Expiratory CT scanning in COVID-19 patients: can we add useful data?

OBJECTIVE: To evaluate small airway disease in COVID-19 patients using the prevalence of air trapping (AT) and correlating it with clinical outcomes. The relationship between CT-based opacities in small blood vessels and ventilation in patients with SARS-CoV-2 pneumonia was also assessed. METHODS: We retrospectively included 53 patients with positive RT-PCR results for SARS-CoV-2 between March and April of 2020. All subjects underwent HRCT scanning, including inspiratory and expiratory acquisitions. Subjects were divided into two groups based on visual identification of AT. Small blood vessel volumes were estimated by means of cross-sectional areas < 5 mm2 (BV5) derived from automated segmentation algorithms. Mixed-effect models were obtained to represent the BV5 as a function of CT-based lobar opacities and lobar ventilation. RESULTS: Of the 53 participants, AT was identified in 23 (43.4%). The presence of AT was associated with increased SpO2 at admission (OR = 1.25; 95% CI, 1.07-1.45; p = 0.004) and reduced D-dimer levels (OR = 0.99; 95% CI, 0.99-0.99; p = 0.039). Patients with AT were less likely to be hospitalized (OR = 0.27; 95% CI, 0.08-0.89; p = 0.032). There was a significant but weak inverse correlation between BV5 and CT-based lobar opacities (R2 = 0.19; p = 0.03), as well as a nonsignificant and weak direct correlation between BV5 and lobar ventilation (R2 = 0.08; p = 0.54). CONCLUSIONS: AT is a common finding in patients with COVID-19 that undergo expiratory CT scanning. The presence of AT may correlate with higher SpO2 at admission, lower D-dimer levels, and fewer hospitalizations when compared with absence of AT. Also, the volume of small pulmonary vessels may negatively correlate with CT opacities but not with lobar ventilation.

Lung deposition of inhaled once-daily long-acting muscarinic antagonists via standard jet nebulizer or dry powder inhaler, measured using functional respiratory imaging, in patients with chronic obstructive pulmonary disease.

BACKGROUND: Data for bronchodilator deposition via nebulizers and dry powder inhalers (DPIs) in the respiratory tract of patients with chronic obstructive pulmonary disease (COPD) are limited. We used functional respiratory imaging (FRI) to determine deposition patterns for revefenacin solution via a PARI LC® Sprint® nebulizer and tiotropium powder via HandiHaler® DPI. METHODS: Ten patients with COPD, of whom 9 had severe airflow obstruction, were selected from FLUIDDA's database. The study did not enroll patients. Drug deposition in the extrathoracic and intrathoracic regions, including the central and peripheral airways was simulated by FRI. The percentage of delivered dose and central-to-peripheral (C/P) deposition ratio for nebulizer and DPI were evaluated. RESULTS: Mean ±â€„standard deviation (SD) age was 64.7 ±â€„7.1 years, height was 168.8 ±â€„8.5 cm, and percent predicted forced expiratory volume in 1 s was 40.8 ±â€„12.3%; 50% of patients were men. At optimal inhalation flow, intrathoracic and peripheral deposition was three-fold higher for revefenacin via nebulizer than tiotropium via HandiHaler (mean ±â€„SD 34.6 ±â€„8.53% versus 10.9 ±â€„5.67% and 18.2 ±â€„4.30% versus 5.8 ±â€„2.73% of delivered dose, respectively). Similar results were observed for suboptimal flow (mean ±â€„SD percentage of revefenacin versus tiotropium: intrathoracic, 32.1 ±â€„8.3% versus 15.1 ±â€„5.9%; peripheral; 16.6 ±â€„4.1% versus 8.4 ±â€„2.9%). The C/P deposition ratio for nebulizer was similar to DPI (mean ±â€„SD 0.915 ±â€„0.241 versus 0.812 ±â€„0.249 at optimal; 0.947 ±â€„0.253 versus 0.784 ±â€„0.219 at suboptimal flow), even though the mass median aerodynamic diameter of revefenacin was higher than tiotropium. C/P deposition ratio for revefenacin decreased after bronchodilation (0.915 ±â€„0.241 pre-bronchodilation versus 0.799 ±â€„0.192 post-bronchodilation), suggesting progressively better deposition in the peripheral region, assuming bronchodilation occurred during the nebulization process. CONCLUSIONS: These results demonstrate more efficient intrathoracic and peripheral deposition for revefenacin via standard jet nebulizer than tiotropium via HandiHaler, with similar C/P deposition ratio in patients with COPD. Nebulizers are an efficient alternative to DPIs for bronchodilator administration in patients with COPD.

Expiratory CT scanning in COVID-19 patients: can we add useful data? / TC expiratória em pacientes com COVID-19: podemos adicionar dados úteis?

