Lung Volume Measurements Research Articles

Validity of B-Mode Ultrasound for Body Composition Assessment in the Field

Introduction: Identifying an accurate, user friendly alternative to skinfold calipers may allow for accurate assessment of body composition in more applied settings, such as various training and competition venues. The purpose of our study was to determine the validity of B-mode ultrasound (BMUS) for body composition assessment by comparing this method to values obtained using air displacement plethysmography (ADP). Methods: Twenty-four active runners underwent two forms of body composition assessment during a single lab visit; ADP and BMUS. ADP body density was estimated using an air displacement chamber in combination with measured lung volume. BMUS body density was estimated from measuring the Jackson-Pollock 7 site skinfolds with a portable, app-based ultrasound device to determine subcutaneous fat thickness. Images were analyzed using proprietary software. Body density values for both methods were converted to body fat percentage using the Siri equation. A paired samples t-test was used to compare values obtained from ADP and BMUS. Results: There was no difference between ADP (18.3 ± 7.3%) and BMUS (17.2 ± 7.6%; p = 0.1) for percent body fat. Conclusions: BMUS provides a valid method for assessing body composition when compared to ADP, thus providing a portable, accurate method for assessing body composition in applied settings.

Estimating Preterm Lung Volume: A Comparison of Lung Ultrasound, Chest Radiography, and Oxygenation

To determine the relationship between lung ultrasound (LUS), chest x-ray (CXR), radiographic and clinical evaluation in the assessment of lung volume in preterm infants STUDY DESIGN: In this prospective cohort study LUS was performed before CXR on 70 preterm infants and graded using: 1. a LUS score; 2. an atelectasis score; and 3. measurement of atelectasis depth. Radiographic diaphragm position and radio-opacification were used to determine global and regional radiographic atelectasis. The relationship between LUS, CXR, and oxygenation was assessed using receiver operator characteristics (ROC) and correlation analysis. LUS scores, atelectasis scores, and atelectasis depth did not correspond with radiographic global atelectasis (area under ROC curves [95% CI]: 0.54[0.36,0.71], 0.49[0.34,0.64], 0.47[0.31,0.64], respectively). Radiographic atelectasis of the right upper, right lower, left upper, and left lower quadrants was predicted by LUS scores (0.75[0.59,0.92], 0.75[0.62,0.89], 0.69[0.56,0.82], 0.63[0.508,0.751]) and atelectasis depth (0.66 [0.54,0.78], 0.65[0.53,0.77], 0.63[0.50,0.76], 0.56[0.44,0.70]). LUS findings were moderately correlated with oxygen saturation index (ρ=0.52[0.30,0.70]) and saturation to fraction of inspired oxygen ratio (ρ=-0.63[-0.76,-0.46]). The correlation between radiographic diaphragm position, oxygenation saturation index, and SpO2 to FiO2 ratio was very weak (ρ=0.36[0.11,0.59] and ρ=-0.32[-0.53,-0.07] respectively). LUS assessment of lung volume does not correspond with radiographic diaphragm position preterm infants. However, LUS predicted radiographic regional atelectasis and correlated with oxygenation. The relationship between radiographic diaphragm position and oxygenation was very weak. While LUS may not replace all radiographic measures of lung volume, LUS more accurately reflects respiratory status in preterm infants.

Impact of impaired pulmonary function on clinical outcomes in survivors of severe COVID-19 without pre-existing respiratory disease.

