Airway dysfunction in obesity: response to voluntary restoration of end expiratory lung volume

Effect of bariatric surgery on lung function and asthma control after 8 years of follow-up

Background: Bariatric surgery has a proven beneficial effect on asthma symptoms and lung function in patients with class III obesity and asthma. The effects of bariatric surgery on asthma control and small airway function persist for at least 12 months after bariatric surgery. However, long-term follow-up data are lacking. Objectives: To evaluate the very-long term effects of bariatric surgery on asthma symptoms and lung function. Methods: In a prospective, longitudinal follow-up study, we planned an 8-year follow-up visit for patients previously included in the OBAS 1.0 trial, which evaluated the effects of bariatric surgery on asthma control and lung function in patients with asthma and class III obesity in The Netherlands. Results: Fifteen of 78 patients from the OBAS trial completed the 8-year follow-up visit. Nine patients underwent bariatric surgery, and six patients did not. After 8 years of follow-up, asthma control (Asthma Control Questionnaire [ACQ] score at 12 months of 0,4 versus an ACQ score of 0.7 at 8 years of follow-up; p = 0.075) and small airway function (R₅-R₂₀ (frequency-dependent resistance at 5Hz-20Hz); score at 12 months of 0,25 versus an ACQ score of 0.07 at 8 years of follow-up; p = 0.345) remained clinically stable compared with 12 months of follow-up. Patients who underwent bariatric surgery had a statistically significant weight regain between 12 months of follow-up and 8 years of follow-up (median [interquartile range] body mass index 30.2 kg/m² [23.9-43.4 kg/m²] versus 32.3 kg/m² [24.0-36.4 kg/m²]; p = 0.025). However, the impact of weight regain on asthma control, and asthma quality of life was clinically insignificant (ACQ, β (regression coefficient) = 0.04; 95% Confidence Interval [0.02; 0.06]; p < 0.001; and AQLQ; β = -0.04 CI [-0.07; -0.009]; p = 0.013). Conclusion: These results emphasize the importance of bariatric surgery in treating obesity-related asthma.

A new approach for the detection of obesity-related airway obstruction in lung-healthy individuals

BACKGROUND

Subjects with obesity show an increased prevalence of airway obstruction but it is not clear in each case whether this reflects genuine lung disease. Via intentional increase in end-expiratory lung volume we studied the detection of obesity-induced airway obstruction in lung-healthy obese subjects.

METHODS

The primary study population comprised 66 lung-healthy obese subjects and 23 normal weight subjects. Measurements were performed in a body plethysmograph allowing for recording and quantification of breathing loops in terms of specific airway resistance at both normal and intentionally elevated end-expiratory lung volume. The change in volume was documented by a shutter maneuver.

RESULTS

The voluntary increase of lung volume led to a significant reduction of expiratory airway resistance in 11 of the 66 obese subjects. This reduction could be quantified by a change of total expiratory resistance (sRtEX) of >1 kPa*s but was also clearly visible in the breathing loops. sRtEX showed the largest change among all resistance parameters. The loops of normal weight subjects remained virtually unaffected by the change in lung volume. Moreover, those of 5 obese patients with COPD who were measured for comparison partially showed a reduction of resistance but airway obstruction remained.

CONCLUSION

The proposed breathing maneuver was simple to perform and allowed for a quantitative and qualitative detection of obesity-induced airway obstruction. This might help in reducing the likelihood of misdiagnosis and overtreatment of obese patients.

Cytokines Profile and Lung Function in Children with Obesity and Asthma: A Case Control Study

The existence of common inflammatory biomarkers linking obesity and asthma in children has been hypothesized. Nevertheless, laboratory and clinical characteristics of children with obesity and asthma are still poorly defined. The primary aim of the present study is to investigate the lung function and the cytokine profile, in children with obesity and asthma. In this prospective, cross-sectional pilot study, pulmonary function tests, biochemical parameters, and serum cytokines levels were compared in three groups of 28 children each, matched for age and sex. Obese children showed normal forced spirometry values except an increased distal airway resistance in subjects with obesity and no asthma. Both groups including obese children showed higher leptin and IL-10 levels and lower adiponectin and TNF-alpha levels compared to children with no obesity and asthma. IL-33 and TGF-beta1 levels were higher in children with obesity and asthma vs. children with normal weight and asthma. Finally, IL-6 was undetectable in approximately 70% of obese children with no asthma, in 57% obese asthmatic children and in 100% of children with normal-weight and asthma. Children with obesity and asthma show the most striking cytokine profile, suggesting a pro-inflammatory role of fat mass in asthma development.

