Small airway dysfunction on impulse oscillometry and pathological signs on lung ultrasound are frequent in post-COVID-19 patients with persistent respiratory symptoms

Impulse oscillometry in patients with persistent post-COVID-19 symptoms: A retrospective study

Introduction

Impaired lung function has been observed in patients following COVID-19 infection, with studies reporting persistent lung volume and diffusing capacity impairments. Some studies have demonstrated significantly higher small airway resistance in COVID-19 positive cases. This retrospective study aims to examine impulse oscillometry (IOS) data of patients with persistent symptoms after COVID-19 infection, focusing on the relationship between time and symptoms.

Material and Method

The study analyzed data from adult patients with persistent symptoms who underwent IOS testing within and after 84 days from the diagnosis date.

Result

The results showed that patients within 84 days and those between 31 and 84 days had higher small airway resistance values, indicating peripheral airway disease. Patients with dyspnea exhibited higher IOS values compared to those with cough symptoms, suggesting more significant impairment in the peripheral airways.

Conclusion

The study highlights the importance of using comprehensive diagnostic tools like IOS to assess respiratory impairments in post-COVID-19 patients, particularly in the small airways. Understanding the relationship between time and symptoms can provide valuable insights for the treatment of peripheral airway dysfunction in post-COVID-19 patients.

Long COVID symptoms after 8-month recovery: persistent static lung hyperinflation associated with small airway dysfunction

BACKGROUND

Limited research has investigated the relationship between small airway dysfunction (SAD) and static lung hyperinflation (SLH) in patients with post-acute sequelae of COVID-19 (PASC) especially dyspnea and fatigue.

METHODS

64 patients with PASC were enrolled between July 2020 and December 2022 in a prospective observational cohort. Pulmonary function tests, impulse oscillometry (IOS), and symptom questionnaires were performed two, five and eight months after acute infection. Multivariable logistic regression models were used to test the association between SLH and patient-reported outcomes.

RESULTS

SLH prevalence was 53.1% (34/64), irrespective of COVID-19 severity. IOS parameters and circulating CD4/CD8 T-cell ratio were significantly correlated with residual volume to total lung capacity ratio (RV/TLC). Serum CD8 + T cell count was negatively correlated with forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) with statistical significance. Of the patients who had SLH at baseline, 57% continued to have persistent SLH after eight months of recovery, with these patients tending to be older and having dyspnea and fatigue. Post-COVID dyspnea was significantly associated with SLH and IOS parameters R5-R20, and AX with adjusted odds ratios 12.4, 12.8 and 7.6 respectively. SLH was also significantly associated with fatigue.

CONCLUSION

SAD and a decreased serum CD4/CD8 ratio were associated with SLH in patients with PASC. SLH may persist after recovery from infection in a substantial proportion of patients. SAD and dysregulated T-cell immune response correlated with SLH may contribute to the development of dyspnea and fatigue in patients with PASC.

Impulse oscillometry assessment of respiratory function in pediatric patients with a history of COVID-19

OBJECTIVE

While coronavirus disease 2019 (COVID-19) is generally considered to exhibit a less severe clinical course in children than in adults, studies have demonstrated that respiratory symptoms can endure for more than 3 months following infection in at least one-third of pediatric cases. The present study evaluates the respiratory functions of children aged 3-15 years within 3-6 months of their recovery from COVID-19 using impulse oscillometry (IOS) and compares them with the values of healthy children.

METHODS

Included in this prospective cross-sectional study were 63 patients (patient group) aged 3-15 years who contracted COVID-19 between December 2021 and May 2022, as well as 57 healthy children as a control group, matched for age and sex. The demographic, clinical, and laboratory data of the patients were recorded, and respiratory function was assessed based on airway resistance (zR5, zR20, R5-20) and reactance (zX5, zX20, reactance area [AX], resonant frequency [Fres]) using an IOS device.

RESULTS

There were no significant differences in the age, weight, height, and body weight z score values of the two groups (p > .05). While the zR5 and R5-20 levels of the patient group were higher (p = .008 and p < .001, respectively) than those of the controls, the zR20, AX, and Fres values did not differ significantly between the groups (p > .05). The parameters indicating the reactance, including zX5 and zX20, were significantly lower in the patient group than in the control group (p = .028 and p < .001, respectively).

CONCLUSION

Total and peripheral airway resistances were found to be elevated in children who had recovered from COVID-19 in the preceding 3-6 months.

