Lung Volume Measurements Research Articles

Changes in Diaphragm Intrusion and Thoracic Dimensions After Posterior Spinal Fusion in Patients With Neuromuscular Scoliosis.

Cerebral palsy (CP) can cause scoliosis with large thoracolumbar or lumbar curves. Such curves may impair pulmonary function by causing the abdomen and diaphragm to encroach on the thorax. Our purpose was to investigate changes in diaphragm position and other thoracic radiographic measurements at 2 years after posterior spinal fusion (PSF). Retrospective review of data from 56 pediatric patients (Gross Motor Function Classification System >3) who underwent PSF for CP-related (neuromuscular) scoliosis at one US academic hospital from 2010 to 2018. In this study, we used radiographs taken preoperatively and 2 years after PSF to measure lung volume, diaphragm intrusion index (DII), diaphragm vertebral level (DVL), space available for the lung (SAL), and T1-S1 height. Lung volume had increased by a mean 902cm3 (range, -735 to 2697cm3) at 2-year follow-up. DII improved from a mean (and SD) of 61%±12% to 71%±11% on the left side and 58%±14% to 68%±11% on the right (P<0.001). DVL increased caudally by a mean 1.2 vertebral levels bilaterally, with a mean postoperative position between T8 and T9. Lung space became more symmetrical as the SAL increased from 0.76 to 0.91 (P<0.001). T1-S1 height increased by a mean 7.5±4.3cm. These findings suggest a new way to understand changes in thoracic volume and redistribution of thoracic and lumbar balance when correcting the collapsing spinal deformity in CP. A more caudal postoperative diaphragm position with less diaphragm intrusion into the thorax may reflect an improved length-tension configuration, which could in turn produce greater diaphragmatic strength and endurance. Level III.

Correlation between handgrip strength and air trapping in patients with stable chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) often presents with dyspnea resulting from the condition of air trapping, assessed by lung volume measurement studies. This study aimed to investigate the relationship between handgrip strength (HGS) and air trapping in COPD patients. Cross-sectional research was conducted in COPD patients at Thammasat University Hospital, Thailand between May 2022 and December 2023. HGS was assessed using the Jamar® Smart Hand Dynamometer, and air trapping was measured using a body plethysmograph. Air trapping was defined as a ratio of residual volume (RV) to total lung capacity (TLC) greater than 40%. Receiver operator characteristic (ROC) curves, sensitivity, and specificity values were calculated to determine the optimal cutoff value of HGS for predicting air trapping. A total of 72 patients (90.3% male) were included, with an average age of 72.4±9.7 years. The body mass index was 23.5±4.3 kg/m2. The smoking history was 23.2±14.8 pack-years. Common comorbidities included hypertension (36.1%) and diabetes (22.2%). Post-bronchodilator forced expiratory volume in 1 second (FEV1) was 72.1%±21.2%. Air trapping was found in 55.6%. A negative correlation was found between HGS and RV/TLC (R=-0.399, P=0.001). The best cutoff value for HGS to predict air trapping was 28.3 kg, with 71.9% sensitivity and 65.0% specificity. The area under the ROC curve for identifying air trapping was 0.681 (95% CI: 0.554 to 0.808, P=0.009). Air trapping is common in COPD patients, and HGS is significantly correlated with air trapping. Thus, HGS may serve as an alternative tool for assessing air trapping.

Improving Asthma Management through Iot-Based Telemedicine Spirometry in The Post-COVID-19 Era in Sidoarjo Tofu Making Community, Indonesia