Stomatognathic System Changes in Obese Patients Undergoing Bariatric Surgery: A Systematic Review

Background: Obesity is a multifactorial chronic disease involving multiple organs, devices, and systems involving important changes in the stomatognathic system, such as in the orofacial muscles, temporomandibular joint, cheeks, nose, jaw, maxilla, oral cavity, lips, teeth, tongue, hard/soft palate, larynx, and pharynx. Patients with obesity indicated for bariatric surgery reportedly presented with abnormalities in the structures and function of the stomatognathic apparatus. This occurs through the accumulation of adipose tissue in the oral cavity and pharyngeal and laryngeal regions. Therefore, this systematic review aimed to elucidate the changes occurring in the stomatognathic system of patients with obesity after undergoing bariatric surgery. Method: Information was searched based on the equations developed with the descriptors obtained in DECS and MESH using the PRISMA methodology. Studies published between 2010 and October 2021 in databases including PubMed, ProQuest, Scielo, Dialnet, EBSCO, and Springer Link were considered. Results: Eighty articles met the inclusion criteria after evaluating the articles, thereby allowing for the determination of the morphophysiological correlation of the stomatognathic system with the population studied. At the morphological or structural level, changes were observed in the face, nose, cheeks, maxilla, jaw, lips, oral cavity, teeth, tongue, palate, temporomandibular joint, neck, muscles, head, shoulders, larynx, and pharynx. At the morphological level, the main changes occurred in, and the most information was obtained from, the labial structures, teeth, muscles, pharynx, and larynx. Physiological changes were in breathing, phonation, chewing, and swallowing, thereby revealing the imbalance in basic and vital functions. Conclusions: Analyzing the changes and structures of obese patients and candidates for bariatric surgery revealed that, in the preoperative period, the evidence is clear owing to the presence of a wide range of information. However, the information is more limited regarding the postoperative period; thus, further research focusing on characterization of the system postoperatively is warranted.

Clinical significance and applications of oscillometry

Recently, “Technical standards for respiratory oscillometry” was published, which reviewed the physiological basis of oscillometric measures and detailed the technical factors related to equipment and test performance, quality assurance and reporting of results. Here we present a review of the clinical significance and applications of oscillometry. We briefly review the physiological principles of oscillometry and the basics of oscillometry interpretation, and then describe what is currently known about oscillometry in its role as a sensitive measure of airway resistance, bronchodilator responsiveness and bronchial challenge testing, and response to medical therapy, particularly in asthma and COPD. The technique may have unique advantages in situations where spirometry and other lung function tests are not suitable, such as in infants, neuromuscular disease, sleep apnoea and critical care. Other potential applications include detection of bronchiolitis obliterans, vocal cord dysfunction and the effects of environmental exposures. However, despite great promise as a useful clinical tool, we identify a number of areas in which more evidence of clinical utility is needed before oscillometry becomes routinely used for diagnosing or monitoring respiratory disease.

This paper provides a current review of the interpretation, clinical significance and application of oscillometry in respiratory medicine, with special emphasis on limitations of evidence and suggestions for future research.https://bit.ly/3GQPViA

Energy cost of walking and body composition changes during a 9-month multidisciplinary weight reduction program and 4-month follow-up in adolescents with obesity

The purpose of the present study was to investigate changes in the energy cost of locomotion during walking (Cw) related to changes in body mass (BM, kg) and body composition in adolescents with obesity. Twenty-six (12 boys and 14 girls) obese adolescents (mean: body mass index, 33.6 ± 3.7 kg·m-2; 42.7 ± 4.5% fat mass (FM)) followed a 9-month multidisciplinary inpatient weight-reduction program consisting of lifestyle education, moderate energy restriction, and regular physical activity in a specialised institution. At baseline (M0), the end of the 9-month program (M9), and after the 4-month follow-up (M13), oxygen consumption and carbon dioxide production of the standardised activity program were assessed by whole-body indirect calorimetry over 24 hours, and body composition was assessed by dual-energy X-ray absorptiometry. At M9, adolescents showed an 18% reduction in BM (p < 0.001) and 40% in total FM, while fat-free mass (kg) remained stable in boys but decreased by ∼6% in girls (p = 0.001). Similarly, the mean Cw decreased by 20% (p < 0.001). At M13, BM, FM, and Cw were slightly higher compared with at M9. In conclusion, moderate energy restriction and regular moderate physical activities improved walking economy, improved exercise tolerance, and induced beneficial changes in the body composition of adolescents with obesity. Novelty: Reduction of FM in the trunk region, and consequently reducing the work carried out by respiratory muscles, contributes to reducing Cw in adolescents with obesity. A lower walking cost can be effective in improving exercise tolerance and quality of life in obese adolescents.

Prophylactic Postoperative High Flow Nasal Oxygen Versus Conventional Oxygen Therapy in Obese Patients Undergoing Bariatric Surgery (OXYBAR Study): a Pilot Randomised Controlled Trial

BACKGROUND

Patients with obesity are predisposed to a reduction in end-expiratory lung volume (EELV) and atelectasis after anaesthesia. High flow nasal oxygen (HFNO) may increase EELV, reducing the likelihood of postoperative pulmonary complications (PPC). We conducted a pilot randomised controlled trial (RCT) of conventional oxygen therapy versus HFNO after bariatric surgery. The aim was to investigate the feasibility of using electrical impedance tomography (EIT) as a means of assessing respiratory mechanics and to inform the design of a definitive RCT.

