Designing and validating an experimental protocol to induce airway narrowing in older adults with and without asthma.

BACKGROUND: Persons with asthma may experience excessive airway narrowing due to exercise or exposure to cold air, worsening their daily functionality. Exercise has several benefits for asthma control, but it may induce airway narrowing in some persons with asthma. When combined with cold temperatures, it introduces another layer of challenges. Therefore, managing this interaction is crucial to increase the quality of life in individuals with asthma. The purpose of this study was to develop a reliable experimental protocol to assess the effects of exercise and cold air on airway narrowing in adults with asthma in a controlled and safe environment. METHODS: This study was a randomized cross-over study in adults with and without asthma. Participants underwent a protocol involving a 10-min seated rest, followed by a 10-min cycling on a stationary bike in different temperatures of 0, 10, or 20  ∘ C. The sequence of room temperatures was randomized, and there was a 30-min interval for recovery between each temperature transition. In each temperature, to measure lung function and respiratory symptoms, oscillometry and a questionnaire were used at 0 min (baseline), after 10 min of sitting and before starting biking (pre-exercise), and after 10 min of biking (post-exercise). At each room temperature, the changes in airway mechanics and asthma symptoms among baseline, pre-exercise, and post-exercise were compared with one-way repeated measures ANOVA or Friedman Rank Test. Within each arm, cardiac and thoraco-abdominal motion respiration signals were also measured continuously using electrodes and calibrated respiratory inductance plethysmographs, respectively. RESULTS: A total of 23 persons with asthma (11 females, age: 56.3 ± 10.9 years, BMI: 27.4 ± 5.7 kg/m2) and 6 healthy subjects (3 females, age: 61.8 ± 9.1 years, BMI: 28.5 ± 3.1 kg/m2) were enrolled in the study. Cold temperature of 0 ∘ C induced airway narrowing in those with and without asthma after 10 and 20 min, respectively. Exercise intervention had significant changes in airway narrowing in participants with asthma in the range of 10-20 ∘ C. Our results showed that in asthma, changes in subjective respiratory symptoms were due to both cold temperatures of 0 and 10 ∘ C and exercise in the 0-20 ∘ C range. Respiratory symptoms were not noticed among the healthy participants. CONCLUSION: In conclusion, our findings suggest that exposure to cold temperatures of 0 ∘ C could serve as a reliable method in the experimental protocol for inducing airway narrowing in asthma. The impact of exercise on airway narrowing was more variable among participants. Understanding these triggers in the experimental protocol is essential for the successful management of asthma in future studies.

A pilot study to assess the effects of preventing fluid retention in the legs by wearing compression stockings on overnight airway narrowing in mild asthma.

PURPOSE: Nocturnal asthma is a sign of asthma worsening and could be partially due to more fluid drawn into the thorax during sleep by gravitational force and/or pharyngeal collapse in those with obstructive sleep apnea. Wearing compression stockings during the day reduces fluid shift from the legs to the neck overnight. However, the potential effect of wearing compression stockings to reduce fluid accumulation in the leg and to improve nocturnal small airway narrowing in patients with asthma has not been investigated. This study investigates whether reducing leg fluid volume by wearing compression stockings during the day would attenuate small airway narrowing in patients with asthma before and after sleep. METHODS: We enrolled 11 participants with asthma. All participants underwent overnight polysomnography with or without wearing compression stockings for 2 weeks. Before and after sleep, leg fluid volume (LFV) was measured by bioelectrical impedance, and airway narrowing was primarily assessed by respiratory system resistance and reactance at 5 Hz (R5 and X5 respectively) using oscillometry. RESULTS: After 2 weeks of wearing compression stockings, the LFV measured in the evening was reduced (∆ = - 192.6 ± 248.3 ml, p = 0.02), and R5 and X5 improved (∆ = - 0.7 ± 0.9 cmH2O/L/s, p = 0.03 and 0.2 ± 1.4 cmH2O/L/s, p = 0.05 respectively). No changes were observed in the morning. CONCLUSIONS: Preventing fluid retention in the legs by wearing compression stockings for 2 weeks during the day, reduced LFV and airway narrowing in the evening in all participants with asthma, but not in the morning after sleep.

Silicosis, asbestosis, and pulmonary fibrosis in Ontario, Canada from 1996 to 2019.

