Evaluating Airflow Sensor Methods: Precision in Indirect Calorimetry.

This study assesses the impact of three volumetric gas flow measurement methods-turbine (fT); pneumotachograph (fP), and Venturi (fV)-on predictive accuracy and precision of expired gas analysis indirect calorimetry (EGAIC) across varying exercise intensities. Six males (Age: 38 ± 8 year; Height: 178.8 ± 4.2 cm; V ̇ O 2 peak $$ \dot{V}{\mathrm{O}}_2\mathrm{peak} $$ : 42 ± 2.8 mL O2 kg-1 min-1) and 14 females (Age = 44.6 ± 9.6 year; Height = 164.6 ± 6.9 cm; V ̇ O 2 peak $$ \dot{V}{\mathrm{O}}_2\mathrm{peak} $$ = 45 ± 8.6 mL O2 kg-1 min-1) were recruited. Participants completed physical exertion on a stationary cycle ergometer for simultaneous pulmonary minute ventilation ( V ̇ $$ \dot{V} $$ ) measurements and EGAIC computations. Exercise protocols and subsequent conditions involved a 5-min cycling warm-up at 25 W min-1, incremental exercise to exhaustion ( V ̇ O 2 $$ \dot{V}{\mathrm{O}}_2 $$ ramp test), then a steady-state exercise bout induced by a constant Watt load equivalent to 80% ventilatory threshold (80% VT). A linear mixed model revealed that exercise intensity significantly affected V ̇ O 2 $$ \dot{V}{\mathrm{O}}_2 $$ measurements (p < 0.0001), whereas airflow sensor method (p = 0.97) and its interaction with exercise intensity (p = 0.91) did not. Group analysis of precision yielded a V ̇ O 2 $$ \dot{V}{\mathrm{O}}_2 $$ CV % = 21%; SEM = 5 mL O2 kg-1 min-1. Intra- and interindividual analysis of precision via Bland-Altman revealed a 95% confidence interval (CI) precision benchmark of 3-5 mL kg-1 min-1. Agreement among methods decreased at power outputs eliciting V ̇ $$ \dot{V} $$ up to 150 L min-1, indicating a decrease in precision and highlighting potential challenges in interpreting biological variability, training response heterogeneity, and test-retest comparisons. These findings suggest careful consideration of airflow sensor method variance across metabolic cart configurations.

Regional Pulmonary Ventilation Assessment Method and System Based on Impedance Sensing Information from the Pentapulmonary Lobes.

Regional lung ventilation assessment is a critical tool for the early detection of lung diseases and postoperative evaluation. Biosensor-based impedance measurements, known for their non-invasive nature, among other benefits, have garnered significant attention compared to traditional detection methods that utilize pressure sensors. However, solely utilizing overall thoracic impedance fails to accurately capture changes in regional lung air volume. This study introduces an assessment method for lung ventilation that utilizes impedance data from the five lobes, develops a nonlinear model correlating regional impedance with lung air volume, and formulates an approach to identify regional ventilation obstructions based on impedance variations in affected areas. The electrode configuration for the five lung lobes was established through numerical simulations, revealing a power-function nonlinear relationship between regional impedance and air volume changes. An analysis of 389 pulmonary function tests refined the equations for calculating pulmonary function parameters, taking into account individual differences. Validation tests on 30 cases indicated maximum relative errors of 0.82% for FVC and 0.98% for FEV1, all within the 95% confidence intervals. The index for assessing regional ventilation impairment was corroborated by CT scans in 50 critical care cases, with 10 validation trials showing agreement with CT lesion localization results.

Comparative analysis of pulmonary ventilation distribution between low-cost and branded incentive spirometers using electrical impedance tomography in healthy adults: Study protocol.

BACKGROUND: The Incentive Spirometer (IS) increases lung volume and improves gas exchange by visually stimulating patients to take slow, deep breaths. It prevents respiratory complications and treats postoperative atelectasis in patients undergoing abdominal, thoracic, and neurosurgical procedures. Its effectiveness has been validated in studies that support improved lung capacities and volumes in individuals with respiratory complications, postoperative thoracic surgery, upper abdominal surgery, and bariatric surgery. The modified Pachón incentive spirometer (MPIS) is a cost-effective alternative to branded IS. It is crucial to validate whether the MPIS distributes ventilation as effectively as commercial devices do. Ventilation distribution will be measured using electrical impedance tomography. OBJECTIVE: The aim is to compare the distribution of pulmonary ventilation between the MPIS and another commercial IS in healthy adults using electrical impedance tomography. METHODS: A crossover clinical trial is proposed to evaluate the measurement of pulmonary ventilation distribution using EIT in a sample of healthy adults. All participants will use a commercial flow IS and the MPIS, with the order of assignment randomized. This research will use electrical impedance tomography to validate the operation of the MPIS. CONCLUSIONS: This study protocol will compare two incentive spirometers' impact on pulmonary ventilation, potentially endorsing the adoption of a cost-effective device to enhance accessibility for targeted populations. TRIAL REGISTRATION: The study was registered in ClinicalTrials.gov (NTC05532748).