METHODS

We performed a single-centre, parallel-group, pilot RCT. Adult patients with obesity undergoing elective bariatric surgery were eligible for inclusion. We excluded patients with a known contraindication to HFNO or with chronic lung disease.

RESULTS

Fifty patients were randomised in equal proportions. One patient crossed over from conventional O₂ to HFNO. Delta EELI was higher at 1 hour in patients receiving HFNO (mean difference = 831 Au (95% CI - 1636-3298), p = 0.5). Continuous EIT beyond 1 hour was poorly tolerated. At 6 hours, there were no differences in PaO₂/FiO₂ ratio or PaCO₂. Only one patient developed a PPC (in the HFNO group) by 6 weeks.

CONCLUSIONS

These data suggest that a large-scale RCT of HFNO after bariatric surgery in an 'all-comers' population is likely infeasible. While EIT was an effective means of assessing respiratory mechanics, it was impractical over time. Similarly, the infrequency of PPC precludes its use as a primary outcome. Future studies should focus on identifying patients at the greatest risk of PPC.

Effects of Controlled Voluntary Increase in the Ventilatory Demand on Respiratory System Resistance in Healthy and Non-Cystic Fibrosis Bronchiectasis Subjects: A Cross-Sectional Study

INTRODUCTION

Bronchiectasis patients may present a reduced functional capacity due to an increase in the ventilatory demand during exercise.

OBJECTIVE

To evaluate the effects of controlled voluntary hyperinflation and increased respiratory rate on the mechanics of the respiratory system, simulating what happens during exercise, in bronchiectasis and healthy subjects.

METHODS

Bronchiectasis (n=30) and healthy (n=16) subjects were evaluated by impulse oscillometry (IOS) during a baseline condition, and in controlled conditions with baseline (b) tidal volume (V) and hyperinflation (H), with respiratory rates at 30(R30) and 40(R40) bpm, in a random order. The mixed effects and a significance level at 0.05 were used for comparisons.

RESULTS

Resistance at 5Hz (R5), and at minus 20Hz (R5-R20), in kPa/L/s, were higher in subjects with bronchiectasis in all experimental conditions (p<0.05). For the bronchiectasis group, R5 and R5-20 increased with R increase at V (VRb versus VR30 and VR40; VR30 versus VR40; R5, R20 and R5-20 increased with R increase at H (HRb versus HR40; HR30 versus HR40). For the same R, there was a decrease with H compared to V (HRb versus VR30 and VR40; and HR30 versus VR30 and VR40). For the healthy group, only R20 showed differences (HR30 versus HR40; HR40 versus VR40).

CONCLUSION

The tachypnea increases the resistance and reactance of the respiratory system in bronchiectasis patients, and the voluntary hyperinflation caused attenuates this increase. These results can guide the development of strategies to reduce the limitation of physical activity in patients with bronchiectasis.

Respiratory impedance measured using impulse oscillometry in a healthy urban population

This study derives normative prediction equations for respiratory impedance in a healthy asymptomatic urban population using an impulse oscillation system (IOS). In addition, this study uses body mass index (BMI) in the equations to describe the effect of obesity on respiratory impedance.

Data from an urban population comprising 472 healthy asymptomatic subjects that resided or worked in lower Manhattan, New York City were retrospectively analysed. This population was the control group from a previously completed case–control study of the health effects of exposure to World Trade Center dust. Since all subjects underwent spirometry and oscillometry, these previously collected data allowed a unique opportunity to derive normative prediction equations for oscillometry in an urban, lifetime non-smoking, asymptomatic population without underlying respiratory disease.

Normative prediction equations for men and women were successfully developed for a broad range of respiratory oscillometry variables with narrow confidence bands. Models that used BMI as an independent predictor of oscillometry variables (in addition to age and height) demonstrated equivalent or better fit when compared with models that used weight. With increasing BMI, resistance and reactance increased compatible with lung and airway compression from mass loading.

This study represents the largest cohort of healthy urban subjects assessed with an IOS device. Normative prediction equations were derived that should facilitate application of IOS in the clinical setting. In addition, the data suggest that modelling of lung function may be best performed using height and BMI as independent variables rather than the traditional approach of using height and weight.

Prediction equations for respiratory impedance were derived in an urban cohort incorporating the effects of mass loading from obesity. Urban exposures had minimal effect on impedance allowing application of the equations to a broad range of populations.https://bit.ly/3a3zZvd

The Effect of Adiposity Markers on Fractional Exhaled Nitric Oxide (FeNO) and Pulmonary Function Measurements

Background

The effect of increasing body weight on pulmonary function and the fractional exhaled nitric oxide (FeNO) remains controversial and the role of different body compositions in the relationship between obesity with pulmonary function and FeNO is still unrevealed. Thus, we aim to determine the effect of overweight/obesity on lung function and FeNO, focusing on the relationship with different body compositions.