BACKGROUND: Silicosis is a fibrotic lung disease caused by exposure to respirable crystalline silica. Historically, silicosis was common among miners and other professions in the 20th century, and in recent decades has re-emerged in coal mining and appeared in new workplaces, including the manufacture of distressed jeans and artificial stone countertops. METHODS: Physician billing data for the province of Ontario between 1992 and 2019 were analyzed across six time-periods (1993-1995, 1996-2000, 2001-2005, 2006-2010, 2011-2015, and 2016-2019). The case definition was two or more billing records within 24 months with a silicosis diagnosis code (ICD-9 502, ICD-10 J62). Cases from 1993 to 1995 were excluded as prevalent cases. Crude incidence rates per 100,000 persons were calculated by time-period, age, sex, and region. Analyses were repeated in parallel for pulmonary fibrosis (PF) (ICD-9 515, ICD-10 J84) and asbestosis (ICD-9 501; ICD-10 J61). RESULTS: From 1996 to 2019, 444 cases of silicosis, 2719 cases of asbestosis and 59,228 cases of PF were identified. Silicosis rates decreased from 0.42 cases per 100,000 in 1996-2000 to 0.06 per 100,000 people in 2016-2019. A similar trend was observed for asbestosis (1.66 to 0.51 per 100,000 persons) but the incidence rate of PF increased from 11.6 to 33.9 per 100,000 persons. Incidence rates for all outcomes were higher among men and older adults. CONCLUSIONS: A decreasing incidence of silicosis was observed in this analysis. However, the incidence of PF increased, consistent with findings from other jurisdictions. While cases of silicosis have been recorded among artificial stone workers in Ontario these cases do not seem to have impacted the population rates thus far. Ongoing, periodic surveillance of occupational diseases is helpful for tracking population-level trends over time.

Cleaning agent usage in healthcare professionals and relationship to lung and skin symptoms.

BACKGROUND AND OBJECTIVES: Healthcare workers have an increased risk of respiratory symptoms and dermatitis, likely related to cleaning/disinfecting agents. The aim of this study was to identify work tasks and cleaning/disinfecting agents associated with respiratory symptoms and hand dermatitis among healthcare workers in a tertiary hospital. METHODS: Cleaning agent usage, respiratory symptoms and skin symptoms were recorded by participants using a questionnaire in a cross-sectional study. Age and sex adjusted odds ratios (OR) were used to examine associations between job tasks, exposures, respiratory, and skin outcomes. RESULTS: Two hundred and thirty healthcare workers who were exposed to cleaning agents were compared with 77 who had no, or minimal, exposure. Exposed workers had an increased risk of respiratory symptoms (adjusted OR = 2.17; 95% CI: 1.18-4.14) and skin symptoms (adjusted OR = 1.77; 95% CI: 1.00 - 3.17). Washing instruments manually, using aerosol products, cleaning operating rooms, cleaning sanitary rooms, preparing disinfectants, and filling devices with cleaning products were cleaning tasks associated with various respiratory symptoms. Bleach was the only cleaning agent associated with a respiratory symptom: tightness in the chest (unadjusted OR = 2.46; 95% CI: 1.01-6.89) but statistical significance did not persist after adjustment for age and sex. Hand dermatitis was associated with actual disinfecting tasks (adjusted OR = 2.19; 95% CI: 1.10-4.66). Bleach was the only cleaning agent significantly associated with hand dermatitis (adjusted OR = 2.54; 95% CI: 1.32-5.13). CONCLUSIONS: This study provides insight into possible work tasks that need interventions to reduce or prevent respiratory and skin symptoms in healthcare workers.

The effectiveness of removal from exposure and reduction of exposure for managing occupational asthma: Summary of an updated Cochrane systematic review.