Experimental validation of an advanced impedance pneumography for monitoring ventilation volume during programmed cycling exercise.

Objective.Impedance pneumography (IP) has provided static assessments of subjects' breathing patterns in previous studies. Evaluating the feasibility and limitation of ambulatory IP based respiratory monitoring needs further investigation on clinically relevant exercise designs. The aim of this study was to evaluate the capacity of an advanced IP in ambulatory respiratory monitoring, and its predictive value in independent ventilatory capacity quantification during cardiopulmonary exercise testing (CPET).Approach.35 volunteers were examined with the same calibration methodology and CPET exercise protocol comprising phases of rest, unloaded, incremental load, maximum load, recovery and further-recovery. In 3 or 4 deep breaths of calibration stage, thoracic impedance and criterion spirometric volume were simultaneously recorded to produce phase-specific prior calibration coefficients (CCs). The IP measurement during exercise protocol was converted by prior CCs to volume estimation curve and thus calculate minute ventilation (VE) independent from the spirometry approach.Main results.Across all measurements, the relative error of IP-derived VE (VER) and flowrate-derived VE (VEf) was less than 13.8%. In Bland-Altman plots, the aggregate VE estimation bias was statistically insignificant for all 3 phases with pedaling exercise and the discrepancy between VERand VEffell within the 95% limits of agreement (95% LoA) for 34 or all subjects in each of all CPET phases.Significance.This work reinforces the independent use of IP as an accurate and robust alternative to flowmeter for applications in cycle ergometry CPET, which could significantly encourage the clinical use of IP and improve the convenience and comfort of CPET.

The status and influencing factors of lung ventilation function in employees exposed to dust in enterprises of the XPCC, China.

Background: Occupational health is closely related to harmful factors in the workplace. Dust is the primary contributing factor causing impaired lung ventilation function among employees with dust exposure, and their lung ventilation function may also be influenced by other factors. We aimed at assessing the status and influencing factors of lung ventilation function among employees exposed to dust in the enterprises of the Eighth Division located in the Xinjiang Production and Construction Corps (XPCC), China. Methods: Employees exposed to dust in enterprises of the Eighth Division located in the XPCC in 2023 were selected as the subjects of this cross-sectional study. Their lung ventilation function indicators were extracted from health examination records, and an on-site electronic questionnaire survey was conducted among them. Binary logistic regression analyses were conducted to evaluate the factors influencing lung ventilation function. Results: According to the fixed value criteria, the abnormal rates of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), and FEV1/FVC were 31.6, 1.4, and 0.4%, respectively. The lower limit of normal (LLN) criteria could overestimate the rate of abnormal lung ventilation function. Several factors were related to impaired lung ventilation function, including gender, age, education level, marital status, body mass index (BMI), smoking status, physical activity, the type of dust, industry, enterprise scale, occupation, length of service, working shift, monthly income, and respiratory protection. Conclusions: A relatively low abnormal rate of lung ventilation function was observed among employees exposed to dust in enterprises of the Eighth Division, XPCC, and their lung ventilation function was associated with various factors. Effective measures should be taken urgently to reduce the effects of adverse factors on lung ventilation function, thereby further protecting the health of the occupational population.

Pressure never sucks, pressure only pushes: a physiological exploration of the pushing power of pressure.

The movement of air into and out of the lungs is facilitated by changes in pressure within the thoracic cavity relative to atmospheric pressure, as well as the resistance encountered by airways. In this process, the movement of air into and out of the lungs is driven by pressure gradients established by changes in lung volume and intra-alveolar pressure. However, pressure never sucks! The concept that pressure never sucks, pressure only pushes encapsulates a fundamental principle in the behavior of gases. This concept challenges common misconceptions about pressure, shedding light on the dynamic forces that govern the movement of gases. In this Illumination, we explore the essence of this concept and its applications in pulmonary ventilation. Pressure is one of the most important concepts in physics and physiology. Atmospheric pressure at sea level is equal to 1 atmosphere or around 101,325 Pascal [Pa (1 Pa = 1 N/m2)]. This huge pressure is pushing down on everything all the time. However, this pressure is difficult to understand because we do not often observe the power of this incredible force. We used five readily available, simple, and inexpensive demonstrations to introduce the physics and power of pressure. This extraordinarily complex physics concept was approached in a straightforward and inexpensive manner while still providing an understanding of the fundamental concepts. These simple demonstrations introduced basic concepts and addressed common misconceptions about pressure.NEW & NOTEWORTHY The concept that pressure never sucks, pressure only pushes challenges common misconceptions about pressure, shedding light on the dynamic forces that govern the movement of gases. In this Illumination, we will explore the essence of this concept and its applications in pulmonary ventilation. Specifically, we used five readily available, simple, inexpensive demonstrations to introduce the physics and power of pressure.