To investigate the impact of impaired pulmonary function on patient-centered outcomes after hospital discharge due to severe COVID-19 in patients without preexisting respiratory disease. This is an ongoing prospective cohort study evaluating patients (> 18 years of age) 2-6 months after hospital discharge due to severe COVID-19. Respiratory symptoms, health-related quality of life, lung function, and the six-minute walk test were assessed. A restrictive ventilatory defect was defined as TLC below the lower limit of normal, as assessed by plethysmography. Chest CT scans performed during hospitalization were scored for the presence and extent of parenchymal abnormalities. At a mean follow-up of 17.2 ± 5.9 weeks after the diagnosis of COVID-19, 120 patients were assessed. Of those, 23 (19.2%) reported preexisting chronic respiratory diseases and presented with worse lung function and exertional dyspnea at the follow-up visit in comparison with their counterparts. When we excluded the 23 patients with preexisting respiratory disease plus another 2 patients without lung volume measurements, a restrictive ventilatory defect was observed in 42/95 patients (44%). This subgroup of patients (52.4% of whom were male; mean age, 53.9 ± 11.3 years) showed reduced resting gas exchange efficiency (DLCO), increased daily-life dyspnea, increased exertional dyspnea and oxygen desaturation, and reduced health-related quality of life in comparison with those without reduced TLC (50.9% of whom were male; mean age, 58.4 ± 11.3 years). Intensive care need and higher chest CT scores were associated with a subsequent restrictive ventilatory defect. The presence of a restrictive ventilatory defect approximately 4 months after severe COVID-19 in patients without prior respiratory comorbidities implies worse clinical outcomes.

Prevalence of restrictive lung function in children and adults in the general population

BackgroundRestrictive lung function (RLF) is characterized by a reduced lung expansion and size. In the absence of lung volume measurements, restriction can be indirectly assessed with restrictive spirometric patterns (RSP) by spirometry. Prevalence data on RLF by the golden standard body plethysmography in the general population are scarce. Therefore, we aimed to evaluate the prevalence of RLF and RSP in the general population by body plethysmography and to determine factors influencing RLF and RSP. MethodsPre-bronchodilation lung function data of 8891 subjects (48.0% male, age 6–82 years) have been collected in the LEAD Study, a single-centered, longitudinal, population-based study from Vienna, Austria. The cohort was categorized in the following groups based on the Global Lung Initiative reference equations: normal subjects, RLF (TLC < lower limit of normal (LLN)), RSP (FEV1/FVC ≥ LLN and a FVC < LLN), RSP only (RSP with TLC ≥ LLN). Normal subjects were considered those with FEV1, FVC, FEV1/FVC and TLC between LLN and ULN (upper limit of normal). ResultsThe prevalence of RLF and RSP in the Austrian general population is 1.1% and 4.4%. Spirometry has a positive and negative predictive value of 18.0% and 99.6% to predict a restrictive lung function. Central obesity was associated with RLF. RSP was related to smoking and underweight. ConclusionsThe prevalence of true restrictive lung function and RSP in the Austrian general population is lower than previously estimated. Our data confirm the need for direct lung volume measurement to diagnose true restrictive lung function.

Fetal Lung Volume Appears to Predict Respiratory Morbidity in Congenital Diaphragmatic Hernia.

Congenital diaphragmatic hernia (CDH) is associated with pulmonary hypoplasia and respiratory morbidity. To assess whether respiratory morbidity during the first 2 years of life in infants with left-sided CDH is associated with fetal lung volume (FLV) evaluated by the observed-to-expected FLV ratio (o/e FLV) on antenatal magnetic resonance imaging (MRI). In this retrospective study, o/e FLV measures were collected. Respiratory morbidity in the first 2 years of life was studied according to two endpoints: treatment with inhaled corticosteroids for >3 consecutive months and hospitalization for any acute respiratory disease. The primary outcome was a favorable progression defined by the absence of either endpoint. Forty-seven patients were included. The median o/e FLV was 39% (interquartile range, 33-49). Sixteen (34%) infants were treated with inhaled corticosteroids and 13 (28%) were hospitalized. The most efficient threshold for a favorable outcome was an o/e FLV ≥ 44% with a sensitivity of 57%, specificity of 79%, negative predictive value of 56%, and positive predictive value of 80%. An o/e FLV ≥ 44% was associated with a favorable outcome in 80% of cases. These data suggest that lung volume measurement on fetal MRI may help to identify children at lower respiratory risk and improve information during pregnancy, patient characterization, decisions about treatment strategy and research, and personalized follow-up.

Which is more accurate measuring pulmonary artery resistance index or 4D lung volume for prediction of neonatal respiratory distress in preterm pregnancies?

