Thoracoabdominal mechanics during tidal breathing in normal subjects and in emphysema and fibrosing alveolitis

Selective dysfunction of the crural diaphragm in patients with chronic restrictive and obstructive lung disease

BACKGROUND

Gastroesophageal reflux (GER) is known to be associated with chronic lung diseases. The driving force of GER is the transdiaphragmatic pressure (Pdi) generated mainly by costal and crural diaphragm contraction. The latter also enhances the esophagogastric junction (EGJ) pressure to guard against GER.

METHODS

The relationship between Pdi and EGJ pressure was determined using high resolution esophageal manometry in patients with interstitial lung disease (ILD, n = 26), obstructive lung disease (OLD, n- = 24), and healthy subjects (n = 20).

KEY RESULTS

The patient groups did not differ with respect to age, gender, BMI, and pulmonary rehabilitation history. Patients with ILD had significantly higher Pdi but lower EGJ pressures as compared to controls and OLD patients (p < 0.001). In control subjects, the increase in EGJ pressure at all-time points during inspiration was greater than Pdi. In contrast, the EGJ pressure during inspiration was less than Pdi in 14 patients with ILD and 7 patients with OLD. The drop in EGJ pressure was usually seen after the peak Pdi in ILD group (p < 0.0001) and before the peak Pdi in OLD group, (p = 0.08). Nine patients in the ILD group had sliding hiatus hernia, compared to none in control subjects (p = 0.003) and two patients in the OLD, (p = 0.04).

CONCLUSIONS AND INFERENCES

A higher Pdi and low EGJ pressure, and dissociation between Pdi and EGJ pressure temporal relationship suggests selective dysfunction of the crural diaphragm in patients with chronic lung diseases and may explain the higher prevalence of GERD in ILD as seen in previous studies.

Elucidating the Link: Chronic Obstructive Pulmonary Disease and the Complex Interplay of Gastroesophageal Reflux Disease and Reflux-Related Complications

Background and Objective: Presenting chronic obstructive pulmonary disease (COPD) patients frequently report concurrent symptoms of gastroesophageal reflux disease (GERD). Few studies have shown a correlation between GERD and COPD. We aimed to examine the correlation between GERD and COPD as well as secondary related reflux complications, such as esophageal stricture, esophageal cancer, and Barrett's esophagus. Methods: This population-based analysis included 7,159,694 patients. Patients diagnosed with GERD with and without COPD were compared to those without GERD. The enrollment of COPD included centrilobular and panlobular emphysema and chronic bronchitis. Risk factors of COPD or GERD were used for adjustment. Bivariate analyses were performed using the chi-squared test or Fisher exact test (2-tailed) for categorical variables as appropriate to assess the differences in the groups. Results: Our results showed that COPD patients had a significantly higher incidence of GERD compared to those without COPD (27.8% vs. 14.1%, p < 0.01). After adjustment of demographics and risk factors, COPD patients had a 1.407 times higher risk of developing non-erosive esophagitis (p < 0.01), 1.165 higher risk of erosive esophagitis (p < 0.01), 1.399 times higher risk of esophageal stricture (p < 0.01), 1.354 times higher risk of Barrett's esophagus without dysplasia (p < 0.01), 1.327 times higher risk of Barrett's esophagus with dysplasia, as well as 1.235 times higher risk of esophageal cancer than those without COPD. Conclusions: Based on the evidence from this study, there are sufficient data to provide convincing evidence of an association between COPD and GERD and its secondary reflux-related complications.

Diaphragmatic ultrasonography in patients with IPF: Is diaphragmatic structure and mobility related to fibrosis severity and pulmonary functional changes?

Introduction

There is evidence to suggest that dyspnea and impaired exercise capacity are associated with respiratory muscle dysfunction in idiopathic pulmonary fibrosis (IPF) patients. We aimed to evaluate the functions of the diaphragm with ultrasonography (US) and to determine the correlation of the data obtained with the pulmonary function parameters of the patients, exercise capacity, and the extent of fibrosis radiologically.

Materials and Methods

Diaphragmatic mobility, thickness, and thickening fraction (TF) were measured by ultrasonography in IPF patients and the control group. The correlation between these measurements, pulmonary function tests (PFT), six-minute walking test (6MWT), mMRC score, and total fibrosis score (TFS) was evaluated.