Comparable Ventilatory Inefficiency at Maximal and Submaximal Performance in COPD vs. CHF subjects: An Innovative Approach. / Ineficiência Ventilatória Comparável no Desempenho Máximo e Submáximo em Indivíduos com DPOC e ICC: Uma Abordagem Inovadora.

BACKGROUND: Currently, excess ventilation has been grounded under the relationship between minute-ventilation/carbon dioxide output ( V ˙ E - V ˙ CO 2 ). Alternatively, a new approach for ventilatory efficiency ( η E V ˙ ) has been published. OBJECTIVE: Our main hypothesis is that comparatively low levels of η E V ˙ between chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD) are attainable for a similar level of maximum and submaximal aerobic performance, conversely to long-established methods ( V ˙ E - V ˙ CO 2 slope and intercept). METHODS: Both groups performed lung function tests, echocardiography, and cardiopulmonary exercise testing. The significance level adopted in the statistical analysis was 5%. Thus, nineteen COPD and nineteen CHF-eligible subjects completed the study. With the aim of contrasting full values of V ˙ E - V ˙ CO 2 and η V ˙ E for the exercise period (100%), correlations were made with smaller fractions, such as 90% and 75% of the maximum values. RESULTS: The two groups attained matched characteristics for age (62±6 vs. 59±9 yrs, p>.05), sex (10/9 vs. 14/5, p>0.05), BMI (26±4 vs. 27±3 Kg m2, p>0.05), and peak V ˙ O 2 (72±19 vs. 74±20 %pred, p>0.05), respectively. The V ˙ E - V ˙ CO 2 slope and intercept were significantly different for COPD and CHF (27.2±1.4 vs. 33.1±5.7 and 5.3±1.9 vs. 1.7±3.6, p<0.05 for both), but η V ˙ E average values were similar between-groups (10.2±3.4 vs. 10.9±2.3%, p=0.462). The correlations between 100% of the exercise period with 90% and 75% of it were stronger for η V ˙ E (r>0.850 for both). CONCLUSION: The η V ˙ E is a valuable method for comparison between cardiopulmonary diseases, with so far distinct physiopathological mechanisms, including ventilatory constraints in COPD.

FUNDAMENTO: Atualmente, o excesso de ventilação tem sido fundamentado na relação entre ventilação-minuto/produção de dióxido de carbono ( V ˙ E − V ˙ CO 2 ). Alternativamente, uma nova abordagem para eficiência ventilatória ( η E V ˙ ) tem sido publicada. OBJETIVO: Nossa hipótese principal é que níveis comparativamente baixos de η E V ˙ entre insuficiência cardíaca crônica (ICC) e doença pulmonar obstrutiva crônica (DPOC) são atingíveis para um nível semelhante de desempenho aeróbico máximo e submáximo, inversamente aos métodos estabelecidos há muito tempo (inclinação V ˙ E − V ˙ CO 2 e intercepto). MÉTODOS: Ambos os grupos realizaram testes de função pulmonar, ecocardiografia e teste de exercício cardiopulmonar. O nível de significância adotada na análise estatística foi 5%. Assim, dezenove indivíduos elegíveis para DPOC e dezenove indivíduos elegíveis para ICC completaram o estudo. Com o objetivo de contrastar valores completos de V ˙ E − V ˙ CO 2 e η E V ˙ para o período de exercício (100%), correlações foram feitas com frações menores, como 90% e 75% dos valores máximos. RESULTADOS: Os dois grupos tiveram características correspondentes para a idade (62±6 vs 59±9 anos, p>.05), sexo (10/9 vs 14/5, p>0,05), IMC (26±4 vs 27±3 Kg m2, p>0,05), e pico V ˙ O 2 (72±19 vs 74±20 % pred, p>0,05), respectivamente. A inclinação V ˙ E − V ˙ CO 2 e intercepto foram significativamente diferentes para DPOC e ICC (207,2±1,4 vs 33,1±5,7 e 5,3±1,9 vs 1,7±3,6, p<0,05 para ambas), mas os valores médios da η E V ˙ foram semelhantes entre os grupos (10,2±3,4 vs 10,9±2,3%, p=0,462). As correlações entre 100% do período do exercício com 90% e 75% dele foram mais fortes para η E V ˙ (r>0,850 para ambos). CONCLUSÃO: A η E V ˙ é um método valioso para comparação entre doenças cardiopulmonares, com mecanismos fisiopatológicos até agora distintos, incluindo restrições ventilatórias na DPOC.

