[Correlation between bioelectrical impedance and nutritional status in neurocritical care patients]

Objective: To explore the correlation between electrical impedance indicators and commonly used nutritional indicators in neurocritical care patients. Methods: A cross-sectional study was conducted to collect 58 neurocritical care patients in neurosurgery Department of Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine from June to September 2022. Bioelectrical impedance tests were performed after surgery or one week after injury, and nutrition-related biochemical indicators of the patients were collected on the same day, including nutritional status related indicators, inflammation related indicators, anemia related indicators and blood lipid related indicators. The patients were assessed with acute physiology and chronic health evaluation (APACHE) Ⅱ score and sequential organ failure assessment (SOFA) score. Based on the results obtained, the patients were assessed with nutritional score and spearman correlation analysis. The correlations of electrical impedance with nutrition related indicators and nutrition risk related indicators were analyzed. The prediction model of nutritional status was constructed by multi-factor binary logistic regression. Stepwise regression was used to screen electrical impedance indicators related to nutritional status. The receiver operating characteristic (ROC) curve was plotted and the area under the curve (AUC) was calculated to evaluate the predictive ability of the nutritional status prediction model. Results: A total of 58 patients were collected, including 33 males and 25 females, and aged 72.0 (59.0, 81.8) years. Extracellular water (ECW) was positively correlated with interleukin 6 (r=0.529, P<0.001). The edema index [ECW/total body water (TBW)] was negatively correlated with albumin (r=-0.700, P<0.001), hematocrit (r=-0.641, P<0.001) and hemoglobin (r=-0.667, P<0.001). The phase angle was positively correlated with albumin (r_RA=0.667, r_LA=0.649, r_RL=0.669, r_LL=0.685, all P<0.001), hematocrit (r_RA=0.600, r_LA=0.604, r_TR=0.565, r_RL=0.529, r_LL=0.602, all P<0.001) and hemoglobin (r_RA=0.626, r_LA=0.635, r_TR=0.594, r_RL=0.624, r_LL=0.631, all P<0.001). By stepwise regression screening of predictive factors for nutritional status and incorporating age, gender and white blood cells as confounding factors into the model, the final model was obtained as follows: nutritional status=-0.01×age+1.22×gender-0.12×white blood cells+202.20×ECW/TBW+0.5 torso phase angle -82.16 [The OR value of ECW/TBW: 20.8 (95%CI: 3.7-117.1), P<0.001], with the AUC of 0.921. Conclusion: Bioelectrical impedance indicators have good correlations with commonly used clinical nutritional indicators, and can provide a new method for nutritional evaluation of neurocritical care patients.