A Clinical Study of AWT Measurement and Polynomial Regression Model Analysis in Critically Ill patients: A Retrospective Study

Abstract Background：In this study, a new measurement device was used to measure the AWT in critically ill patients and a polynomial regression model was applied to analyze the correlation between intra-abdominal hypertension (IAH) and AWT in critically ill patients.Methods: A retrospective analysis was conducted in critically ill patients who were admitted to the Department of Critical Care Medicine of Daping Hospital of Army Medical University from March 13, 2019, to May 23, 2020. According to the intravesical pressure (IVP) on the first day of ICU admission and death within 28 days, the patients were divided into the IAH group (IVP ≥12 mmHg), the non-IAH group, the survival group and the nonsurvival group. The demographic and clinical data, prognostic indicators, AWT and IVP on days 1-7 after entering the ICU, IAH risk factors, and 28-day death risk factors were collected.Results: The AWT on the 1st and mean 7th day of the IAH group was (2.89±0.32)N/mm and (2.82±0.46) N/mm, respectively, which was higher than that of the non-IAH group [ (2.45±0.29) N/mm, (2.43±0.39) N/mm], p＜0.001. The average IVP on the 1st and mean 7th day of all patients were 12.78 (6.14, 18.99) and 11.49 (6.66, 19.43) mmHg, and the AWT on the 1st and mean 7th days were (2.75±0.38) and (2.75±0.47) N/mm, respectively, with significant differences (p< 0.0001). The polynomial regression models showed that the average AWT and IVP on the 1st and mean 7th were AWTday1=-2.450×10-3, IVP2+9.695×10-2 IVP+2.046，r=0.667（p＜0.0001），and AWTmean=-2.293×10-3, IVP2+9.273×10-2 IVP+2.081, respectively. The logistic regression analysis showed that AWTday1 2.73-2.97N/mm increased the patient's 28-day mortality risk (OR: 6.834; 95%: 1.105-42.266, p=0.010).Conclusion: There is a nonlinear correlation between AWT and IVP in critically ill patients, and a high AWT may indicate poor prognosis.Trial registration：ChiCTR，ChiCTR1900020562. Registered 8 January 2019，http://www.chictr.org.cn/showproj.aspx?proj=34441