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Activity-related dyspnoea is often the most distressing symptom experienced by patients with chronic obstructive pulmonary disease (COPD) and can persist despite comprehensive medical management. It is now clear that dyspnoea during physical activity occurs across the spectrum of disease severity, even in those with mild airway obstruction. Our understanding of the nature and source of dyspnoea is incomplete, but current aetiological concepts emphasise the importance of increased central neural drive to breathe in the setting of a reduced ability of the respiratory system to appropriately respond. Since dyspnoea is provoked or aggravated by physical activity, its concurrent measurement during standardised laboratory exercise testing is clearly important. Combining measurement of perceptual and physiological responses during exercise can provide valuable insights into symptom severity and its pathophysiological underpinnings. This review summarises the abnormal physiological responses to exercise in COPD, as these form the basis for modern constructs of the neurobiology of exertional dyspnoea. The main objectives are: 1) to examine the role of cardiopulmonary exercise testing (CPET) in uncovering the physiological mechanisms of exertional dyspnoea in patients with mild-to-moderate COPD; 2) to examine the escalating negative sensory consequences of progressive respiratory impairment with disease advancement; and 3) to build a physiological rationale for individualised treatment optimisation based on CPET., (Copyright ©ERS 2016.)

Background: Endogenous opioids are naturally occurring peptides released by the brain in response to noxious stimuli. Although these naturally occurring peptides modulate pain, it is unknown whether endogenous opioids affect the perception of breathlessness associated with a specific respiratory challenge. The hypothesis is that intravenous administration of naloxone, used to block opioid signaling and inhibit neural pathways, will increase ratings of breathlessness during resistive load breathing (RLB) in patients with chronic obstructive pulmonary disease (COPD)., Methods: Fourteen patients with COPD (age, 64 ± 9 years) inspired through resistances during practice sessions to identify an individualized target load that caused ratings of intensity and/or unpleasantness of breathlessness ≥ 50 mm on a 100 mm visual analog scale. At two intervention visits, serum beta-endorphins were measured, naloxone (10 mg/25 ml) or normal saline (25 ml) was administered intravenously, and patients rated the two dimensions of breathlessness each minute during RLB., Results: Patient ratings of intensity (p = 0.0004) and unpleasantness (p = 0.024) of breathlessness were higher with naloxone compared with normal saline. Eleven patients (79%) reported that it was easier to breathe during RLB with normal saline (p = 0.025). RLB led to significant increases in serum beta-endorphin immunoreactivity and decreases in inspiratory capacity. There were no significant differences in physiological responses between interventions., Conclusions: Endogenous opioids modulate the intensity and the unpleasantness of breathlessness in patients with COPD. Differences in breathlessness ratings between interventions were clinically relevant based on the patients' global assessment.

Background: Peak inspiratory flow (PIF) has been proposed as a measure to assess a patient's ability to use dry powder inhalers (DPIs). However, robust quality criteria to determine a repeatability limit for measuring PIF are lacking.Research Questions: What are the repeatability limits for measuring PIF? What is the relationship between PIF measured using the In-Check DIAL device at Diskus (GlaxoSmithKline; PIFD) and HandiHaler (Boehringer Ingelheim; PIFHH) resistances?Study Design and Methods: Data from a randomized, controlled, phase 3 trial (study 0149; see Clinical Trial Registration data) were used to define repeatability limits for PIF. In addition, a model to characterize the relationship between PIF measured with the In-Check DIAL device at PIFD and PIFHH was defined using data from two randomized, controlled, phase 3 trials (studies 0128 and 0149).Results: In study 0128, the mean values (SD) for PIF at zero resistance and PIFHH were 84.6 (33.4) and 57.3 (26.1) L/min, respectively. In study 0149, the mean values (SD) for PIFD and PIFHH were 42.4 (11.2) and 29.0 (8.3) L/min, respectively. At the mean level, the mean difference between measurement attempts for PIFD and PIFHH was small, < 5 and < 3 L/min, respectively. The repeatability limit was determined as 10 and 5 L/min for PIFD and PIFHH, respectively. Modeling the relationship between PIFD and PIFHH, after controlling for significant covariates, demonstrated that a PIFD value of 60 L/min was approximately equivalent to PIFHH of 40 L/min.Interpretations: This analysis demonstrated that the two highest values of PIF using the In-Check DIAL device among three inspiratory efforts, met the repeatability limit. Altogether, these data provide guidance for measuring PIF against the simulated resistance of a specific DPI in clinical practice and research studies.Clinical Trial Registration: ClinicalTrials.gov; Nos.: NCT02518139 (study 0128) and NCT03095456 (study 0149); URL: www.clinicaltrials.gov. [ABSTRACT FROM AUTHOR]

