The impact of bariatric surgery on pulmonary function: a meta-analysis

A clinician's guide to effects of obesity on childhood asthma and into adulthood

INTRODUCTION

Obesity, one of the most common chronic conditions affecting the human race globally, affects several organ systems, including the respiratory system, where it contributes to onset and high burden of asthma. Childhood onset of obesity-related asthma is associated with high persistent morbidity into adulthood.

AREAS COVERED

In this review, we discuss the disease burden in children and adults to highlight the overlap between symptoms and pulmonary function deficits associated with obesity-related asthma in both age ranges, and then discuss the potential role of three distinct mechanisms, that of mechanical fat load, immune perturbations, and of metabolic perturbations on the disease burden. We also discuss interventions, including medical interventions for weight loss such as diet modification, that of antibiotics and anti-inflammatory therapies, as well as that of surgical intervention on amelioration of burden of obesity-related asthma.

EXPERT OPINION

With increase in obesity-related asthma due to increasing burden of obesity, it is evident that it is a disease entity distinct from asthma among lean individuals. The time is ripe to investigate the underlying mechanisms, focusing on identifying novel therapeutic targets as well as consideration to repurpose medications effective for other obesity-mediated complications, such as insulin resistance, dyslipidemia and systemic inflammation.

Longitudinal effects of obesity on pulmonary function in obese children and adolescents

BACKGROUND

To investigate the longitudinal effects of obesity on change in lung function after 1 year of follow-up in obese children and adolescents.

METHODS

Obese children/adolescents aged 8-15 years with pulmonary function test (PFT) results and recorded anthropometric obesity indices from 1 year earlier for comparison were recruited. Multiple linear regression of change in each lung function parameter was applied to determine the effect of sex, change in body mass index (ΔBMI), change in chest circumference (ΔCC), change in waist circumference (ΔWC), and change in waist circumference-to-height ratio (ΔWC/Ht).

RESULTS

Sixty-six children/adolescents (mean age: 12.5 ± 2.6 years) were recruited. Multiple linear regression analysis showed that ΔWC negatively affects the ratio of the forced expiratory volume in the first 1 s to the forced vital capacity of the lungs Δ(FEV1/FVC) (b = -0.3, p = 0.002), forced expiratory flow rate within 25-75% of vital capacity (ΔFEF25-75%) (b = -0.92, p = 0.006), and Δ(FEF25-75%/FVC) (b = -0.99, p = 0.003). When replacing ΔWC with Δ(WC/Ht) as the independent variable, Δ(WC/Ht) also negatively affects Δ(FEV1/FVC) (b = -33.71, p = 0.02), ΔFEF25-75% (b = -102.9, p = 0.03) and Δ(FEF25-75%/FVC) (b = -102.7, p = 0.03).

CONCLUSION

After 1 year of follow-up, change in abdominal adiposity determined by WC and WC/Ht exerted significant negative effect on lung function change specific to FEV1/FVC, FEF25-75% /FVC, and FEF25-75%.

IMPACT

Longitudinal effects of change in obesity on lung function in obese children and adolescents are evidenced. Change in waist circumference or waist-to-height ratio, which indicates abdominal adiposity, was inversely correlated with a change in FEV1/FVC, FEF25-75% /FVC, and FEF25-75% in children and adolescents with obesity after 1 year of follow-up. Our results suggest using waist circumference and/or waist-to-height ratio in addition to BW and/or BMI for monitoring obesity. Fat loss programs, especially those focused on reducing abdominal adiposity should be encouraged to prevent late lung function impairment.

Obesity-related reduced spirometry and altered breathing pattern are associated with mechanical disadvantage of the diaphragm