BackgroundNeonatal respiratory distress syndrome (RDS) is a leading cause of neonatal respiratory failure and neonatal mortality. It is frequent in preterm infants, because deficient surfactant needed to keep the airways (alveoli) open to assist infants breathe after birth. Nonetheless, it was also seen in full-term pregnancies. Noninvasive approaches for predicting the development of neonatal respiratory distress (RD) in preterm newborns include comparing the prenatal clinical outcome with the pulmonary artery resistance index (PA-RI) and fetal lung capacity as assessed by the virtual organ computer-aided analysis (VOCAL). Our study aimed to estimate optimal cutoff values and compare measurements of fetal pulmonary artery resistance index (PA-RI) and fetal lung volume (LV) assessed by VOCAL as noninvasive measures to predict neonatal RD development in preterm pregnancies to show which is more accurate.ResultsOut of the examined 147 women who delivered 147 living newborns, 59 of newborn (40.1%) developed neonatal RD. PA-RI has a higher value in 45 (76.27%), while fetal lung volume (FLV) was significantly lower in 43 (72.88%) of neonates who developed RD. Combining both measurements of PA-RI and FLV could predict all cases of RDS 59 (100%). Thirty of RDS neonates had mechanical ventilation and died (50.85%). Cutoff values of PA-RI ≥ 0.75 with 76.27% sensitivity, 82.95% specificity and 81.5% accuracy, whereas a cutoff of FLV ≤ 28 cm3 with sensitivity of 72.88%, specificity of 65.91% and accuracy of 74.8%, for prediction of RDS. Combining both cutoffs generated a more accurate detection 100%, specificity of 65.91% and 66.3% positive predictive value (PPV) and 100% negative predictive value (NPV) and 83% accuracy.ConclusionsBoth PA-RI and FLV are promising noninvasive tools which help in predicting RD fetuses with high sensitivity and specificity. PA-RI is more accurate than FLV cm3 in prediction of neonatal RDS. Combining these parameters increases the predictive value.

Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease is a widely prevalent condition usually associated with cigarette consumption. It has a worldwide impact on the allocation of healthcare resources. The diagnosis is made by history and physical examination supported by measures of airflow and lung volume. The levels of impairment, disability and handicap dictate the requirements for medical care. Smoking cessation, immunization, maximal pharmacologic therapy including the use of supplemental oxygen and prompt attention to exacerbations, represent the basic principles of management. Pulmonary rehabilitation has been shown in a number of randomized clinical trials to improve functional exercise capacity and health-related quality of life. Many interesting approaches, such as lung volume reduction, lung transplantation, nutritional support and mechanical ventilation for acute exacerbations, are in various stages of clinical use and evaluation.

Comparison between functional lung volume measurement and segment counting for predicting postoperative pulmonary function after pulmonary resection in lung cancer patients

BackgroundFunctional lung volume (FLV) obtained from computed tomography images was a breakthrough for lung imaging and functional assessment. We compared the accuracy of the FLV measurement method and the segment-counting (SC) method in predicting postoperative pulmonary function.MethodsA total of 113 patients who underwent two thoracoscopic surgeries were enrolled in our study. We predicted postoperative pulmonary function by the FLV measurement method and the SC method. Novel formulas based on the FLV measurement method were established using linear regression equations between the factors affecting pulmonary function and the measured values.ResultsThe predicted postoperative forced vital capacity (ppoFVC) and forced expiratory volume in 1 s (ppoFEV1) measured by the 2 methods showed high concordance between the actual postoperative forced vital capacity (postFVC) and the forced expiratory volume in 1 s (postFEV1) [r = 0.762, P < 0.001 (FLV method) and r = 0.759, P < 0.001 (SC method) for FVC; r = 0.790, P < 0.001 (FLV method) and r = 0.795, P < 0.001 (SC method) for FEV1]. Regression analysis showed that the measured preoperative pulmonary function parameters (FVC, FEV1) and the ratio of reduced FLV to preoperative FLV were significantly associated with the actual postoperative values and could predict these parameters (all P < 0.001). The feasibility of using these equations [postFVC = 0.8 × FVC − 0.784 × ΔFLV/FLV + 0.283 (R2 = 0.677, RSD = 0.338), postFEV1 = 0.766 × FEV1 − 0.694 × ΔFLV/FLV + 0.22 (R2 = 0.743, RSD = 0.265)] to predict the pulmonary function parameters after wedge resection was also verified.ConclusionsThe new FLV measurement method is valuable for predicting postoperative pulmonary function in patients undergoing lung resection surgery, with accuracy and consistency similar to those of the conventional SC method.