[Control status and follow-up of acute attacks in children with bronchial asthma with normal pulmonary ventilation function]. / è‚ºé€šæ°”åŠŸèƒ½æ­£å¸¸çš„å„¿ç«¥æ”¯æ°”ç®¡å“®å–˜æŽ§åˆ¶æƒ å†µåŠæ€¥æ€§å‘ä½œéšè®¿çš„ç ”ç©¶.

OBJECTIVES: To investigate the control status of bronchial asthma (referred to as "asthma") in school-age children with normal pulmonary ventilation function and the occurrence of acute attacks within 1 year of follow-up. METHODS: A retrospective analysis was conducted on clinical data of 327 children aged 6-14 years with bronchial asthma and normal pulmonary ventilation function from April to September 2021. Based on the measured value of one second rate (FEV1/FVC), the children were divided into the ≥80% group (267 cases) and the <80% group (60 cases). The pulmonary ventilation function, asthma control level, and occurrence of acute attacks within 1 year were compared between the two groups. RESULTS: The baseline pulmonary ventilation function in the <80% group was lower than that in the ≥80% group, and the proportion of small airway dysfunction was higher than that in the ≥80% group (P<0.05). After standardized treatment for 1 year, the small airway function indices in the <80% group improved but remained lower than those in the ≥80% group (P<0.05). The rate of incomplete asthma control at baseline was 34.6% (113/327), and the asthma control level in the <80% group was lower than that in the ≥80% group (P<0.05). After standardized treatment for 1 year, the asthma control level in the <80% group remained lower than that in the ≥80% group, and the proportion of acute asthma attacks was higher than that in the ≥80% group (P<0.05). CONCLUSIONS: Approximately one-third of school-age children with asthma still have incomplete asthma control when their pulmonary ventilation function is normal. Among them, children with measured FEV1/FVC<80% have an increased risk of acute asthma attacks and require close follow-up and strengthened asthma management.

Acute sodium bicarbonate administration improves ventilatory efficiency in experimental respiratory acidosis: clinical implications.

Administering sodium bicarbonate (NaHCO3) to patients with respiratory acidosis breathing spontaneously is contraindicated because it increases carbon dioxide load and depresses pulmonary ventilation. Nonetheless, several studies have reported salutary effects of NaHCO3 in patients with respiratory acidosis but the underlying mechanism remains uncertain. Considering that such reports have been ignored, we examined the ventilatory response of unanesthetized dogs with respiratory acidosis to hypertonic NaHCO3 infusion (1 N, 5 mmol/kg) and compared it with that of animals with normal acid-base status or one of the remaining acid-base disorders. Ventilatory response to NaHCO3 infusion was evaluated by examining the ensuing change in PaCO2 and the linear regression of the PaCO2 vs. pH relationship. Strikingly, PaCO2 failed to increase and the ΔPaCO2 vs. ΔpH slope was negative in respiratory acidosis, whereas PaCO2 increased consistently and the ΔPaCO2 vs. ΔpH slope was positive in the remaining study groups. These results cannot be explained by differences in buffering-induced decomposition of infused bicarbonate or baseline levels of blood pH, PaCO2, and pulmonary ventilation. We propose that NaHCO3 infusion improved the ventilatory efficiency of animals with respiratory acidosis, i.e., it decreased their ratio of total pulmonary ventilation to carbon dioxide excretion (VE/VCO2). Such exclusive effect of NaHCO3 infusion in animals with respiratory acidosis might emanate from baseline increased VD/VT (dead space/tidal volume) caused by bronchoconstriction and likely reduced pulmonary blood flow, defects that are reversed by alkali infusion. Our observations might explain the beneficial effects of NaHCO3 reported in patients with acute respiratory acidosis.

Mechanisms and consequences of excess exercise ventilation in fibrosing interstitial lung disease.