BACKGROUND: The objective was to update the 2011 Cochrane systematic review on the effectiveness of workplace interventions for the treatment of occupational asthma. METHODS: A systematic review was conducted with the selection of articles and reports through 2019. The quality of extracted data was evaluated, and meta-analyses were conducted using techniques recommended by the Cochrane Handbook for Systematic Reviews of Interventions. RESULTS: Data were extracted from 26 nonrandomized controlled before-and-after studies. The mean number of participants per study was 62 and the mean follow-up time was 4.5 years. Compared with continued exposure, removal from exposure had an increased likelihood of improved symptoms and change in spirometry. Reduction of exposure also had more favorable results for symptom improvement than continued exposure, but no difference for change in spirometry. Comparing exposure removal to reduction revealed an advantage for removal with both symptom improvement and change in spirometry for the larger group of patients exposed to low-molecular-weight agents. Also, the risk of unemployment was greater for exposure removal versus reduction. CONCLUSIONS: Exposure removal and reduction had better outcomes than continued exposure. Removal from exposure was more likely to improve symptoms and spirometry than reduction among patients exposed to low-molecular-weight agents. The potential benefits associated with exposure removal versus reduction need to be weighed against the potential for unemployment that is more likely with removal from exposure. The findings are based on data graded as very low quality, and additional studies are needed to generate higher quality data.

COVID-19 as an occupational disease.

The impact of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 permeates all aspects of society worldwide. Initial medical reports and media coverage have increased awareness of the risk imposed on healthcare workers in particular, during this pandemic. However, the health implications of COVID-19 for the global workforce are multifaceted and complex, warranting careful reflection and consideration to mitigate the adverse effects on workers worldwide. Accordingly, our review offers a framework for considering this topic, highlighting key issues, with the aim to prompt and inform action, including research, to minimize the occupational hazards imposed by this ongoing challenge. We address respiratory disease as a primary concern, while recognizing the multisystem spectrum of COVID-19-related disease and how clinical aspects are interwoven with broader socioeconomic forces.

Emissions and health risks from the use of 3D printers in an occupational setting.

The aim of this study was to determine concentrations of particulates and volatile organic compounds (VOCs) emitted from 3D printers using polylactic acid (PLA) filaments at a university workroom to assess exposure and health risks in an occupational setting. Under typical-case (one printer) and worst-case (three printers operating simultaneously) scenarios, particulate concentration (total and respirable), VOCs and formaldehyde were measured. Air samples were collected in the printing room and adjacent hallway. Size-resolved levels of nano-diameter particles were also collected in the printing room. Total particulate levels were higher in the worst-case scenario (0.7 mg/m3) vs. typical-case scenario (0.3 mg/m3). Respirable particulate and formaldehyde concentrations were similar between the two scenarios. Size-resolved measurements showed that most particles ranged from approximately 27 to 116 nm. Total VOC levels were approximately 6-fold higher during the worst-case scenario vs. typical situation with isopropyl alcohol being the predominant VOC. Airborne concentrations in the hallway were generally lower than inside the printing room. All measurements were below their respective occupational exposure limits. In summary, emissions of particulates and VOCs increased when multiple 3D printers were operating simultaneously. Airborne levels in the adjacent hallway were similar between the two scenarios. Overall, data suggest a low risk of significant and persistent adverse health effects. Nevertheless, the health effects attributed to 3D printing are not fully known and adherence to good hygiene principles is recommended during use of this technology.

Workplace interventions for treatment of occupational asthma.

