Individualized positive end-expiratory pressure setting in patients with severe acute respiratory distress syndrome supported with veno-venous extracorporeal membrane oxygenation.

BACKGROUND: Patients with acute respiratory distress syndrome supported with veno-venous extracorporeal membrane oxygenation benefit from higher positive end-expiratory pressure combined with conventional ventilation during the early extracorporeal membrane oxygenation period. The role of incremental positive end-expiratory pressure titration in patients with severe acute respiratory distress syndrome supported with veno-venous extracorporeal membrane oxygenation remains unclear. This study aimed to determine the preferred method for setting positive end-expiratory pressure in patients with severe acute respiratory distress syndrome on veno-venous extracorporeal membrane oxygenation support. METHODS: We retrospectively reviewed all subjects supported with veno-venous extracorporeal membrane oxygenation for severe acute respiratory distress syndrome from 2009 to 2019 in the intensive care units in Tianjin Third Central Hospital. Subjects were divided into two groups according to the positive end-expiratory pressure titration method used: P-V curve (quasi-static pressure-volume curve-guided positive end-expiratory pressure setting) group or Crs (respiratory system compliance-guided positive end-expiratory pressure setting) group. RESULTS: Forty-three subjects were included in the clinical outcome analysis: 20 in the P-V curve group and 23 in the Crs group. Initial positive end-expiratory pressure levels during veno-venous extracorporeal membrane oxygenation were similar in both groups. Incidence rates of barotrauma and hemodynamic events were significantly lower in the Crs group (all p < 0.05). Mechanical ventilation duration, intensive care unit length of stay, and hospital length of stay were significantly shorter in the Crs group than the P-V curve group (all p < 0.05). Subjects in the Crs group showed non-significant improvements in the duration of extracorporeal membrane oxygenation support and 28-day mortality (p > 0.05). CONCLUSION: Respiratory system compliance-guided positive end-expiratory pressure setting may lead to more optimal clinical outcomes for patients with severe acute respiratory distress syndrome supported by veno-venous extracorporeal membrane oxygenation. Moreover, the operation is simple, safe, and convenient in clinical practice.

[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 (PaO2/FiO2), 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 PaO2/FiO2 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.