[Dynamic measurement of volume of atelectasis area in the evaluation of the prognosis of patients with moderate-to-severe acute respiratory distress syndrome].

OBJECTIVE

To assess the impact of not inflated lung tissue (NILT) volume on the prognosis of patients with moderate-to-severe acute respiratory distress syndrome (ARDS).

METHODS

The clinical data of 131 patients with moderate-to-severe ARDS admitted to the intensive care unit (ICU) of Tianjin Third Central Hospital from March 2016 to June 2019 were collected. The basic data of patients, including gender, age, body mass index (BMI), causes of ARDS, acute physiology and chronic health evaluation II (APACHE II) score, sequential organ failure assessment (SOFA) score and oxygenation index (PaO/FiO), were collected. The CT imaging data of patients on the 1st and 7th day in the ICU were collected. According to the CT value, they were divided into hyperventilated areas (-1 000 to -900 HU), normal ventilation areas (-899 to -500 HU), poorly ventilated areas (-499 to -100 HU), and atelectasis area (-99 to 100 HU). The total lung volume and the percentage of NILT to the total lung volume (NILT%) were calculate. At the same time, duration of mechanical ventilation, length of ICU stay, total length of hospital stay were collected. According to the 28-day follow-up, they were divided into survival group and death group. Multivariate Logistic regression analysis was used to determine the risk factors for 28-day death in ARDS patients. The receiver operating characteristic (ROC) curve was drawn, the area under ROC curve (AUC) and 95% confidence interval (95%CI) were calculated to determine the accuracy of NILT% in predicting the 28-day prognosis of ARDS patients, and the NILT% threshold was used for subgroup analysis of patients.

RESULTS

Among the 131 patients with moderate-to-severe ARDS, patients were excluded for more than 48 hours after ARDS diagnosis, repeated admission to ICU due to ARDS, the ICU duration less than 7 days, death within 72 hours of admission, chronic interstitial lung disease or congestive heart failure, no chest CT examination within 7 days of admission to ICU, and no specimen collection within 2 hours of admission to ICU. Finally, a total of 53 patients were enrolled in the analysis. Of the 53 patients, 31 patients survived and 22 patients died. The 28-day mortality was 41.5%. Compared with the survival group, patients in the death group were older (years old: 65.32±11.29 vs. 55.77±14.23), and had a higher SOFA score (11.68±3.82 vs. 8.39±2.23) with significant differences (both P < 0.05), while there were no significant differences in gender, BMI, ARDS cause, APACHE II score and PaO/FiO between the two groups. There was no significant difference in CT value, total lung volume and NILT% between the two groups at 1st day after admission to ICU; NILT% on day 7 after admission to ICU in the death group was significantly higher than that in the survival group [(28.95±8.40)% vs. (20.35±5.91)%, P < 0.01], but there was no significant difference in CT value and total lung volume between the two groups. Multivariate Logistic regression analysis showed that the 28-day prognosis of ARDS was related to age, SOFA score and NILT% independently [age: odds ratio (OR) = 0.892, 95%CI was 0.808-0.984, P = 0.023; SOFA score: OR = 0.574, 95%CI was 0.387-0.852, P = 0.006; NILT%: OR = 0.841, 95%CI was 0.730-0.968, P = 0.016]. ROC curve analysis showed that 7-day NILT% could predict the 28-day prognosis of patients with moderate-to-severe ARDS, and AUC was 0.810 (95%CI was 0.678-0.952, P < 0.01). The NILT% threshold was 15.50%, sensitivity was 95.5%, specificity was 80.6%, positive predictive value was 85.7%, and negative predictive value was 74.6%. According to the 7-day NILT% threshold, a subgroup analysis of patients was performed, and 7-day NILT% > 15.50% was defined as a high-risk clinical prognosis, and ≤ 15.50% was a low-risk. Compared with low-risk patients (n = 7), the duration of mechanical ventilation, the length of ICU stay and total length of hospital stay in high-risk patients (n = 46) were significantly prolonged [duration of mechanical ventilation (days): 9.37±6.14 vs. 4.43±1.72, length of ICU stay (days): 12.11±5.85 vs. 7.57±1.13, total length of hospital stay (days): 18.39±5.87 vs. 11.29±2.22, all P < 0.05].

CONCLUSIONS

The 7-day NILT% > 15.50% of patients with moderate-to-severe ARDS after ICU admission is related to poor prognosis.