Oscillometry Longitudinal Data on COVID-19 Acute Respiratory Syndrome Treated with Non-Invasive Respiratory Support

Background: Oscillometry allows for the non-invasive measurements of lung mechanics. In COVID-19 ARDS patients treated with Non-Invasive Oxygen Support (NI-OS), we aimed to (1) observe lung mechanics at the patients' admission and their subsequent changes, (2) compare lung mechanics with clinical and imaging data, and (3) evaluate whether lung mechanics helps to predict clinical outcomes. Methods: We retrospectively analyzed the data from 37 consecutive patients with moderate-severe COVID-19 ARDS. Oscillometry was performed on their 1st, 4th, and 7th day of hospitalization. Resistance (R5), reactance (X5), within-breath reactance changes (ΔX5), and the frequency dependence of the resistance (R5-R19) were considered. Twenty-seven patients underwent computed tomographic pulmonary angiography (CTPA): collapsed, poorly aerated, and normally inflated areas were quantified. Adverse outcomes were defined as intubation or death. Results: Thirty-two patients were included in this study. At the first measurement, only 44% of them had an abnormal R5 or X5. In total, 23 patients had measurements performed on their 3rd day and 7 on their 7th day of hospitalization. In general, their R5, R5-R19, and ΔX decreased with time, while their X5 increased. Collapsed areas on the CTPA correlated with the X5 z-score (ρ = -0.38; p = 0.046), while poorly aerated areas did not. Seven patients had adverse outcomes but did not present different oscillometry parameters on their 1st day of hospitalization. Conclusions: Our study confirms the feasibility of oscillometry in critically ill patients with COVID-19 pneumonia undergoing NI-OS. The X5 z-scores indicates collapsed but not poorly aerated lung areas in COVID-19 pneumonia. Our data, which show a severe impairment of gas exchange despite normal reactance in most patients with COVID-19 ARDS, support the hypothesis of a composite COVID-19 ARDS physiopathology.

Impaired function in the lung periphery following COVID-19 is associated with lingering breathing difficulties

Lingering breathing difficulties are common after COVID-19. However, the underlying causes remains unclear, with spirometry often being normal. We hypothesized that small airway dysfunction (SAD) can partly explain these symptoms. We examined 48 individuals (32 women, 4 hospitalized in the acute phase) who experienced dyspnea and/or cough in the acute phase and/or aftermath of COVID-19, and 22 non-COVID-19 controls. Time since acute infection was, median (range), 65 (10-131) weeks. We assessed SAD using multiple breath washout (MBW) and impulse oscillometry (IOS) and included spirometry and diffusing-capacity test (DLCO). One-minute-sit-to-stand test estimated physical function, and breathing difficulties were defined as answering "yes" to the question "do you experience lingering breathing difficulties?" Spirometry, DLCO, and IOS were normal in almost all cases (spirometry: 90%, DLCO: 98%, IOS: 88%), while MBW identified ventilation inhomogeneity in 50%. Breathing difficulties (n = 21) was associated with increased MBW-derived Sacin . However, physical function did not correlate with SAD. Among individuals with breathing difficulties, 25% had reduced physical function, 25% had SAD, 35% had both, and 15% had normal lung function and physical function. Despite spirometry and DLCO being normal in almost all post-COVID-19 individuals, SAD was present in a high proportion and was associated with lingering breathing difficulties.

Post-COVID changes in lung function 6 months after veno-venous extracorporeal membrane oxygenation: a prospective observational clinical trial

Background

Severe coronavirus disease 2019 (COVID-19) may require veno-venous extracorporeal membrane oxygenation (V-V ECMO). While V-V ECMO is offered in severe lung injury to COVID-19, long-term respiratory follow-up in these patients is missing. Therefore, we aimed at providing comprehensive data on the long-term respiratory effects of COVID-19 requiring V-V ECMO support during the acute phase of infection.

Methods

In prospective observational cohort study design, patients with severe COVID-19 receiving invasive mechanical ventilation and V-V ECMO (COVID group, n = 9) and healthy matched controls (n = 9) were evaluated 6 months after hospital discharge. Respiratory system resistance at 5 and 19 Hz (R5, R19), and the area under the reactance curve (AX5) was evaluated using oscillometry characterizing total and central airway resistances, and tissue elasticity, respectively. R5 and R19 difference (R5-R19) reflecting small airway function was also calculated. Forced expired volume in seconds (FEV1), forced expiratory vital capacity (FVC), functional residual capacity (FRC), carbon monoxide diffusion capacity (DLCO) and transfer coefficient (KCO) were measured.