The causes and consequences of excess exercise ventilation (EEV) in patients with fibrosing interstitial lung disease (f-ILD) were explored. Twenty-eight adults with f-ILD and 13 controls performed an incremental cardiopulmonary exercise test. EEV was defined as ventilation-carbon dioxide output (⩒E-⩒CO2) slope ≥36 L/L. Patients showed lower pulmonary function and exercise capacity compared to controls. Lower DLCO was related to higher ⩒E-⩒CO2 slope in patients (P<0.05). 13/28 patients (46.4%) showed EEV, reporting higher dyspnea scores (P=0.033). Patients with EEV showed a higher dead space (VD)/tidal volume (VT) ratio while O2 saturation dropped to a greater extent during exercise compared to those without EEV. Higher breathing frequency and VT/inspiratory capacity ratio were observed during exercise in the former group (P<0.05). An exaggerated ventilatory response to exercise in patients with f-ILD is associated with a blunted decrease in the wasted ventilation in the physiological dead space and greater hypoxemia, prompting higher inspiratory constraints and breathlessness.

[Application of electrical impedance tomography imaging technology combined with generative adversarial network in pulmonary ventilation monitoring].

Electrical impedance tomography (EIT) plays a crucial role in the monitoring of pulmonary ventilation and regional pulmonary function test. However, the inherent ill-posed nature of EIT algorithms results in significant deviations in the reconstructed conductivity obtained from voltage data contaminated with noise, making it challenging to obtain accurate distribution images of conductivity change as well as clear boundary contours. In order to enhance the image quality of EIT in lung ventilation monitoring, a novel approach integrating the EIT with deep learning algorithm was proposed. Firstly, an optimized operator was introduced to enhance the Kalman filter algorithm, and Tikhonov regularization was incorporated into the state-space expression of the algorithm to obtain the initial lung image reconstructed. Following that, the imaging outcomes were fed into a generative adversarial network model in order to reconstruct accurate lung contours. The simulation experiment results indicate that the proposed method produces pulmonary images with clear boundaries, demonstrating increased robustness against noise interference. This methodology effectively achieves a satisfactory level of visualization and holds potential significance as a reference for the diagnostic purposes of imaging modalities such as computed tomography.

Factores asociados a ventilación mecánica prolongada en niños con fallo respiratorio de causa pulmonar: Estudio de cohortes del registro de LARed Network / Factors associated with prolonged mechanical ventilation in children with pulmonary failure: Cohort study from the LARed Network registry

Objetivos Identificar los factores asociados con la ventilación mecánica prolongada (pVMI) en pacientes pediátricos en la unidad de cuidados intensivos pediátricos (UCIP). Diseño Análisis secundario de una cohorte prospectiva. Ámbito UCIP en los centros que integran LARed Network entre abril del 2017 y enero del 2022. Participantes Pacientes pediátricos en ventilación mecánica (VMI) debido a causas respiratorias. Definimos pVMI como eventos con tiempo VMI mayor al percentil 75 global. Intervenciones Ninguna.Variables de interés principales Datos demográficos, diagnósticos, puntajes de gravedad, terapias, complicaciones, estancias y morbimortalidad. Resultados Se incluyó a 1.698 niños con VMI de 8 ± 7 días y se definió pVMI en 9 días. Los factores relacionados al ingreso fueron la edad menor de 6 meses (OR 1,61, IC del 95%, 1,17-2,22), la displasia broncopulmonar (OR 3,71, IC del 95%, 1,87-7,36) y las infecciones fúngicas (OR 6,66, IC del 95%, 1,87-23,74), mientras que los pacientes con asma tuvieron menor riesgo de pVMI (OR 0,30, IC del 95%, 0,12-0,78). En cuanto a la evolución y la estancia en UCIP, se relacionó a neumonía asociada a la ventilación mecánica (OR 4,27, IC del 95%, 1,79-10,20), necesidad de traqueostomía (OR 2,91, IC del 95%, 1,89-4,48), transfusiones (OR 2,94, IC del 95%, 2,18-3,96), bloqueo neuromuscular (OR 2,08, IC del 95%, 1,48-2,93) y ventilación de alta frecuencia (OR 2,91, IC del 95%, 1,89-4,48) y una mayor estadía en UCIP (OR 1,13, IC del 95%, 1,10-1,16). Además, la presión media aérea mayor a 13cmH2O se asoció a pVMI (OR 1,57, IC del 95%, 1,12-2,21). Conclusiones Se identificaron factores relacionados con VMI de duración mayor a 9 días en pacientes pediátricos en UCIP en cuanto a ingreso, evolución y estancia. (AU)