The aim of this study was to characterize the breathing patterns of individuals with obesity during routine activities such as sitting and standing, and to identify potential contributors to alterations in these patterns. Measurements performed in 20 male subjects with obesity (BMI, 31.8±1.5 kg/m2) and 20 controls (BMI, 23.5±1.4 kg/m2) included anthropometric parameters, breathing-patterns in sitting and standing positions, spirometry, maximal respiratory pressures, and diaphragm B-mode ultrasonography. Individuals with obesity exhibited lower tidal volume and increased respiratory rate to maintain a similar minute-ventilation (p<0.05). Subjects with obesity demonstrated impaired spirometry and respiratory muscle strength, with inspiratory functions being notably compromised (p<0.05). Individuals with obesity had a greater diaphragm thickness at end inspiration but lower thickening-fraction at end quiet and forced breathings and reduced diaphragmatic displacement and excursion during maximal breaths (p<0.05). BMI was negatively associated with all respiratory function markers (p<0.05). Individuals with obesity exhibit a higher respiratory rate but lower tidal volume, likely to accommodate decreased compliance and excess thoracic and abdominal fat, further hindering inspiratory function. Moreover, increased adiposity is associated with a thicker but weaker diaphragm, primarily due to the diaphragm's mechanical disadvantage rather than its intrinsic inability to generate force.

Long-term changes in lung function after Roux-en-Y gastric bypass in patients with severe obesity

Obesity can decrease the lung function. The proposed mechanisms of reduced lung function in persons with obesity have been altered mechanical properties in the lung and chest wall, airway narrowing and increased respiratory resistance. The aim of this current study was to analyse the long-term results after gastric bypass surgery in patients with reduced lung function. The bariatric surgery observation study invited patients to a follow up 10 years after gastric bypass surgery. We compared the spirometry results before surgery to the spirometry 10 years after surgery. Thirty percent of 198 participants had reduced lung function before surgery. There was no significant relation between body mass index before surgery and lung function. Seventy-three percent of the participants with reduced lung function had normal lung function 10 years after surgery. There was no significant relation between the degree of weight loss and the improvement in lung function. Most participants with reduced lung function had normal lung function 10 years after gastric bypass surgery. There was no significant correlation between weight loss and improvement in lung function.

Bariatric Surgery and COVID-19: a Change of Perspective in a New Phase of the Pandemic

PURPOSE

The protective role of bariatric surgery (BS) against COVID-19 has been reported by several studies, showing, in the first pandemic waves, better outcome of the infection in patients that had undergone BS. With the virus progressive endemicity, BS benefits on COVID-19 clinical course could appear less evident, while COVID-19 effects on BS outcomes must be investigated. In this national multicentric cross-sectional study, we compared COVID-19 incidence and clinical course between a cohort of patients that had undergone BS (OP) and a cohort of candidates to BS (WS); moreover, we analyzed BS outcomes based on SARS-CoV-2 positivity/negativity.

METHODS

From June to December 2021, 522 patients from five Italian referral centers were administered an 87-item telephonic questionnaire completing the analysis of electronic medical records. Demographics, COVID-19 "tested" incidence, suggestive symptoms and clinical outcome parameters of OP and WS were compared. BS outcomes parameters were compared between OP that developed the disease or not.

RESULTS

COVID-19 incidence was the same in OP and WS, while symptoms and clinical course seemed milder in OP, with no data individually reaching statistical significance. OP who developed SARS-CoV-2 infection had higher excess weight loss than negative OP (66.8% ± 22.1 vs. 57.7% ± 22.8, p = 0.029). Positive OP had had gastric-bypass (RYGB/OAGB) more frequently than negative ones (38.4% vs. 18.2%, p = 0.025).

CONCLUSION

With the disease becoming endemic, BS protective role against COVID-19 seems clinically less relevant. BS outcomes can be affected by COVID-19, thus imposing careful follow-up for positive patients, especially if undergoing gastric-bypass.

The efficacy of bariatric surgery on pulmonary function and sleep architecture of patients with obstructive sleep apnea and co-morbid obesity: a systematic review and meta-analysis

