Airway oscillometry parameters in baseline lung allograft dysfunction: Associations from a multicenter study.

BACKGROUND: Baseline lung allograft dysfunction (BLAD), the failure to achieve ≥80%-predicted spirometry after lung transplant (LTx), is associated with impaired survival. Physiologic abnormalities in BLAD are poorly understood. Airway oscillometry measures respiratory system mechanics and may provide insight into understanding the mechanisms of BLAD. OBJECTIVES: This study aims to describe and measure the association between airway oscillometry parameters [Reactance (Xrs5, Ax), Resistance (Rrs5, Rrs5-19)] (1) stable LTx recipients, comparing those with normal spirometry and those with BLAD; and (2) in recipients with chronic lung allograft dysfunction (CLAD), comparing those with normal baseline spirometry and those with BLAD. METHODS: A multi-center cross-sectional study was performed including bilateral LTx between January 2020 and June 2021. Participants performed concurrent airway oscillometry and spirometry. Multivariable logistic regression was performed to measure the association between oscillometry parameters and BLAD. RESULTS: A total of 404 LTx recipients performed oscillometry and 253 were included for analysis. Stable allograft function was confirmed in 149 (50.2%) recipients (92 (61.7%) achieving normal spirometry and 57 (38.3%) with BLAD). Among stable LTx recipients, lower Xrs5 Z-Score (aOR 0.50 95% CI 0.37-0.76, p = 0.001) was independently associated with BLAD. CLAD was present in 104 (35.0%) recipients. Among recipients with CLAD, lower Xrs5 Z-Score (aOR 0.73 95% CI 0.56-0.95, p = 0.02) was associated with BLAD. CONCLUSIONS: Oscillometry provides novel physiologic insights into mechanisms of BLAD. The independent association between Xrs5 and BLAD, in both stable recipients and those with CLAD suggests that respiratory mechanics, in particular abnormal elastance, is an important physiologic feature. Further longitudinal studies are needed to understand the trajectory of oscillometry parameters in relation to allograft outcomes.

Diffusing capacity of the lung for carbon monoxide: association with long-term outcomes after lung transplantation in a 20-year longitudinal study.

RATIONALE: The diffusing capacity of the lung for carbon monoxide corrected for haemoglobin (D LCOcor) measures gas movement across the alveolar-capillary interface. We hypothesised that D LCOcor is a sensitive measure of injurious allograft processes disrupting this interface. OBJECTIVES: To determine the prognostic significance of the D LCOcor trajectory on chronic lung allograft dysfunction (CLAD) and survival. METHODS: A retrospective analysis was conducted of all bilateral lung transplant recipients at a single centre, between January 1998 and January 2018, with one or more D LCOcor measurements. Low baseline D LCOcor was defined as the failure to achieve a D LCOcor >75% predicted. Drops in D LCOcor were defined as >15% below recent baseline. RESULTS: 1259 out of 1492 lung transplant recipients were included. The median (range) time to peak D LCOcor was 354 (181-737) days and the mean±sd D LCOcor was 80.2±21.2% pred. Multivariable analysis demonstrated that low baseline D LCOcor was significantly associated with death (hazrd ratio (HR) 1.68, 95% CI 1.27-2.20; p<0.001). Low baseline D LCOcor was not independently associated with CLAD after adjustment for low baseline forced expiratory volume in 1 s or forced vital capacity. Any D LCOcor declines ≥15% were significantly associated with death, independent of concurrent spirometric decline. Lower percentage predicted D LCOcor values at CLAD onset were associated with shorter post-CLAD survival (HR 0.75 per 10%-unit change, p<0.01). CONCLUSION: Low baseline D LCOcor and post-transplant declines in D LCOcor were significantly associated with survival, independent of spirometric measurements. We propose that D LCOcor testing may allow identification of a subphenotype of baseline and chronic allograft dysfunction not captured by spirometry. There may be benefit in routine monitoring of D LCOcor after lung transplantation to identify patients at risk of poor outcomes.

Limited recovery from post-acute sequelae of SARS-CoV-2 at 8 months in a prospective cohort.

In a longitudinal cohort, a significant proportion of patients had persistent symptoms 8 months after initial #COVID19 infection. There was no significant improvement in symptoms or health-related quality of life between 4- and 8-month assessments. https://bit.ly/2Wtb7IX.