Objectives To identify factors associated with prolonged mechanical ventilation (pMV) in pediatric patients in pediatric intensive care units (PICUs). Design Secondary analysis of a prospective cohort.SettingPICUs in centers that are part of the LARed Network between April 2017 and January 2022. Participants Pediatric patients on mechanical ventilation (IMV) due to respiratory causes. We defined IMV time greater than the 75th percentile of the global cohort. Interventions None.Main variables of interestDemographic data, diagnoses, severity scores, therapies, complications, length of stay, morbidity, and mortality. Results One thousand 6hundred and ninety 8children with MV of 8±7 days were included, and pIMV was defined as 9 days. Factors related to admission were age under 6 months (OR 1.61, 95% CI 1.17–2.22), bronchopulmonary dysplasia (OR 3.71, 95% CI 1.87–7.36), and fungal infections (OR 6.66, 95% CI 1.87–23.74), while patients with asthma had a lower risk of pIMV (OR 0.30, 95% CI 0.12–0.78). Regarding evolution and length of stay in the PICU, it was related to ventilation-associated pneumonia (OR 4.27, 95% CI 1.79–10.20), need for tracheostomy (OR 2.91, 95% CI 1.89–4.48), transfusions (OR 2.94, 95% CI 2.18–3.96), neuromuscular blockade (OR 2.08, 95% CI 1.48–2.93), high-frequency ventilation (OR 2.91, 95% CI 1.89–4.48), and longer PICU stay (OR 1.13, 95% CI 1.10–1.16). In addition, mean airway pressure greater than 13cmH2O was associated with pIMV (OR 1.57, 95% CI 1.12–2.21). Conclusions Factors related to IMV duration greater than 9 days in pediatric patients in PICUs were identified in terms of admission, evolution, and length of stay. (AU)

Regional ventilation distribution before and after laparoscopic lung parenchymal resection.

Objective.The aim of the present study was to evaluate the influence of one-sided pulmonary nodule and tumour on ventilation distribution pre- and post- partial lung resection.Approach.A total of 40 consecutive patients scheduled for laparoscopic lung parenchymal resection were included. Ventilation distribution was measured with electrical impedance tomography (EIT) in supine and surgery lateral positions 72 h before surgery (T1) and 48 h after extubation (T2). Left lung to global ventilation ratio (Fl), the global inhomogeneity index (GI), standard deviation of regional ventilation delay (RVDSD) and pendelluft amplitude (Apendelluft) were calculated to assess the spatial and temporal ventilation distribution.Main results.After surgery (T2), ventilation at the operated chest sides generally deteriorated compared to T1 as expected. For right-side resection, the differences were significant at both supine and left lateral positions (p< 0.001). The change of RVDSDwas in general more heterogeneous. For left-side resection, RVDSDwas worse at T2 compared to T1 at left lateral position (p= 0.002). The other EIT-based parameters showed no significant differences between the two time points. No significant differences were observed between supine and lateral positions for the same time points respectively.Significance.In the present study, we found that the surgery side influenced the ventilation distribution. When the resection was performed on the right lung, the postoperative ipsilateral ventilation was reduced and the right lung ratio fell significantly. When the resection was on the left lung, the ventilation delay was significantly increased.

Estimating ventilation correlation coefficients in the lungs using PREFUL-MRI in chronic obstructive pulmonary disease patients and healthy adults.

PURPOSE: Various parameters of regional lung ventilation can be estimated using phase-resolved functional lung (PREFUL)-MRI. The parameter "ventilation correlation coefficient (Vent-CC)" was shown advantageous because it assesses the dynamics of regional air flow. Calculating Vent-CC depends on a voxel-wise comparison to a healthy reference flow curve. This work examines the effect of placing a reference region of interest (ROI) in various lung quadrants or in different coronal slices. Furthermore, algorithms for automated ROI selection are presented and compared in terms of test-retest repeatability. METHODS: Twenty-eight healthy subjects and 32 chronic obstructive pulmonary disease (COPD) patients were scanned twice using PREFUL-MRI. Retrospective analyses examined the homogeneity of air flow curves of various reference ROIs using cross-correlation. Vent-CC and ventilation defect percentage (VDP) calculated using various reference ROIs were compared using one-way analysis of variance (ANOVA). The coefficient of variation was calculated for Vent-CC and VDP when using different reference selection algorithms. RESULTS: Flow-volume curves were highly correlated between ROIs placed at various lung quadrants in the same coronal slice (r > 0.97) with no differences in Vent-CC and VDP (ANOVA: p > 0.5). However, ROIs placed at different coronal slices showed lower correlation coefficients and resulted in significantly different Vent-CC and VDP values (ANOVA: p < 0.001). Vent-CC and VDP showed higher repeatability when calculated using the presented new algorithm. CONCLUSION: In COPD and healthy cohorts, assessing regional ventilation dynamics using PREFUL-MRI in terms of the Vent-CC metric showed higher repeatability using a new algorithm for selecting a homogenous reference ROI from the same slice.