Asthma is a chronic inflammatory disease of the airways that causes recurrent episodes of wheezing, shortness of breath, chest tightness and coughing. The partners in this study face the problem that tofu factories in their area use plastic waste as fuel, which can aggravate respiratory conditions. In addition, the partners need more knowledge about the clear signs of asthma attacks, asthma symptom control and risk factors for asthma patients. The solution provided through the Community Service Programme with the PKM (Student Creativity Programme) scheme is to measure lung volumes using an IoT-based telemedicine device, specifically a spirometry tool that can be used with an Android mobile phone. In addition, partners will receive support to improve their knowledge, skills and attitudes in the management of asthma exacerbations. The implementation method includes providing health education on asthma, clear signs of asthma attacks, asthma symptom control and risk factors for asthma patients, as well as self-management skills for asthma patients and efforts to monitor asthma signs and symptoms. Lung capacity is measured using a spirometry device connected to an Android mobile phone for direct measurement by health workers. The results of the community service show an increase in respondents' knowledge about asthma after a lecture intervention. This was tested using the Wilcoxon signed rank test, which showed a statistically significant increase in scores from pre-test to post-test. All changes were positive, indicating the effectiveness of the learning methods used. Spirometry measurements showed that the respondents' lungs were functioning well without significant airway obstruction, indicating that the intervention was successful in increasing knowledge about asthma and asthma control

Lung volumes by CT and plethysmography: are we measuring the same? - CanCOLD study data

BackgroundMeasurement of lung volumes forms an integral part of pulmonary function testing. Lung volumes determined by CT scans are well established, but the comparability to other methods like plethysmography in large cohorts remains in question.MethodsCanCOLD is a prospective longitudinal cohort study from Canada, including three matched groups of individuals with COPD I-II, smokers at risk and healthy controls. All participants underwent lung volume measurement by plethysmography and CT, using inspiratory and expiratory imaging. We compared total lung capacity (TLC) and residual volume (RV) in the different cohorts between plethysmography and CT.ResultsData from 1235 (518 females) individuals were analysed. Baseline characteristics were comparable in all three groups. Significant differences between CT and plethysmography could be observed in all groups, with consistently higher TLC and lower RV by plethysmography, respectively. Correlation was strong for TLC between the methods of measurement with a very stable bias of about 1.68 liters for all groups, but the correlation was only low/moderate for RV. Variability of differences seemed to be higher for RV. No correction for supine position or dead air space was used for CT based measurements.ConclusionMeasurement of TLC and RV by plethysmography yields higher and lower values than by CT, respectively, so results of the different methods should not be used interchangeably.

DeepBreath: Breathing Exercise Assessment with a Depth Camera

Practicing breathing exercises is crucial for patients with chronic obstructive pulmonary disease (COPD) to enhance lung function. Breathing mode (chest or belly breathing) and lung volume are two important metrics for supervising breathing exercises. Previous works propose that these metrics can be sensed separately in a contactless way, but they are impractical with unrealistic assumptions such as distinguishable chest and belly breathing patterns, the requirement of calibration, and the absence of body motions. In response, this research proposes DeepBreath, a novel depth camera-based breathing exercise assessment system, to overcome the limitations of the existing methods. DeepBreath, for the first time, considers breathing mode and lung volume as two correlated measurements and estimates them cooperatively with a multitask learning framework. This design boosts the performance of breathing mode classification. To achieve calibration-free lung volume measurement, DeepBreath uses a data-driven approach with a novel UNet-based deep-learning model to achieve one-model-fit-all lung volume estimation, and it is designed with a lightweight silhouette segmentation model with knowledge transferred from a state-of-the-art large segmentation model that enhances the estimation performance. In addition, DeepBreath is designed to be resilient to involuntary motion artifacts with a temporal-aware body motion compensation algorithm. We collaborate with a clinical center and conduct experiments with 22 healthy subjects and 14 COPD patients to evaluate DeepBreath. The experimental result shows that DeepBreath can achieve high breathing metrics estimation accuracy but with a much more realistic setup compared with previous works.

Prenatal Prognosis of Omphalocele Using Magnetic Resonance Imaging Measurement of Fetal Lung Volumes