BACKGROUND: The impact of workplace interventions on the outcome of occupational asthma is not well understood. OBJECTIVES: To evaluate the effectiveness of workplace interventions on occupational asthma. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE (PubMed); EMBASE(Ovid); NIOSHTIC-2; and CISILO (CCOHS) up to July 31, 2019. SELECTION CRITERIA: We included all eligible randomized controlled trials, controlled before and after studies and interrupted time-series of workplace interventions for occupational asthma. DATA COLLECTION AND ANALYSIS: Two authors independently assessed study eligibility and risk of bias, and extracted data. MAIN RESULTS: We included 26 non-randomized controlled before and after studies with 1,695 participants that reported on three comparisons: complete removal from exposure and reduced exposure compared to continued exposure, and complete removal from exposure compared to reduced exposure. Reduction of exposure was achieved by limiting use of the agent, improving ventilation, or using protective equipment in the same job; by changing to another job with intermittent exposure; or by implementing education programs. For continued exposure, 56 per 1000 workers reported absence of symptoms at follow-up, the decrease in forced expiratory volume in one second as a percentage of a reference value (FEV1 %) was 5.4% during follow-up, and the standardized change in non-specific bronchial hyperreactivity (NSBH) was -0.18.In 18 studies, authors compared removal from exposure to continued exposure. Removal may increase the likelihood of reporting absence of asthma symptoms, with risk ratio (RR) 4.80 (95% confidence interval (CI) 1.67 to 13.86), and it may improve asthma symptoms, with RR 2.47 (95% CI 1.26 to 4.84), compared to continued exposure. Change in FEV1 % may be better with removal from exposure, with a mean difference (MD) of 4.23 % (95% CI 1.14 to 7.31) compared to continued exposure. NSBH may improve with removal from exposure, with standardized mean difference (SMD) 0.43 (95% CI 0.03 to 0.82).In seven studies, authors compared reduction of exposure to continued exposure. Reduction of exposure may increase the likelihood of reporting absence of symptoms, with RR 2.65 (95% CI 1.24 to 5.68). There may be no considerable difference in FEV1 % between reduction and continued exposure, with MD 2.76 % (95% CI -1.53 to 7.04) . No studies reported or enabled calculation of change in NSBH.In ten studies, authors compared removal from exposure to reduction of exposure. Following removal from exposure there may be no increase in the likelihood of reporting absence of symptoms, with RR 6.05 (95% CI 0.86 to 42.34), and improvement in symptoms, with RR 1.11 (95% CI 0.84 to 1.47), as well as no considerable change in FEV1 %, with MD 2.58 % (95% CI -3.02 to 8.17). However, with all three outcomes, there may be improved results for removal from exposure in the subset of patients exposed to low molecular weight agents. No studies reported or enabled calculation of change in NSBH.In two studies, authors reported that the risk of unemployment after removal from exposure may increase compared with reduction of exposure, with RR 14.28 (95% CI 2.06 to 99.16). Four studies reported a decrease in income of 20% to 50% after removal from exposure.The quality of the evidence is very low for all outcomes. AUTHORS' CONCLUSIONS: Both removal from exposure and reduction of exposure may improve asthma symptoms compared with continued exposure. Removal from exposure, but not reduction of exposure, may improve lung function compared to continued exposure. When we compared removal from exposure directly to reduction of exposure, the former may improve symptoms and lung function more among patients exposed to low molecular weight agents. Removal from exposure may also increase the risk of unemployment. Care providers should balance the potential clinical benefits of removal from exposure or reduction of exposure with potential detrimental effects of unemployment. Additional high-quality studies are needed to evaluate the effectiveness of workplace interventions for occupational asthma.

Severe and near-fatal anaphylactic reactions triggered by chlorhexidine-coated catheters in patients undergoing renal allograft surgery: a case series.

PURPOSE: Although intraoperative anaphylaxis during surgery is a rare event, we describe five patients who experienced perioperative anaphylactic reactions during renal transplantation and were referred for investigation. CLINICAL FEATURES: Skin-prick and intradermal skin tests were done to investigate potential allergies to drugs given perioperatively prior to the development of anaphylaxis, including basiliximab, propofol, cefazolin, cis-atracurium, fentanyl, latex, remifentanil, and chlorhexidine. In addition, in vitro serologic testing for specific IgE was done in patients suspected to have had chlorhexidine anaphylaxis. All five patients were male, with a mean age of 48 yr (range 30-69). Skin testing for all drugs was non-reactive except for chlorhexidine, which was positive in four of five patients (one patient refused intradermal testing). In vitro test results for chlorhexidine-specific IgE were positive in all of the patients. Anesthetic records showed that intraoperative anaphylaxis had occurred immediately after insertion of a chlorhexidine-coated central venous catheter. CONCLUSIONS: Intraoperative insertion of chlorhexidine-coated central venous catheters can trigger life-threatening anaphylaxis in susceptible patients undergoing renal transplantation.

Occupational asthma.

Occupational asthma has been defined as asthma due to conditions attributable to work exposures, not to causes outside the workplace. This review focuses on current data on pathogenesis, evaluation, and management.

Evaluation of the efficacy of a web-based work-related asthma educational tool.