Methods

Eighty-two non-smoker students (20 ± 1.9 years) were divided into two groups: 38 subjects with normal weight (BMI = 18.5–24.99) and 44 overweight/obese subjects (BMI ≥ 25). Spirometric parameters and FeNO were measured and compared between groups and were correlated with different adiposity markers.

Results

FeNO measurements were elevated in the overweight/obese group [median (IQR) 19.5 (13)] in comparison to the normal weight group [11 (10), p value = 0.017]. A positive correlation was found between FeNO measurements and body mass index (BMI), waist circumference, hip circumference, waist-hip ratio, and visceral fat percentage (all p values < 0.01). The absolute values of forced vital capacity (FVC) forced expiratory volume in the first second (FEV₁), peak expiratory flow (PEF), forced expiratory flow during mid-expiration (FEF_25–75%), and FEV₁/FVC ratio showed no significant differences between groups. However, the percentage of the predicted values of FEV₁ and FVC was significantly higher and the value of percentage predicted FEF_25–75% was reduced significantly in the overweight/obese subjects.

Conclusion

Increase in BMI could significantly increase airway inflammation as measured by FeNO, as well as on distal airway function as determined by the percentage predicted values of FEF_25–75%. A significant correlation was also identified between visceral fat and FeNO measurement.

Small airway function in obese individuals with self-reported asthma

Diagnosis of asthma in obese individuals frequently relies on clinical history, as airflow by spirometry may remain normal. This study hypothesised that obese subjects with self-reported asthma and normal spirometry will demonstrate distinct clinical characteristics, metabolic comorbidities and enhanced small airway dysfunction as compared with healthy obese subjects. Spirometry, plethysmography and oscillometry data pre/post-bronchodilator were obtained in 357 obese subjects in three groups as follows: no asthma group (n=180), self-reported asthma normal spirometry group (n=126), and asthma obstructed spirometry group (n=51). To assess the effects of obesity related to reduced lung volume, oscillometry measurements were repeated during a voluntary inflation to predicted functional residual capacity (FRC). Dyspnoea was equally prevalent in all groups. In contrast, cough, wheeze and metabolic comorbidities were more frequent in the asthma normal spirometry and asthma obstructed spirometry groups versus the no asthma group (p<0.05). Despite similar body size, oscillometry measurements demonstrated elevated R _5-20 (difference between resistance at 5 and 20 Hz) in the no asthma and asthma normal spirometry groups (0.19±0.12; 0.23±0.13 kPa/(L·s^-1), p<0.05) but to a lesser degree than the asthma obstructed spirometry group (0.34±0.20 kPa/(L·s^-1), p<0.05). Differences between groups persisted post-bronchodilator (p<0.05). Following voluntary inflation to predicted FRC, R _5-20 in the no asthma and asthma normal spirometry groups fell to similar values, indicating a reversible process (0.11±0.07; 0.12±0.08 kPa/(L·s^-1), p=NS). Persistently elevated R _5-20 was seen in the asthma obstructed spirometry group, suggesting chronic inflammation and/or remodelling (0.17±0.11 kPa/(L·s^-1), p<0.05). Thus, small airway abnormalities of greater magnitude than observations in healthy obese people may be an early marker of asthma in obese subjects with self-reported disease despite normal airflow. Increased metabolic comorbidities in these subjects may have provided a milieu that impacted airway function.

Effects of Controlled Voluntary Increase in the Ventilatory Demand on Respiratory System Resistance in Healthy and Non-Cystic Fibrosis Bronchiectasis Subjects: A Cross-Sectional Study

INTRODUCTION

Bronchiectasis patients may present a reduced functional capacity due to an increase in the ventilatory demand during exercise.

OBJECTIVE

To evaluate the effects of controlled voluntary hyperinflation and increased respiratory rate on the mechanics of the respiratory system, simulating what happens during exercise, in bronchiectasis and healthy subjects.

METHODS

Bronchiectasis (n=30) and healthy (n=16) subjects were evaluated by impulse oscillometry (IOS) during a baseline condition, and in controlled conditions with baseline (b) tidal volume (V) and hyperinflation (H), with respiratory rates at 30(R30) and 40(R40) bpm, in a random order. The mixed effects and a significance level at 0.05 were used for comparisons.

RESULTS

Resistance at 5Hz (R5), and at minus 20Hz (R5-R20), in kPa/L/s, were higher in subjects with bronchiectasis in all experimental conditions (p<0.05). For the bronchiectasis group, R5 and R5-20 increased with R increase at V (VRb versus VR30 and VR40; VR30 versus VR40; R5, R20 and R5-20 increased with R increase at H (HRb versus HR40; HR30 versus HR40). For the same R, there was a decrease with H compared to V (HRb versus VR30 and VR40; and HR30 versus VR30 and VR40). For the healthy group, only R20 showed differences (HR30 versus HR40; HR40 versus VR40).

CONCLUSION

The tachypnea increases the resistance and reactance of the respiratory system in bronchiectasis patients, and the voluntary hyperinflation caused attenuates this increase. These results can guide the development of strategies to reduce the limitation of physical activity in patients with bronchiectasis.