BackgroundOmphalocele is a congenital midline abdominal wall defect resulting in herniation of viscera into a membrane-covered sac. Pulmonary complications, including pulmonary hypoplasia, pulmonary hypertension, and prolonged respiratory support are a leading cause of neonatal morbidity and mortality. Objective(s)This study aimed to assess the role of fetal MRI-derived lung volumes and omphalocele defect size as clinical tools to prognosticate postnatal pulmonary morbidity and neonatal mortality in those with a prenatally diagnosed omphalocele (PDO). Study DesignThis was a retrospective cohort study of all pregnancies with PDO at our fetal center from 2007–2023. Pregnancies with aneuploidy or concurrent life-limiting fetal anomalies were excluded. Using fetal MRI, observed-to-expected total fetal lung volume (O/E TLV) ratios were determined by a previously published method. The transverse diameter of the abdominal defect was also measured. The O/E TLV ratios and abdominal defect measurements were compared with postnatal outcomes. The primary outcome was death at any time. Secondary outcomes included death in the first 30 days of life or before discharge from birth hospitalization, the requirement of respiratory support with intubation and mechanical ventilation, or development of pulmonary hypertension. ResultsOf 101 pregnancies with a PDO, 54 pregnancies (53.5%) with prenatally diagnosed omphalocele met inclusion criteria. There was a significant increase in the rate of death when compared between the three O/E TLV classifications: 1/36 (2.8%) in the O/E≥50% group, 3/14 (21.4%) in the O/E 25%–49.9% group, and 4/4 (100%) in the O/E<25% group (P<.001). The rate of intubation increased with the severity of O/E TLV classification, with 27.8% in the O/E≥50% group, 64.3% in the O/E 25%–49.9% group, and 100% in the O/E<25% group (P=.003). The rate of pulmonary hypertension was also higher in the O/E 25%–49.9% (50.0%) and the O/E<25% (50.0%) groups compared to the O/E≥50% group (8.3%, P=.002). There was no association between the transverse diameter of the abdominal wall defect and the primary outcome of death (OR=1.08 95% CI=[0.65–1.78], P=.77). ConclusionsIn our cohort of patients with PDO, O/E TLV<50% is associated with death, need for intubation, prolonged intubation, and pulmonary hypertension. In contrast, omphalocele size demonstrated no prognostic value for these outcomes. The strong association between low fetal lung volume on MRI and poor neonatal outcomes highlights the utility of fetal MRI for estimating postnatal prognosis. Clinicians can utilize fetal lung volumes to direct perinatal counseling and optimize the plan of care.

Pulmonary function in patients with adolescent idiopathic scoliosis: an explorative study of a wearable smart shirt as a measurement instrument.

Adolescent idiopathic scoliosis (AIS) presents various challenges, including respiratory symptoms that impact pulmonary function. This study aims to explore the feasibility of using a smart shirt for continuous monitoring of lung volumes and heart rate during routine activities in AIS patients. A single-center exploratory feasibility study was conducted with AIS patients aged 16-22years with a thoracic curvature of ≥ 30 degrees and absence of respiratory comorbidities. A smart shirt was utilized to continuously monitor cardiopulmonary parameters during mild exercise, which included a standardized walking route with the ascent of multiple stairs. Five participants completed the study. Baseline spirometry measurements showed a range of values for forced vital capacity (FVC), forced expiratory volume in 1s (FEV1), and FEV1/FVC ratio. During mild exercise, participants exhibited variability in tidal volume, heart rate, breathing rate, and minute ventilation, with increases observed during stair climbing. Breathlessness levels also varied throughout the activity but did not correlate with the measured lung volumes. Overall, the use of the smart shirt for assessing pulmonary function in AIS patients was deemed feasible and well tolerated by participants during the test activities. The study confirms the feasibility of using a smart shirt for continuous measurement of cardiopulmonary parameters in AIS patients during daily activities. Incongruities between spirometry results and perceived dyspnea exists, which questions the nature of the perceived dyspnea. Further research is needed to validate these findings and explore the impact of AIS characteristics on measurement accuracy.