Results

The COVID group had a higher AX5 and R5-R19 than the healthy matched control group. However, there was no significant difference in terms of R5 or R19. The COVID group had a lower FEV1 and FVC on spirometry than the healthy matched control group. Further, the COVID group had a lower FRC on plethysmography than the healthy matched control group. Meanwhile, the COVID group had a lower DLCO than healthy matched control group. Nevertheless, its KCO was within the normal range.

Conclusion

Severe acute COVID-19 requiring V-V ECMO persistently impairs small airway function and reduces respiratory tissue elasticity, primarily attributed to lung restriction. These findings also suggest that even severe pulmonary pathologies of acute COVID-19 can manifest in a moderate but still persistent lung function impairment 6 months after hospital discharge.

Trial registration

NCT05812196.

Does Mild Coronavirus Disease 2019 Pneumonia in Healthy Adults Cause Permanent Small Airway Injury?

OBJECTIVES

Impulse oscillometry (IOS) is a type of oscillation technique that measures the input impedance (Z) of the respiratory system and can be used to detect pathological changes in the small airways at an early stage. Although coronavirus disease 2019 (COVID-19) affects the vascular and parenchymal structures in the lung, chronic postinfection coughs also may be attributed to small airway pathologies. Our research aimed to use IOS for the assessment of the presence of small airway resistance (R) in patients who have had COVID-19.

METHODS

Thirty-eight patients with past COVID-19 infections and without any presence or medical treatment of an airway disease who presented to the post-COVID outpatient clinic with coughing symptoms were included in the study. The control group consisted of 17 patients with no past COVID-19 infection and without an airway disease. IOS and spirometry were performed twice in the case group, at 3 and 6 months after COVID-19.

RESULTS

The mean age of the case group was 44.7 ± 12.3 years, whereas the mean age of the control group was 49.4 ± 11.8 years. The case group consisted of 38 patients, whereas 17 patients constituted the control group. No statistically significant difference was found between the two groups in the first and second test measurements, performed 3 months apart (P > 0.05).

CONCLUSIONS

The fact that there was no difference between respiratory system impedance, airway resistance, and spirometry values between groups with and without past COVID-19 infections supported the hypothesis that small airways were not affected 3 months after COVID-19.

Preoperative small airway dysfunction is associated with skeletal muscle loss in early-stage non-small cell lung cancer

BACKGROUND

Postoperative skeletal muscle loss (SM loss) was reported to be associated with a poor prognosis in early-stage non-small cell lung cancer (NSCLC). Small airway dysfunction (SAD) is a common but neglected respiratory abnormality. Little information is known about the association between preoperative SAD and postoperative SM loss in early-stage NSCLC. Therefore, this study aimed to investigate the correlation between preoperative SAD and SM loss after surgery in early-stage NSCLC patients.

METHODS

There were 348 NSCLC patients with stages I-IIIA in this study from January 2017 to December 2020. All CT images were contrast-enhanced scans, and the skeletal muscle index (SMI) was measured using CT images. A 10.0% decrease in SMI over 12 months was determined as the cut-off value to define excessive SM loss. Logistic regression analyses were used to examine the relationship between SAD and SM loss.

RESULTS

This study included 348 subjects who underwent pulmonary operation (159 males and 189 females; mean age: 57.5 ± 8.8 years). 152 (43.7%) patients were identified as having SAD before surgery, and 179 patients (51.4%) were identified as having SM loss after 1 year. Moreover, a higher incidence of SAD was found in the SM loss group compared with that in the non-SM loss group (52.0% vs. 34.9%, p = 0.001). The patients with SAD were older, had larger tumor size, and had lower albumin levels. Furthermore, there were significant correlations between the lung function parameters manifesting SAD and the percentage change in SMI (for the forced expiratory flow when 75% of forced vital capacity has been exhaled (FEF75%), Pearson r=-0.107, p = 0.046; for FEF50%, r = -0.142, p = 0.008; and for FEF25-75%, r=-0.124, p = 0.021; respectively). However, no significant correlations were found between SMI and the lung function parameters reflecting proximal airway obstruction (p > 0.05). Logistic regression analysis revealed that preoperative SAD (HR, 2.465; 95% CI, 1.256-4.838; p = 0.009) was independent risk factor for postoperative SM loss in early-stage NSCLC. In addition, multivariable analysis revealed that SAD (HR, 1.816; 95% CI, 1.025-3.216, P = 0.041) were associated with postoperative complications.