Obesity alters the topographical distribution of ventilation and the regional response to bronchoconstriction

Obesity is associated with reduced operating lung volumes that may contribute to increased airway closure during tidal breathing and abnormalities in ventilation distribution. We investigated the effect of obesity on the topographical distribution of ventilation before and after methacholine-induced bronchoconstriction using single-photon emission computed tomography (SPECT)-computed tomography (CT) in healthy subjects. Subjects with obesity ( n = 9) and subjects without obesity ( n = 10) underwent baseline and postbronchoprovocation SPECT-CT imaging, in which Technegas was inhaled upright and followed by supine scanning. Lung regions that were nonventilated (Ventnon), low ventilated (Ventlow), or well ventilated (Ventwell) were calculated using an adaptive threshold method and were expressed as a percentage of total lung volume. To determine regional ventilation, lungs were divided into upper, middle, and lower thirds of axial length, derived from CT. At baseline, Ventnon and Ventlow for the entire lung were similar in subjects with and without obesity. However, in the upper lung zone, Ventnon (17.5 ± 10.6% vs. 34.7 ± 7.8%, P < 0.001) and Ventlow (25.7 ± 6.3% vs. 33.6 ± 5.1%, P < 0.05) were decreased in subjects with obesity, with a consequent increase in Ventwell (56.8 ± 9.2% vs. 31.7 ± 10.1%, P < 0.001). The greater diversion of ventilation to the upper zone was correlated with body mass index ( rs = 0.74, P < 0.001), respiratory system resistance ( rs = 0.72, P < 0.001), and respiratory system reactance ( rs = −0.64, P = 0.003) but not with lung volumes or basal airway closure. Following bronchoprovocation, overall Ventnon increased similarly in both groups; however, in subjects without obesity, Ventnon only increased in the lower zone, whereas in subjects with obesity, Ventnon increased more evenly across all lung zones. In conclusion, obesity is associated with altered ventilation distribution during baseline and following bronchoprovocation, independent of reduced lung volumes.

NEW & NOTEWORTHY Using ventilation SPECT-computed tomography imaging in healthy subjects, we demonstrate that ventilation in obesity is diverted to the upper lung zone and that this is strongly correlated with body mass index but is independent of operating lung volumes and of airway closure. Furthermore, methacholine-induced bronchoconstriction only occurred in the lower lung zone in individuals who were not obese, whereas in subjects who were obese, it occurred more evenly across all lung zones. These findings show that obesity-associated factors alter the topographical distribution of ventilation.

Small Airway Disease Syndromes. Piercing the Quiet Zone

The role for direct assessment of small airway function in subjects with respiratory symptoms but normal airflow by spirometry is discussed. Small airway disease syndrome is described in numerous disease states using a multidisciplinary approach. Data demonstrate that small airway disease is related to presence of respiratory symptoms, exposure to inhaled toxins, presence of local and systemic inflammation, and presence of histologic abnormalities within the distal lung. Investigation of immunological derangements associated with distal airway dysfunction in the setting of normal spirometry may provide insight into pathophysiological mechanisms that are present at disease onset. For the purposes of this symposium, data were reviewed in selected clinical conditions (obesity, environmental inhalational injury, and cigarette smoking) that have been recently studied in the André Cournand Pulmonary Physiology Laboratory at Bellevue Hospital using the forced oscillation technique.

Serum perfluoroalkyl substances and lung function in adolescents exposed to the World Trade Center disaster

The effects of childhood exposure to perfluoroalkyl substances (PFASs) on lung function remain mostly unknown. Previous research indicates that children living or going to school near the World Trade Center (WTC) disaster were exposed to high levels of PFASs, among other toxic chemicals. To explore the effects of PFAS exposure on lung function, we measured serum PFASs in a cohort of children from the WTC Health Registry and a matched control group. Perfluorooctanesulfonate had the highest median concentrations in both groups (WTCHR = 3.72 ng/mL, Comparison = 2.75 ng/mL), while the lowest median concentrations were seen for perfluoroundecanoic acid (WTCHR = 0.12 ng/mL, Comparison = 0.01 ng/mL). Lung function outcomes were measured by spirometry, plethysmography, and oscillometry. Asthma diagnosis and serum eosinophil count were also recorded. We examined the relationships of each PFAS with lung function parameters and eosinophil count using linear regressions. Odds ratios for asthma were obtained for each PFAS using logistic regression. The effect of total PFASs on these outcomes was also assessed. All regression models were adjusted for sex, race/ethnicity, age, body mass index (BMI) and tobacco smoke exposure. We found that serum PFASs were not statistically associated with the measured lung function parameters, asthma diagnosis, or eosinophil count in this cohort (p < 0.05). These findings highlight the need for more longitudinal studies to explore the long-term effects of childhood PFAS exposure on lung function past adolescence and early adulthood.

Respiratory Health and Lung Function in Children Exposed to the World Trade Center Disaster

OBJECTIVES

To compare lung function in a representative sample of World Trade Center (WTC)-exposed children with matched comparisons, and examine relationships with reported exposures.

