Risk factors of delirium and outcomes in senile critical patients undergoing mechanical ventilation

Abstract

Objective To investigate the risk factors of delirium and outcomes in senile critical patients undergoing mechanical ventilation. Methods A retrospective study was conducted. The clinical data of patients admitted to surgical intensive care unit (ICU) of Peking University People's Hospital from September 2014 to January 2015 were enrolled, including gender, age, severity of the disease, liver and renal function, analgesic and sedative treatment, delirium and mortality rate. According to whether with delirium or not and whether died or not, the patients were divided into delirium and non-delirium groups as well as non-survival and survival groups. The risk factors of delirium and outcomes of the patients were analyzed by Logistic regression analysis. Results A total of 105 patients were enrolled, and 42 patients suffered from delirium with an incidence of 40.0%. Fifteen patients died within 28 days with a mortality rate of 14.3%. ① Compared with those without delirium, the patients with delirium had higher acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) score (22.2±5.6 vs. 18.8±4.8), lower incidence of Child-Pugh grade A (57.1% vs. 79.4%), lower rate of analgesic and sedative combination therapy (52.4% vs. 76.2%), lower mean arterial pressure [MAP (mmHg, 1 mmHg = 0.133 kPa): 75.5 (67.0-94.0) vs. 86.0 (77.0-95.0)] and higher behavior pain scale (BPS) score and critical-care pain observation tool (CPOT) score [4.0 (4.0-5.0) vs. 4.0 (3.0-4.0), 4.0 (3.0-4.2) vs. 2.0 (2.2-4.0)] before sedation, as well as a longer recovery time (hours: 2.65±0.99 vs. 2.29±0.87), weaning time [hours: 25.5 (8.4-50.8) vs. 10.0 (6.4-28.8)], duration of mechanical ventilation [hours: 157.0 (100.8-353.5) vs. 86.0 (59.0-143.0)], and length of ICU stay [days: 8.5 (5.0-24.2) vs. 6.0 (5.0-8.0)], and higher 28-day mortality rate (33.3% vs. 1.6%, all P < 0.05). It was shown by Logistic regression analysis that remifentanil combined with midazolam was the independent protective factor of delirium [odds ratio (OR) = 0.122, 95% confidence interval (95%CI) = 0.029-0.510, P = 0.004]. ② Compared with survival group, the patients in the non-survival group had significant higher APACHE Ⅱ score (23.2±6.1 vs. 19.7±5.1), lower MAP [mmHg: 70.0 (66.0-81.0) vs. 85.0 (74.0-96.2)] and higher BPS score [4.0 (4.0-5.0) vs. 4.0 (3.8-4.0)] before sedation, lower rate of analgesic and sedative combination therapy (40.0% vs. 68.9%) and higher rate of delirium (93.3% vs. 31.1%, all P < 0.05). It was shown by Logistic regression analysis that delirium (OR = 1 249.000, 95%CI = 25.690-6 077.000, P = 0.000) and higher APACHEⅡ score (OR = 1.251, 95%CI = 1.019-1.535, P = 0.032) were independent risk factors of death, the analgesic and sedative combination therapy was the independent protective factor of death (OR = 0.026, 95%CI = 0.001-0.535, P = 0.018). Conclusions High APACHEⅡ score and delirium are independent risk factors of death in senile patients on mechanical ventilation. The analgesic and sedative combination therapy is the independent protective factor of delirium and death in senile patients on mechanical ventilation. Key words: Critically ill;  Delirium;  Risk factor;  Mechanical ventilation;  Senile;  Prognosis