Effect of CFTR modulator therapy with elexacaftor/tezacaftor/ivacaftor on pulmonary ventilation derived by 3D phase-resolved functional lung MRI in cystic fibrosis patients.

OBJECTIVES: To investigate whether 3D phase-resolved functional lung (PREFUL)-MRI parameters are suitable to measure response to elexacaftor/tezacaftor/ivacaftor (ETI) therapy and their association with clinical outcomes in cystic fibrosis (CF) patients. METHODS: Twenty-three patients with CF (mean age: 21; age range: 14-46) underwent MRI examination at baseline and 8-16 weeks after initiation of ETI. Morphological and 3D PREFUL scans assessed pulmonary ventilation. Morphological images were evaluated using a semi-quantitative scoring system, and 3D PREFUL scans were evaluated by ventilation defect percentage (VDP) values derived from regional ventilation (RVent) and cross-correlation maps. Improved ventilation volume (IVV) normalized to body surface area (BSA) between baseline and post-treatment visit was computed. Forced expiratory volume in 1 second (FEV1) and mid-expiratory flow at 25% of forced vital capacity (MEF25), as well as lung clearance index (LCI), were assessed. Treatment effects were analyzed using paired Wilcoxon signed-rank tests. Treatment changes and post-treatment agreement between 3D PREFUL and clinical parameters were evaluated by Spearman's correlation. RESULTS: After ETI therapy, all 3D PREFUL ventilation markers (all p < 0.0056) improved significantly, except for the mean RVent parameter. The BSA normalized IVVRVent was significantly correlated to relative treatment changes of MEF25 and mucus plugging score (all |r| > 0.48, all p < 0.0219). In post-treatment analyses, 3D PREFUL VDP values significantly correlated with spirometry, LCI, MRI global, morphology, and perfusion scores (all |r| > 0.44, all p < 0.0348). CONCLUSIONS: 3D PREFUL MRI is a very promising tool to monitor CFTR modulator-induced regional dynamic ventilation changes in CF patients. CLINICAL RELEVANCE STATEMENT: 3D PREFUL MRI is sensitive to monitor CFTR modulator-induced regional ventilation changes in CF patients. Improved ventilation volume correlates with the relative change of mucus plugging, suggesting that reduced endobronchial mucus is predominantly responsible for regional ventilation improvement. KEY POINTS: • 3D PREFUL MRI-derived ventilation maps show significantly reduced ventilation defects in CF patients after ETI therapy. • Significant post-treatment correlations of 3D PREFUL ventilation measures especially with LCI, FEV1 %pred, and global MRI score suggest that 3D PREFUL MRI is sensitive to measure improved regional ventilation of the lung parenchyma due to reduced inflammation induced by ETI therapy in CF patients. • 3D PREFUL MRI-derived improved ventilation volume (IVV) correlated with MRI mucus plugging score changes suggesting that reduced endobronchial mucus is predominantly responsible for regional ventilation improvement 8-16 weeks after ETI therapy.

Prone position ventilation for the relief of acute respiratory distress syndrome through improved pulmonary ventilation: Efficacy and safety.

BACKGROUND: At present, there is a preliminary clinical consensus that prone position ventilation (PPV) is beneficial to the treatment of acute respiratory distress syndrome (ARDS), and further research on the details of treatment and patients' benefits will help to assess its effectiveness and safety. AIM: To evaluate the timing, efficacy, and safety of different mechanical ventilation positions (MVP) in treating ARDS. STUDY DESIGN: The results of clinical trials were directly or indirectly compared by network meta-analysis to compare the effects of different MVP. Two authors independently searched the papers published in PubMed, Embase, Cochrane Library, China Knowledge Infrastructure (CNKI), China Biomedical Discs (CBM), WanFang, and VIP database from January 2000 to August 2022. The outcome indicators were oxygenation index, mechanical ventilation time, ICU hospitalization time, in-hospital mortality, and incidence of adverse events. Two authors independently screened the literature, evaluated the quality of the studies, and completed the data extraction. Stata 14.0 was used to conduct a network Meta-analysis, and the intervention measures were ranked according to the surface under the cumulative ranking curve (SUCRA). Funnel plots were drawn to evaluate publication bias. RESULTS: According to the inclusion and exclusion criteria, 75 studies (including 6333 patient data) were finally included. According to the analysis results, PPV was the best for improving the oxygenation index. The SUCRA values of mechanical ventilation time, ICU hospitalization time, and in-hospital mortality were ranked as PPV > lateral position ventilation (LPV) > supine position ventilation (SuPV) > semireclining position ventilation (SePV). The SUCRA values in the incidence of adverse events were ranked as LPV > PPV > SuPV > SePV. All outcome measures had good consistency and low statistical heterogeneity. Funnel plot analysis shows that papers reported within three days of mechanical ventilation time, over five days of mechanical ventilation time, and in-hospital mortality were more likely to have publication bias. CONCLUSIONS: PPV has the best effect on improving the oxygenation index, reducing mechanical ventilation time, shortening ICU hospitalization time, and reducing in-hospital mortality. Early and long-term use of PPV to improve pulmonary ventilatory function will be the key to improving patients' survival and quality of life with ARDS. RELEVANCE TO CLINICAL PRACTICE: PPV significantly affects patients with ARDS, which can shorten the treatment time and reduce hospital costs. During the treatment, nursing observation should be strengthened to prevent adverse events.