STUDY DESIGN

Study population consisted of 402 participants. Oscillometry, spirometry, and plethysmography were performed on WTC Health Registry (WTCHR) respondents who were ≤8 years of age on September 11, 2001 (n = 180) and a sociodemographically matched group of New York City residents (n = 222). We compared lung function by study arm (WTCHR and comparison group) as well as dust cloud (acute); home dust (subchronic); and other traumatic, nondust exposures.

RESULTS

In multivariable models, post-9/11 risk of incident asthma was higher in the WTCHR participants than in the comparison group (OR 1.109, 95% CI 1.021, 1.206; P = .015). Comparing by exposure rather than by group, dust cloud (OR 1.223, 95% CI 1.095, 1.365; P < .001) and home dust (OR 1.123, 95% CI 1.029, 1.226; P = .009) exposures were also associated with a greater risk of incidence of post-9/11 asthma. No differences were identified for lung function measures.

CONCLUSIONS

Although we cannot exclude an alternative explanation to the null findings, these results may provide some measure of reassurance to exposed children and their families regarding long-term consequences. Further study with bronchodilation and/or methacholine challenge may be needed to identify and further evaluate effects of WTC exposure. Biomarker studies may also be more informative in delineating exposure-outcome relationships.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02068183.

High flow nasal oxygen after bariatric surgery (OXYBAR), prophylactic post-operative high flow nasal oxygen versus conventional oxygen therapy in obese patients undergoing bariatric surgery: study protocol for a randomised controlled pilot trial

BACKGROUND

The incidence of obesity is increasing worldwide. In selected individuals, bariatric surgery may offer a means of achieving long-term weight loss, improved health, and healthcare cost reduction. Physiological changes that occur because of obesity and general anaesthesia predispose to respiratory complications following bariatric surgery. The aim of this study is to determine whether post-operative high flow nasal oxygen therapy (HFNO2) improves respiratory function and reduces the incidence of post-operative pulmonary complications (PPCs) in comparison to conventional oxygen therapy in these patients.

METHOD

The OXYBAR study is a prospective, un-blinded, single centre, randomised, controlled pilot study. Patients with body mass index (BMI) > 30 kg/m2, undergoing laparoscopic bariatric surgery, will be randomised to receive either standard low flow oxygen therapy or HFNO2 in the post-operative period. The primary outcome measure is the change in end expiratory lung impedance (∆EELI) as measured by electrical impedance tomography (EIT). Secondary outcome measures include change in tidal volume (∆Vt), partial arterial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio, incidence of PPCs, hospital length of stay and measures of patient comfort.

DISCUSSION

We hypothesise that the post-operative administration of HFNO2 will increase EELI and therefore end expiratory lung volume (EELV) in obese patients. To our knowledge this is the first trial designed to assess the effects of HFNO2 on EELV in this population. We anticipate that data collected during this pilot study will inform a larger multicentre trial.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR), ACTRN12617000694314 . Registered on 15 May 2017.

Improvement in upright and supine lung mechanics with bariatric surgery affects bronchodilator responsiveness and sleep quality

Obesity and weight-loss have complex effects on respiratory physiology, but these have been insufficiently studied, particularly at early time points following weight-loss surgery and in the supine position. We evaluated 15 severely obese female participants before, and 5 weeks and 6 months after bariatric surgery using the Pittsburgh Sleep Quality Index (PSQI), spirometry, plethysmography, and oscillometry to measure respiratory system mechanics. Oscillometry and spirometry were conducted in the upright and supine position, and pre- and post-bronchodilation with 200µg of salbutamol. At 5 weeks post-surgery, weight-loss was 11.9±2.7kg with no effect on spirometric outcomes and a slight effect on oscillometric outcomes. However, at 6 months, weight-loss was 21.4±7.1kg with a 14.1±6.1% and 17.8±5.4% reduction in upright and supine Rrs,6, respectively. Ers also decreased by 25.7±9.4% and 20.2±7.2% in the upright and supine positions. No changes were observed in spirometry, but sleep quality improved from PSQI of 8.4±3.5 to 4.1±2.9. Bronchodilator responsiveness was low at baseline but increased significantly post-surgery, and this response was comparable to the improvement in Rrs produced by weight-loss. Modeling the impedance spectra with a two-compartment model demonstrated that improvements in lung mechanics with weight-loss begin in the upper or central compartment of the lungs and progress to include the peripheral compartment. Respiratory mechanics are impaired in the severely obese and is associated with poor sleep quality, but these improved substantially with weight-loss. Our data provide new evidence that severely obese individuals may have poor sleep quality due to abnormal respiratory mechanics that weight-loss improves.

Impulse oscillometry and obesity in children

OBJECTIVE

To compare impulse oscillometry system parameters of normal-weight children with overweight and obese children.