CONCLUSION

Preoperative SAD is significantly associated with postoperative complications and SM loss in early NSCLC patients. Our results suggest that preoperative assessment of SAD may be useful for risk stratification of surgical candidates with potential for targeted interventions.

Window of opportunity for respiratory oscillometry: A review of recent research

Oscillometry has been around for almost 70 years, but there are still many unknowns. The test is performed during tidal breathing and is therefore free from patient-dependent factors that could influence the results. The Forced Oscillation Technique (FOT), which requires minimal patient cooperation, is gaining ground, particularly with elderly patients and children. In pulmonology, it is a valuable tool for assessing obstructive conditions (with a distinction between central and peripheral obstruction) and restrictive disorders (intrapulmonary and extrapulmonary). Its sensitivity allows the assessment of bronchodilator and bronchoconstrictor responses. Different lung diseases show different patterns of changes in FOT, especially studied in asthma and chronic obstructive pulmonary disease. Because of these differences, many studies have analysed the usefulness of this technique in different areas of medicine. In this paper, the authors would like to present the basics of oscillometry with the areas of its most recent clinical applications.

Small airway disease in post-acute COVID-19 syndrome, a non-conventional approach in three years follow-up of a patient with long COVID: a case report

BACKGROUND

Small airways disease (SAD), a novel finding described in post-acute COVID-19 patients, should be suspected when respiratory symptoms continue, air trapping persists on expiratory CT scans, and imaging findings fail to improve despite objectively better conventional pulmonary function test (PFT) parameters. The forced oscillation technique (FOT) and Multiple breathing washout (MBW) are both very sensitive methods for detecting anomalies in the peripheral airways.

CASE PRESENTATION

We discuss the case of a 60-year-old Hispanic patient who had severe COVID-19 pneumonia and developed dyspnea, fatigue, and limited daily activity a year later. The PFTs revealed restrictive lung disease, as seen by significant diffusing capacity of the lungs for carbon monoxide (DLCO) decrease, severe desaturation, and poor 6-min walk test (6MWT) performance. The patient was treated with lowering corticosteroids as well as pulmonary rehabilitation (PR). During the 24-month follow-up, the dyspnea and fatigue persisted. On PFTs, 6MWT performance and restricted pattern improved slightly, but MBW discovered significant ventilatory inhomogeneity. FOT revealed substantial peripheral airway obstructive abnormalities. On CT scans, air trapping and ground-glass opacities (GGO) improved somewhat. The patient used a bronchodilator twice a day and low-dose inhaled corticosteroids (160 µg of budesonide and 4.5 µg of formoterol fumarate dihydrate) for nine months. PR sessions were resuming. The restricting parameters were stabilized and the DLCO had normalized after 36 months, with a 6MWT performance of 87% but significant desaturation. The CT scan revealed traction bronchiectasis, low GGO, and persistent air trapping. Without normalization, FOT and MBW scores improved, indicating small airway disease.

CONCLUSIONS

The necessity of integrating these tests when detecting SAD is emphasized in our paper. This article lays the foundation for future research into the best ways to manage and monitor SAD in post-acute COVID-19 patients.

Elevated complement C3 and increased CD8 and type 1 helper lymphocyte T populations in patients with post-COVID-19 condition

BACKGROUND

Biological markers associated to post-COVID-19 condition (PCC) have not been clearly identified.

METHODS

Eighty-two patients attending our post-COVID-19 outpatient clinic were recruited and classified as fully recovered (40.2%) or presenting with PCC (59.8%). Clinical and radiological data, laboratory markers, cytokines, and lymphocyte populations were analyzed.