Effect of deep squat intervention in patients with chronic respiratory diseases

Abstract Background: This study aimed to evaluate the impact of a structured, tailor-made 12-week deep squat intervention on lower extremity muscle strength, cardiorespiratory functional capacity, and health-related quality of life in patients with chronic respiratory dysfunction. Materials and Methods: Thirty patients aged 18–65 years were randomly assigned to a deep squat intervention group (n = 15) or a walking program group (n = 15). Assessments conducted before and after the 12-week intervention included lower extremity muscle strength, pulmonary function, cardiorespiratory endurance, and health-related quality of life (HRQoL). These were measured using trunk-leg dynamometry, the chair-stand test, the deep squat test, lung volume measurements, maximum inspiratory and expiratory pressures, the 6-min walk test, and the 12-item Short Form Survey questionnaire. Results: The results revealed that the deep squat intervention group showed greater muscle strength and cardiorespiratory endurance improvements than the walking group. Significant improvements were observed in lower extremity muscle strength (42.9%), chair-stand repetitions (26%), deep squat repetitions (30.2%), maximum inspiratory pressure (67%), maximum expiratory pressure (29%), peak expiratory flow rate (32%), 6-min walk test distance (16%), forced expiratory volume in 1 s (53%), forced vital capacity (36%), and HRQoL (physical component 42% and mental component 25%) with a large effect size ranging from 1.6 to 10.7 (P &lt; 0.001). Conclusion: This study concludes that the deep squat intervention proved to be a safe and effective exercise program for mitigating physical deconditioning in individuals with mild to moderate chronic respiratory dysfunction compared with a walking program. These findings support the inclusion of deep squat training in routine pulmonary rehabilitation programs.

Changes in the Functional Classification of Spirometry Using the New Interpretation Standard 2022: A Multicenter Study

IntroductionPulmonary function tests are vital for diagnosing lung diseases, assessing treatment responses, and monitoring respiratory health. Recent updates to interpretive standards by the European Respiratory and American Thoracic Societies (ERS/ATS) in 2022 introduced significant changes compared to the 2005 standards. They include incorporating lung volume measurements, non-specific and mixed disorders, introducing z-scores for functional abnormality assessment, reducing severity categories from five to three, and revising criteria for positive bronchodilator responses. MethodsWe conducted a retrospective, multi-center study across four centers using spirometric data spanning from 2002 to 2022. We categorized spirometry results using both the 2005 and 2022 ATS/ERS standards and calculated predicted values following the GLI 2012 equation (Caucasian subset). ResultsAmong 79,039 subjects, we observed that 23% shifted from an obstructive diagnosis under the 2005 standard to a mixed pattern diagnosis under the 2022 standard, necessitating lung volume assessments. In the evaluation of bronchodilator responses among 59,203 tests, 12.3% of those initially classified as responders were reclassified as non-responders with the new standards. We found variations in severity categorization across age groups, with older patients tending to receive milder severity classifications and younger individuals receiving greater severity classifications under the 2022 standards. ConclusionsThe 2022 document emphasizes early lung volume assessment, potentially leading to increased utilization of more complex tests. Furthermore, the bronchodilator response was predominant in extreme age groups and among individuals with milder spirometric impairments. This shift may impact treatment decisions, potentially initiating medication in milder cases and de-escalating treatment in more severe cases.

Size-matching in lung transplantation by computed tomography for end-stage interstitial disease: a retrospective analysis.

Size matching between donors and recipients is a major issue in lung transplantation (LTx), especially in patients with restrictive lung disease (RLD). This study aims to evaluate computed tomography (CT) as an additional method for defining the total lung capacity (TLC) in patients with end-stage interstitial disease awaiting LTx. Clinical data and CT scans from patients who underwent a first LTx from January 2014 to July 2018 in Bichat Hospital, Paris, were prospectively included in a database. CT TLC (ctTLC) was retrospectively calculated after semi-automatic contouring of the parenchyma and compared with measured TLC (mTLC) and predicted TLC (pTLC) values. The study group included 89 patients (male:female =68:21; mean age, 59.5±10.0 years). The time between pulmonary function tests (PFTs) and CT scan was 162±270 days [median, 67 days; interquartile range (IQR), 0-233 days]. ctTLC was inferior to mTLC and pTLC (respectively 2,979±1,001 mL, 3,530±1,077 and 6,381±955 mL, P<0.001). The relative difference between CT lung volume (ctLV) and measured lung volume (mLV) was higher on the left than on the right side (25.4% vs. 16.3%, respectively, P=0.11). After exclusion of two outliers, we found a significant correlation between ctTLC and mTLC (r=0.762, P<0.001). CT volume is a feasible method to assess TLC in patients with end-stage interstitial disease awaiting LTx. This study highlights potential size-mismatch for graft selection before LTx and opens the perspective of a prospective trial evaluating impact of size-matching by donor-recipient (D-R) ctTLC ratio on postoperative outcomes.