Obstructive sleep apnea (OSA) is highly prevalent in patients with morbid obesity. There is a growing interest in the role of bariatric surgery in OSA management. This study aims to evaluate the therapeutic efficacy of bariatric surgery on changes in pulmonary function and sleep architecture. Studies of patients with OSA that underwent bariatric surgery were searched in 4 different databases (PubMed, Cochrane, Web of Science, and Embase) until October 31, 2022. We identified studies evaluating the efficacy of surgical intervention on primary outcomes (body mass index [BMI] and apnea-hypopnea index [AHI]) and secondary outcomes such as forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), FEV1/FVC, oxygen desaturation index (ODI), T90, mean oxygen saturation (SpO2), nadirSpO2, sleep efficiency (SE), N1%, N2%, N3%, rapid eye movement (REM%), arousal index, Epworth sleepiness scale (ESS), neck circumference, waist circumference, and weight. A total of 24 eligible studies were finally chosen. Risk of bias assessed through funnel plots was collected and analyzed via random effects meta-analyses. There were significant reductions in BMI and AHI after bariatric surgery induced weight loss. Accordingly, improvement in FVC, meanSpO2, nadirSpO2, SE, N3%, REM%, and ESS were observed compared with baseline. Patients with OSA also exhibit lower ODI, T90, arousal index, neck circumference, waist circumference, and weight after treatment. Bariatric surgery has beneficial effects on patients with OSA and obesity, particularly with morbid obesity. Surgical weight loss significantly eliminates apnea-hypopnea events, reduces weight, increases oxygen saturation, N3 and REM sleep stage, reduces sleep fragmentation, and improves pulmonary functions with augmented FVC.

Prior metabolic surgery reduced COVID-19 severity: Systematic analysis from year one of the COVID-19 pandemic

Background

Obesity is a risk factor for COVID-19 severity. Recent studies suggest that prior metabolic surgery (MS) modifies the risk of COVID-19 severity.

Methods

COVID-19 outcomes were compared between patients with MS (n = 287) and a matched cohort of unoperated patients (n = 861). Multiple logistic regression was used to identify predictors of hospitalization. A systematic literature review and pooled analysis was conducted to provide overall evidence of the influence of prior metabolic surgery on COVID-19 outcomes.

Results

COVID-19 patients with MS had less hospitalization (9.8% versus 14.3%, p = 0.049). Age 70+, higher BMI, and low weight regain after MS were associated with more hospitalization after COVID-19. A systematic review of 7 studies confirmed that MS reduced the risk of post-COVID-19 hospitalization (OR = 0.71, 95%CI = [0.61-0.83], p < 0.0001) and death (OR = 0.44, 95%CI = [0.30-0.65], p < 0.0001).

Conclusion

MS favorably modifies the risks of severe COVID-19 infection. Older age and higher BMI are major risk factors for severity of COVID-19 infection.

Short-Term Effect of Bariatric Surgery on Cardiorespiratory Response at Submaximal, Ventilatory Threshold, and Maximal Exercise in Women with Severe Obesity

PURPOSE

People with obesity have varying degrees of cardiovascular, pulmonary, and musculoskeletal dysfunction that affect aerobic exercise testing variables. Short time after bariatric surgery, these dysfunctions could affect both peak oxygen consumption ([Formula: see text] O₂ peak), the gold standard for assessing cardiorespiratory fitness (CRF) and aerobic capacity evaluated with ventilatory threshold (VT1). The purpose of this study was to evaluate the short-term effect of bariatric surgery, i.e. before the resumption of physical activity, on submaximal, at VT1 and maximal cardiorespiratory responses in middle-aged women with severe obesity.

MATERIALS AND METHODS

Thirteen middle-aged women with severe obesity (age: 36.7 ± 2.3 years; weight: 110.5 ± 3.6 kg, BMI: 41.8 ± 1.1 kg/m²) awaiting bariatric surgery participated in the study. Four weeks before and 6 to 8 weeks after surgery, body composition was determined by bioelectrical impedance. The participants performed an incremental cycling test to [Formula: see text] O₂ peak.

RESULTS

After bariatric surgery, all body composition parameters were reduced, absolute [Formula: see text] O₂ peak and peak workload decline with a lower VT1. Relative [Formula: see text] O₂ at peak and at VT1 (ml/min/kg or ml/min/kg of FFM) remained unchanged. Ventilation was lower after bariatric surgery during exercise with no change in cardiac response.

CONCLUSION

Our results showed that weight loss alone at short-term after bariatric surgery decreased CRF as seen by a decrease in absolute [Formula: see text] O₂ peak, and peak workload with lower VT1, whereas relative [Formula: see text] O₂ (ml/min/kg or ml/min/kg of FFM) during exercise remained unchanged in women with obesity. Rapid FFM loss affects cardiorespiratory responses at submaximal and maximal.

