Adenosine 5'-monophosphate in asthma: gas exchange and sputum cellular responses.

Adenosine 5'-monophosphate (AMP) bronchoprovocation reproduces the lung function abnormalities that occur spontaneously during acute asthma and detects peripheral airway inflammation better than direct bronchoconstrictive agents. Pulmonary gas exchange disturbances may reflect changes in small airways related to airway inflammation rather than bronchoconstriction alone. The present authors investigated whether AMP induced a greater imbalance in the ventilation/perfusion ratio than methacholine (MCh), at an equivalent degree of bronchoconstriction, with and without salbutamol pre-medication. In total, 36 asthmatics were studied in three randomised, double-blind, crossover studies: 1) before and after AMP or MCh; 2) before and 30 min after salbutamol or placebo, followed by AMP; or 3) MCh challenge. Sputum was collected before and 4 h post-challenge. Compared with MCh, AMP provoked similar pulmonary gas exchange abnormalities at an equivalent degree of intense bronchoconstriction (forced expiratory volume in one second decrease of 28-44%). While salbutamol blocked AMP- or MCh-induced bronchoconstriction, arterial oxygen tension (P(a,O(2))) and alveolar-arterial oxygen tension difference (P(A-a,O(2))) disturbances induced by AMP and MCh were only partially blocked (P(a,O(2)) by 46 and 42%, respectively; P(A-a,O(2)) by 58 and 57%, respectively). Compared with MCh, AMP increased the percentage of neutrophils (mean+/-se increased from 28+/-4% to 38+/-4%), but this increase did not occur after salbutamol pre-treatment. Both adenosine 5'-monophosphate and methacholine induced similar peripheral airway dysfunction. The fully inhibited adenosine 5'-monophosphate-induced neutrophilia with residual hypoxaemia observed after salbutamol treatment is probably related to beta(2)-agonists acting on both bronchial and pulmonary circulation.

Mitochondrial dysfunction in COPD patients with low body mass index.

Patients with chronic obstructive pulmonary disease (COPD) show abnormal adaptations of skeletal muscle redox status after exercise training. Increased skeletal muscle oxidative stress in COPD patients may prompt mitochondrial dysfunction. The present study explores the association between body composition and mitochondrial respiration in seven COPD patients with low body mass index (BMI(L)), eight COPD patients with normal body mass index (BMI(N)) and seven healthy controls. All of them underwent a vastus lateralis biopsy in which muscle structure, in vitro mitochondrial respiratory function, uncoupling protein 3 (UCP3) mRNA expression and glutathione levels in both isolated mitochondria and the whole muscle were determined. Mitochondrial respiratory function (assessed by acceptor control ratio (ACR)) was impaired in BMI(L) (2.2+/-0.6) compared with both BMI(N) (5.3+/-1.3) and controls (8.2+/-1.3). ACR significantly correlated with arterial oxygen tension and with muscle endurance but it showed a negative association with exercise-induced increase in blood lactate levels. UCP3 mRNA expression was reduced in BMI(L) patients. In conclusion, chronic obstructive pulmonary disease patients with low body mass index show electron transport chain dysfunction, which may contribute to low muscle endurance in the current subgroup of patients.

COPD exacerbations.5: management.

A review of the most relevant evidence based therapeutic options currently available for the management of exacerbations of COPD.

Antibiotics for exacerbations of chronic obstructive pulmonary disease.