Benchtop Characterization of Wearable Respiratory Monitors for Assessing Feasibility of Measuring Lung Volume

Abstract Objective: This study characterizes three commercially available wearable respiratory monitors (WRMs): (1) Hexoskin Smart Garment, (2) Smartex WWS, and (3) Equivital EQ02 LifeMonitor, each with a unique chest motion sensor technology: respiratory inductance plethysmography, piezoresistor, and strain gauge, respectively. WRMs comprise of a body garment with embedded sensors that measure ambulatory chest motion in real-time. Once calibrated, chest motion waveforms from WRMs can be converted to lung volume waveform, which is then used to derive respiratory topography. The aim of this study is to assess and compare these WRMs in terms of: (i) their response signal to chest motion linearity, which is necessary for successful calibration, and (ii) their ability to measure breath-hold, which is a parameter of interest for lung deposition modeling. Methods: A benchtop test setup was built to simulate chest motion in a controlled way to facilitate comparison across the three devices. A staircase square-wave chest motion profile was used to simultaneously assess both signal linearity and ability to measure breath-hold. The respiratory response from the sensors was compared to the simulated chest motion. Results: The Hexoskin showed the best performance in both metrics, whereas the Equivital had the worst performance in both. The Smartex showed moderate ability to measure breath-hold but poor signal linearity. Conclusion: Of the three WRMs tested, the Hexoskin appears to be the best choice for ambulatory lung volume measurement. Significance: This study demonstrates the feasibility of adapting current technology to observe respiratory behavior valuable in many research domains, including tobacco research.

A STUDY TO CORRELATE PULMONARY FUNCTION TEST AND MAXIMUM OXYGEN CONSUMPTION IN HEALTHY YOUNG ADULTS

Relevance. Pulmonary function test (PFT) is an important assessment for lung function. The most commonly used method for PFT is Spirometry. It involves the use of a spirometer to measure lung volumes and capacities. Different diseases cause different patterns of abnormalities in a battery of pulmonary function tests. An earlier study suggested that reductions in maximal oxygen consumption (VO2 max) occur reasonably among patients of obstructive and restrictive lung diseases. &#x0D; Objective of this study was to assess the correlation between the parameters of pulmonary function and cardio-respiratory fitness with the amount of physical activity.&#x0D; Material and Methods. This pilot study was conducted in the Department of Physiology, RUHS College of Medical Sciences, in a group of 100 apparently healthy subjects (students) of 18-25 years age group of either sex. Anthropometric parameters (height, weight and BMI), pulmonary function test (PFT), GPAQ, body fat percentage and VO2 max were assessed in standard laboratory settings.&#x0D; Results. The mean±SD for Age, Height, Weight, GPAQ score, FEV1, PEFR, MVV, FEF25-75% and VO2 max was found to be higher in male participants as compared to female participants while BMI and FVC were almost equal in both the genders but Body Fat % and FEV1/FVC were higher in female participants. Correlation of VO2 max with FVC, FEV1. PEFR, MVV and FEF25-75% is moderately positive while correlation of VO2 max with FEV1/FVC is poorly negative in male subjects. In female subjects correlation of VO2 max with FVC, FEV1. PEFR and MVV is poorly positive while with FEV1/FVC and FEF25-75% it is poorly negative.&#x0D; Conclusion. Present study concludes that maximum oxygen consumption (VO2 max) was positively correlated with pulmonary functions except FEV1/FVC ratio in male. While it was poor positive in females except FEV1/FVC ratio and FEF. Study also concludes that observations of PFT parameters vary for male and female subjects. VO2 max i.e. maximum Oxygen Consumption was found to be higher in male participants of the study as compared to female participant’s i.e. male subjects utilizes more amount of Oxygen while exercising than female subjects.