Systematic Evaluation of the Impact of Lung Segmentation Methods on 4-Dimensional Computed Tomography Ventilation Imaging Using a Large Patient Database.

PURPOSE: A novel form of lung functional imaging applied for functional avoidance radiation therapy has been developed that uses 4-dimensional computed tomography (4DCT) data and image processing techniques to calculate lung ventilation (4DCT-ventilation). Lung segmentation is a common step to define a region of interest for 4DCT-ventilation generation. The purpose of this study was to quantitatively evaluate the sensitivity of 4DCT-ventilation imaging using different lung segmentation methods. METHODS AND MATERIALS: The 4DCT data of 350 patients from 2 institutions were used. Lung contours were generated using 3 methods: (1) reference segmentations that removed airways and pulmonary vasculature manually (Lung-Manual), (2) standard lung contours used for planning (Lung-RadOnc), and (3) artificial intelligence (AI)-based contours that removed the airways and pulmonary vasculature (Lung-AI). The AI model was based on a residual 3-dimensional U-Net and was trained using the Lung-Manual contours of 279 patients. We compared the Lung-RadOnc or Lung-AI with Lung-Manual contours for the entire 4DCT-ventilation functional avoidance process including lung segmentation (surface Dice similarity coefficient [Surface DSC]), 4DCT-ventilation generation (correlation), and subanalysis of 10 patients on a dosimetric endpoint (percentage of high functional volume of lung receiving ≥20 Gy [fV20{%}]). RESULTS: Surface DSC comparing Lung-Manual/Lung-RadOnc and Lung-Manual/Lung-AI contours was 0.40 ± 0.06 and 0.86 ± 0.04, respectively. The correlation between 4DCT-ventilation images generated with Lung-Manual/Lung-RadOnc and Lung-Manual/Lung-AI were 0.48 ± 0.14 and 0.85 ± 0.14, respectively. The difference in fV20[%] between 4DCT-ventilation generated with Lung-Manual/Lung-RadOnc and Lung-Manual/Lung-AI was 2.5% ± 4.1% and 0.3% ± 0.5%, respectively. CONCLUSIONS: Our work showed that using standard planning lung contours can result in significantly variable 4DCT-ventilation images. The study demonstrated that AI-based segmentations generate lung contours and 4DCT-ventilation images that are similar to those generated using manual methods. The significance of the study is that it characterizes the lung segmentation sensitivity of the 4DCT-ventilation process and develops methods that can facilitate the integration of this novel imaging in busy clinics.

Assessing airflow unsteadiness in the human respiratory tract under different expiration conditions.

To enhance the understanding of airflow characteristics in the human respiratory system, the expiratory airflow in a human respiratory tract model was simulated using large eddy simulation and dynamic mesh under different expiration conditions aligned with clinically measured data. The airflow unsteadiness was quantitatively assessed using power spectral density (PSD) and spectral entropy (SE). The following findings were obtained: (1) The airflow is highly turbulent in the mouth-pharynx region during expiration, with its dynamic characteristics being influenced by both the transient expiration flow pattern at mouth piece and the glottis motion. (2) PSD analysis reveals that the expiratory airflow is very unsteady, exhibiting a broad-band attenuation spectrum in the pharynx-trachea region. When only transient expiration or glottis motion is considered, the PSD spectrum changes slightly. When both are ignored, however, the change is significant, with the peak frequency reduced to 10% of the real expiration condition. (3) SE analysis indicates that the airflow transitions into turbulence in the trachea, and there may be multiple transitions in the region of soft palate. The transient expiration or glottis motion alone increases turbulence intensity by 2%-15%, while ignoring both reduces turbulence intensity by 10%-20%. This study implies that turbulence characteristics can be significantly different under different expiratory conditions, and therefore it is necessary to determine the expiratory flow characteristics using clinically measured expiratory data.