RESULTS

Median number of days after hospitalization was 78.5 [p25-p75: 60-93] days. PCC was significantly more frequent in women, in patients with a previously critical COVID-19, and in those with two or more comorbidities. No differences were found in lymphocyte counts, ferritin, C-reactive protein, D-dimer or sCD25, IL-1β, IL-1Ra, IL-6, CXCL8, IL-17A, IL-18, IL-22, IFN-γ, TNF-α, and IL-10 cytokines levels. PCC patients showed significantly higher levels of complement factor C3 than fully recovered patients: median C3 128 mg/dL [p25-p75:107-135] vs 111 mg/dL [p25-p75: 100-125] (p =.005), respectively. In the flow cytometry assessment of peripheral blood lymphocyte subpopulations, PCC patients showed significantly increased CD8 populations compared to fully recovered patients: median CD8: 529 [p25-p75: 384-683] vs 370/mm3 [p25-p75:280-523], p =.007. When type 1, 2, 17/22, and 17.1 helper and follicular T lymphocyte subpopulations were analyzed, the frequency of Th1 was significantly higher in PCC patients compared to fully recovered patients (30% vs 38.5%, p =.028).

CONCLUSION

Patients with a post-COVID-19 condition showed significantly increased immunological parameters of inflammation (complement factor C3 and CD8 and Th1 T lymphocyte populations) compared to fully recovered patients. These parameters could be used as biological markers of this condition.

Post-Infection Oscillometry and Pulmonary Metrics in SARS-CoV-2 Patients: A 40-Day Follow-Up Study

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has had significant impacts on pulmonary function. This study aimed to comprehensively evaluate pulmonary function and structure in patients 40 days post-SARS-CoV-2 infection, employing an array of testing methodologies including spirometry, plethysmography, forced oscillometry, and CT scanning. It also sought to establish potential correlations between these metrics and evaluate if forced oscillometry could provide additional value in post-infective lung function assessment. A 40-day post-infection follow-up observational study was conducted involving 66 patients with confirmed SARS-CoV-2 infection. The results revealed decreases in FVC and FEF25-75 with the increasing severity of COVID-19. Specifically, patients with severe symptoms exhibited statistically significant decreases in FVC (mean = 86.8) compared with those with mild symptoms (mean = 106.0; p = 0.018). The FEF25-75 showed a similar trend, with severe patients exhibiting a mean of 77.7 compared with 82.9 in the mild group (p = 0.017). Furthermore, resonant frequency (RF) increased with disease severity, with the severe group exhibiting a statistically significant increase (mean = 17.4) compared with the mild group (mean = 14.3; p = 0.042). CT scans showed an increase in ground-glass opacities with disease severity, with 81.8% of severe patients demonstrating this finding (p = 0.037). Multiple regression analysis revealed that Reactance at 4 Hz (X4), Forced Expiratory Flow 25-75% (FEF25-75), and Resonant Frequency (RF) were significantly related to COVID-19 severity. Specifically, for each unit increase in these factors, the risk of the event was estimated to increase by a factor of 3.16, 2.09, and 1.90, respectively. Conversely, Resistance at 4 Hz (R4) and Airway Resistance (RAW) were found to significantly decrease the event hazard, highlighting their potential protective role. Spirometry, plethysmography, and forced oscillometry are effective in assessing these changes. Forced oscillometry may be particularly beneficial in identifying subtle changes in lung function post-COVID-19. Further studies are warranted to validate these findings and develop strategies to manage post-infective pulmonary changes in SARS-CoV-2 patients.

Ventilation dynamics using a portable device coupled to the six-minute walk test in people with long-COVID syndrome: a preliminary study

OBJECTIVE

To investigated the dynamic ventilatory responses and their influence on functional exercise capacity in patients with long-COVID-19 syndrome (LCS).

RESULTS

Sixteen LCS patients were subjected to resting lung function (spirometry and respiratory oscillometry-RO) and cardiopulmonary performance to exercise (Spiropalm®-equipped six-minute walk test-6MWT and cardiopulmonary exercise test-CPX). At rest, spirometry showed a normal, restrictive and obstructive pattern in 87.5%, 6.25% and 6.25% of participants, respectively. At rest, RO showed increased resonance frequency, increased integrated low-frequency reactance and increased difference between resistance at 4-20 Hz (R4-R20) in 43.7%, 50%, and 31.2% of participants, respectively. The median of six-minute walking distance (DTC6) was 434 (386-478) m, which corresponds to a value of 83% (78-97%) of predicted. Dynamic hyperinflation (DH) and reduced breathing reserve (BR) were detected in 62.5% and 12.5% of participants, respectively. At CPX, the median peak oxygen uptake (VO_2peak) was 19 (14-37) ml/kg/min. There was a significant correlation of 6MWD with both R4-R20 (r_s=-0.499, P = 0.039) and VO_2peak (r_s=0.628, P = 0.009). Our results indicate that DH and low BR are contributors to poor exercise performance, which is associated with peripheral airway disease. These are promising results considering that they were achieved with simple, portable ventilatory and metabolic systems.