Lung volumes measurement using novel pressure derived method in participants with obstructive, restrictive and healthy lungs

Background. Lung volumes can be measured by body plethysmography (BP), by inert gas dilution during a single-breath or multiple breaths and by radiographic methods based on chest roentgenogram or CT scanning. Our objective was to analyze the concordance between several methods including a new pressure-derived method (PDM) in a variety of pulmonary conditions. Methods. We recruited four groups of adult volunteers at the chronic obstructive pulmonary disease and tobacco clinic of a respiratory referral hospital: patients with lung bullae, with obstructive lung diseases, with restrictive lung diseases and healthy controls; all subjects underwent lung volume measurements according to ATS/ERS standards in random order with each method and then CT scanning. Differences among groups were estimated by Kruskal–Wallis tests. Concordance correlation coefficients (CCC) and Bland–Altman plots were performed. Results. Sixty-two patients were studied including 15 with lung bullae, 14 with obstructive lung diseases, 12 with restrictive lung disease and 21 healthy subjects. Highest concordance was obtained between BP and CT scanning (CCC 0.95, mean difference −0.35 l) and the lowest, with TLC-DLCOsb (CCC 0.65, difference −1.05 l). TLC measured by BP had a moderate concordance with the PDM (CCC = 0.91, mean difference −0.19 l). The PDM on the other hand had the lowest intra-test repeatability (2.7%) of all tested methods. Conclusions. Lung volumes measured by BP and CT had high concordance in the scenario of varied pulmonary conditions including lung bullae, restrictive and obstructive diseases. The new PDM device, had low intra-test variability, and was easy to perform, with a reasonable concordance with BP.

Induced sputum eosinophilia and pulmonary function tests in ex-smokers with asthma controlled with an inhaled steroid and long-acting beta-agonist therapy.

This study aims to investigate the relationship between induced sputum eosinophilia and pulmonary functions in ex-smoker asthma patients controlled with an ICS/LABA therapy. Asthma patients who are known to use ICS/LABA regularly for at least three months, without an attack in the last month, quit smoking (5-20 pack-years) and have asthma under control (ACT> 20), and concurrent with induced sputum cytology who had spirometry and lung volume measurements were included in the study. Cytology results, induced sputum eosinophil and neutrophil counts, FEV1 (L), FEV1 (%), FVC (L), FVC (%), RV (L), RV (%) and RV/TLC (%) values of all patients were recorded. The relationship between sputum neutrophil and eosinophil count and pulmonary function test parameters was evaluated. Seventeen (68%) of the patients were female, eight (32%) were male, and the mean age was 49.7 ± 13.6 years. The mean sputum eosinophil percentage was 9.4 ± 16.7, and the neutrophil percentage was 71.4 ± 20.5. A positive correlation was found between induced sputum eosinophil percentage values and FEV1 (L) (r= +0.472; p= 0.01) and FVC (L) (r= +0.502; p= 0.01). No correlation was found between the FEV1/FVC%, FEV1%, FVC%, RV (L), RV%, and RV/TLC% values and the percentage of induced sputum eosinophils (p> 0.05). It was observed that controlled asthmatic patients with induced sputum eosinophilia treated with ICS/LABA and who quit smoking had high FVC (L) and FEV1 (L) levels.

Expression of Concern: The role of three-dimensional ultrasonography fetal lung volume measurement in the prediction of neonatal respiratory function outcome

Expression of Concern: The role of three-dimensional ultrasonography fetal lung volume measurement in the prediction of neonatal respiratory function outcome

Lung-protective ventilation during Trendelenburg pneumoperitoneum surgery: A randomized clinical trial

