Association between ventilatory ratio and ICU mortality in interstitial lung disease patients on mechanical ventilation: A retrospective study.

BACKGROUND: Ventilatory ratio (VR) is a simple bedside index of ventilatory efficiency. Interstitial lung disease (ILD) is a diverse group of diseases that causes fibrosis or inflammation of the pulmonary parenchyma, and the main clinical manifestation is hypoxemia. To date, no study has explored ventilation efficiency in patients with ILD. OBJECTIVES: This study aimed to explore the features of VR in mechanically ventilated patients with ILD and their relationship with intensive care unit (ICU) mortality. METHODS: In this retrospective analysis, we included mechanically ventilated patients with ILD in the ICU of West China Hospital, Sichuan University, from 2013 to 2021. Demographic data and mechanical ventilation (MV) parameters within 24 h of intubation were collected. The characteristics of VR and their relationships with ICU mortality were also analyzed. RESULTS: 224 patients were included in the final analysis. There were 146 males (53.9%), and the median age was 65 years (interquartile range [IQR]54∼74). The mean value of VR was 2.22, and VR was significantly higher in nonsurvivors than in survivors (1.79 vs 2.32, P < 0.001). A high VR value was an independent risk factor for ICU mortality (odds ratio=1.602, P = 0.038) after adjustment. A high value of VR was associated with a shorter survival time after admission to ICU (hazard ratio=1.485, P = 0.006) CONCLUSIONS: VR in patients with ILD on MV was increased, and the VR of nonsurvivors within 24 h of intubation was higher than that of survivors. The high VR value within 24 h of intubation was an independent risk factor for ICU mortality after adjusting for other factors.

Impulse oscillometry for detection of small airway dysfunction in subjects with chronic respiratory symptoms and preserved pulmonary function.

BACKGROUND: Subjects with chronic respiratory symptoms and preserved pulmonary function (PPF) may have small airway dysfunction (SAD). As the most common means to detect SAD, spirometry needs good cooperation and its reliability is controversial. Impulse oscillometry (IOS) may complete the deficiency of spirometry and have higher sensitivity. We aimed to explore the diagnostic value of IOS to detect SAD in symptomatic subjects with PPF. METHODS: The evaluation of symptoms, spirometry and IOS results in 209 subjects with chronic respiratory symptoms and PPF were assessed. ROC curves of IOS to detect SAD were analyzed. RESULTS: 209 subjects with chronic respiratory symptoms and PPF were included. Subjects who reported sputum had higher R5-R20 and Fres than those who didn't. Subjects with dyspnea had higher R5, R5-R20 and AX than those without. CAT and mMRC scores correlated better with IOS parameters than with spirometry. R5, R5-R20, AX and Fres in subjects with SAD (n = 42) significantly increased compared to those without. Cutoff values for IOS parameters to detect SAD were 0.30 kPa/L s for R5, 0.015 kPa/L s for R5-R20, 0.30 kPa/L for AX and 11.23 Hz for Fres. Fres has the largest AUC (0.665, P = 0.001) among these parameters. Compared with spirometry, prevalence of SAD was higher when measured with IOS. R5 could detect the most SAD subjects with a prevalence of 60.77% and a sensitivity of 81% (AUC = 0.659, P = 0.002). CONCLUSION: IOS is more sensitive to detect SAD than spirometry in subjects with chronic respiratory symptoms and PPF, and it correlates better with symptoms. IOS could be an additional method for SAD detection in the early stage of diseases.