Objective: To investigate the correlation between dead space fraction and lung ultrasound score (LUS) and their prognostic value in patients with acute respiratory distress syndrome (ARDS).
Methods: The data of 98 patients with ARDS treated in the intensive care unit (ICU) of the First Affiliated Hospital of Jinzhou Medical University from January to December 2020 were collected and analyzed. The gender, age, acute physiology and chronic health evaluation II (APACHE II), oxygenation index, dead space fraction and LUS score immediately and 24, 48, 72 and 96 hours after ICU admission and 28-day outcomes of all patients were collected. Pearson correlation was used to analyze the correlation between dead space fraction and LUS score. Binary Logistic regression was performed to analyze whether the dead space fraction and LUS score could be the risk factors of the prognosis in patients with ARDS. Receiver operator characteristic curve (ROC) was used to analyze the predictive effect of dead space fraction and LUS score on 28-day mortality in patients with ARDS.
Results: A total of 98 patients with ARDS were included, of which 76 cases survived and 22 cases died within 28 days. With the prolongation of ICU stay, the dead space fraction and LUS score in the survival group increased first and then decreased. The dead space fraction and LUS score in the death group continued to increase to 96 hours, and were significantly higher than those in the survival group (dead space fraction: 0.569±0.019 vs. 0.491±0.021, LUS score: 20.09±2.39 vs. 15.13±1.91, both P < 0.05). There was a positive correlation between the dead space fraction and LUS score at 48, 72 and 96 hours in ICU (r values were 0.200, 0.471 and 0.677, all P < 0.05). Binary Logistic regression analysis showed that dead space fraction and LUS score were independent risk factors affecting the prognosis of patients with ARDS [dead space fraction: odds ratio (OR) was 69.064, 95% confidence interval (95%CI) was 22.680-123.499, P = 0.008; LUS score: OR was 4.790, 95%CI was 1.609-14.261, P = 0.005]. The results of ROC curve analysis showed that the dead space fraction at 48, 72 and 96 hours after ICU admission could be used to predict the 28-day mortality of patients with ARDS, the sensitivity was 59.1%, 90.9% and 95.5%, and the specificity was 89.5%, 80.3% and 98.7%. The area under the curve (AUC) of dead space fraction predicting 28-day mortality was 0.802, 0.952 and 0.998, all P < 0.01. The LUS score of 72 hours and 96 hours in ICU could be used to predict the 28-day mortality of patients with ARDS, the sensitivity was 77.3%, 77.3% and 100.0%, and the specificity was 68.4%, 88.2% and 80.3%, respectively. The AUC of the LUS score to predict the 28-day mortality of patients were 0.935 and 0.959, both P < 0.01.
Conclusions: There was significant correlation between dead space fraction and LUS score, both of which were risk factors of 28-day mortality and be used to evaluate the 28-day prognosis of patients with ARDS.