Study objectiveTo assess the effects of a protective ventilation strategy during Trendelenburg pneumoperitoneum surgery on postoperative oxygenation. DesignsParallel-group, randomized trial. SettingOperating room of a university hospital, Italy. PatientsMorbidly obese patients undergoing Trendelenburg pneumoperitoneum gynaecological surgery. InterventionsParticipants were randomized to standard (SV: tidal volume = 10 ml/kg of predicted body weight, PEEP = 5 cmH2O) or protective (PV: tidal volume = 6 ml/kg of predicted body weight, PEEP = 10 cmH2O, recruitment maneuvers) ventilation during anesthesia. MeasurementsPrimary outcome was PaO2/FiO2 one hour after extubation. Secondary outcomes included day-1 PaO2/FiO2, day-2 respiratory function and intraoperative respiratory/lung mechanics, assessed through esophageal manometry, end-expiratory lung volume (EELV) measurement and pressure-volume curves. Main resultsSixty patients were analyzed (31 in SV group, 29 in PV group). Median [IqR] tidal volume was 350 ml [300–360] in PV group and 525 [500–575] in SV group. Median PaO2/FiO2 one hour after extubation was 280 mmHg [246–364] in PV group vs. 298 [250–343] in SV group (p = 0.64). Day-1 PaO2/FiO2, day-2 forced vital capacity, FEV-1 and Tiffenau Index were not different between groups (all p > 0.10). Intraoperatively, 59% of patients showed complete airway closure during pneumoperitoneum, without difference between groups: median airway opening pressure was 17 cmH2O. In PV group, airway and transpulmonary driving pressure were lower (12 ± 5 cmH2O vs. 17 ± 7, p < 0.001; 9 ± 4 vs. 13 ± 7, p < 0.001), PaCO2 and respiratory rate were higher (48 ± 8 mmHg vs. 42 ± 12, p < 0.001; 23 ± 5 breaths/min vs. 16 ± 4, p < 0.001). Intraoperative EELV was similar between PV and SV group (1193 ± 258 ml vs. 1207 ± 368, p = 0.80); ratio of tidal volume to EELV was lower in PV group (0.45 ± 0.12 vs. 0.32 ± 0.09, p < 0.001). ConclusionsIn obese patients undergoing Trendelenburg pneumoperitoneum surgery, PV did not improve postoperative oxygenation nor day-2 respiratory function. PV was associated with intraoperative respiratory mechanics indicating less injurious ventilation. The high prevalence of complete airway closure may have affected study results. Trial registrationProspectively registered on http://clinicaltrials.govNCT03157479 on May 17th, 2017.

Lifetime spirometry patterns of obstruction and restriction, and their risk factors and outcomes: a prospective cohort study

Interest in lifetime lung function trajectories has increased in the context of emerging evidence that chronic obstructive pulmonary disease (COPD) can arise from multiple disadvantaged lung function pathways, including those that stem from poor lung function in childhood. To our knowledge, no previous study has investigated both obstructive and restrictive lifetime patterns concurrently, while accounting for potential overlaps between them. We aimed to investigate lifetime trajectories of the FEV1/forced vital capacity (FVC) ratio, FVC, and their combinations, relate these combined trajectory groups to static lung volume and gas transfer measurements, and investigate both risk factors for and consequences of these combined trajectory groups. Using z scores from spirometry measured at ages 7, 13, 18, 45, 50, and 53 years in the Tasmanian Longitudinal Health Study (n=2422), we identified six FEV1/FVC ratio trajectories and five FVC trajectories via group-based trajectory modelling. Based on whether trajectories of the FEV1/FVC ratio and FVC were low (ie, low from childhood or adulthood) or normal, four patterns of lifetime spirometry obstruction or restriction were identified and compared against static lung volumes and gas transfer. Childhood and adulthood characteristics and morbidities of these patterns were investigated. The prevalence of the four lifetime spirometry patterns was as follows: low FEV1/FVC ratio only, labelled as obstructive-only, 25·8%; low FVC only, labelled as restrictive-only, 10·5%; both low FEV1/FVC ratio and low FVC, labelled as mixed, 3·5%; and neither low FEV1/FVC ratio nor low FVC, labelled as reference, 60·2%. The prevalence of COPD at age 53 years was highest in the mixed pattern (31 [37%] of 84 individuals) followed by the obstructive-only pattern (135 [22%] of 626 individuals). Individuals with the mixed pattern also had the highest prevalence of parental asthma, childhood respiratory illnesses, adult asthma, and depression. Individuals with the restrictive-only pattern had lower total lung capacity and residual volume, and had the highest prevalence of childhood underweight, adult obesity, diabetes, cardiovascular conditions, hypertension, and obstructive sleep apnoea. To our knowledge, this is the first study to characterise lifetime phenotypes of obstruction and restriction simultaneously using objective data-driven techniques and unique life course spirometry measures of FEV1/FVC ratio and FVC from childhood to middle age. Mixed and obstructive-only patterns indicate those who might benefit from early COPD interventions. Those with the restrictive-only pattern had evidence of true lung restriction and were at increased risk of multimorbidity by middle age. National Health and Medical Research Council of Australia, The University of Melbourne, Clifford Craig Medical Research Trust of Tasmania, The Victorian, Queensland & Tasmanian Asthma Foundations, The Royal Hobart Hospital, Helen MacPherson Smith Trust, and GlaxoSmithKline.

