Subdivisions Of Lung Volume Research Articles

Ventilatory Limitation in Patients with HFpEF and Obesity: The Balance Between Increased Ventilatory Demand vs. Reduced Ventilatory Capacity

Study Objective: Patients with heart failure with preserved ejection fraction (HFpEF) have an increased ventilatory demand during exertion. Whether ventilatory capacity can meet this increased demand is unknown, especially in those with obesity. Hypothesis: We hypothesized that ventilatory capacity would be reduced in patients with HFpEF due to age- and obesity-related mechanical ventilatory constraints. Methodology: Body composition (DEXA) and pulmonary function were measured in 20 patients with invasively confirmed HFpEF (69±6yr; 9M/11W). Cardiorespiratory responses, breathing mechanics, and arterial blood gases were measured at rest, during exercise at 20 W, and at peak exercise. Based upon inspection of resting forced vital capacity (FVC, L) values, the patients were grouped into those with an FVC<3L (n=12; 2M/10W) and those with an FVC>3.8L (n=8; 7M/1W). Differences between the two groups were compared using independent t-tests. Comparisons were not made between conditions (rest, 20W, & peak exercise). Results: Percent body fat was greater in the FVC<3L group (51% vs. 38%, p<0.01). Ventilatory demand (V̇ E /V̇CO 2 ) was equally elevated in both groups at rest and during exercise. FVC was 2 L less in the FVC<3L group (79±14 vs. 100±13 %predicted) and maximal voluntary ventilation was approximately 50 L/min less (p<0.01). All lung volume subdivisions (L) were significantly lower in the FVC<3L group at rest and during exercise (p<0.05). End expiratory lung volume (L) was higher during exercise in both groups as many of the patients had expiratory flow limitation at rest and during exercise (>50% V T at peak exercise). End inspiratory lung volume (L) approached 90% of total lung capacity in both groups, thus V T (%FVC) expansion was limited in both groups. The FVC<3L group was not able to increase V̇ E (L/min) enough to lower arterial CO 2 at peak exercise as much as the FVC>3.8L group (40±4 vs 35±3; p<0.05). Peak V̇O 2 (%predicted) was approximately 22% less (p<0.05) in the FVC<3L group. Ratings of perceived breathlessness and unpleasantness were higher in the FVC<3L group at 20 W (p<0.05). Conclusion: Ventilatory capacity is limited in patients with HFpEF and obesity; this is particularly true for patients who have a small or reduced FVC. We propose that quantifying ventilatory limitations in patients with HFpEF is critical to establishing whether they can meet the challenges of an elevated ventilatory demand and whether these limitations may play a role in provoking exertional dyspnea and exercise intolerance. This research was supported by the National Institutes of Health (1P01HL137630), King Foundation, Cain Foundation, and Texas Health Presbyterian Hospital Dallas. B.N. Balmain is supported by an American Heart Association Fellowship (grant number: 826064). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Feasibility of dynamic chest radiography to calculate lung volumes in adult people with cystic fibrosis: a pilot study

IntroductionDynamic chest radiography (DCR) is a novel, low-dose, real-time digital imaging system where software identifies moving thoracic structures and can automatically calculate lung areas. In an observational, prospective, non-controlled, single-centre...

P102 Utility of Dynamic Chest Radiography (DCR) for calculating lung volume subdivisions in adult people with cystic fibrosis

P102 Utility of Dynamic Chest Radiography (DCR) for calculating lung volume subdivisions in adult people with cystic fibrosis

Relation of Indices of Lung Hyperinflation to Dyspnea in Patients with Chronic Obstructive Pulmonary Disease: A Physiologic Assessment and Discussion