METHOD

All participants were submitted to the evaluation of lung function (spirometry and impulse oscillometry) following the American Thoracic Society standards. The evaluation of respiratory mechanics was performed using the Jaeger™ MasterScreen™ Impulse Oscillometry System (Erich Jaeger, Germany), three tests were recorded, with acquisition for at least 20seconds.

RESULTS

The study included 81 children (30 in the control group, 21 in the overweight group, and 30 the in obesity group), matched for age and sex. Regarding spirometry data, obesity group showed higher numerical values in relation to the control group; however, there were no significant differences among the three groups. For impulse oscillometry parameters, there was a difference between control group and obesity group for respiratory impedance (p=0.036), resistance at 5hertz (p=0.026), resonant frequency (p=0.029), and reactance area (p=0.014). For the parameters expressed in percentage of predicted, there were differences in resistance at 5 hertz, resonant frequency, and reactance area between control group and obesity group.

CONCLUSIONS

Obese children showed increased oscillometry parameters values representative of airway obstruction, compared to normal-weight children. Changes in some oscillometry parameters can already be observed in overweight school-aged children.

Pulmonary Vascular Congestion: A Mechanism for Distal Lung Unit Dysfunction in Obesity

RATIONALE

Obesity is characterized by increased systemic and pulmonary blood volumes (pulmonary vascular congestion). Concomitant abnormal alveolar membrane diffusion suggests subclinical interstitial edema. In this setting, functional abnormalities should encompass the entire distal lung including the airways.

OBJECTIVES

We hypothesize that in obesity: 1) pulmonary vascular congestion will affect the distal lung unit with concordant alveolar membrane and distal airway abnormalities; and 2) the degree of pulmonary congestion and membrane dysfunction will relate to the cardiac response.

METHODS

54 non-smoking obese subjects underwent spirometry, impulse oscillometry (IOS), diffusion capacity (DLCO) with partition into membrane diffusion (DM) and capillary blood volume (VC), and cardiac MRI (n = 24). Alveolar-capillary membrane efficiency was assessed by calculation of DM/VC.

MEASUREMENTS AND MAIN RESULTS

Mean age was 45±12 years; mean BMI was 44.8±7 kg/m2. Vital capacity was 88±13% predicted with reduction in functional residual capacity (58±12% predicted). Despite normal DLCO (98±18% predicted), VC was elevated (135±31% predicted) while DM averaged 94±22% predicted. DM/VC varied from 0.4 to 1.4 with high values reflecting recruitment of alveolar membrane and low values indicating alveolar membrane dysfunction. The most abnormal IOS (R5 and X5) occurred in subjects with lowest DM/VC (r2 = 0.31, p<0.001; r2 = 0.34, p<0.001). Cardiac output and index (cardiac output / body surface area) were directly related to DM/VC (r2 = 0.41, p<0.001; r2 = 0.19, p = 0.03). Subjects with lower DM/VC demonstrated a cardiac output that remained in the normal range despite presence of obesity.

CONCLUSIONS

Global dysfunction of the distal lung (alveolar membrane and distal airway) is associated with pulmonary vascular congestion and failure to achieve the high output state of obesity. Pulmonary vascular congestion and consequent fluid transudation and/or alterations in the structure of the alveolar capillary membrane may be considered often unrecognized causes of airway dysfunction in obesity.

Effects of a multidisciplinary body weight reduction program on static and dynamic thoraco-abdominal volumes in obese adolescents

The objective of this study was to characterize static and dynamic thoraco-abdominal volumes in obese adolescents and to test the effects of a 3-week multidisciplinary body weight reduction program (MBWRP), entailing an energy-restricted diet, psychological and nutritional counseling, aerobic physical activity, and respiratory muscle endurance training (RMET), on these parameters. Total chest wall (VCW), pulmonary rib cage (VRC,p), abdominal rib cage (VRC,a), and abdominal (VAB) volumes were measured on 11 male adolescents (Tanner stage: 3-5; BMI standard deviation score: >2; age: 15.9 ± 1.3 years; percent body fat: 38.4%) during rest, inspiratory capacity (IC) maneuver, and incremental exercise on a cycle ergometer at baseline and after 3 weeks of MBWRP. At baseline, the progressive increase in tidal volume was achieved by an increase in end-inspiratory VCW (p < 0.05) due to increases in VRC,p and VRC,a with constant VAB. End-expiratory VCW decreased with late increasing VRC,p, dynamically hyperinflating VRC,a (p < 0.05), and progressively decreasing VAB (p < 0.05). After MBWRP, weight loss was concentrated in the abdomen and total IC decreased. During exercise, abdominal rib cage hyperinflation was delayed and associated with 15% increased performance and reduced dyspnea at high workloads (p < 0.05) without ventilatory and metabolic changes. We conclude that otherwise healthy obese adolescents adopt a thoraco-abdominal operational pattern characterized by abdominal rib cage hyperinflation as a form of lung recruitment during incremental cycle exercise. Additionally, a short period of MBWRP including RMET is associated with improved exercise performance, lung and chest wall volume recruitment, unloading of respiratory muscles, and reduced dyspnea.