NO RELATIONSHIP BETWEEN PULMONARY FUNCTION AND EXERCISE CAPACITY IN PEOPLE WITH POSTACUTE SEQUELAE OF SARS-COV-2 INFECTION

NO RELATIONSHIP BETWEEN PULMONARY FUNCTION AND EXERCISE CAPACITY IN PEOPLE WITH POSTACUTE SEQUELAE OF SARS-COV-2 INFECTION

Quantifying lung aeration in neonatal lambs at birth using lung ultrasound.

BackgroundLung ultrasound (LUS) is a safe and non-invasive tool that can potentially assess regional lung aeration in newborn infants and reduce the need for X-ray imaging. LUS produces images with characteristic artifacts caused by the presence of air in the lung, but it is unknown if LUS can accurately detect changes in lung air volumes after birth. This study compared LUS images with lung volume measurements from high-resolution computed tomography (CT) scans to determine if LUS can accurately provide relative measures of lung aeration.MethodsDeceased near-term newborn lambs (139 days gestation, term ∼148 days) were intubated and the chest imaged using LUS (bilaterally) and phase contrast x-ray CT scans at increasing static airway pressures (0–50 cmH2O). CT scans were analyzed to calculate regional air volumes and correlated with measures from LUS images. These measures included (i) LUS grade; (ii) brightness (mean and coefficient of variation); and (iii) area under the Fourier power spectra within defined frequency ranges.ResultsAll LUS image analysis techniques correlated strongly with air volumes measured by CT (p < 0.01). When imaging statistics were combined in a multivariate linear regression model, LUS predicted the proportion of air in the underlying lung with moderate accuracy (95% prediction interval ± 22.15%, r2 = 0.71).ConclusionLUS can provide relative measures of lung aeration after birth in neonatal lambs. Future studies are needed to determine if LUS can also provide a simple means to assess air volumes and individualize aeration strategies for critically ill newborns in real time.

Quantitative lung ultrasound detects dynamic changes in lung recruitment in the preterm lamb