Result

Forty-one IPF patients and twenty-one healthy volunteers were included in the study. No difference was found between the patient and control groups in diaphragmatic mobility during quiet breathing (QB) on ultrasound (2.35 cm and 2.56 cm; p= 0.29). Diaphragmatic mobility during deep breathing (DB) was found to be lower in the patient group when compared to the control group (5.02 cm and 7.66 cm; p<0.0001). Diaphragmatic thickness was found to be higher during QB and DB in IPF patients (0.33 cm and 0.31 cm, p= 0.043; 0.24 cm and 0.22 cm, p= 0.045). No difference was found between the two groups in terms of thickening fraction (39.37%, 44.16%; p= 0.49). No significant correlation was found between US measurements and PFT, 6MWT, mMRC score, and TFS in IPF patients (p> 0.05).

Conclusions

The functions of the diaphragm do not appear to be affected in patients with mild-to-moderate restrictive IPF. This study showed that there was no relationship between diaphragmatic functions and respiratory function parameters and the extent of fibrosis. Further studies, including advanced stages of the disease, are needed to understand the changes in diaphragmatic functions in IPF and to determine whether this change is associated with respiratory function parameters and the extent of fibrosis.

Diaphragmatic plication among lung transplant patients: A single-center experience

BACKGROUND

There is lack of data reporting outcomes among patients needing diaphragmatic plication (DP) during or after lung transplantation (LT). We sought to assess the association of DP with post-transplant spirometry among other outcomes.

METHODS

We included all patients who underwent LT between 2012&2016 (n = 324, mean age 56.3±13.4 years; M:F 198:126). We compared early and late outcomes based on the need for DP.

RESULTS

The frequency of diaphragm dysfunction (DD)on pre-transplant fluoroscopy was 52.2%. A total of 38 DP procedures were performed among 37 patients (11.4% of LT patients). DP was done for anatomic (sizing or spacing issues) or functional indications (symptomatic DD). While patients with DP had significantly lower spirometry throughout the 3-year follow-up period, their slope of decline, functional assessments at the first annual visit, the risk of CLAD, and mortality were similar to patients without DP. A sub-group analysis limited to patients with restrictive lung diseases as the transplant indication had similar findings.

CONCLUSIONS

Pre-transplant DD is common among LT candidates although it did not predict the need for DP. DP may be performed for functional or anatomic indications especially for addressing the donor-recipient size mismatch. Despite the lack of favorable effect on post-transplant spirometry, patients undergoing DP have acceptable and comparable early and late outcomes. This article is protected by copyright. All rights reserved.

Reflux-Aspiration in Chronic Lung Disease

Microaspiration, or silent aspiration, is commonly suspected in patients with refractory respiratory symptoms, including unexplained chronic cough, asthma, chronic obstructive pulmonary disease, bronchiolitis, bronchiectasis, and idiopathic pulmonary fibrosis. This suspicion is driven by the high prevalence of gastroesophageal reflux in these otherwise disparate disorders. Frequently, patients receive aggressive treatment for gastroesophageal reflux disease as a means of treating their underlying respiratory conditions, even in the absence of overt symptoms of reflux. However, clinical trials have not demonstrated a clear impact on outcomes with this strategy, and in some instances there may be potential for harm. Mechanistic studies have increasingly used gastric biomarkers obtained directly from the airways to confirm the association between reflux and respiratory disease, but results are limited by methodologic flaws and correlation. The best evidence of aspiration directly causing respiratory disorders is the histopathologic detection of foreign bodies. For most of the other chronic respiratory disorders, microaspiration may be uncommon or a secondary aggravating factor, as in patients with acute exacerbations of chronic obstructive pulmonary disease or idiopathic pulmonary fibrosis. In some cases, microaspiration is probably not a significant factor at all, such as in unexplained chronic cough. It is important to distinguish between conditions in which aspiration is primarily or directly causal and conditions in which aspiration may be indirectly aggravating, to help identify whether interventions targeting reflux and aspiration precautions should be recommended to patients. Our clinical review examines some of the evidence supporting reflux-aspiration as a mechanism for several chronic respiratory disorders and offers some management considerations when reflux-aspiration is suspected.

Extraesophageal syndrome of gastroesophageal reflux: relationships with lung disease and transplantation outcome

Gastroesophageal reflux disease (GERD) is prevalent and may be associated with both esophageal and extraesophageal syndromes, which include various pulmonary conditions. GERD may lead to pulmonary complications through the "reflux" (aspiration) or "reflex" (refluxate-triggered, vagally mediated airway spasm) mechanisms. While GERD may cause or worsen pulmonary disorders, changes in respiratory mechanics due to lung disease may also increase reflux. Typical esophageal symptoms are frequently absent and objective assessment with reflux monitoring is often needed for diagnosis. Impedance monitoring should be considered in addition to traditional pH study due to the involvement of both acidic and weakly acidic/nonacidic reflux. Antireflux therapy may improve outcomes of some pulmonary complications of GERD, although careful selection of a candidate is paramount to successful outcomes. Further research is needed to identify the optimal testing strategy and patient phenotypes that would benefit from antireflux therapy to improve pulmonary outcomes.

