 43 patients medical history and cognitive status were assessed preoperatively. Intraoperative mean arterial pressure (MAP) and Bispectral Index (BIS) were measured continuously. Delirium was assessed in the first 7 post-operative days using the Confusion Assessment Method for the Intensive Care Unit. Characteristics of patients with or without delirium were compared using Mann-Whitney Rank Sum Test or Fisher Exact Test, as appropriate. Results: Post-operative delirium was diagnosed in 6 patients (14%). Table 1 summarizes patients’ characteristics divided by the presence or absence of delirium. Variables Delirium (n=6) No-delirium (n=37) p Age, years 81 (77-84) 79 (77-82) 0.418 Major surgery, no. (%) 4 (67) 10 (27) 0.077 Mini mental state examination 26.5 (25.1-26.7) 27.6 (26.4-28.6) 0.228 Charlson Comorbidity Index 5 (2-7) 2 (1-3) 0.040 ASA score 3 (2-3) 2 (2-3) 0.086 Anesthesia duration, minutes 266 (191-429) 164 (111-202) 0.018 Surgery duration, minutes 164 (104-328) 116 (61-161) 0.111 Hypotension time, % 8 (5-18) 4 (1-27) 0.390 Hypertension time,% 13 (1-38) 2 (0-8) 0.154 BIS <40 time, % 15 (0-46) (n=4) 10 (3-27) (n=32) 0.960 Admission to ICU, no. (%) 4 (66%) 5 (14%) 0.012 Table 1. Data are presented as median (interquartile range) unless otherwise stated. Hypotension/hypertension time and BIS<40 time were defined as percent of anesthesia time spent with MAP below/above 20% of baseline values and BIS<40, respectively. Conclusions: In our population, 14% of patients developed postoperative delirium. Patients developing delirium had more comorbidities and spent more time under general anesthesia. Furthermore, a higher rate of ICU admissions was observed. Time spent in hypotension or hypertension and depth of anesthesia did not differ between the groups.