BACKGROUND: Work-related asthma (WRA) has been estimated to account for 15-20% of adult asthma cases. Studies have indicated that a substantial number of asthma patients have inadequate knowledge of work-related effects on their disease, which may contribute to suboptimal asthma control. A Canadian web-based educational tool on WRA was developed to address this knowledge gap in the population. OBJECTIVE: To evaluate the effectiveness of this web-based tool. METHODS: Participants were recruited prior to a routine visit at a tertiary care asthma clinic in Toronto. A brief WRA knowledge questionnaire was developed and administered immediately before and after using of the web-based educational tool, and one year later. RESULTS: The study sample (N = 34) was mostly female (68%) with a mean age of 50.7 (SD, 17.2). Participants demonstrated significant improvement in questionnaire scores following interaction with the tool. The mean score increased from 76% (SEM = 2.1) to 84% (SEM = 1.7) (p = 0.001). On average, scores improved on 12 of the 13 questionnaire items. A 1-year follow-up of a sample of 19 participants demonstrated a slight reduction in mean scores, from 86% (SEM = 1.9) to 84% (SEM = 1.9), but still demonstrated a trend towards a higher score than the baseline (78%; SEM = 2.9; p = 0.08). CONCLUSIONS: Our findings suggest that the educational tool has a positive effect on WRA knowledge, and that knowledge may be retained long-term. Future studies are needed in non-tertiary care clinic populations which may possess less baseline knowledge of WRA.

Developing a framework for assessing chemical respiratory sensitization: A workshop report.

Respiratory tract sensitization can have significant acute and chronic health implications. While induction of respiratory sensitization is widely recognized for some chemicals, validated standard methods or frameworks for identifying and characterizing the hazard are not available. A workshop on assessment of respiratory sensitization was held to discuss the current state of science for identification and characterization of respiratory sensitizer hazard, identify information facilitating development of validated standard methods and frameworks, and consider the regulatory and practical risk management needs. Participants agreed on a predominant Th2 immunological mechanism and several steps in respiratory sensitization. Some overlapping cellular events in respiratory and skin sensitization are well understood, but full mechanism(s) remain unavailable. Progress on non-animal approaches to skin sensitization testing, ranging from in vitro systems, -omics, in silico profiling, and structural profiling were acknowledged. Addressing both induction and elicitation phases remains challenging. Participants identified lack of a unifying dose metric as increasing the difficulty of interpreting dosimetry across exposures. A number of research needs were identified, including an agreed list of respiratory sensitizers and other asthmagens, distinguishing between adverse effects from immune-mediated versus non-immunological mechanisms. A number of themes emerged from the discussion regarding future testing strategies, particularly the need for a tiered framework respiratory sensitizer assessment. These workshop present a basis for moving towards a weight-of-evidence assessment.

The development and test re-test reliability of a work-related asthma screening questionnaire.

OBJECTIVE: Work-related asthma (WRA) is under-recognized and delays in recognition contribute to long-term morbidity. The objective of the project was to develop a WRA screening questionnaire for use by primary care providers in the assessment of individuals with asthma, and to evaluate the respondent burden, test re-test reliability and face validity of the questionnaire. METHODS: A literature search was undertaken and an expert advisory committee was convened. A questionnaire was drafted and assessed for feasibility of use and content validity. The study enrolled patients with asthma attending outpatient clinics and an asthma education center. Participants were asked to respond to the questionnaire on two occasions, and comment on the content (face validity) and ease of completion (respondent burden). Ethics approval was obtained from an institutional review board. RESULTS: A 14-item self-administered screening questionnaire was created. Thirty-nine participants were recruited, and 26 participants completed a second administration of the questionnaire. The items on the relation of asthma symptoms to work demonstrated substantial agreement between testings. The workplace exposures items were found to have good reproducibility. The majority of participants denied that items were repetitive, not useful or difficult to understand. CONCLUSIONS: We have developed a WRA screening questionnaire designed to aid primary care providers in the recognition of possible WRA. The tool exhibited content and face validity, good test re-test reliability and low respondent burden. Participant feedback is being considered in revisions of the questionnaire.

Official American Thoracic Society technical standards: spirometry in the occupational setting.

PURPOSE: This document addresses aspects of the performance and interpretation of spirometry that are particularly important in the workplace, where inhalation exposures can affect lung function and cause or exacerbate lung diseases, such as asthma, chronic obstructive pulmonary disease, or fibrosis. METHODS: Issues that previous American Thoracic Society spirometry statements did not adequately address with respect to the workplace were identified for systematic review. Medline 1950-2012 and Embase 1980-2012 were searched for evidence related to the following: training for spirometry technicians; testing posture; appropriate reference values to use for Asians in North America; and interpretative strategies for analyzing longitudinal change in lung function. The evidence was reviewed and technical recommendations were developed. RESULTS: Spirometry performed in the work setting should be part of a comprehensive workplace respiratory health program. Effective technician training and feedback can improve the quality of spirometry testing. Posture-related changes in FEV1 and FVC, although small, may impact interpretation, so testing posture should be kept consistent and documented on repeat testing. Until North American Asian-specific equations are developed, applying a correction factor of 0.88 to white reference values is considered reasonable when testing Asian American individuals in North America. Current spirometry should be compared with previous tests. Excessive loss in FEV1 over time should be evaluated using either a percentage decline (15% plus loss expected due to aging) or one of the other approaches discussed, taking into consideration testing variability, worker exposures, symptoms, and other clinical information. CONCLUSIONS: Important aspects of workplace spirometry are discussed and recommendations are provided for the performance and interpretation of workplace spirometry.