Background: The severity of COPD is commonly assessed by the reduction in forced expiratory volume at one second (FEV1), although more recently prognostic factors influencing survival have also incorporated functional capacity, degree of breathlessness on exertion, and body mass index. Increasingly, the reliability of physiological parameters such as FEV1 to predict patient-centered outcomes has been brought into question. Objectives: To evaluate the relationship between dyspnea as assessed by the Modified Medical Council Dyspnea (MMRC) scale, the Global Initiative for Chronic Obstructive Lung Disease (GOLD 2014) staging and indices of lung hyperinflation and spirometry. Methods: Data were retrospectively analyzed at a 600-bed tertiary care center including spirometry, plethysmographic lung volumes, single breath carbon monoxide diffusion capacity and dyspnea graded according to MMRC, and GOLD staging. Results: Data for 331 patients were analyzed. Differences amongst FEV1, IC, IC/TLC, FRC and RV/TLC were significant between GOLD I/II and GOLD III/IV groups. The closest relationship to GOLD staging was seen with FEV1, FVC and slow vital capacity (SVC). FEV1/FVC, IC, and IC/TLC were inversely associated with MMRC score, while RV/TLC exhibited a positive relation with MMRC score. Conclusions: Indices of lung hyperinflation are closely associated, with dyspnea as assessed by MMRC grading with TLC, RV/TLC and IC exhibiting the closest relations, more so than FEV1. GOLD staging also shows strong correlations with lung volume subdivisions (weakly with TLC), more so than with FEV1. That TLC changed little between GOLD stages can be explained by the presence of collateral interalveolar channels and population characteristics different from those of other studies. These findings further support the concept that more than a reduction in FEV1, lung hyperinflation contributes to the sensation of dyspnea in airflow limitation.

Effect of weight loss on operational lung volumes and oxygen cost of breathing in obese women.

BackgroundThe effect of moderate weight loss on operational lung volumes during exercise and the oxygen (O2) cost of breathing are unknown in obese women but could have important implications regarding exercise endurance.MethodsIn twenty-nine obese women (33 ± 8yr, 97 ± 14kg, BMI: 36 ± 4, body fat: 45.6 ± 4.5%; means ± SD), body composition, fat distribution (by MRI), pulmonary function, operational lung volumes during exercise, and the O2 cost of breathing during eucapnic voluntary hyperpnea ( vs. slope) were studied before and after a 12-week diet and resistance exercise weight loss program.ResultsParticipants lost 7.5 ± 3.1kg or ≈8% of body weight (p < 0.001), but fat distribution remained unchanged. After weight loss, lung volume subdivisions at rest were increased (p < 0.05) and were moderately associated (p < 0.05) with changes in weight. End-expiratory lung volume (%Total Lung Capacity) increased at rest and during constant load exercise (p < 0.05). O2 cost of breathing was reduced by 16% (2.52 ± 1.02 to 2.11 ± 0.72ml/L; P=0.003). As a result, O2 uptake of the respiratory muscles , estimated as the product of O2 cost of breathing and exercise during cycling at 60W, was significantly reduced by 27 ± 31ml (P<0.001), accounting for 46% of the reduction in total body during cycling at 60W.ConclusionsModerate weight loss yields important improvements in respiratory function at rest and during submaximal exercise in otherwise healthy obese women. These changes in breathing load could have positive effects on the exercise endurance and adherence to physical activity.

Static Respiratory Mechanics are Unaltered in Mild-to-Moderate Obese Men and Women

Morbid obesity can affect spirometric function and lung volume subdivisions. Additionally, compliance of the lung and chest wall are unfavorably altered. However, in mild-to-moderate obesity, rarely are expiratory flows and lung volumes influenced to an extent that they become less than normal. It is unclear if mild-to-moderate obesity alters the flow-pressure-volume relationship of the respiratory system. PURPOSE: To examine whether the interrelationships of maximal flow-pressure-volume are altered due to mild-to-moderate obesity in men and women METHODS: Obese (30 ≤ BMI ≤ 45) and lean (BMI < 25) men (n = 20) and women (n = 17) completed pulmonary function testing. Maximal expiratory flow, static lung elastic recoil pressure (Pst), and the minimal pressure for maximal flow (Pcrit) were determined in a pressure-compensated, volume-displacement body plethysmograph. Parameters were compared at 25, 50, and 75% of forced vital capacity (FVC). Additionally, dysanapsis, the association between airway size and lung size, was estimated using measured values of maximal expiratory flow at 50% FVC, FVC, and Pst at 50% FVC. Dysanapsis also was estimated using a regression equation for the calculation of Pst at 50% FVC. RESULTS: Obese and lean men had similar maximal expiratory flow, Pst and Pcrit at each lung volume examined. Additionally, obese and lean women displayed similar flow-pressure-volume characteristics. However, men had greater maximal expiratory flows, Pst, and Pcrit at all lung volumes, with the exception of Pcrit at 25% FVC, compared with women (p < 0.05). Dysanapsis was unaffected due to mild-to-moderate obesity in men and in women. Dysanapsis estimated using the predicted value for Pst at 50% FVC was significantly different from that obtained using measured parameters. CONCLUSIONS: Unlike in morbid obesity, mild-to-moderate obesity does not affect flow-pressure-volume relationships in men or in women. Furthermore, due to the inability to accurately predict static lung elastic recoil pressure, the use of prediction equations in the estimation of dysanapsis is cautioned.

