Methods for assessing expiratory flow limitation during tidal breathing in COPD patients

Patients with severe COPD often exhale along the same flow-volume curve during quite breathing as during forced expiratory vital capacity manoeuvre, and this has been taken as indicating expiratory flow limitation at rest (EFL T). Therefore, EFLT, namely, attainment of maximal expiratory flow during tidal expiration, occurs when an increase in transpulmonary pressure causes no increase in expiratory flow. EFLT leads to small airway injury and promotes dynamic pulmonary hyperinflation with concurrent dyspnoea and exercise limitation. In fact, EFLT occurs commonly in COPD patients (mainly in GOLD III and IV stage) in whom the latter symptoms are common. The existing up-to-date physiological methods for assessing expiratory flow limitation (EFLT) are reviewed in the present work. Among the currently available techniques, the negative expiratory pressure (NEP) has been validated in a wide variety of settings and disorders. Consequently, it should be regarded as a simple, non invasive, most practical, and accurate new technique. Copyright © 2012 Nickolaos G. Koulouris et al

Pathophysiology of evolution of small airways disease to overt COPD

Background: The slope of phase III (single breath nitrogen test), an index of ventilation inhomogeneity, has been used for early detection of COPD. Tidal airway closure (cyclic opening and closure of the peripheral airways during tidal breathing; ACT) and expiratory flow limitation (attainment of maximal expiratory flow during tidal expiration; EFLT) cause small airways disease (SAD). The relationships of these indices with COPD severity may reflect the progress from SAD to overt COPD. Methods: In this cross-sectional study we have assessed for the first time the phase III slope, ACT and EFLT in 10 smokers with normal spirometry (group O) and 40 COPD patients with GOLD scores from I to IV. Results: In most group O smokers the phase III slope was increased, and further increased with GOLD severity (up to 800pred in GOLD IV). A close correlation was found of slope with GOLD (r 0.77). ACT was absent in smokers with normal spirometry and in most patients with mild COPD. EFLT first appeared in GOLD II patients and its prevalence progressively increased in GOLD III and IV patients. Conclusions: Most group O smokers exhibit increased phase III. With overt COPD there is a progressive increase in phase III and reduction of FEV1/FVC ratio from GOLD I to IV. A reduction of FEV1 occurs from GOLD stage II. As the disease progresses from moderate to severe, there is an increasing presence of ACT. Tidal EFL, with dynamic hyperinflation and severe dyspnea is present only in GOLD III and IV. © 2010 Informa Healthcare USA, Inc

Driving-related neuropsychological performance in stable COPD patients

Background. Cognitive deterioration may impair COPD patient's ability to perform tasks like driving vehicles. We investigated: (a) whether subclinical neuropsychological deficits occur in stable COPD patients with mild hypoxemia (PaO> 55 mmHg), and (b) whether these deficits affect their driving performance. Methods. We recruited 35 stable COPD patients and 10 normal subjects matched for age, IQ, and level of education. All subjects underwent an attention/alertness battery of tests for assessing driving performance based on the Vienna Test System. Pulmonary function tests, arterial blood gases, and dyspnea severity were also recorded. Results. COPD patients performed significantly worse than normal subjects on tests suitable for evaluating driving ability. Therefore, many (22/35) COPD patients were classified as having inadequate driving ability (failure at least in one of the tests), whereas most (8/10) healthy individuals were classified as safe drivers (P=0.029). PaOand FEV1 were correlated with almost all neuropsychological tests. Conclusions. COPD patients should be warned of the potential danger and risk they face when they drive any kind of vehicle, even when they do not exhibit overt symptoms related to driving inability. This is due to the fact that stable COPD patients may manifest impaired information processing operations. © 2013 Foteini Karakontaki et al