Artificial Intelligence-Based Algorithms and Healthcare Applications of Respiratory Inductance Plethysmography: A Systematic Review

Respiratory Inductance Plethysmography (RIP) is a non-invasive method for the measurement of respiratory rates and lung volumes. Accurate detection of respiratory rates and volumes is crucial for the diagnosis and monitoring of prognosis of lung diseases, for which spirometry is classically used in clinical applications. RIP has been studied as an alternative to spirometry and shown promising results. Moreover, RIP data can be analyzed through machine learning (ML)-based approaches for some other purposes, i.e., detection of apneas, work of breathing (WoB) measurement, and recognition of human activity based on breathing patterns. The goal of this study is to provide an in-depth systematic review of the scope of usage of RIP and current RIP device developments, as well as to evaluate the performance, usability, and reliability of ML-based data analysis techniques within its designated scope while adhering to the PRISMA guidelines. This work also identifies research gaps in the field and highlights the potential scope for future work. The IEEE Explore, Springer, PLoS One, Science Direct, and Google Scholar databases were examined, and 40 publications were included in this work through a structured screening and quality assessment procedure. Studies with conclusive experimentation on RIP published between 2012 and 2023 were included, while unvalidated studies were excluded. The findings indicate that RIP is an effective method to a certain extent for testing and monitoring respiratory functions, though its accuracy is lacking in some settings. However, RIP possesses some advantages over spirometry due to its non-invasive nature and functionality for both stationary and ambulatory uses. RIP also demonstrates its capabilities in ML-based applications, such as detection of breathing asynchrony, classification of apnea, identification of sleep stage, and human activity recognition (HAR). It is our conclusion that, though RIP is not yet ready to replace spirometry and other established methods, it can provide crucial insights into subjects’ condition associated to respiratory illnesses. The implementation of artificial intelligence (AI) could play a potential role in improving the overall effectiveness of RIP, as suggested in some of the selected studies.

Metered-Dose Inhaler Spacer with Integrated Spirometer for Home-Based Asthma Monitoring and Drug Uptake.

This work introduces Spiromni, a single device incorporating three different pressurised metered-dose inhaler (pMDI) accessories: a pMDI spacer, an electronic monitoring device (EMD), and a spirometer. While there are devices made to individually address the issues of technique, adherence and monitoring, respectively, for asthma patients as laid out in the Global Initiative for Asthma's (GINA) global strategy for asthma management and prevention, Spiromni was designed to address all three issues using a single, combination device. Spiromni addresses the key challenge of measuring both inhalation and exhalation profiles, which are different by an order of magnitude. Moreover, the innovative design prevents exhalation from entering the spacer chamber and prevents medication loss during inhalation using umbrella valves without a loss in flow velocity. Apart from recording the peak exhalation flow rate, data from the sensors allow us to extract other key lung volume and capacities measures similar to a medical pulmonary function test. We believe this low-cost portable multi-functional device will benefit both asthma patients and clinicians in the management of the disease.

Residual radiological opacities correlate with disease outcomes in ICU-treated COVID-19.