Diaphragmatic motion studied by M-mode ultrasonography in combined pulmonary fibrosis and emphysema

BACKGROUND

The coexistence of emphysema and pulmonary fibrosis is known as combined pulmonary fibrosis and emphysema (CPFE). The aim of this study was to compare diaphragmatic motion measured by M-mode ultrasonography of patients with CPFE, idiopathic pulmonary fibrosis (IPF), and chronic obstructive pulmonary disease (COPD).

METHODS

Pulmonary function, high-resolution computed tomography (HRCT), and diaphragmatic motion were examined in patients with CPFE (n = 25), IPF (n = 18), and COPD (n = 60), and in healthy controls (n = 21). Diaphragmatic motions were measured on M-mode ultrasonographic images during quiet breathing and deep breathing.

RESULTS

There were no significant differences in right or left diaphragmatic motion during quiet breathing among the four groups, whereas differences were significant in right and left motion during deep breathing. Diaphragmatic motion in CPFE patients was the lowest among the four groups. COPD patients, especially those with severe COPD, showed significantly lower diaphragmatic motion than IPF patients or healthy controls. There were no differences in diaphragmatic motion between IPF patients and healthy controls. Right diaphragmatic motions during deep breathing were negatively correlated with emphysema scores (r = -0.606, p < 0.001), but were not correlated with fibrosis scores on HRCT.

CONCLUSIONS

Diaphragmatic weakness was found in CPFE patients. Emphysema but not fibrosis may be one cause of limited diaphragmatic motion in patients with CPFE. M-mode ultrasonographic evaluation of diaphragmatic motion during deep breathing may be a useful tool in diagnosing CPFE and in discriminating CPFE patients from IPF or COPD patients.

Mechanical stretch induces epithelial-mesenchymal transition in alveolar epithelia via hyaluronan activation of innate immunity

Epithelial injury is a central event in the pathogenesis of many inflammatory and fibrotic lung diseases like acute respiratory distress syndrome, pulmonary fibrosis, and iatrogenic lung injury. Mechanical stress is an often underappreciated contributor to lung epithelial injury. Following injury, differentiated epithelia can assume a myofibroblast phenotype in a process termed epithelial to mesenchymal transition (EMT), which contributes to aberrant wound healing and fibrosis. We demonstrate that cyclic mechanical stretch induces EMT in alveolar type II epithelial cells, associated with increased expression of low molecular mass hyaluronan (sHA). We show that sHA is sufficient for induction of EMT in statically cultured alveolar type II epithelial cells and necessary for EMT during cell stretch. Furthermore, stretch-induced EMT requires the innate immune adaptor molecule MyD88. We examined the Wnt/β-catenin pathway, which is known to mediate EMT. The Wnt target gene Wnt-inducible signaling protein 1 (wisp-1) is significantly up-regulated in stretched cells in hyaluronan- and MyD88-dependent fashion, and blockade of WISP-1 prevents EMT in stretched cells. In conclusion, we show for the first time that innate immunity transduces mechanical stress responses through the matrix component hyaluronan, and activation of the Wnt/β-catenin pathway.

Investigating the claims of Konstantin Buteyko, M.D., Ph.D.: the relationship of breath holding time to end tidal CO2 and other proposed measures of dysfunctional breathing

OBJECTIVES

Konstantin Buteyko, M.D., Ph.D., claimed that breath holding time (BHT) can be used to detect chronic hyperventilation and that BHT predicts alveolar CO(2) (Pa(CO(2))) according to his patented mathematical formula. The Buteyko Breathing Technique (BBT) is believed to correct chronic hyperventilation as evidenced by increased BHT. In this study, we test Buteyko's claims and explore the relationship between BHT and end-tidal carbon dioxide (ETCO(2)) as well as measures of dysfunctional breathing (DB) including the Nijmegen questionnaire, the Self Evaluation of Breathing Questionnaire, and thoracic dominant breathing pattern.

SUBJECTS

Eighty-three (83) adults healthy or suspected of having dysfunctional breathing, 29 with abnormal spirometry readings, 54 with normal spirometry.

OUTCOME MEASURES

BHT, performed according to BBT protocols, was measured along with ETCO(2) and other measures of DB including the Nijmegen questionnaire, and manual assessment of respiratory motion, a palpatory technique for measuring thoraco-abdominal balance during breathing. Correlations between measures of DB were made in the whole sample and also in subgroups with normal or abnormal spirometry. DB measures were compared in normal and abnormal spirometry groups.

