Physiological differences and similarities in asthma and COPD--based on respiratory function testing

Common physiologic and proteomic biomarkers in pulmonary and coronary artery disease

Objective

Chronic obstructive pulmonary disease (COPD) and coronary artery disease (CAD) are leading causes of global morbidity and mortality. There is a well-known comorbidity between COPD and CAD, which is only partly explained by smoking and other known common risk factors. In order to better understand the relationship between COPD and CAD, we analyzed myocardial perfusion, pulmonary function and novel cardiovascular biomarkers in patients with symptoms suggesting myocardial ischemia.

Methods

A total of 396 subjects from the Swedish Biomarkers and Genetics CardioPulmonary Physiology Study (BiG CaPPS) were included, all of whom had been referred to myocardial perfusion imaging due to suspected myocardial ischemia. Subjects performed myocardial perfusion imaging (MPI), pulmonary function tests (PFT) and analysis of 92 proteomic biomarkers, previously associated with cardiovascular disease. Linear regression was used to study the relationship between MPI and PFT results and proteomic biomarkers.

Results

Subjects with CAD (n = 159) had lower diffusing capacity (D_LCO) than patients without CAD (6.64 versus 7.17 mmol/(min*kPa*l); p = 0.004) in models adjusted for common covariates such as smoking, but also diabetes and brain natriuretic peptide (BNP). The association remained significant after additional adjustment for forced expiratory volume in one second (FEV₁) (p = 0.009). Subjects with CAD, compared with subjects without CAD, had higher total airway resistance (0.37 vs 0.36 kPa/(l/s); p = 0.036). Among 92 protein biomarkers, nine were associated with a combined diagnosis of CAD and airflow obstruction: VSIG2, KIM1, FGF-23, REN, XCL1, GIF, ADM, TRAIL-R2 and PRSS8.

Significance

Diffusing capacity for carbon monoxide is decreased in patients with CAD, independently of decreased FEV₁, diabetes, and elevated BNP. Several cardiovascular biomarkers are associated with co-existent CAD and airflow obstruction, but none with airflow obstruction only. The current findings indicate that the interaction between CAD and lung function is complex, including mechanisms beyond the known association between CAD and reduced ventilation.

Ratio of Maximal Inspiratory to Expiratory Flow Aids in the Separation of COPD from Asthma

Patients who have chronic obstructive pulmonary disease (COPD) and bronchial asthma (BA) share symptoms such as, dyspnoea, cough and wheeze. Differentiating these diseases in the ambulatory setting can be challenging especially in older adult smokers who are being treated with a variety of medications. The objective of this study was to test the value of adding a maximal inspiratory manoeuvre to basic spirometry to differentiate COPD and BA. One hundred forty-three COPD patients and 142 BA patients had measurements of maximal inspiratory and expiratory flow during routine spirometry. Parameters from these tests were used to assess diagnostic accuracy using receiver-operating characteristic (ROC) analyses followed by logistic regression. The association of two independent parameters were analyzed using linear regression analyses. Results show that forced expiratory volume in one second/forced vital capacity (FEV₁/FVC%) <62.4 was the best independent predictor to diagnose COPD. The combination of FEV₁/FVC% <62.4 and the ratio of peak inspiratory flow/maximal expiratory flow at 50% FVC (PIF/MEF₅₀) >3.06 significantly predicted COPD. Post-test probability for prediction of COPD was 82.0% when patients had both parameters. When asthmatic patients with a smoking history were compared with COPD patients, FEV₁/FVC% <63.4 and PIF/MEF₅₀ >3.29 were both independent predictors of COPD. The post-test probability for COPD was 94.4% when patients had both parameters. The association between FEV₁/FVC% and PIF/MEF₅₀ was significantly different between COPD and BA. In conclusion, the addition of the maximal inspiratory effort to routine pulmonary function measurements provides a simple test to help differentiate COPD and BA.

Asthma and COPD: Similarities and Differences in the Pathophysiology, Diagnosis and Therapy

Asthma and chronic obstructive pulmonary disease (COPD) are two of the most common chronic lung diseases worldwide. Distinguishing between these different pulmonary diseases can be difficult in practice because of symptomatic similarities. A definitive diagnosis is essential for correct treatment. This review article presents the different symptoms of these two chronic inflammatory lung diseases following a selective search of the PubMed database for relevant literature published between 1996 and 2012. While cough occurs in both diseases, asthmatics often have a dry cough mainly at night, which is often associated with allergies. In contrast, COPD is usually caused by years of smoking. Paroxysmal dyspnea, which occurs in asthma, is characterized by shortness of breath, while in COPD it occurs during physical exertion in early stages and at rest in later stages of the disease. Asthma often begins in childhood or adolescence, whereas COPD occurs mainly in smokers in later life. It is possible to live with asthma into old age, whereas the life expectancy of patients with COPD is significantly limited. Currently, there is no general curative treatment for either disorder.

