ABSTRACT
Background: Small airway disease (SAD) can occur following viral infection, but the prevalence of this in individuals recovering post SARS-COV2 infection is not known. Aim(s): We sought to assess the prevalence of SAD in patients 1 year post hospital discharge for COVID-19. Method(s): A subset of patients recruited to the PHENOTYPE study (NCT 04459351) underwent forced oscillometry assessment (THORASYS). We assessed the fall in resistance from 5 to 20 Hz (R5-R20) as a marker of peripheral airway dysfunction. A value of >0.07kPa/L/s was used as a cut off definition for small airways dysfunction. All patients had lung function testing and a clinical assessment of symptoms within a median of 7.5 (IQR 4-15) days and median of 7 (IQR 4-11) days, respectively, of small airways testing. Result(s): 40 patients were enrolled between November 2021 and January 2022, at a median of 371 days (IQR 359- 380) post hospital discharge. 31/40 (78%) were male with a median age of 63 (IQR 51-72). The median length of hospital stay was 6.5 days (IQR 4-12). 11/40 patients had required non-invasive ventilation and 29/40 oxygen therapy alone. 11/40 (28%) of patients had evidence of SAD. Self-reported breathlessness (p=0.75) and cough (p=0.50) at 1 year were not increased in SAD. Similarly, there was no association between SAD and ventilatory status (p=0.98), FENO>=25 (p=0.63) or FENO> 50 (p=0.86) at 3 months or FENO >=25 (p=0.87) or FENO>50 (p=0.29) at 1 year. Conclusion(s): Small airways disease is present in patients recovering post COVID-19 but the risk factors for developing this is unclear. Longitudinal studies are required to assess the trajectory and long term impact of small airways pathology.
ABSTRACT
Introduction: NIRS reduces intubation rate in COVID-19 pneumonia. Outcome is related to age, comorbidities, and baseline illness severity. Thoracic CT has prognostic value in COVID-19 pneumonia. Forced Oscillatory Technique (FOT) allows non-invasive assessment of respiratory reactance (Xrs) that is related to lung compliance. A pilot study showed FOT feasibility in patients with COVID-19 pneumonia receiving NIRS (1). Aim(s): Measuring Xrs in COVID19 patients receiving NIRS and correlate with CT. Method(s): The local ERB approved the study. 32 consecutive patients with moderate-severe COVID-19 ARDS were enrolled. Patients underwent non-invasive ventilation (NIV) alternated to High Flow Nasal Cannula (HFNC). In the first 24 hours of hospitalization triplicate FOT measurements were performed (Resmon ProFULL) according to current guidelines during HFNC. Within 1 week 28 patients underwent computed tomographic pulmonary angiography (CTPA) and collapsed, infiltrated and normally inflated areas were quantified (3D Slicer software). Result(s): 12 patients had altered Xrs-z score. Collapsed areas correlated with Xrs z-score (rho=0.37;p=0.046) and almost with inspiratory Xrs (rho=-0.36;p=0.055). Inflated areas correlated with inspiratory Xrs (rho=0.42;p=0.024) while infiltrated areas didn't. In our cohort CTPA and FOT parameters didn't discriminate outcomes but inflated areas were inversely related to hospitalization (rho=-0.43;p=0.04). Conclusion(s): FOT showed abnormal Xrs in a subset of patients. Xrs z-score is a noninvasive index of collapsed areas in COVID-19 pneumonia and could be useful in patients assessment and follow up.
ABSTRACT
Background: Forcrd oscillation technique (FOT) is a non-invasive method for investigation of lung mechanics without active participation of the patient. The objectives of the study were to find out whether FOT method could be used for monitoring of covid-19 pneumonia (CVP) course and how FOT indices correlate with other, commonly used indicators of disease severity. Method(s): During the hospital stay and 3 months after the discharge from hospital repeated measurements of lung mechanics were performed with portable device Tremoflo-100 (Thorasys, Canada). Result(s): Most relevant differences between disease stages reflected the lung reactance indices - Fres and AX. Indices characterizing the airflow resistance didn't reach the significance level. Correlation analysis also was performed between FOT indices and CT score, body mass index (BMI), patients age, blood CRP and ferritin levels, duration of hospital stay and patients oxygen demand (FiO2). Significant correlations View inline were found only between the last two. The highest significance showed Fres % pred and AX % pred. Fres correlated to FiO2 with R=0,498 and p-0,0000004, but AX% with r=0,502 Conclusion(s): The study has shown that FOT method reflects the changes in lung mechanics occurring during acute phase and recovery period from covid-19 pneumonia. FOT indices correlate with patients oxygen demand and hospital stay-time.
ABSTRACT
Introduction: Lung functions impairment in covid-19 pneumoniasurvivors cause continued symptoms.Forced oscillation technique (FOT) and impulse oscillometry are valuable in serial monitoring and management of postcovid respiratory symptoms. We aimed to study changes in pulmonary mechanics over 1 year period in covid-19 survivors. Methods: Covid-19 survivors of mixed severity of 18-80 age group underwent serial measurements of FOT using Antlia Caltech © device: on the first follow-up post-discharge, second at 4 weeks after the first and third one-year post-diagnosis of Covid-19. Demographic details, pulse oximetry at rest and modified medical research council scale (mMRC) for dyspnea were recorded at each visit. Pre and post-bronchodilator resistance and reactance were analysed. Results: Out of 94 patientsenrolled,17 completed 1-year follow-up post-covid. 3 patients had moderate, 1 severe and 13 mild covid-19 disease.Age group of participant was 45-75 years (Mean= 58.1±2.2) consisting of 13 males and 4 females. 4 had diabetes and an equal number had hypertension. Rest were without any comorbidity. Small airway resistance R5-R20 was0.87±0.57, [0.25-2.03] (Mean±SD, Range. (n=17), p=0.047), 0.79±0.52, [0.01- 1.93] and 0.66±0.49, [-0.05 - 1.59] similarly reactance-X5 was -0.18±0.12, [-0.43-(-0.04)], -0.16±0.1, [-0.36 - 0.001] and -0.16±0.13, [-0.47-(-0.03)] at first visit, 4 weeks and after 1 year respectively. Results of post-bronchodilator change in small airways are depicted in Figure-1. Conclusion: We found statistically significant change towards improvement in small airway resistance R5-R20. Reactance at 5Hz-X5during monitoring period showed decremental change over a year. Some post-bronchodilator reversibility persisted at the end of 1 year.
ABSTRACT
High-frequency oscillatory ventilation (HFOV) is a type of mechanical ventilation with a protective potential characterized by a small tidal volume. Unfortunately, HFOV has limited monitoring of ventilation parameters and mechanical parameters of the respiratory system, which makes it difficult to adjust the continuous distension pressure (CDP) according to the individual patient’s airway status. Airway resistance Raw is one of the important parameters describing the mechanics of the respiratory system. The aim of the presented study was to verify in vitro whether the resistance of the respiratory system Rrs can be reliably determined during HFOV to evaluate Raw in pediatric and adult patients. An experiment was performed with a 3100B high-frequency oscillator, a physical model of the respiratory system, and a pressure and flow measurement system. The physical model with different combinations of resistance and compliance was ventilated during the experiment. The resistance Rrs was calculated from the impedance of the physical model, which was determined from the spectral density of the pressure at airway opening and the spectral cross-density of the gas flow and pressure at airway opening. Rrs of the model increased with an added resistor and did not change significantly with a change in compliance. The method is feasible for monitoring respiratory system resistance during HFOV and has the potential to optimize CDP settings during HFOV in clinical practice.