Irritant-induced asthma in the workplace.

Irritant-induced asthma in the workplace has been the focus of several articles in the past few years, and reviewed here. A clinical case definition is most readily associated with a single acute/accidental exposure to a presumed high concentration of an agent or agents expected to be irritant to the airways, as was initially reported with the subgroup Reactive Airways Dysfunction Syndrome (RADS). When most but not all criteria for RADS are met, then a diagnosis of irritant-induced asthma may also be considered to be "more probable than not". However, in addition, there is evolving understanding from epidemiological studies that chronic exposures may be associated with an increased risk of developing asthma. Despite this recognition, the mechanisms and clinical case definitions of work-related asthma that might be caused by chronic exposures to irritants (vs. new-onset asthma that begins coincidentally to work exposures), remain unclear at present.

Respiratory Diseases Associated With Wildfire Exposure in Outdoor Workers.

Wildfires, including forest fires, bushfires, and landscape fires, have become increasingly prevalent, fueled by climate change and environmental factors and posing significant challenges to both ecosystems and public health. This review article examines the relationship between wildfires and respiratory diseases in outdoor workers, with a main focus on airway disease. In addition to the expected effects of direct thermal respiratory injuries and possible carbon monoxide poisoning, there are associations between wildfires and upper and lower respiratory effects, including infections as well as exacerbations of asthma and chronic obstructive pulmonary disease. A few studies have also shown an increased risk of new-onset asthma among wildfire firefighters. Outdoor workers are likely to have greater exposure to wildfire smoke with associated increased risks of adverse effects. As wildfires become increasingly prevalent globally, it is crucial to understand the various dimensions of this association. Furthermore, this review addresses preventive measures and potential interventions to alleviate the airway burden on individuals during and after work with wildfires events.

The Effect of Simulated Obstructive Apneas on Mechanical Characteristics of Lower Airways in Individuals with Asthma.

Increased negative intrathoracic pressure that occurs during pharyngeal obstruction can increase thoracic fluid volume that may contribute to lower airway narrowing in individuals with obstructive sleep apnea (OSA) and asthma. Our previous study showed that fluid accumulation in the thorax induced by simulated OSA can increase total respiratory resistance. However, the effect of fluid shift on lower airway narrowing has not been investigated. To examine the effect of fluid accumulation in the thorax on the resistance of the lower airway. Non-asthma participants and individuals with (un)controlled asthma were recruited and underwent a single-day experiment. A catheter with six pressure sensors was inserted through the nose to continuously measure pressure at different sites of the airway, while a pneumotachograph was attached to a mouthpiece to record airflow. To simulate obstructive apneas, participants performed 25 Mueller maneuvers (MMs) while lying supine. Using the recordings of pressure sensor and airflow, total respiratory (RT), lower respiratory components (RL), and upper airway (RUA) resistances were calculated before and after MMs. Generalized estimation equation method was used to find the predictors of RL among variables including age, sex, body mass index, and the effect of MMs and asthma. Eighteen participants were included. Performing MMs significantly increased RT (2.23 ± 2.08 cmH2O/L/s, p = 0.003) and RL (1.52 ± 2.00 cmH2O/L/s, p = 0.023) in participants with asthma, while only RL was increased in non-asthma group (1.96 ± 1.73 cmH2O/L/s, p = 0.039). We found the model with age, and the effect of MMs and asthma severity generated the highest correlation (R2 = 0.69, p < 0.001). We provide evidence that fluid accumulation in the thorax caused by excessive intrathoracic pressure increases RL in both non-asthma and asthma groups. The changes in RL were related to age, having asthma and the effect of simulated OSA. This can explain the interrelationship between OSA and asthma.