Increased Abdominal Perimeter Differently Affects Respiratory Function in Men and Women

Obesity is a worldwide epidemic being the main cause of cardiovascular, metabolic disturbances and chronic pulmonary diseases. The increase in body weight may affect the respiratory system due to fat deposition and systemic inflammation. Herein, we evaluated the sex differences in the impact of obesity and high abdominal circumference on basal ventilation. Thirty-five subjects, 23 women and 12 men with a median age of 61 and 67, respectively, were studied and classified as overweight and obese according to body mass index (BMI) and were also divided by the abdominal circumference. Basal ventilation, namely, respiratory frequency, tidal volume, and minute ventilation, was evaluated. In normal and overweight women, basal ventilation did not change, but obese women exhibited a decrease in tidal volume. In men, overweight and obese subjects did not exhibit altered basal ventilation. In contrast, when subjects were subdivided based on the abdominal perimeter, a higher circumference did not change the respiratory frequency but induced a decrease in tidal volume and minute ventilation in women, while in men these two parameters increased. In conclusion, higher abdominal circumference rather than BMI is associated with alterations in basal ventilation in women and men.

[Indications in Obesity Therapy - Surgeons First?]

Obesity is a growing problem worldwide. For the first time since 2010, more people have been overweight than underweight. In particular, obesity-associated diseases, above all type 2 diabetes mellitus, pose enormous challenges to the healthcare system. On July 3, 2020, the German Bundestag recognised obesity as a disease and initiated the development of a diseases management program (DMP), which is currently being drawn up. So far, the indication for treatment of obesity in Germany has been based on the S3 guideline "Surgery of obesity and metabolic diseases" of the DGAV from 2018 and the S3 guideline "Prevention and therapy of obesity" of the German Obesity Society e. V. from 2014. This article gives an overview of the currently available conservative, medical, endoscopic and surgical treatment methods for overweight and obesity in Germany and explains the indications. Against the background of the reorientation of obesity treatment as a part of the DMP and the forthcoming revisions of the guidelines, the previous indication should be discussed critically. The scientific findings of the last few years show that surgical treatment of obesity not only achieves the greatest weight loss in the long term, but also that obesity-associated diseases are then treated more effectively and overall mortality is reduced significantly more effectively than with conservative treatment.

Bariatric surgery, gastrointestinal hormones, and the microbiome: An Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) 2022

Background

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) is intended to provide clinicians an overview of bariatric surgery (i.e., bariatric procedures that improve metabolic disease are often termed "metabolic and bariatric surgery"), gastrointestinal hormones, and the microbiome as they relate to patients with obesity.

Methods

The scientific information for this CPS is based upon published scientific citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership.

Results

This CPS includes the pros and cons of the most common types of bariatric procedures; the roles of gastrointestinal (GI) hormones in regulating hunger, digestion, and postabsorptive nutrient metabolism; and the microbiome's function and relationship with body weight. This CPS also describes patient screening for bariatric surgery, patient care after bariatric surgery, and treatment of potential nutrient deficiencies before and after bariatric surgery. Finally, this CPS explores the interactions between bariatric surgery, GI hormones, and the microbiome.

Conclusions

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) regarding bariatric surgery, gastrointestinal hormones, and the microbiome is one of a series of OMA CPSs designed to assist clinicians in the care of patients with the disease of obesity. Implementation of appropriate care before and after bariatric surgery, as well as an awareness of GI hormones and the microbiome, may improve the health of patients with obesity, especially patients with adverse fat mass and adiposopathic metabolic consequences.

Improvements of lung volumes and respiratory symptoms after weight loss through laparoscopic sleeve gastrectomy

PURPOSE

This study evaluated the improvement of respiratory function and airway volumes using spirometry and computed tomography (CT) in severely obese Japanese patients undergoing laparoscopic sleeve gastrectomy (LSG). We also evaluated the quality of life (QOL) of enrolled patients using questionnaires.

METHODS

A total of 71 patients who underwent LSG at Iwate Medical University Hospital between October 2013 and September 2020 were enrolled. The changes and relationships between respiratory parameters including CT volumetry and weight-loss effects were evaluated. Improvements to QOL and bronchial asthma (BA) were also assessed before LSG and 1 year after LSG.