Assessment of short- and long-term functionality and quality of life in patients with post-acute COVID-19 syndrome

BACKGROUND

Although the number of new cases of coronavirus 2019 (COVID-19) has been drastically reduced worldwide, patients who demonstrate long-term symptoms need more attention from health systems, as these symptoms can negatively affect functionality and quality of life.

OBJECTIVE

To evaluate muscle function and quality of life at 3, 6, 9 and 12 months in patients with post-acute COVID-19 syndrome and to assess their associations with general fatigue and lung function.

METHODS

This observational and longitudinal study evaluated patients with post-acute COVID-19 syndrome. Participants were subjected to the following evaluations: Short Form-36; handgrip strength; Functional Assessment of Chronic Illness Therapy-Fatigue scale; and spirometry.

RESULTS

Among the 350 participants who were evaluated in the third month, 74.6%, 61.4% and 45.4% reported general fatigue, dyspnoea and cough, respectively. In the comparisons between the third month and the sixth month, there were significant increases in Functional Assessment of Chronic Illness Therapy-Fatigue scale, pulmonary function and several Short Form-36 domains. In the comparisons between the sixth month and the ninth month, there was a significant increase only in the social functioning domain of the Short Form-36. In the comparisons between the ninth month and the twelfth month, there was an increase only in some Short Form-36 domains. Significant correlations were observed between the Short Form-36 domains with Functional Assessment of Chronic Illness Therapy-Fatigue scale, handgrip strength and pulmonary function.

CONCLUSION

In patients with post-acute COVID-19 syndrome, there was a progressive improvement in quality of life, general fatigue and pulmonary function during the 12 months of follow-up, with this improvement being more pronounced in the first 6 months. There was a relationship between functionality and quality of life in these patients.

The Glittre-ADL test in non-hospitalized patients with post-COVID-19 syndrome and its relationship with muscle strength and lung function

BACKGROUND

Patients with post-acute COVID-19 syndrome tend to have limitations in performing activities of daily living, which may negatively impact performance during the Glittre-ADL test. This study aimed to verify if the Glittre-ADL test is associated with measures of pulmonary function, muscle function, and health-related quality of life in the assessment of non-hospitalized patients with sequelae of COVID-19, and also to identify the predictor variables related to the Glittre-ADL test in order to create a predictive model.

METHODS

Cross-sectional study with 37 women with post-acute COVID-19 syndrome who underwent Glittre-ADL test. They performed pulmonary function tests and measurements of handgrip strength and quadriceps strength. Additionally, they completed the Post-COVID-19 Functional Status scale and the Short Form-36 questionnaire.

FINDINGS

The mean value of Glittre-ADL test time was 4.8 ± 1.1 min, which was 163.7 ± 39.7% of the predicted. The Glittre-ADL test time showed correlation with diffusing capacity for carbon monoxide (r = -0.671, P < 0.0001), forced vital capacity (r = -0.588, P = 0.0001), maximum inspiratory pressure (r = -0.391, P = 0.015), handgrip strength (r = -0.453, P = 0.005), quadriceps strength (r = -0.591, P = 0.0001), and various dimensions of the Short Form-36 questionnaire. In the regression analysis, diffusing capacity for carbon monoxide, quadriceps strength, and forced vital capacity explained 64% of the Glittre-ADL test time variability.

INTERPRETATION

In patients with post-acute COVID-19 syndrome, lung function and quadriceps strength strongly affect the time to perform Glittre-ADL test multiple tasks.

Long-term dyspnea, regional ventilation distribution and peripheral lung function in COVID-19 survivors: a 1 year follow up study

Background

Dyspnea is common after COVID-19 pneumonia and can be characterized by a defective CO2 diffusion (DLCO) despite normal pulmonary function tests (PFT). Nevertheless, DLCO impairment tends to normalize at 1 year, with no dyspnea regression. The altered regional distribution of ventilation and a dysfunction of the peripheral lung may characterize dyspnea at 1 year after COVID-19 pneumonia. We aimed at assessing the pattern of airway resistance and inflammation and the regional ventilation inhomogeneity in COVID-19 pneumonia survivors at 12-months after hospital discharge.