Entropy Change of Lungs: Determinant of the Static Properties of the Lungs

The static properties of the lungs have been explained by energy-change considerations on the elasticity, but this article explains the elasticity of the lungs by entropy-change considerations. Entropy of the individual lobule was defined by application of stochastic geometry on aggregated alveolar polyhedrons. Entropy of the lungs is the result of integrating a number of lobular entropies through the fractal bronchial tree. Entropy of the lungs was thus determined by the individual lobular entropy and the connectivity of the bronchial tree to the lobular bronchioles. Thermody-namic considerations on the static conditions of the pulmonary system composed of the lungs and the chest wall have provided a theoretical approach to understand the subdivisions of lung volume as the entropy-change of lungs. Entropy-change considerations on the elasticity of the lungs have shown that alveolar collapse and subsequent alveolar induration as the primary pathway for the loss of elasticity in the lungs is an acceptable hypothesis.

Weight Loss via Diet and Exercise Improves Exercise Breathing Mechanics in Obese Men

Obesity alters breathing mechanics during exercise. Weight loss improves lung function at rest, but the effect of weight loss, especially regional fat loss, on exercise breathing mechanics is unclear. We hypothesized that weight loss, especially a decrease in abdominal fat, would improve breathing mechanics during exercise because of an increase in end-expiratory lung volume (EELV). Nine obese men were studied before and after weight loss (13% ± 8% of total fat weight, mean ± SD). Subjects underwent pulmonary function testing, underwater weighing, fat distribution estimates (MRI), and graded cycle ergometry before and after a 12-week diet and exercise program. In seven men, esophageal and gastric pressures were measured. The effects of weight loss were analyzed at rest, at ventilatory threshold (VTh), and during peak exercise by dependent Student t test, and the relationship among variables was determined by correlation analysis. Subjects lost 7.4 ± 4.2 kg of body weight (P < .001), but the distribution of fat remained unchanged. After weight loss, lung volume subdivisions at rest were increased (P < .05) and were moderately associated (P < .05) with changes in chest, waist, and hip circumferences. At VTh, EELV increased, and gastric pressure decreased significantly (P < .05). The changes in waist circumference, hip circumference, BMI, and sum of chest, waist, and hip circumferences were also consistently and significantly correlated (P < .05) with changes in gastric pressure during exercise at VTh. Modest weight loss improves breathing mechanics during submaximal exercise in otherwise healthy obese men, which is clinically encouraging. Improvement appears to be related to the cumulative loss of chest wall fat.

Thoracic Gunshot Wounds: Alterations to Pulmonary Function and Respiratory Muscle Strength

The impact on respiratory function of gunshot injuries to the chest is unknown. The objective is to assess pulmonary function and respiratory muscle strength (RMS) in patients who have recently sustained an isolated gunshot injury to the chest. After institutional review board approval, patients with isolated gunshot injuries to the chest were prospectively identified. Study patients underwent pulmonary function testing and an assessment of RMS and gas exchange. Ten male patients sustaining an isolated pulmonary gunshot wound were prospectively enrolled with a mean age of 29 years ± 10 years and mean Injury Severity Score of 15 ± 5. All patients had an associated pneumothorax (n = 1), hemothorax (n = 4), or a combination of both (n = 5). After removal of all thoracostomy tubes and before discharge [7.4 days ± 5.4 days (range, 2-21 days)], patients underwent respiratory function testing. Lung volume subdivisions were reduced by 25% to 60% of predicted and diffusion capacity by 37% with preservation of the normal ratio of diffusion capacity to alveolar volume. In the six subjects able to perform spirometry in seated and supine postures, forced vital capacity decreased by 20% when changing posture (p = 0.046). Arterial blood gas analysis showed significant reduction in the P(AO)₂/FIO₂ ratio (or increase in AaDO₂). Maximal respiratory pressures were severely reduced from predicted values, the maximal inspiratory pressure by 60% and the maximal expiratory pressure by 78%. Lung volumes and RMS are decreased moderately to severely in patients who have sustained an isolated pulmonary gunshot wound. Expiratory muscle force generation is more severely affected than inspiratory muscle force. Further investigation of the long-term impact of these injuries on respiratory function is warranted.