Dyspnea and respiratory muscle strength in end-stage liver disease

AIM: To investigate the prevalence of chronic dyspnea and its relationship to respiratory muscle function in end-stage liver disease. METHODS: Sixty-eight consecutive, ambulatory, Caucasian patients with end-stage liver disease, candidates for liver transplantation, were referred for preoperative respiratory function assessment. Forty of these (29 men) were included in this preliminary study after applying strict inclusion and exclusion criteria. Seventeen of 40 patients(42%) had ascites, but none of them was cachectic. Fifteen of 40 patients (38%) had a history of hepatic encephalopathy, though none of them was symptomatic at study time. All patients with a known history and/or presence of co-morbidities were excluded. Chronic dyspnea was rated according to the modified medical research council (mMRC) 6-point scale. Liver disease severity was assessed according to the Model for end-stage liver disease (MELD). Routine lung function tests, maximum static expiratory (Pemax) and inspiratory (Pimax) mouth pressures were measured. Respiratory muscle strength (RMS)was calculated from Pimax and Pemax values. In addition, arterial blood gases and pattern of breathing (VE: minute ventilation; VT: tidal volume; VT/TI: mean inspiratory flow; TI: duration of inspiration) were measured. RESULTS: Thirty-five(88%) of 40 patients aged (mean ± SD) 52 ± 10 years reported various degrees of chronic dyspnea (mMRC), ranging from 0 to 4, with a mean value of 2.0 ± 1.2. MELD score was 14 ± 6. Pemax, percent of predicted (%pred) was 105 ± 35, Pimax, %pred was 90 ± 29, and RMS, %pred was 97 ± 30. These pressures were below the normal limits in 12 (30%), 15 (38%), and 14 (35%) patients, respectively. Furthermore, comparing the subgroups of ascites to non-ascites patients, all respiratory muscle indices measured were found significantly decreased in ascites patients. Patients with ascites also had a significantly worse MELD score compared to non-ascites ones (P = 0.006). Significant correlations were found between chronic dyspnea and respiratory muscle function indices in all patients. Specifically, mMRC score was significantly correlated with Pemax, Pimax, and RMS (r = -0.53, P < 0.001; r = -0.42, P < 0.01; r = -0.51, P < 0.001, respectively). These correlations were substantially closer in the non-ascites subgroup (r = -0.82, P < 0.0001; r = -0.61, P < 0.01; r = -0.79, P < 0.0001, respectively) compared to all patients. Similar results were found for the relationship between mMRC vs MELD score, and MELD score vs respiratory muscle strength indices. In all patients the sole predic- tor of mMRC score was RMS (r = -0.51, P < 0.001). In the subgroup of patients without ascites this relationship becomes closer (r = -0.79, P < 0.001), whilst this relationship breaks down in the subgroup of patients with ascites. The disappearance of such a correlation may be due to the fact that ascites acts as a "confounding" factor. PaCO2 (4.4 ± 0.5 kPa) was increased, whereas pH (7.49 ± 0.04) was decreased in 26 (65%) and 34 (85%) patients, respectively. PaO2 (12.3 ± 0.04 kPa) was within normal limits. VE (11.5 ± 3.5 L/min), VT (0.735 ± 0.287 L), and VT/TI (0.449±0.129 L/s) were increased signifying hyperventilation in both subgroups of patients. VT/TI was significantly higher in patients with ascites than without ascites. Significant correlations, albeit weak, were found for PaCO2 with VE and VT/TI (r = -0.44, P < 0.01; r = -0.41, P < 0.01, respectively).CONCLUSION: The prevalence of chronic dyspnea is 88% in end-stage liver disease. The mMRC score closely correlates with respiratory muscle strength. © 2013 Baishideng

Effect of pulmonary rehabilitation on tidal expiratory flow limitation at rest and during exercise in COPD patients

We hypothesized that severe COPD patients who present with the disadvantageous phenomenon of Expiratory Flow Limitation (EFL) may benefit as COPD patients without EFL do after implementation of a Pulmonary Rehabilitation (PR) program. Forty-two stable COPD patients were studied at rest and during exercise. EFL and dynamic hyperinflation (DH) were documented using the negative expiratory pressure (NEP) technique and inspiratory capacity (IC) maneuvers, respectively. Patient centered outcomes were evaluated by the Saint-George's Respiratory Questionnaire (SGRQ) and the mMRC dyspnea scale. Before PR, 16 patients presented with EFL at rest and/or during exercise. After PR, EFL was abolished in 15 out of those 16 EFL patients who exhibited a significant increase in IC values. These were mainly accomplished through a modification of the breathing pattern. In the 26 NFL patients no increase was noted in their IC or a modification of their breathing pattern. However, both NFL and EFL COPD patients improved exercise capacity and patients centered outcomes undergoing the same PR program. © 2017 Elsevier B.V

Acute effects of short term use of ecigarettes on Airways Physiology and Respiratory Symptoms in Smokers with and without Airway Obstructive Diseases and in Healthy non smokers

BACKGROUND Although the use of e-cigarettes is increasing worldwide, their short and long-term effects remain undefined. We aimed to study the acute effect of short-term use of e-cigarettes containing nicotine on lung function and respiratory symptoms in smokers with airways obstructive disease (COPD, asthma), “healthy” smokers, and healthy never smokers. METHODS Respiratory symptoms, vital signs, exhaled NO, airway temperature, airway resistance (Raw), specific airway conductance (sGaw) and single nitrogen breath test were assessed before and immediately after short term use of an e-cigarette containing 11mg of nicotine among adults with COPD, asthma, “healthy” smokers, and never-smokers. The effect of the use of nicotine-free e-cigarettes among “healthy” never smokers was also studied. RESULTS The majority of participants reported acute cough. Short term use of nicotine e-cigarettes was associated: a) with increased heart rate in all subjects except in the COPD group, b) decreased oxygen saturation in “healthy” and COPD smokers, c) increased Raw in asthmatic smokers, “healthy” smokers, and healthy never smokers, d) decreased sGaw in healthy subjects, and e) changed slope of phase III curve in asthmatic smokers. Short-term use of nicotine-free e-cigarettes increased Raw and decreased sGaw among healthy never smokers. CONCLUSIONS Short-term use of an e-cigarette has acute effects on airways physiology and respiratory symptoms in COPD smokers, asthmatic smokers, “healthy” smokers and healthy never smokers. Ercigarette use was associated with effects in “healthy” never smokers irrespectively of nicotine concentration. More studies are needed to investigate both short and long-term effects of e-cigarette us