RESULTS

The results revealed a negative correlation between BHT and ETCO(2) (r= -0.241, p<0.05), directly opposite to Buteyko's claims. BHT was significantly shorter in people with abnormal spirometry (FEV(1) or FVC<15% below predicted), with no difference in ETCO(2) levels between the abnormal and normal spirometry groups. In the abnormal spirometry group, lower BHT was found to correlate with a thoracic dominant breathing pattern. (r= -0.408, p<0.028).

CONCLUSIONS

Although BHT does not predict resting ETCO(2), it does correlate with breathing pattern in subjects with abnormal spirometry. It is proposed that altered breathing pattern could contribute to breathing symptoms such as dyspnea and that breathing therapies such as BBT might influence symptoms by improving the efficiency of the biomechanics of breathing.

Physical diagnosis of chronic obstructive pulmonary disease

Among the various diagnostic strategies of chronic obstructive pulmonary disease (COPD), physical diagnosis is the quickest and requires no extra cost. Rapid physical diagnosis of COPD in primary care practice can lead to earlier actions of preventive measures and counseling for patients. Further, rapid physical diagnosis of COPD in an emergency department is also crucial for timely use of potentially lifesaving therapy specific for COPD patients. In this review, we will present a broad scope of physical findings for rapid physical diagnosis of COPD.

Thoracic dimensions at maximum lung inflation in normal subjects and in patients with obstructive and restrictive lung diseases

OBJECTIVES

To compare the distribution of lung volume at total lung capacity (TLC) among adult men and women known to have normal lung function or chronic obstructive disease or restrictive lung disease (RLD).

DESIGN

Five-year retrospective study.

SETTING

Review of available clinical pulmonary function testing (PFT) reports and chest radiographs.

PATIENTS

Sixty-four patients presenting with normal PFT and chest radiograph findings (normal subjects), 26 patients with severe COPD and increased TLC (COPD group), 29 patients with cystic fibrosis (CF) and increased TLC (CF group), and 19 patients with RLD with a clinical diagnosis of pulmonary fibrosis and a reduced TLC (RLD group).

MEASUREMENTS

Average posteroanterior rib cage diameter (PAave), average lateral rib cage diameter (LAave), and average vertical height of the diaphragm (HDIave) were measured using radiography. Normal prediction equations were generated based on stature, body mass index (BMI), age, and sex as independent variables and then used in between-group comparisons.

RESULTS

PAave correlated positively with BMI and age but not with height, whereas LAave correlated positively with BMI and height but not with age. HDIave correlated positively with height and age but negatively with BMI. PAave and LAave were smaller and HDIave was greater in women than men having the same stature. In the COPD group and in male CF group patients, BMI was low and only HDIave was greater than in sex-, age-, and height-matched normal subjects, but in female CF group patients, only the rib cage diameters were greater than normal. In the RLD group, PAave and HDIave were smaller than predicted and inversely related to each other, but LAave was normal.

CONCLUSION

Variations in maximum lung volume caused by gender, growth, or by lung diseases are nonisotropic and entail substantial changes in chest wall shape.

Abnormalities of chest wall motion in patients with chronic airflow obstruction

Forty patients with severe chronic stable airflow obstruction and hyperinflation were studied to assess patterns of abnormal chest wall motion and their frequency. Dimensional changes were measured during tidal breathing, four pairs of magnetometers being used to record anteroposterior diameters of ribcage and abdomen and two lateral diameters of the ribcage. Chest wall movements were qualitatively normal in only five patients. Three main types of abnormality were found and 13 subjects had two or more abnormal patterns. Lateral ribcage paradox was present in 31 of the 40 patients and was recognised clinically in all except one. Inspiratory indrawing of the lower sternum was recorded in 12 patients, paradoxical inspiratory motion of the abdomen was present in four patients and in six there was a biphasic expiratory pattern of abdominal movement. Analysis of variance showed no significant group differences in severity of airflow obstruction or hyperinflation between the patients with qualitatively normal motion and those with different types of abnormal motion. Relationships between the tidal displacement of each dimension and severity of airflow obstruction and hyperinflation were examined. In general, patients with more severe hyperinflation showed less abdominal movement and those with severe airflow obstruction had less lateral expansion of the ribcage, but the correlations were weak. It is concluded that abnormal motion of the chest wall is very common in patients with airflow obstruction and hyperinflation, that clinical recognition of abnormal motion other than lateral ribcage paradox is easily overlooked, and that quantitative relationships between abnormal motion and disease severity are weak.