BACKGROUND: Most patients with an exacerbation of chronic obstructive pulmonary disease (COPD) are treated with antibiotics. However the value of their use remains uncertain. Some controlled trials of antibiotics have shown benefit (Berry 1960; Pines 1972) while others have not (Elmes 1965b; Nicotra 1982). OBJECTIVES: To conduct a systematic review of the literature estimating the value of antibiotics in the management of acute COPD exacerbations. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2005); MEDLINE (1966 to December 2005); EMBASE (1974 to December 2005); Web of Science (December 2005), and other electronically available databases. SELECTION CRITERIA: Randomised controlled trials (RCTs) in patients with acute COPD exacerbations comparing antibiotic (for a minimum of five days) and placebo. DATA COLLECTION AND ANALYSIS: Data were analysed using Review Manager software. Continuous data were analysed using weighted mean differences (WMD) and 95% confidence intervals (CI). Relative risks (RR) (and 95% CI) were calculated for all dichotomous data. Where appropriate, number needed to treat to benefit (NNT) and 95% CI were calculated. MAIN RESULTS: Eleven trials with 917 patients were included. Ten trials used increased cough, sputum volume and purulence diagnostic criteria for COPD exacerbation. Eight-hundred and fifty-seven patients provided data for outcomes including mortality, treatment failure, increased sputum volume, sputum purulence, PaCO(2), PaO(2), peak flow and adverse events. Antibiotic therapy regardless of antibiotic choice significantly reduced mortality (RR 0.23; 95% CI 0.10 to 0.52 with NNT of 8; 95% CI 6 to 17), treatment failure (RR 0.47; 95% CI 0.36 to 0.62 with NNT of 3; 95% CI 3 to 5) and sputum purulence (RR 0.56; 95% CI 0.41 to 0.77 with NNT of 8; 95% CI 6 to 17). There was a small increase in risk of diarrhoea with antibiotics (RR 2.86; 95% CI 1.06 to 7.76). Antibiotics did not improve arterial blood gases and peak flow. AUTHORS' CONCLUSIONS: This review shows that in COPD exacerbations with increased cough and sputum purulence antibiotics, regardless of choice, reduce the risk of short-term mortality by 77%, decrease the risk of treatment failure by 53% and the risk of sputum purulence by 44%; with a small increase in the risk of diarrhoea. These results should be interpreted with caution due to the differences in patient selection, antibiotic choice, small number of included trials and lack of control for interventions that influence outcome, such as use of systemic corticosteroids and ventilatory support. Nevertheless, this review supports antibiotics for patients with COPD exacerbations with increased cough and sputum purulence who are moderately or severely ill.

Integrated care prevents hospitalisations for exacerbations in COPD patients.

Hospital admissions due to chronic obstructive pulmonary disease (COPD) exacerbations have a major impact on the disease evolution and costs. The current authors postulated that a simple and well-standardised, low-intensity integrated care intervention can be effective to prevent such hospitalisations. Therefore, 155 exacerbated COPD patients (17% females) were recruited after hospital discharge from centres in Barcelona (Spain) and Leuven (Belgium). They were randomly assigned to either integrated care (IC; n = 65; age mean+/-sd 70+/-9 yrs; forced expiratory volume in one second (FEV(1)) 1.1+/-0.5 L, 43% predicted) or usual care (UC; n = 90; age 72+/-9 yrs; FEV(1) 1.1+/-0.05 L, 41% pred). The IC intervention consisted of an individually tailored care plan upon discharge shared with the primary care team, as well as accessibility to a specialised nurse case manager through a web-based call centre. After 12 months' follow-up, IC showed a lower hospitalisation rate (1.5+/-2.6 versus 2.1+/-3.1) and a higher percentage of patients without re-admissions (49 versus 31%) than UC without differences in mortality (19 versus 16%, respectively). In conclusion, this trial demonstrates that a standardised integrated care intervention, based on shared care arrangements among different levels of the system with support of information technologies, effectively prevents hospitalisations for exacerbations in chronic obstructive pulmonary disease patients.

Leukotriene D4-induced hypoxaemia in asthma is mediated by the cys-leukotriene1 receptor.