BACKGROUND: Successful inhalation therapy depends on the ability of patients with COPD to properly use devices. We explored subjects' COPD knowledge, including education they receive from health care providers, treatment experiences, and practices with inhalation devices.METHODS: A multiple-choice online survey, developed by a steering committee of American Thoracic Society clinicians and scientists, was administered to subjects with COPD who were sourced from the Harris Poll Online panel. RESULTS: Of the 254 respondents (mean age 61.8 y; 49% males), most subjects (82%) claimed to understand their disease and available treatments, yet COPD symptoms and causes were well known to only 45% and 44% of subjects, respectively. Forty-three percent of subjects had ever used a pressurized metered-dose inhaler or dry-powder inhaler. Of the 54% of subjects who had ever used a small-volume nebulizer (SVN), 63% considered this device to be easy to use, 55% considered it to be fast-acting, 53% considered it to be convenient, and 38% considered it to be essential for treatment. Among subjects who had ever used them, SVNs were preferred by 54% over other devices. One third of subjects desired more extensive education during office visits; 25% felt the time was insufficient to cover questions, and 15% felt their concerns about COPD treatment(s) were ignored. Subjects believed physicians (32%), nurses (26%), and no single provider (28%) were primarily responsible for training and assessing proper inhalation technique. CONCLUSION: The survey showed differences between patients' beliefs and knowledge of COPD; the need for continuous education from health care providers, particularly on inhalation devices; and extensive use of pressurized metered-dose inhalers and dry-powder inhalers despite positive perceptions of SVNs. [ABSTRACT FROM AUTHOR]

Background: Although patients may find it difficult to describe their breathing discomfort, most are able to select statements among a list to describe their experience. The primary objective of this study was to examine sensitivity and specificity of descriptors of breathing discomfort prospectively in patients with common respiratory conditions as well as those patients who had refractory dyspnea.Methods: Outpatients answered "Yes" or "No" for each of 15 statements describing breathing discomfort, next selected the best three that most closely applied, and then completed the Hospital Anxiety Depression Scale-Anxiety subscale. Sensitivity, specificity, and predictive values were calculated for the descriptors by diagnosis.Results: "Work/effort" descriptors were selected as the best three by patients with COPD (n = 68), respiratory muscle weakness (n = 11), and refractory dyspnea (n = 17). Along with "work/effort" descriptors, "My chest feels tight" was among the best three in asthma (n = 22), with 38% sensitivity and 88% specificity. Along with "work/effort" descriptors, "My breathing is shallow" was among the best three in interstitial lung disease (n = 8), with 33% sensitivity and 84% specificity. Affective descriptors "frightening" (61% vs 31%, P = .002) and "awful" (66% vs 37%, P = .004) were reported more frequently in those with high anxiety scores compared with low anxiety scores.Conclusions: Although no descriptor achieved satisfactory sensitivity and specificity for identifying a particular condition, chest "tightness" was unique for asthma, whereas "shallow breathing" was unique for interstitial lung disease. Affective descriptors were associated with high anxiety scores. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated differences in ventilatory responses and gas exchange as proposed mechanisms for such an observation. The researchers measured arterial blood gas and lactate levels in 12 patients with chronic obstructive pulmonary disease (COPD) during incremental treadmill and cycle exercise. It was found that partial pressures of alveolar and artificial oxygen in patients was significantly lower at peak exercise for treadmill walking.

An abstract of the study "Predictors of Peak Inspiratory Flow Rate (PIFR) in Advanced COPD," by Alex Gifford et al. is presented.