Few studies consider both radiological and functional outcomes in COVID-19 survivors treated in the intensive care unit (ICU). We investigated clinical findings and pulmonary abnormalities on chest computed tomography (CT) and compared outcomes of severe versus mild-moderate acute respiratory distress syndrome (ARDS) on long-term follow-up. This longitudinal cohort study included 118 COVID-19 patients (median age, 58 years; 79% men). Thoracic CT scans were performed 4, 10, and 22 months after hospital discharge. Two independent blinded radiologists analyzed the 10 months scans and scored the radiology findings semi-quantitatively, as no/minor versus widespread opacities [low-radiology opacity grade (ROG) versus high-ROG]. ARDS severity was based on the PaO2/FiO2 ratio. The 6 min walk test (6MWT) was performed after 3 and 9 months, and lung diffusion capacity for carbon monoxide (DLCO) and lung volume measurement after 9 and 15 months. Dynamic spirometry was done at all time points. Residual symptoms and health-related quality-of-life (HRQL) were evaluated using validated questionnaires. At 10 months, most patients (81/118; 69%) were classified as high-ROG, of which 70% had severe ARDS during hospitalisation; 69% of those with mild-moderate ARDS also had high-ROG. Patients with high-ROG had longer ICU stay and lower PaO2/FiO2 during hospitalisation (p < 0.01). At 9 months follow-up, patients with high-ROG had smaller lung volumes as % of predicted values [mean (±CI): 80 (77-84) vs. 93 (88-98) (p < 0.001)], lower DLCO as % of predicted values [74 (70-78) vs. 87 (82-92) (p < 0.001)], lower oxygen saturation during 6MWT (p = 0.02), and a tendency to more severe dyspnoea (p = 0.07), but no difference was found in HRQL compared with no/minor ROG (p = 0.92). A higher opacity score was related to lower DLCO at follow-up (r = -0.48, p < 0.001, Spearman rank test). Severe ARDS patients had slightly more severe fatigue at 9 months compared to mild-moderate, but no differences in dyspnoea or lung function at follow-up. Fibrotic-like changes were found in 93% of patients examined with CT scans at 2 years (55/118; 47%). Severe ARDS could predict widespread opacities (ROG > 25%) in most patients at follow-up at 10 months (AUC 0.74). Residual radiological abnormalities in ICU-treated COVID-19 patients, evaluated for up to 2 years, relate to persisting symptoms and impaired lung function, demanding careful follow-up regardless of ARDS severity at hospitalisation.

Lung volume measurement using chest CT in COVID-19 patients: a cohort study in Japan

ObjectiveThis study aimed to investigate the utility of CT quantification of lung volume for predicting critical outcomes in COVID-19 patients.MethodsThis retrospective cohort study included 1200 hospitalised patients with COVID-19 from...

Prise en charge anténatale des fœtus porteurs d’une hernie de coupole diaphragmatique

Congenital diaphragmatic hernia (CDH) can be diagnosed prenatally and its severity assessed by fetal imaging. The prognosis of a fetus with CDH is based on whether or not the hernia is isolated, the measurement of lung volume on ultrasound and MRI, and the position of the liver. The birth of a child with CDH should take place in a center adapted to the care of such children, and in accordance with the recommendations defined by the French National Diagnosis and Care Protocol. It has recently been demonstrated that for moderate and severe forms of CDH, tracheal occlusion using a balloon placed in utero by fetoscopy (FETO) increases survival until discharge from the neonatal unit, but at the cost of an increased risk of prematurity. At the same time, advances in neonatal resuscitation and the standardization of follow-up of these children within the framework of the “Centre de référence maladies rares: hernie de coupole diaphragmatique” have improved the prognosis of these children and young adults.

Dynamic hyperinflation is a risk factor for mortality and severe exacerbations in COPD patients

ObjectiveTo assess if dynamic hyperinflation is an independent risk factor for mortality and severe exacerbations in COPD patients. MethodsA cohort of 141 patients with stable COPD and moderate to very severe airflow limitation, treated according to conventional guidelines, was followed for a median of 9 years. Clinical characteristics were recorded and arterial blood gases, pulmonary function tests, 6-min walk and incremental exercise test with measurement of respiratory pattern and operative lung volumes were performed. Endpoints were all-cause mortality and hospitalization for COPD exacerbation. Results58 patients died during the follow-up period (1228 patients x year). The mortality rate was higher in patients with dynamic hyperinflation (n = 106) than in those without it (n = 35) (14.6; 95% CI, 14.5–14.8 vs. 7.2; 95% CI, 7.1–7.4 per 1000 patients-year). After adjusting for sex, age, body mass index, pack-years and treatment with inhaled corticosteroids, dynamic hyperinflation was associated with a higher mortality risk (adjusted hazard ratio [aHR], 2.725; 95% CI, 1.010–8.161), and in a multivariate model, comorbidity, peak oxygen uptake and dynamic hyperinflation were retained as independent predictors of mortality. The time until first severe exacerbation was shorter for patients with dynamic hyperinflation (aHR, 3.961; 95% CI, 1.385–11.328), and dynamic hyperinflation, FEV1 and diffusing capacity were retained as independent risk factors for severe exacerbation. Moreover, patients with dynamic hyperinflation had a higher hospitalization risk than those without it (adjusted incidence rate ratio, 1.574; 95% CI, 1.087–2.581). ConclusionIn stable COPD patients, dynamic hyperinflation is an independent prognostic factor for mortality and severe exacerbations.