RESULTS

The mean excess weight loss percentage (%EWL) and total weight loss percentage (%TWL) were measured at 55.1% and 26.1%, respectively. The attack frequency of BA significantly decreased (6.1/month vs. 1.5/month; P < 0.001), and the disease severity decreased according to severity classification (P = 0.032). Almost spirometric parameters, lung volume (LV) (4905.0 mL vs. 5490.3 mL; P < 0.001), and airway volume (AV) (108.6 mL vs. 119.3 mL; P = 0.022) significantly improved. The change of functional residual capacity (FRC) was correlated with both %EWL (ρ = 0.69, P < 0.001) and %TWL (ρ = 0.62, P < 0.001). The increase of LV (ρ = 0.79, P < 0.001) and AV (ρ = 0.69, P < 0.001) were correlated with the increase of FRC. Scores of QOL questionnaires dramatically became better owing to improvements in dyspnea.

CONCLUSION

Weight loss effects and the reduction of body fat mass correlated significantly with increase in LV and AV. Improvements of respiratory functions after LSG contributes to QOL and BA symptoms.

Association of BMI with pulmonary function, functional capacity, symptoms, and quality of life in ILD

Obesity is a health epidemic associated with greater morbidity and mortality in the general population. Mass loading of the thorax from obesity leads to a restrictive pulmonary defect that reduces lung capacity in obese individuals without pulmonary disease, and may exacerbate the restrictive pulmonary physiology that is characteristic of interstitial lung disease (ILD). The purpose of this study was to test the association of body mass index (BMI) with pulmonary function, functional capacity, and patient-reported outcomes (dyspnea and quality of life) in patients with ILD. We analyzed 3169 patients with fibrotic ILD from the Canadian Registry for Pulmonary Fibrosis. Patients were subcategorized as underweight (BMI<18.5 kg/m2), normal weight (18.5≤BMI<25), overweight (25≤BMI<30), obese I (30≤BMI<35), obese II (35≤BMI<40), and obese III (BMI>40). Analysis was performed using a linear regression with adjustment for common prognostic variables. Overweight and obese BMI categories were associated with worse pulmonary function, functional capacity, dyspnea, and quality of life compared to normal weight. This is likely a result of mass loading on the thorax, and we speculate that intentional weight-loss may improve lung function and functional capacity in obese patients with fibrotic ILD. The underweight BMI category was also associated with worse functional capacity compared to normal weight, which may reflect greater disease severity or the presence of other comorbidities. Future work should explore the clinical utility of BMI to improve patient outcomes.

Lean Mass Loss and Altered Muscular Aerobic Capacity after Bariatric Surgery

INTRODUCTION

Patients undergoing weight loss surgery do not improve their aerobic capacity or peak oxygen uptake (VO2peak) after bariatric surgery and some still complain about asthenia and/or breathlessness. We investigated the hypothesis that a post-surgery muscular limitation could impact the ventilatory response to exercise by evaluating the post-surgery changes in muscle mass, strength, and muscular aerobic capacity, measured by the first ventilatory threshold (VT).

METHODS

Thirteen patients with obesity were referred to our university exercise laboratory before and 6 months after bariatric surgery and were matched by sex, age, and height to healthy subjects with normal weight. All subjects underwent a clinical examination, blood sampling, and body composition assessment by dual-energy X-ray absorptiometry, respiratory and limb muscle strength assessments, and cardiopulmonary exercise testing on a cyclo-ergometer.

RESULTS

Bariatric surgery resulted in a loss of 34% fat mass, 43% visceral adipose tissue, and 12% lean mass (LM) (p < 0.001). Absolute handgrip, quadriceps, or respiratory muscle strength remained unaffected, while quadriceps/handgrip strength relative to LM increased (p < 0.05). Absolute VO2peak or VO2peak/LM did not improve and the first VT was decreased after surgery (1.4 ± 0.3 vs. 1.1 ± 0.4 L min-1, p < 0.05) and correlated to the exercising LM (LM legs) (R = 0.84, p < 0.001).

CONCLUSIONS

Although bariatric surgery has numerous beneficial effects, absolute VO2peak does not improve and the weight loss-induced LM reduction is associated to an altered muscular aerobic capacity, as reflected by an early VT triggering early exercise hyperventilation.

Outcomes of obese patients hospitalized with COVID-19: the impact of prior bariatric surgery

Background

Obesity and several obesity-related co-morbidities are risk factors for severe COVID-19 disease. Because bariatric surgery successfully treats obesity-related conditions, we hypothesized that prior bariatric surgery may be associated with less severe COVID-19 disease.