Comprehensive integrated spirometry using raised volume passive and forced expirations and multiple-breath nitrogen washout in infants.

With the rapid somatic growth and development in infants, simultaneous accurate measurements of lung volume and airway function are essential. Raised volume rapid thoracoabdominal compression (RTC) is widely used to generate forced expiration from an airway opening pressure of 30 cmH(2)O (V(30)). The (dynamic) functional residual capacity (FRC(dyn)) remains the lung volume most routinely measured. The aim of this study was to develop comprehensive integrated spirometry that included all subdivisions of lung volume at V(30) or total lung capacity (TLC(30)). Measurements were performed on 17 healthy infants aged 8.6-119.7 weeks. A commercial system for multiple-breath nitrogen washout (MBNW) to measure lung volumes and a custom made system to perform RTC were used in unison. A refined automated raised volume RTC and the following two novel single maneuvers with dual volume measurements were performed from V(30) during a brief post-hyperventilation apneic pause: (1) the passive expiratory flow was integrated to produce the inspiratory capacity (IC) and the static (passive) FRC (FRC(st)) was estimated by initiating MBNW after end-passive expiration; (2) RTC was initiated late during passive expiration, flow was integrated to produce the slow vital capacity ((j)SVC) and the residual volume (RV) was measured by initiating MBNW after end-expiration while the jacket (j) was inflated. Intrasubject FRC(dyn) and FRC(st) measurements overlapped (p=0.6420) but neither did with the RV (p<0.0001). Means (95% confidence interval) of FRC(dyn), IC, FRC(st), (j)SVC, RV, forced vital capacity and tidal volume were 21.2 (19.7-22.7), 36.7 (33.0-40.4), 21.2 (19.6-22.8), 40.7 (37.2-44.2), 18.1 (16.6-19.7), 40.7 (37.1-44.2) and 10.2 (9.6-10.7)ml/kg, respectively. Static lung volumes and capacities at V(30) and variables from the best forced expiratory flow-volume curve were dependent on age, body length and weight. In conclusion, we developed a comprehensive physiologically integrated approach for in-depth investigation of lung function at V(30) in infants.

Lessons from structure-function studies in asthma: myths and truths about what we teach

Asthma is a syndrome that is distinguished and diagnosed on the basis of abnormalities of pulmonary function ([7][1]). Patients with asthma should exhibit airflow obstruction characterized by periodic falls in forced expiratory volume in 1 s (FEV1), airflow obstruction that responds or normalizes to

Associations of Fat Distribution with Functional Residual Capacity in Obese Women