Effects of Lung Injury and Abdominal Insufflation on Respiratory Mechanics and Lung Volume During Time-Controlled Adaptive Ventilation.

Lung volume measurements are important for monitoring functional aeration and recruitment, and may help guide adjustments in ventilator settings. The expiratory phase of APRV may provide physiologic information about lung volume based on the expiratory flow-time slope, angle, and time to approach a no-flow state (TExp). We hypothesized that expiratory flow rate would correlate with estimated lung volume (ELV), as measured using a modified nitrogen washout/washin technique in a large animal lung injury model. Eight pigs (35.2±1.0kg) were mechanically ventilated using an Engström Carescape R860 on the APRV mode. All settings were held constant except the expiratory duration (TLow), which was adjusted based on the expiratory flow curve. Abdominal pressure was increased to 15mmHg in normal and Tween-injured lungs to replicate a combination of pulmonary and extrapulmonary lung injury. ELV was estimated using the Carescape FRC InView Tool. The expiratory flow-time slope and TExp were measured from the expiratory flow profile. Lung elastance increased with Tween-induced lung injury from 29.3±7.3cmH2O/L to 39.9±15.1cmH2O/L and chest wall elastance increased with increasing intra-abdominal pressures from 15.3±4.1cmH2O/L to 25.7±10.0cmH2O/L in the normal lung and 15.8±6.0cmH2O/L to 33.0±6.2cmH2O/L in the Tween-injured lung (p=0.39). ELV decreased from 1.90±0.83L in the Tween-Injured lung to 0.67±0.1L by increasing intra-abdominal pressures to 15mmHg. This had a significant correlation with a TExp decrease from 2.3±0.8s to 1.0±0.1s in the Tween-injured group with increasing insufflation pressures (ρ = 0.95) and with the expiratory flow-time slope, which increased from 0.29±0.06L/s2 to 0.63±0.05L/s2 (ρ = 0.78). Changes in ELV over time, and the TExp and flow-time slope, can be used to demonstrate evolving lung injury during APRV. Using the slope to infer changes in functional lung volume represents a unique, reproducible, real-time, bedside technique that does not interrupt ventilation and may be used for clinical interpretation.

Individual benefit in heart sparing during DIBH-supported left breast radiotherapy

IntroductionDeep-inspirational breath hold (DIBH) is an option for heart protection in breast radiotherapy; we intended to study its individual benefit. Materials and Methods3DCRT treatment planning was performed in a cohort of 103 patients receiving radiotherapy of the whole breast (WBI)/chest wall (CWI) ± nodal regions (NI) both under DIBH and free breathing (FB) in the supine position, and in the WBI only cases prone (n = 45) position, too. A series of patient-related and heart dosimetry parameters were analyzed. ResultsThe DIBH technique provided dramatic reduction of all heart dosimetry parameters the individual benefit, however, varied. In the whole population the best predictor of benefit was the ratio of ipsilateral lung volume (ILV)FB and ILVDIBH. In the WBI cohort 9–11 patients and 5–8 patients received less dose to selected heart structures with the DIBH and prone positioning, respectively; based on meeting various dose constraints DIBH was the only solution in 6–13 cases, and prone positioning in 5–6 cases. In addition to other excellent predictors, a small ILVFB or ILVDIBH with outstanding predicting performance (AUC ≥ 0.90) suggested prone positioning. Detailed analysis consistently indicated the outstanding performance of ILVFB and ILVDIBH in predicting the benefit of one over the other technique in lowering the mean heart dose (MHD), left anterior descending coronary artery (LAD) mean dose and left ventricle(LV)-V5Gy. The preference of prone positioning was further confirmed by anatomical parameters measured on a single CT scan at the middle of the heart. Performing spirometry in a cohort of 12 patients, vital capacity showed the strongest correlation with ILVFB and ILVDIBH hence this test could be evaluated as a clinical tool for patient selection. DiscussionIndividual lung volume measures estimated by spirometry and anatomical data examined prior to acquiring planning CT may support the preference of DIBH or prone radiotherapy for optimal heart protection.

