Postoperative delirium and its influencing factors in elderly patients with lung cancer in the intensive care unit.

Background: In 2020, there were 2,206,771 new cases of lung cancer worldwide, ranking first in mortality rate postoperative delirium (POD) is a common surgical complication and typically occurs 1-3 days after surgery which leads to prolonged hospital stay. The currently available research on POD in elderly patients was mainly carried out in cardiac surgery, orthopedic, and gastroenterology departments. It is necessary to study the incidence and risk factors of delirium in intensive care unit (ICU) elderly patients after lung cancer surgery.

Methods: This study is a single-center and singe-arm observational study which examined the incidence of and factors affecting POD in elderly patients with lung cancer in ICU at our center from September 2019 to May 2020. 22 relevant variables including arterial oxygen partial pressure, postoperative sedative drug use, and other data were collected. The Confusion Assessment Method of Intensive Care Unit was used to assess the occurrence of POD, the Chinese version of the Richards-Campbell Sleep Questionnaire was used to assess patients' postoperative sleep quality, and the Mini-Mental State Examination was used to assess patients' preoperative cognitive level. Univariate and multivariate logistic regression analyses were conducted to identify the factors affecting POD in elderly ICU patients with lung cancer.

Results: Among the 208 elderly ICU patients who underwent surgery for lung cancer, 32 (15.38%) had POD. The results showed that postoperative blood oxygen level, preoperative cognitive level score and postoperative sleep quality score in delirium group were significantly lower than those in non-delirium group (P values were 0.002, 0.000, 0.000, respectively). The proportion of previous coronary heart disease and postoperative sedation use in delirium group was significantly higher than that in non-delirium group (P=0.008 and 0.008, respectively).

Conclusions: It was observed that the preoperative Mini-Mental State Examination (MMSE) score and postoperative Richards-Campbell Sleep Questionnaire (RCSQ) score of the delirium group were significantly lower than those of the non-delirium group, and this trend was still observed after adjusting for influencing factors. It is suggested that the difference of cognitive level in elderly lung cancer population has a significant effect on the occurrence of POD. In clinical work, we should pay more attention to patients with preoperative cognitive impairment, hypoxic state, and postoperative sleep disturbance.