0495 Obesity is known to alter lung volume subdivisions such as functional residual capacity (FRC). For otherwise healthy mild-to-moderately obese men, we found that fat distribution, particularly visceral fat, was the best predictor of changes in FRC (MSSE 34: S19, 2002). However, this has not been studied in obese women. PURPOSE: The purpose of this study was to determine the effect of fat distribution of non-obese and obese women on FRC. We hypothesized that fat distribution in mild-to-moderately obese women would better predict changes in FRC than overall percent body fat. METHODS: Eleven non-obese (30 ± 6 yr, 165 ± 5 cm, 58 ± 4 kg, 17 ± 2% body fat) and ten obese (33 ± 5 yr, 166 ± 8 cm, 102 ± 14 kg, 43 ± 5% body fat) women participated in this study. All participants underwent spirometry and lung volume measurements, hydrostatic weighing, and fat distribution estimates based on MRI scans. Data were analyzed between groups by independent t-test and the relationship between the variables was determined by regression analysis. RESULTS: Age and height were not different between the groups. All body composition measurements were significantly different between the non-obese and obese women (p < 0.01). Rib cage fat, peripheral fat, and anterior subcutaneous fat (% fat weight) were significantly higher in the obese women (p < 0.05). Yet, visceral fat and posterior subcutaneous fat were not significantly different between the groups. Residual volume and FRC (% total lung capacity) were significantly lower in the obese women (p < 0.01). FRC was significantly (p < 0.0001) correlated with anterior subcutaneous fat (r = −0.864), rib cage fat (−0.855), peripheral fat (−0.805), visceral fat (−0.776), posterior subcutaneous fat (−0.765), and percent body fat (−0.862), which was highly correlated with all measures of fat distribution (r = 0.87 to 0.98). CONCLUSIONS: In these participants, fat distribution is different between non-obese and obese women. Despite a high correlation between anterior subcutaneous fat and FRC, measures of fat distribution only minimally improves the prediction of FRC in comparison to percent body fat in these otherwise healthy mild-to-moderately obese women.

EFFECTS OF FAT DISTRIBUTION ON LUNG VOLUME IN OBESE MEN

Obesity decreases lung volume subdivisions, particularly end-expiratory lung volume (EELV). The effect of abdominal fat distribution (i.e., visceral and subcutaneous) on EELV has not been studied. PURPOSE: To investigate the effects of fat distribution on EELV, we studied body composition and EELV in 9 lean (18 ± 4% body fat) and 10 obese (38 ± 4% body fat) men. We hypothesized that abdominal fat distribution would better predict the change in EELV with mild-to-moderate obesity than overall percent body fat. METHODS: All subjects underwent spirometry and lung volume measurements, hydrostatic weighing, and abdominal fat distribution estimates based on MRI scans. Data were analyzed between groups by independent t-test and the relationship between variables was determined by regression analysis. RESULTS: Age and height were not different between groups. All body composition measurements were significantly different between the lean and obese men (p < 0.001). However, fat distribution was similar between the two groups. Spirometry data were not significantly different, nor was total lung capacity (TLC). On the other hand, EELV was significantly lower in the obese men (39 ± 6 vs. 46 ± 4%TLC, p < 0.01). While the correlation coefficient between percent body fat and EELV was significant (p < 0.05) at −0.56, the correlation between visceral fat (kg) and EELV was 00.70 (p < 0.001). CONCLUSION: It appears that visceral fat is a large contributor to low lung volume breathing in otherwise healthy mild-to-moderately obese men. Supported by the American Lung Association.

Vital capacity following traumatic brain injury

This study was designed to describe lung volume subdivisions in individuals with traumatic brain injury. Records were reviewed for 114 consecutive referrals for motor speech evaluations in a community re-entry residential rehabilitation programme. Obtained measures were vital capacity, inspiratory capacity, and expiratory reserve volume at the time of evaluation. Seventy-nine per cent of subjects evidenced at least moderate deficits in expiratory reserve volume, with 60% evidencing severe deficits. Inspiratory capacity was the least affected, with 61% of subjects evidencing values within normal limits. Possible contributors to reduced expiratory reserve volumes include expiratory muscle weakness due to physical inactivity, inability to voluntarily perform the task, or perceived effort.

Vital capacity following traumatic brain injury

This study was designed to describe lung volume subdivisions in individuals with traumatic brain injury. Records were reviewed for 114 consecutive referrals for motor speech evaluations in a community re-entry residential rehabilitation programme. Obtained measures were vital capacity, inspiratory capacity, and expiratory reserve volume at the time of evaluation. Seventy-nine per cent of subjects evidenced at least moderate deficits in expiratory reserve volume, with 60% evidencing severe deficits. Inspiratory capacity was the least affected, with 61% of subjects evidencing values within normal limits. Possible contributors to reduced expiratory reserve volumes include expiratory muscle weakness due to physical inactivity, inability to voluntarily perform the task, or perceived effort.