Respiratory dysfunction in persistent somatic symptoms: A systematic review of observational studies

ObjectiveThis systematic review aims to analyze the existing literature investigating respiratory functioning in people with Persistent Somatic Symptoms (PSS) compared to healthy controls, to identify patterns of respiratory disturbances by symptom or syndrome, and describe any respiratory outcomes consistent across diagnoses. MethodsA systematic review following PRISMA guidelines was conducted. A comprehensive search was carried out across five databases (PubMed (NCBI), PsycArticles (Ovid), Web of Science (Core Collection), Embase, and Scopus) using two customised search strings for persistent somatic symptoms and objective respiratory parameters. Title/abstract screening and data extraction were carried out independently by two reviewers. The modified Newcastle-Ottawa Scale was used for quality assessment of the studies. Studies investigating baseline respiratory functioning in adult patients with PSS compared to healthy controls, using at least one objective respiratory were included. Results18 studies met the inclusion criteria for the review, with a pooled sample size of n = 3245. Chronic pain conditions were found to be the most prevalent subset of diagnoses of interest, comprising six of the studies. 10 studies included measures of lung capacity, flow and/or volume, nine studies reported measures of ventilation, and four studies investigated respiratory muscle functioning. 13 of the included studies reported significant differences in at least one objective respiratory measure between groups (at rest). Scores on self-reported measures of dysnpea and breathlessness were higher in patients compared to healthy controls, while objective respiratory outcomes were varied. ConclusionThe current systematic review is consistent with previous literature suggesting more pronounced experiences of breathlessness in patients with PSS, and significant disparities between reported dyspnea and objective respiratory outcomes. Research investigating the uncoupling between subjective and objective respiratory outcomes is needed to understand the mechanisms behind breathing disturbances in PSS.

Recruitment-to-inflation ratio for bedside PEEP selection in acute respiratory distress syndrome.

In acute respiratory distress syndrome, the role of positive end-expiratory pressure (PEEP) to prevent ventilator-induced lung injury is controversial. Randomized trials comparing higher versus lower PEEP strategies failed to demonstrate a clinical benefit. This may depend on the inter-individually variable potential for lung recruitment (i.e. recruitability), which would warrant PEEP individualization to balance alveolar recruitment and the unavoidable baby lung overinflation produced by high pressure. Many techniques have been used to assess recruitability, including lung imaging, multiple pressure-volume curves and lung volume measurement. The Recruitment-to-Inflation ratio (R/I) has been recently proposed to bedside assess recruitability without additional equipment. R/I assessment is a simplified technique based on the multiple pressure-volume curve concept: it is measured by monitoring respiratory mechanics and exhaled tidal volume during a 10-cmH<inf>2</inf>O one-breath derecruitment maneuver after a short high-PEEP test. R/I scales recruited volume to respiratory system compliance, and normalizes recruitment to a proxy of actual lung size. With modest R/I (<0.3-0.4), setting low PEEP (5-8 cmH<inf>2</inf>O) may be advisable; with R/I>0.6-0.7, high PEEP (≥15 cmH<inf>2</inf>O) can be considered, provided that airway and/or transpulmonary plateau pressure do not exceed safety limits. In case of intermediate R/I (≈0.5), a more granular assessment of recruitability may be needed. This could be accomplished with advanced monitoring tools, like sequential lung volume measurement with granular R/I assessment or electrical impedance tomography monitoring during a decremental PEEP trial. In this review, we discuss R/I rationale, applications and limits, providing insights on its clinical use for PEEP selection in moderate-to-severe acute respiratory distress syndrome.