Objectives

To examine the association between prior bariatric surgery and outcomes in patients with obesity admitted with COVID-19.

Setting

United States

Methods

The Vizient database was used to obtain demographic and outcomes data for adults with obesity admitted with COVID-19 from May 2020 to January 2021. Patients were divided into 2 groups: those with and those without prior bariatric surgery. The primary outcome was in-hospital mortality. Secondary outcomes were mortality by age, sex, race/ethnicity, and co-morbidity; intubation rate; hemodialysis rate; and length of stay. Because the database only provides aggregate data and not patient-level data, multivariate analysis could not be performed.

Results

Among the 124,699 patients with obesity admitted with COVID-19, 2,607 had previous bariatric surgery and 122,092 did not. The proportion of patients ≥65 years of age was higher in the non–bariatric surgery group (36.0% versus 27.6%, P < .0001). Compared with patients without prior bariatric surgery, patients with prior bariatric surgery had lower in-hospital mortality (7.8 versus 11.2%, P < .0001) and intubation rates (18.5% versus 23.6%, P = .0009). Hemodialysis rate (7.2% versus 6.9%, P = .5) and length of stay (8.8 versus 9.6 days, P = .8) were similar between groups. Mortality was significantly lower in the bariatric surgery group for patients 18–64 years of age (5.9% versus 7.4%, P = .01) and ≥65 years of age (12.9% versus 17.9%, P = .0006).

Conclusions

This retrospective cohort study found that inpatients with obesity and COVID-19 who had prior bariatric surgery had improved outcomes compared with a similar cohort without prior bariatric surgery. Further studies should examine mechanisms for the association between bariatric surgery and less severe COVID-19.

Effects of Bariatric Surgery on COVID-19: a Multicentric Study from a High Incidence Area

INTRODUCTION

The favorable effects of bariatric surgery (BS) on overall pulmonary function and obesity-related comorbidities could influence SARS-CoV-2 clinical expression. This has been investigated comparing COVID-19 incidence and clinical course between a cohort of patients submitted to BS and a cohort of candidates for BS during the spring outbreak in Italy.

MATERIALS AND METHODS

From April to August 2020, 594 patients from 6 major bariatric centers in Emilia-Romagna were administered an 87-item telephonic questionnaire. Demographics, COVID-19 incidence, suggestive symptoms, and clinical outcome parameters of operated patients and candidates to BS were compared. The incidence of symptomatic COVID-19 was assessed including the clinical definition of probable case, according to World Health Organization criteria.

RESULTS

Three hundred fifty-three operated patients (Op) and 169 candidates for BS (C) were finally included in the statistical analysis. While COVID-19 incidence confirmed by laboratory tests was similar in the two groups (5.7% vs 5.9%), lower incidence of most of COVID-19-related symptoms, such as anosmia (p: 0.046), dysgeusia (p: 0.049), fever with rapid onset (p: 0.046) were recorded among Op patients, resulting in a lower rate of probable cases (14.4% vs 23.7%; p: 0.009). Hospitalization was more frequent in C patients (2.4% vs 0.3%, p: 0.02). One death in each group was reported (0.3% vs 0.6%). Previous pneumonia and malignancies resulted to be associated with symptomatic COVID-19 at univariate and multivariate analysis.

CONCLUSION

Patients submitted to BS seem to develop less severe SARS-CoV-2 infection than subjects suffering from obesity.

Weight Loss Interventions as Treatment of Obesity Hypoventilation Syndrome. A Systematic Review