Static Lung Volumes: Reference Values from a Latin Population of Spanish Descent

Background and Objectives: The aim of this study was to develop a set of prediction equations and 90% confidence intervals for static lung volumes using the multibreath helium equilibration method from a sample of asymptomatic Caucasian subjects of Spanish descent. Moreover, these equations were compared with those of previous studies. Methods: Measurements of static lung volumes using techniques recommended by the American Thoracic Society and the European Community for Steel and Coal were carried out on a selected sample of 591 healthy nonsmoking volunteers (305 men and 286 women) aged 18–88 years, living in the metropolitan area of Valencia, on the east coast of Spain. Multiple regression analysis using height, age and weight as independent variables were used to provide predicted values for both sexes. These reference values were compared with other sets of prediction equations reported in the literature using an independent sample of 69 subjects (32 men and 37 women). Results: Simple linear regression equations using age, height and body weight predicted all the subdivisions of lung volumes (vital capacity, expiratory reserve volume (ERV), inspiratory capacity, functional residual capacity (FRC), residual volume (RV), total lung capacity (TLC), FRC/TLC and RV/TLC) as well as more complex equational models. The distribution of residuals fulfilled the assumptions of multiple regression analysis (independence, homoscedasticity and Gaussian distribution of residuals), except for ERV, using simple linear models. The derived equations did not differ significantly from most of the previously reported equations and were usually superior in their ability to predict the lung volumes. Conclusions: The use of the present prediction equations is recommended in the Latin population of Spanish descent and in populations with similar Caucasian characteristics.

This Month in the Journal

This Month in the Journal

Total lung capacity by N2 washout from high and low lung volumes in ventilated infants and children.

Although there is a strong rationale for the assessment of the subdivisions of lung volume, lung function testing has focused on the measurement of FRC alone in ventilated infants and children. To assess the feasibility, reproducibility, and accuracy of measurements of total lung capacity (TLC), FRC, and their ratio, we determined both lung volumes in 50 critically ill, intubated, and paralyzed infants (mean age [SEM]), 19.9 [4.6] mo) with a variety of lung diseases, by a modified N2 washout technique from end-exhalation and from +40 cm H2O inspiratory pressure, respectively. In the same infants, we also defined TLC by adding inspiratory capacity, measured by pneumotachograph during a passive exhalation from +40 cm H2O to FRC measured by N2 washout. Respiratory mechanics were measured by single-breath occlusion, and the patients were classified according to clinical picture and lung function into groups without lung disease or with restrictive or obstructive disease. The TLC data obtained by both methods showed good agreement for the infants without lung disease or restrictive disease (limits of agreement [LOA]: -3.8/4.6 and -2.9/3.2 ml/kg, respectively). The agreement was less in the infants with airflow obstruction where the N2 washout gave slightly higher values (LOA: -7.1/11.3 ml/kg). Mean FRC/TLC was significantly elevated in the obstructive group, whereas mean FRC alone did not differ from the group without lung disease. Our results suggest that TLC can be measured by both methods in intubated infants, but with limited agreement in obstructive disease. FRC/TLC ratios allow an estimation of the degree of pulmonary hyperinflation.

Prediction equations for plethysmographic lung volumes

Due to the lack of information on reference values for plethysmographic lung volumes, standardized measurements were carried out on a selected sample of 482 healthy non-smoking volunteers (300 men and 182 women), aged 20–70 years, living in the Barcelona area (Spain). Prediction equations using age, height and body surface area (BSA) as covariates were calculated for the subdivisions of lung volumes [TLC, IC, EVC, FRC, RV and RV TLC (%)], separately for both sexes. Simple linear equations predicted lung volumes as well as more complex equational models. BSA correction was useful for FRC but not for the other parameters. Our predicted FRC was up to 10% higher (mean 256 ml) than the FRC estimated by other studies using gas dilution techniques, but showed an acceptable agreement with the plethysmographic measurements carried out in an independent sample of 94 healthy non-smokers (42 men and 52 women) from Barcelona using different equipment. The present study provides an internally consistent set of prediction equations for static lung volumes. Differences in predicted FRC between the present study and other reference values obtained using gas dilution measurements should be attributed to the method of measurement.

Comparison of the functional results of single lung transplantation for pulmonary fibrosis and chronic airway obstruction.

BACKGROUND: Single lung transplantation (SLT) is now a treatment option for patients with both pulmonary fibrosis and advanced chronic airway obstruction. Lung function after transplantation might be expected to be...