Responsiveness to bronchodilator procaterol in COPD as assessed by forced oscillation technique

The aim of this retrospective study was to assess responses to a bronchodilator by forced oscillation technique (FOT) and to relate the results of respiratory impedance (Zrs) to spirometric parameters in patients with chronic obstructive pulmonary disease (COPD). Zrs was measured as a function of frequency from 4 to 36Hz before and after inhalation of procaterol, a short-acting β₂-agonist (n=60). Respiratory resistance (Rrs) and reactance (Xrs) were significantly frequency-dependent, and inspiratory and expiratory phases were different both before and after procaterol inhalation. The Rrs at 4Hz and Xrs at 4-20Hz during a whole breath were significantly improved after procaterol inhalation. The response to procaterol inhalation varied among patients, and changes in Xrs at 4Hz significantly correlated with% change in forced expiratory volume in one second and changes in forced vital capacity. Taken together, Zrs, and specifically Xrs parameters, are sensitive to acute physiological responses to a bronchodilator in COPD.

Expiratory CT scan in patients with normal inspiratory CT scan: a finding of obliterative bronchiolitis and other causes of bronchiolar obstruction

Expiratory CT scan is usually obtained as supplement to normal inspiratory CT scan to recognize air-trapping, which is expression of small airways obstruction. In some patients the air-trapping may be the only sign of an early-stage small airways disease in an otherwise normal lung.

The purpose of this article is to illustrate pathologic conditions, namely obliterative bronchiolitis, in which expiratory CT scan can be abnormal despite normal inspiratory CT examination, and to highlight indications for this technique in patients with clinical and functional suspect of bronchiolar obstruction.

Monitoring asthma status

PURPOSE

Asthma is a chronic disorder of the airways involving inflammation and airway hyper-reactivity. Clinical diagnosis and monitoring of asthma must incorporate the immunological, biochemical, and histological changes of a chronic disorder, while recognizing acute phenotypic changes in order to optimally tailor therapeutics to each individual.

RECENT FINDINGS

Articles published within the previous 18 months are summarized in this article in order to present an up to date review of the latest findings regarding the monitoring of asthma. The articles encompass a wide array of specialties from basic research and histology to clinical medicine as well as community medicine and nursing.

SUMMARY

Exciting new advancements in the monitoring of asthma continue to unfold. Potentially new diagnostic and monitoring tools are highlighted in this study. Continued investigations may enable a select few methodologies to reach clinical utility in the ongoing monitoring and treatment of patients with asthma.

Overlap syndrome of asthma and COPD predicts low quality of life

BACKGROUND

In clinical practice, patients whose airway disease shares features of both asthma and chronic obstructive pulmonary disease (COPD) remain poorly recognized.

MATERIAL AND METHODS

The study population consisted of 1546 patients with a diagnosis of asthma or COPD or both. Based on patient-reported outcomes and retrospective medical record data, the study population was divided into three groups: ( 1 ) asthma only, ( 2 ) COPD only, and ( 3 ) both asthma and COPD (overlap syndrome group). We evaluated patient characteristics associated with health-related quality of life (HRQoL).

RESULTS

In many respects, the overlap group fell between the asthma and COPD groups. In the overlap group, however, HRQoL was the poorest of all. In the logistic regression model, with the asthma group as the reference, both the overlap and the COPD group showed higher risk for low HRQoL [odd ratio (OR): 1.9; 95% confidence interval (CI): 1.2-3.2; and OR: 1.8, 95% CI: 1.0-3.2; respectively]. In addition, female gender, obesity, duration of disease, disability pension, and coexisting cardiovascular disease were associated with low HRQoL across the study population.

CONCLUSIONS

Patients with overlapping asthma and COPD differed from those patients with asthma or COPD only. Overlap syndrome was associated with low HRQoL.

[Invasive mechanical ventilation in COPD and asthma]

COPD and asthmatic patients use a substantial proportion of mechanical ventilation in the ICU, and their overall mortality with ventilatory support can be significant. From the pathophysiological standpoint, they have increased airway resistance, pulmonary hyperinflation, and high pulmonary dead space, leading to increased work of breathing. If ventilatory demand exceeds work output of the respiratory muscles, acute respiratory failure follows. The main goal of mechanical ventilation in this kind of patients is to improve pulmonary gas exchange and to allow for sufficient rest of compromised respiratory muscles to recover from the fatigued state. The current evidence supports the use of noninvasive positive-pressure ventilation for these patients (especially in COPD), but invasive ventilation also is required frequently in patients who have more severe disease. The physician must be cautious to avoid complications related to mechanical ventilation during ventilatory support. One major cause of the morbidity and mortality arising during mechanical ventilation in these patients is excessive dynamic pulmonary hyperinflation (DH) with intrinsic positive end-expiratory pressure (intrinsic PEEP or auto-PEEP). The purpose of this article is to provide a concise update of the most relevant aspects for the optimal ventilatory management in these patients.