Rationale: Obesity hypoventilation syndrome (OHS) is an undesirable consequence of obesity. Weight loss is an important component of management based on clinical rationale, but the evidence supporting weight loss has not been summarized and the optimal approach has not been determined.Objectives: This systematic review informed an international, multidisciplinary panel of experts who had converged to develop a clinical practice guideline on OHS for the American Thoracic Society. The panel asked, "Should a weight loss intervention be performed in patients with OHS?"Methods: Medline, the Cochrane Library, and Embase were searched from January 1946 to March 2019 for studies that assessed weight loss interventions in obese adults with confirmed OHS, suspected OHS, or hypercapnia. The quality of the evidence was appraised using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach.Results: The search identified 2,994 articles. Six studies were selected, including two randomized trials and four nonrandomized studies without a comparator. Sample size ranged from 16 to 63 subjects. The studies found that a comprehensive weight loss program (including motivational counseling, dieting, and exercise) can reduce weight by 6% to 7% but confers no clinically significant effects compared with standard care. Bariatric surgery, on the other hand, is associated with more robust weight loss (15-64.6%, depending on the type of intervention), reduction of obstructive sleep apnea severity (18-44% reduction of the apnea-hypopnea index), and improvement in gas exchange (17-20% reduction in partial pressure of carbon dioxide in the arterial blood), ultimately leading to the resolution of OHS. Moreover, daytime sleepiness and pulmonary artery pressure also improve with significant weight loss. Bariatric surgery is associated with adverse effects in roughly one-fifth of patients, but serious adverse effects are very rare. The level of certainty in the estimated effects was very low for most outcomes.Conclusions: The guideline panel for which the systematic review was performed made a conditional (i.e., weak) recommendation suggesting a weight loss intervention for patients with OHS, targeting a sustained weight loss of 25% to 30% of actual body weight. This recommendation was based on very low-quality evidence. Although the weight loss target is based on the observation that greater weight loss is associated with better outcomes, there is a need for better-quality studies to ascertain the degree of weight loss necessary to achieve improvement in clinically relevant outcomes in patients with OHS.

Obesity and the Lung: What We Know Today

Obesity is becoming more and more prevalent especially in Western industrial nations. The understanding of adipose tissue as an endocrine organ as well as the detection of adipocytokines - hormones that are secreted from the adipose tissue - gave reason to examine the interactions between adipose tissue and target organs. These efforts have been intensified especially in the context of bariatric surgery as promising weight loss therapy. Interactions between the lung and adipose tissue have rarely been investigated and are not well understood. There are obvious mechanical effects of obesity on lung function explaining the associations between obesity and lung diseases, in particular obesity hypoventilation syndrome, obstructive sleep apnea syndrome, asthma, and chronic obstructive pulmonary disease. The rise in the prevalence of obesity affects the epidemiology of pulmonary diseases as well. The aim of this review is to summarize the current knowledge on interactions, associations, and consequences of obesity and weight loss on lung function and lung diseases. Based on these data, areas for future research are identified.

The Lung Function Laboratory to Assist Clinical Decision-making in Pulmonology: Evolving Challenges to an Old Issue

The lung function laboratory frequently provides relevant information to the practice of pulmonology. Clinical interpretation of pulmonary function and exercise tests, however, has been complicated more recently by temporal changes in demographic characteristics (higher life expectancy), anthropometric attributes (increased obesity prevalence), and the surge of polypharmacy in a sedentary population with multiple chronic degenerative diseases. In this narrative review, we concisely discuss some key challenges to test interpretation that have been affected by these epidemiologic shifts: (a) the confounding effects of advanced age and severe obesity, (b) the contemporary controversies in the diagnosis of obstruction (including asthma and/or COPD), (c) the importance of considering the diffusing capacity of the lung for carbon monoxide (Dlco)/"accessible" alveolar volume (carbon monoxide transfer coefficient) in association with Dlco to uncover the causes of impaired gas exchange, and (d) the modern role of the pulmonary function laboratory (including cardiopulmonary exercise testing) in the investigation of undetermined dyspnea. Following a Bayesian perspective, we suggest interpretative algorithms that consider the pretest probability of abnormalities as indicated by additional clinical information. We, therefore, adopt a pragmatic approach to help the practicing pulmonologist to apply the information provided by the lung function laboratory to the care of individual patients.

The association of body mass index, weight gain and central obesity with activity-related breathlessness: the Swedish Cardiopulmonary Bioimage Study

Introduction

Breathlessness is common in the population, especially in women and associated with adverse health outcomes. Obesity (body mass index (BMI) >30 kg/m2) is rapidly increasing globally and its impact on breathlessness is unclear.

Methods

This population-based study aimed primarily to evaluate the association of current BMI and self-reported change in BMI since age 20 with breathlessness (modified Research Council score ≥1) in the middle-aged population. Secondary aims were to evaluate factors that contribute to breathlessness in obesity, including the interaction with spirometric lung volume and sex.