ABSTRACT Objective: To evaluate small airway disease in COVID-19 patients using the prevalence of air trapping (AT) and correlating it with clinical outcomes. The relationship between CT-based opacities in small blood vessels and ventilation in patients with SARS-CoV-2 pneumonia was also assessed. Methods: We retrospectively included 53 patients with positive RT-PCR results for SARS-CoV-2 between March and April of 2020. All subjects underwent HRCT scanning, including inspiratory and expiratory acquisitions. Subjects were divided into two groups based on visual identification of AT. Small blood vessel volumes were estimated by means of cross-sectional areas < 5 mm2 (BV5) derived from automated segmentation algorithms. Mixed-effect models were obtained to represent the BV5 as a function of CT-based lobar opacities and lobar ventilation. Results: Of the 53 participants, AT was identified in 23 (43.4%). The presence of AT was associated with increased SpO2 at admission (OR = 1.25; 95% CI, 1.07-1.45; p = 0.004) and reduced D-dimer levels (OR = 0.99; 95% CI, 0.99-0.99; p = 0.039). Patients with AT were less likely to be hospitalized (OR = 0.27; 95% CI, 0.08-0.89; p = 0.032). There was a significant but weak inverse correlation between BV5 and CT-based lobar opacities (R2 = 0.19; p = 0.03), as well as a nonsignificant and weak direct correlation between BV5 and lobar ventilation (R2 = 0.08; p = 0.54). Conclusions: AT is a common finding in patients with COVID-19 that undergo expiratory CT scanning. The presence of AT may correlate with higher SpO2 at admission, lower D-dimer levels, and fewer hospitalizations when compared with absence of AT. Also, the volume of small pulmonary vessels may negatively correlate with CT opacities but not with lobar ventilation.

RESUMO Objetivo: Avaliar a doença das pequenas vias aéreas em pacientes com COVID-19 por meio da prevalência de aprisionamento aéreo (AA) e sua correlação com desfechos clínicos. Também foi avaliada a relação entre opacidades tomográficas nos pequenos vasos sanguíneos e ventilação em pacientes com pneumonia por SARS-CoV-2. Métodos: Foram incluídos, retrospectivamente, 53 pacientes com teste de RT-PCR positivo para SARS-CoV-2 entre março e abril de 2020. Todos os indivíduos foram submetidos à TCAR, incluindo aquisições inspiratórias e expiratórias. Os indivíduos foram divididos em dois grupos com base na identificação visual de AA. Os volumes dos pequenos vasos sanguíneos foram estimados por meio de seções transversais < 5 mm2 (VS5) derivadas de algoritmos automatizados de segmentação. Modelos de efeito misto foram obtidos para representar o VS5 em função das opacidades lobares tomográficas e da ventilação lobar. Resultados: Identificou-se AA em 23 (43,4%) dos 53 participantes. A presença de AA apresentou associação com SpO2 elevada na admissão (OR = 1,25; IC95%: 1,07-1,45; p = 0,004) e níveis reduzidos de dímero D (OR = 0,99; IC95%: 0,99-0,99; p = 0,039). Pacientes com AA apresentaram menor probabilidade de hospitalização (OR = 0,27; IC95%: 0,08-0,89; p = 0,032). Houve correlação inversa significativa, mas fraca, entre VS5 e opacidades lobares tomográficas (R2 = 0,19; p = 0,03) e correlação direta não significativa e fraca entre VS5 e ventilação lobar (R2 = 0,08; p = 0,54). Conclusões: AA é um achado comum em pacientes com COVID-19 submetidos à TC expiratória. A presença de AA pode apresentar correlação com SpO2 elevada na admissão, níveis reduzidos de dímero D e menor probabilidade de hospitalização. Além disso, o volume dos pequenos vasos pulmonares pode apresentar correlação negativa com opacidades tomográficas, mas não com ventilação lobar.

A case series on lung deposition analysis of inhaled medication using functional imaging based computational fluid dynamics in asthmatic patients: effect of upper airway morphology and comparison with in vivo data.

CONTEXT: Asthma affects 20 million Americans resulting in an economic burden of approximately $18 billion in the US alone (Allergies and Asthma Foundation 2000; National Center for Environmental Health (NCEH) 1999). Research studies based on differences in patient-specific airway morphology for asthma and the associated effect on deposition of inhaled aerosols are currently not available in the literature. Therefore, the role of morphological variations such as upper airway (extrathoracic) occlusion is not well documented. OBJECTIVE: Functional imaging based computational fluid dynamics (CFD) of the respiratory airways for five asthmatic subjects is performed in this study using computed tomography (CT) based patient-specific airway models and boundary conditions. METHODS: CT scans for 5 asthma patients were used to reconstruct 3D lung models using segmentation software. An averaged inhalation profile and patient-specific lobar flow distribution were used to perform the simulation. The simulations were used to obtain deposition for BDP/Formoterol® HFA pMDI in the patient-specific airway models. RESULTS: The lung deposition obtained using CFD was in excellent agreement with available in vivo data using the same product. Specifically, CFD resulted in 30% lung deposition, whereas in vivo lung deposition was reported to be approximately 31%. CONCLUSION: It was concluded that a combination of patient-specific airway models and lobar boundary conditions can be used to obtain accurate lung deposition estimates. Lower lung deposition can be expected for patients with higher extrathoracic resistance. Novel respiratory drug delivery devices need to accommodate population sub-groups based on these morphological and anatomical differences in addition to subject age.