Improving the differential diagnosis of chronic obstructive pulmonary disease in primary care

Chronic obstructive pulmonary disease (COPD) and asthma represent a substantial portion of primary care practice. In adults, differentiating asthma from COPD can be difficult but is important because of the marked differences in treatment, disease progression, and outcomes between the 2 conditions. Currently, clinical COPD is often misdiagnosed or undiagnosed until late in the disease. Earlier diagnosis could markedly reduce morbidity and improve quality of life. Establishing a diagnosis of COPD requires spirometry testing, interpreted in the context of the patient's symptoms, smoking status, age, and comorbidities. Additional tests and tools may be helpful in the differential diagnosis, including questionnaires specifically developed to discriminate between COPD and asthma and, in special cases, imaging studies. Follow-up and monitoring of asthma and COPD are always necessary and provide additional benefit in patients in whom only continued care and reassessment can confirm the final diagnosis, such as younger individuals with fixed airway obstruction, smokers with asthma, and patients with both disorders. Key areas for improvement include enhanced case identification, improved quality and interpretation of findings on spirometry, and increased use of tools such as differential diagnosis questionnaires and algorithms to guide the diagnostic and monitoring process. To achieve optimal outcomes, the primary care team should make every effort to establish a firm diagnosis. For this review, we conducted a PubMed search with no time limits using the Medical Subject Headings chronic obstructive pulmonary disease or COPD and asthma, in association with the following search terms: diagnosis, differential diagnosis, mixed or comorbid disease, diagnostic techniques, spirometry, questionnaires, and primary care.

Role of intermittent hypoxia in the treatment of bronchial asthma and chronic obstructive pulmonary disease

PURPOSE OF REVIEW

The purpose of this review is to describe the impact that exposure to intermittent hypoxic training (IHT) could have on bronchial asthma and chronic obstructive pulmonary disease (COPD). This is of particular interest, as an increasing number of patients suffer from severe symptoms of bronchial asthma and COPD and desire more effective and efficient treatment options with fewer side effects.

RECENT FINDINGS

Exposure to IHT has been shown to raise baroreflex sensitivity to normal levels and to selectively increase hypercapnic ventilatory response, total exercise time, total haemoglobin mass, and lung diffusion capacity for carbon monoxide in COPD patients. However, evidence proving that IHT leads to health benefit effects in bronchial asthma patients has not been produced by recent literature.

SUMMARY

Recent research outlines the value of IHT as a therapeutic strategy for the treatment of COPD patients, leading to more efficient ventilation. Additionally, IHT might represent an attractive method to complement the known beneficial effects of exercise training and to rebalance early autonomic dysfunction in COPD patients. Future research examining the potential risks and benefits of IHT could pave the way for the development of new therapeutic approaches for patients suffering from bronchial asthma and COPD.

Multidimensional analyses of long-term clinical courses of asthma and chronic obstructive pulmonary disease

Asthma and chronic obstructive pulmonary disease (COPD) are chronic respiratory disorders involving obstructive airway defects. There have been many discussions on their similarities and differences. Although airflow limitation expressed as forced expiratory volume in one second (FEV(1)) has been considered to be the main diagnostic assessment in both diseases, it does not reflect the functional impairment imparted to the patients by these diseases. Therefore, multidimensional approaches using multiple measurements in assessing disease control or severity have been recommended, and multiple endpoints in addition to FEV(1) have been set recently in clinical trials so as not to miss the overall effects. In particular, as improving symptoms and health status as well as pulmonary function are important goals in the management of asthma and COPD, some patient-reported measurements such as health-related quality of life or dyspnea should be included. Nonetheless, there have been few reviews on the long-term clinical course comparing asthma and COPD as predicted by measurements other than airflow limitation. Here, we therefore analyzed and compared longitudinal changes in both physiological measurements and patient-reported measurements in asthma and COPD. Although both diseases showed similar long-term progressive airflow limitation similarly despite guideline-based therapies, disease progression was different in asthma and COPD. In asthma, patient-reported assessments of health status, disability and psychological status remained clinically stable over time, in contrast to the significant deterioration of these parameters in COPD. Thus, because a single measurement of airflow limitation is insufficient to monitor these diseases, multidimensional analyses are important not only for disease control but also for understanding disease progression in asthma and COPD.