Results

We included 13 437 individuals; mean age 57.5 years; 52.5% women; mean BMI 26.8 (SD 4.3); mean BMI increase since age 20 was 5.0 kg/m2; and 1283 (9.6%) reported breathlessness. Obesity was strongly associated with increased breathlessness, OR 3.54 (95% CI, 3.03 to 4.13) independent of age, sex, smoking, airflow obstruction, exercise level and the presence of comorbidities. The association between BMI and breathlessness was modified by lung volume; the increase in breathlessness prevalence with higher BMI was steeper for individuals with lower forced vital capacity (FVC). The higher breathlessness prevalence in obese women than men (27.4% vs 12.5%; p<0.001) was related to their lower FVC. Irrespective of current BMI and confounders, individuals who had increased in BMI since age 20 had more breathlessness.

Conclusion

Breathlessness is independently associated with obesity and with weight gain in adult life, and the association is stronger for individuals with lower lung volumes.

Body composition from 18 to 22 years and pulmonary function at 22 years-1993 Pelotas Birth Cohort

The objective was to verify the association between body composition from 18 to 22 years and pulmonary function at 22 years of age. This longitudinal analysis was conducted with a Brazilian birth cohort data. The outcomes were the forced expiratory volume in the first second and forced vital capacity (FVC), measured at 22 years follow-up. Main exposures: obesity (body mass index ≥ 30kg/m²), and highest tertiles of fat mass (FM) and fat mass index (air displacement plethysmography) measured at 18 and 22 years-old follow-ups. The reference category (not exposed) was defined by those individuals who were not classified in the highest adiposity categories mentioned, in both ages. Multivariable linear regressions stratified by sex were used. The sample comprised 3,511 participants. Those who belonged to the highest adiposity categories in 18 and 22 years follow-ups showed lower pulmonary function at 22 years when compared to those who were not classified in the higher adiposity categories in both ages (reference category); those in the highest tertile of FM showed a mean FVC -313mL (95%CI -421; -206) and -259mL (95%CI -336; -182) in men and women, compared to the reference category, respectively. Those who changed from the higher to the lower adiposity categories (from 18 to 22 years) showed pulmonary function similar to the reference, and those who presented the opposite body composition trajectory, showed decreased pulmonary function results at 22 years, mainly among women. We concluded that high body adiposity in two follow-ups and especially contemporary adiposity was associated with lower pulmonary function at 22 years.

Bariatric surgery in patients with interstitial lung disease

BACKGROUND

Perioperative pulmonary complications are frequent in patients with interstitial lung diseases (ILD). Limited literature exists regarding the safety of bariatric procedures in patients with ILD. This study aims to assess the safety, feasibility, and outcomes of patients with ILD who underwent bariatric surgery at our institution.

METHODS

After IRB approval, all patients with preoperative diagnosis of ILD who had bariatric surgery at an academic center between 2004 and 2014 were retrospectively reviewed.

RESULTS

A total of 25 patients with ILD underwent bariatric surgery: Roux-en-Y gastric bypass (n = 17, 68%), sleeve gastrectomy (n = 7, 28%), and adjustable gastric banding (n = 1, 4%). Twenty-one patients (84%) were females. The median age and preoperative body mass index (BMI) were 53 (IQR 42-58) years and 39 (IQR 37-44) kg/m², respectively. The median operative time and length of stay was 137 (IQR 110-187) min and 3 (IQR 2-5) days, respectively. The 30-day complications were reported in four patients (16%) but there was no pulmonary complication or unplanned admission to the intensive care unit. At 1-year follow-up (85%), the median BMI and excess weight loss were 30 (IQR 25-36) kg/m² and 67% (IQR 45-100), respectively. Compared to preoperative values, there was significant improvement in the pulmonary function test (PFT) variables at 1 year with respect to forced vital capacity (62% vs 74%; n = 13, p = 0.003), and diffusing capacity of the lungs for carbon monoxide (53% vs 66%; n = 10, p = 0.003). Six out of the seven potential lung transplant candidates became eligible for transplantation after weight loss, and one of them had successful lung transplant at 88 months after bariatric surgery.

CONCLUSION

In our experience, bariatric patients with ILD achieved significant weight loss and improvement in PFT. Bariatric surgery in these higher risk ILD patients appears relatively safe with acceptable perioperative morbidity and improved candidacy for lung transplantation.