The effect of body weight on distal airway function and airway inflammation

BACKGROUND/OBJECTIVES

Obesity is a global health problem that adversely influences the respiratory system. We assessed the effects of body mass index (BMI) on distal airway function and airway inflammation.

SUBJECTS/METHODS

Impulse oscillometry (IOS) as a measure of distal airway function, together with spirometry, were assessed in adults with a range of different BMIs. Airway inflammation was assessed with the fraction of exhaled nitric oxide (FeNO) and participants exhaled at various exhalation flows to determine alveolar and bronchial NO.

RESULTS

In total 34 subjects were enrolled in the study; 19 subjects had a normal BMI (18.50-24.99), whilst 15 subjects were overweight (BMI 25.00-29.99), or obese (BMI ≥30). All subjects had normal spirometry. However, IOS measures of airway resistance (R) at 5Hz, 20Hz and frequency dependence (R_5-20) were elevated in overweight/obese individuals, compared to subjects with a normal BMI (median (interquartile range)); 5Hz: 0.41 (0.37, 0.45) vs. 0.32 (0.30, 0.37)kPa/l/s; 20Hz: 0.34 (0.30, 0.37) vs. 0.30 (0.26, 0.33)kPa/l/s; R_5-20: 0.06 (0.04, 0.11) vs. 0.03 (0.01, 0.05)kPa/l/s; p<0.05), whereas airway reactance at 20Hz was decreased in overweight/obese individuals (20Hz: 0.07 (0.03, 0.09) vs. 0.10 (0.07, 0.13)kPa/l/s, p=0.009; 5Hz: -0.12 (-0.15, -0.10) vs. -0.10 (-0.13, -0.09)kPa/l/s, p=0.07). In contrast, within-breath IOS measures (a sign of expiratory flow limitation) and FeNO inflammatory measures, did not differ between groups (p>0.05).

CONCLUSIONS

Being overweight has significant effects on distal and central airway function as determined by IOS, which is not detected by spirometry. Obesity does not influence airway inflammation as measured by FeNO. IOS is a reliable technique to identify airway abnormalities in the presence of normal spirometry in overweight people.

[Obesity and lung cancer: incidence and repercussions on epidemiology, pathology and treatments]

INTRODUCTION

Obesity and lung cancer are major public health problems. The purpose of this work is to review the data concerning this association.

METHOD

We report clinical and epidemiological data on obesity and discuss the impact on the incidence of lung cancer, as well as the safety and efficiency of anti-tumor treatments.

RESULTS

Obesity does not contribute to the occurrence of lung cancer, unlike other malignancies. Patients may be more likely to undergo treatment at lower risk. Regarding surgery, obesity makes anaesthesia more difficult, increases the operative duration but does not increase postoperative morbidity and mortality. Chemotherapy and radiotherapy seem to be administered according to the same criteria as patients with normal weight. Paradoxically, survival rates of lung cancer are better in obese patients as well after surgery than after non-surgical treatment.

CONCLUSION

Obesity is related to many neoplasms but not to lung cancer. Regarding long-term survival all treatments combined, it has a favorable effect: this is the "obesity paradox".

Influence of distinct asthma phenotypes on lung function following weight loss in the obese

BACKGROUND AND OBJECTIVE

There appears to be two distinct clinical phenotypes of obese patients with asthma-those with early-onset asthma and high serum IgE (TH2-high), and those with late-onset asthma and low serum IgE (TH2-low). The aim of the present study was to determine in the two phenotypes of obese asthma the effect of weight loss on small airway function.

METHODS

TH2-low (n = 8) and TH2-high (n = 5) obese asthmatics underwent methacholine challenge before and 12 months following bariatric surgery. Dose-response slopes as measures of sensitivity to airway closure and narrowing were measured as maximum % fall forced vital capacity (FVC) and forced expiratory volume in 1 s/FVC, respectively, divided by dose. Resting airway mechanics were measured by forced oscillation technique.

RESULTS

Weight loss reduced sensitivity to airway closure in TH 2-low but not TH2-high obese asthmatics (pre-post mean change ± 95% confidence interval: 1.8 ± 0.8 doubling doses vs -0.3 ± 1.7 doubling doses, P = 0.04). However, there was no effect of weight loss on the sensitivity to airway narrowing in either group (P = 0.8, TH2-low: 0.8 ± 1.0 doubling doses, TH2-high: -1.1 ± 2.5 doubling doses). In contrast, respiratory resistance (20 Hz) improved in TH2-high but not in TH2-low obese asthmatics (pre-post change median interquartile range: 1.5 (1.3-2.8) cmH₂O/L/s vs 0.6 (-1.8-0.8) cmH₂O/L/s, P = 0.03).

CONCLUSIONS

TH2-low obese asthmatics appear to be characterized by increased small airway responsiveness and abnormalities in resting airway function that may persist following weight loss. However, this was not the case for TH2-high obese asthmatics, highlighting the complex interplay between IgE status and asthma pathophysiology in obesity.