Methods

We followed up at 1-year patients previously admitted to the respiratory units (intensive care or sub-intensive care unit) for COVID-19 acute respiratory failure at 1-year after hospital discharge. PFT (spirometry, DLCO), impulse oscillometry (IOS), measurements of the exhaled nitric oxide (FENO) and Electrical Impedance Tomography (EIT) were used to evaluate lung volumes, CO2 diffusion capacity, peripheral lung inflammation/resistances and the regional inhomogeneity of ventilation distribution. A full medical examination was conducted, and symptoms of new onset (not present before COVID-19) were recorded. Patients were therefore divided into two groups based on the presence/absence of dyspnea (defined as mMRC ≥1) compared to evaluate differences in the respiratory function derived parameters.

Results

Sixty-seven patients were admitted between October and December 2020. Of them, 42/67 (63%) patients were discharged alive and 33 were evaluated during the follow up. Their mean age was 64 ± 11 years and 24/33 (73%) were males. Their maximum respiratory support was in 7/33 (21%) oxygen, in 4/33 (12%) HFNC, in 14/33 (42%) NIV/CPAP and in 8/33 (24%) invasive mechanical ventilation. During the clinical examination, 15/33 (45%) reported dyspnea. When comparing the two groups, no significant differences were found in PFT, in the peripheral airway inflammation (FENO) or mechanical properties (IOS). However, EIT showed a significantly higher regional inhomogeneity in patients with dyspnea both during resting breathing (0.98[0.96–1] vs 1.1[1–1.1], p = 0.012) and during forced expiration (0.96[0.94–1] vs 1 [0.98–1.1], p = 0.045).

Conclusions

New onset dyspnea characterizes 45% of patients 1 year after COVID-19 pneumonia. In these patients, despite pulmonary function test may be normal, EIT shows a higher regional inhomogeneity both during quiet and forced breathing which may contribute to dyspnea.

Clinical trial registration

Clinicaltrials.gov NCT04343053, registration date 13/04/2020.

Challenges in the Management of Post-COVID-19 Pulmonary Fibrosis for the Latin American Population

This commentary aims to highlight some of the major issues (with possible solutions) that the Latin American region is currently dealing with in managing post-COVID-19 pulmonary fibrosis. Overall, there is little evidence for successful long-term COVID-19 follow-up treatment. The lack of knowledge regarding proper treatment is exacerbated in Latin America by a general lack of resources devoted to healthcare, and a lack of availability and access to multidisciplinary teams. The discussion suggests that better infrastructure (primarily multicenter cohorts of COVID-19 survivors) and well-designed studies are required to develop scientific knowledge to improve treatment for the increasing prevalence of pulmonary fibrosis in Latin America.

Can home rehabilitation impact impulse oscillometry and lung ultrasound findings in patients with scleroderma-associated interstitial lung disease? A pilot study

Objective

Exercise has been demonstrated to be beneficial for improving physical capacity and quality of life in people with scleroderma, although knowledge of its impact on the respiratory system is limited. This study evaluated the impact of therapist-oriented home rehabilitation (TOHR) on impulse oscillometry (IOS) and lung ultrasound (LUS) findings in patients with scleroderma-associated interstitial lung disease (ILD).

Results

Twelve women with scleroderma underwent spirometry, IOS, and LUS before and after performing TOHR. Regarding spirometry, a normal pattern and restrictive damage were observed in five (41.7%) and seven (58.3%) participants pre-TOHR and post-TOHR, respectively. For IOS, an abnormal result was detected in nine (75%) pre-TOHR participants and six (50%) post-TOHR participants. Heterogeneity of resistance between 4–20 Hz (R4-R20) > 20% of the predicted value was observed in eight (66.7%) pre-TOHR participants and three (25%) post-TOHR participants (P = 0.031). An abnormal LUS result was observed in nine (75%) participants both pre-TOHR and post-TOHR. The main change observed was B-lines > 2, which was noted in nine (75%) participants both pre-TOHR and post-TOHR. Our findings suggest that TOHR for women with scleroderma-associated ILD improves the resistance and reactance measured by IOS, including small airway disease.

Trial Registration ClinicalTrials.gov ID: NCT05041868 Registered on: 13th September 2021.