BackgroundLung ultrasound (LUS) may not detect small, dynamic changes in lung volume. Mean greyscale measurement using computer-assisted image analysis (Q-LUSMGV) may improve the precision of these measurements.MethodsPreterm lambs (n = 40) underwent LUS of the dependent or non-dependent lung during static pressure–volume curve mapping. Total and regional lung volumes were determined using the super-syringe technique and electrical impedance tomography. Q-LUSMGV and gold standard measurements of lung volume were compared in 520 images.ResultsDependent Q-LUSMGV moderately correlated with total lung volume (rho = 0.60, 95% CI 0.51–0.67) and fairly with right whole (rho = 0.39, 0.27–0.49), central (rho = 0.38, 0.27–0.48), ventral (rho = 0.41, 0.31–0.51) and dorsal regional lung volumes (rho = 0.32, 0.21–0.43). Non-dependent Q-LUSMGV moderately correlated with total lung volume (rho = 0.57, 0.48–0.65) and fairly with right whole (rho = 0.43, 0.32–0.52), central (rho = 0.46, 0.35–0.55), ventral (rho = 0.36, 0.25–0.47) and dorsal lung volumes (rho = 0.36, 0.25–0.47). All correlation coefficients were statistically significant. Distinct inflation and deflation limbs, and sonographic pulmonary hysteresis occurred in 95% of lambs. The greatest changes in Q-LUSMGV occurred at the opening and closing pressures.ConclusionQ-LUSMGV detected changes in total and regional lung volume and offers objective quantification of LUS images, and may improve bedside discrimination of real-time changes in lung volume.ImpactLung ultrasound (LUS) offers continuous, radiation-free imaging that may play a role in assessing lung recruitment but may not detect small changes in lung volume.Mean greyscale image analysis using computer-assisted quantitative LUS (Q-LUSMGV) moderately correlated with changes in total and regional lung volume.Q-LUSMGV identified opening and closing pressure and pulmonary hysteresis in 95% of lambs.Computer-assisted image analysis may enhance LUS estimation of lung recruitment at the bedside.Future research should focus on improving precision prior to clinical translation.

Intra- and Inter-Reader Variations in Lung Nodule Measurements: Influences of Nodule Size, Location, and Observers.

(1) Background: Accurate measurement of lung-nodule size is necessary, but whether a three-dimensional volume measurement is better or more reliable than the one-dimensional method is still unclear. This study aimed to investigate the intra- and inter-reader variations according to nodule type, size, three-dimensional volume measurements, and one-dimensional linear measurements. (2) Methods: This retrospective study included computed tomography (CT) examinations of lung nodules and volume measurements performed from October to December 2016. Two radiologists independently performed all measurements. Intra-class correlation coefficients (ICC) and Bland-Altman plots were used for analysis. (3) Results: The overall variability in the calculated volume was larger than when using the semiautomatic volume measurement. Nodules <6 mm tended to have larger variability than nodules ≥6 mm in both one-dimensional and calculated volume measurements. The isolated type showed smaller variability in both intra- and inter-reader comparisons. The juxta-vascular type showed the largest variability in both one-dimensional and calculated volume measurements. The variability was decreased when using the 3D volume semiautomated software. (4) Conclusions: The present study suggests that 3D semiautomatic volume measurements showed lower variability than the calculated volume measurement. Nodule size and location influence measurement variability. The intra- and inter-reader variabilities in nodule volume measurement were considerable.

Computer grading of lung disease severity in patients with lymphangioleiomyomatosis referred for transplantation

ObjectivesLymphangioleiomyomatosis (LAM) patients with severe lung disease may be considered for lung transplantation. Clinical, physiologic, and quality of life data are usually employed for referral. The aim of this study was to determine whether computed tomographic measurement of lung volume occupied by cysts (cyst score) complemented clinical and physiologic data in supporting referral for transplantation.MethodsForty-one patients were studied. Pre-referral clinical data, pulmonary function tests, exercise testing, and high-resolution computed tomography (HRCT) scans were obtained. From HRCT, a computer-aided diagnostic program was employed to calculate cyst scores. These data were compared to those of 41 age-matched LAM patients not referred for lung transplantation.ResultsCyst score, and % predicted FEV1 and DLCO were respectively, 48.1 ± 9.4%, 36.5 ± 9.1%, and 35.0 ± 10.7%. For the control group, cyst score, FEV1, and DLCO were respectively, 14.8 ± 8.3%, 77.2 ± 20.3%, and 66.7 ± 19.3%. Cyst score values showed a normal distribution. However, the frequency distribution of FEV1 was skewed to the right while the distribution of DLCO was bimodal. Correlations between cyst score and FEV1 and DLCO for the study group were respectively, r = − 0.319 and r = − 0.421.ConclusionsLAM patients referred for lung transplantation had nearly 50% of lungs occupied by cysts. Correlations between cyst score and FEV1 or DLCO were weak; as shown previously, DLCO was better related to cyst number while FEV1 had a better association with cyst size. Given its normal distribution, cyst score measurements may assist in evaluation of pre-transplant severity of lung disease before referral for transplantation.