Objective: To investigate the relationship between malnutrition and delirium and its effect on prognosis in elderly patients with severe pneumonia undergoing invasive mechanical ventilation.
Methods: A prospective observational study was conducted. Patients with severe pneumonia aged ≥ 60 years old who underwent invasive mechanical ventilation admitted to department of critical care medicine of the Second People's Hospital of Lianyungang from January 2021 to December 2022 were enrolled. The confusion assessment method (CAM) was used to evaluate the delirium of the patients in intensive care unit (ICU). The score of CAM ≥ 1 was defined as delirium. Mini nutritional assessment short-form (MNA-SF) was used to assess the nutritional status of patients, and MNA-SF score ≤ 7 was defined as malnutrition. Patients were divided into delirium group and non-delirium group according to whether delirium occurred. The differences in clinical indicators, length of ICU stay, duration of mechanical ventilation and wake-up time after drug withdrawal were compared between the two groups. After 28 days of short-term follow-up, the patients were divided into death group and survival group, and the differences in the incidence of delirium and malnutrition between the two groups were compared. Binary multivariate Logistic regression analysis was used to screen the risk factors for delirium in elderly patients with severe pneumonia undergoing invasive mechanical ventilation. Kaplan-Meier survival curve was used to analyze the effect of delirium on prognosis.
Results: A total of 132 elderly patients with severe pneumonia undergoing invasive mechanical ventilation were enrolled, of whom 98 survived and 34 died within 28 days, with a mortality of 25.76%. The incidence of malnutrition and delirium in the death group was significantly higher than that in the survival group (61.76% vs. 37.76%, 64.71% vs. 26.53%, both P < 0.05), and the MNA-SF score was significantly lower than that in the survival group (6.32±1.80 vs. 8.72±2.23, P < 0.01). Procalcitonin (PCT), interleukin-6 (IL-6) and blood lactic acid (Lac) in the death group were significantly higher than those in the survival group [PCT (μg/L): 4.47 (2.69, 10.39) vs. 2.77 (1.28, 5.94), IL-6 (ng/L): 204.08 (126.12, 509.85) vs. 120.46 (60.67, 290.99), Lac (mmol/L): 5.14 (2.75, 8.60) vs. 3.13 (2.16, 4.30), all P < 0.05], and the wake-up time after drug withdrawal was significantly longer than that in the survival group (minutes: 33.94±8.51 vs. 28.92±7.03, P < 0.01). Among 132 elderly patients with severe pneumonia undergoing invasive mechanical ventilation, 48 patients had delirium during ICU stay, and 84 patients did not have delirium. The incidence of delirium was 36.36%. The 28-day mortality in the delirium group was significantly higher than that in the non-delirium group (45.83% vs. 14.29%, P < 0.01), and the MNA-SF score was significantly lower than that in the non-delirium group (6.46±1.77 vs. 9.05±2.15, P < 0.01), the length of ICU stay, duration of mechanical ventilation, and wake-up time after drug withdrawal were also significantly longer than those in the non-delirium group [length of ICU stay (days): 13.40±9.59 vs. 10.06±7.81, duration of mechanical ventilation (hours): 197.06±89.80 vs. 138.81±82.30, wake-up time after drug withdrawal (minutes): 35.85±7.01 vs. 26.99±6.12, all P < 0.05]. Binary multivariate Logistic regression analysis showed that malnutrition [odds ratio (OR) = 7.527, 95% confidence interval (95%CI) was 2.585-21.917], Lac (OR = 5.345, 95%CI was 1.733-16.483), wake-up time after drug withdrawal (OR = 6.653, 95%CI was 2.021-21.904) were independent risk factors for delirium during ICU stay in elderly patients with severe pneumonia undergoing invasive mechanical ventilation (all P < 0.01). Kaplan-Meier survival analysis showed that the 28-day cumulative survival rate of patients in the delirium group was significantly lower than that in the non-delirium group (54.17% vs. 85.71%), and the difference was statistically significant (Log-Rank test: χ2 = 16.780, P < 0.001).
Conclusions: The risk factors for delirium in elderly patients with severe pneumonia undergoing invasive mechanical ventilation during ICU stay include malnutrition, Lac, and wake-up time after drug withdrawal. The occurrence of delirium is closely related to poor prognosis.