Bronchoprovocation with cysteinyl-leukotrienes (LTs) induces airflow obstruction and gas exchange abnormalities, namely ventilation-perfusion ratio (V'(A)/Q') imbalance. However, it is unknown which of the two different receptors for cysteinyl-LTs mediate these V'(A)/Q' disturbances. In a double-blinded, crossover design, 10 patients with mild asthma were randomised to receive an oral single dose of the selective cysteinyl-LT1 receptor antagonist montelukast (40 mg) or placebo before leukotriene (LT)D4 inhalation challenge. Gas exchange, including V'(A)/Q' descriptors were measured at baseline, 3 h after montelukast/placebo pretreatment and 5, 15 and 45 min after the LTD4 challenge. Compared with montelukast, inhalation of LTD(4) induced a marked fall in forced expiratory volume in one second (mean+/-se 33+/-2%) and profound V'(A)/Q' mismatching, reflected by a decreased arterial oxygen tension (from 100+/-4 to 75+/-3 mmHg) and an increased overall index of V'(A)/Q' heterogeneity dispersion of retention minus excretion inert gases corrected for dead space (from 4.9+/-1.2 to 8.4+/-1.1; normal< or =3.0; dimensionless), 5 min after placebo. Following montelukast, LTD4 produced no significant changes in any of the variables. In conclusion, these findings point to the view that leukotriene D4)-induced gas exchange disturbances and bronchoconstriction are both mediated by the cysteinyl-leukotriene1 receptor.

Formoterol protects against platelet-activating factor-induced effects in asthma.

Platelet-activating factor (PAF) is an inflammatory mediator that provokes neutropaenia, bronchoconstriction and gas exchange defects due to exudation of bulk plasma within the airways. While the inhibitory effects of short-acting beta2-agonists on PAF-induced disturbances have been consistently shown, those of long-acting beta2-agonists are less convincing. To further explore the mechanisms involved in PAF challenge in asthma, 12 patients (forced expiratory volume in one second, 90 +/- 4% predicted) were investigated 2 h after inhaled formoterol (18 microg), in a double-blind, placebo-controlled, crossover design following PAF (18 microg) inhalation. Compared with the placebo, at 5 min, premedication with formoterol reduced PAF-induced cough and dyspnoea, and attenuated increased respiratory system resistance (by 67%) and arterial deoxygenation (by 50%). Likewise, ventilation-perfusion (V'A/Q') inequality improved, as reflected by the dispersion of pulmonary blood flow (by 63%) and an overall index of V'A/Q' heterogeneity (by 71%). In contrast, PAF-induced facial flushing, neutropaenia and subsequent rebound neutrophilia remained unchanged. The improvement in gas exchange abnormalities shown after platelet-activating factor in patients with asthma pretreated with formoterol at the recommended clinical dose may reflect, in addition to its class effects, an anti-exudative effect of formoterol in the airways.

Neutrophil airway influx by platelet-activating factor in asthma: role of adhesion molecules and LTB4 expression.

Platelet-activating factor (PAF)-induced neutrophil lung sequestration may require cell surface adhesion molecules (macrophage-1 antigen (MAC-1) and lymphocyte function-associated antigen-1 (LFA-1)). In this randomised, double-blinded, crossover study, the neutrophil kinetics after PAF and Lyso-PAF (L-PAF) airway challenge were investigated in nine mild-intermittent asthmatics. Neutrophils were measured in peripheral blood (PB) before and at 5, 15, 45 and 240 min after bronchoprovocation, and in induced sputum before and at 240 min after challenge. MAC-1 and LFA-1 expression were assessed by immunocytochemistry, and leukotriene B4 (LTB4) was measured by enzyme-immunoassay in induced-sputum supernatants. Compared with baseline, neutrophils in PB decreased 5 min after PAF, while at 240 min neutrophils in induced sputum increased. Compared with baseline and L-PAF, PAF decreased the percentages of MAC-1- and LFA-1-positive neutrophils in PB at 5 min, but increased the percentages of MAC-1 and LFA-1 in neutrophil-induced sputum. Moreover, compared with baseline and L-PAF, PAF-induced sputum revealed higher LTB4 levels, a finding that correlated with the elevated number of neutrophils in induced sputum. These findings suggest that macrophage-1 antigen and lymphocyte function-associated antigen-1 are involved in platelet-activating factor-induced neutrophil lung traffic, and that this process is modulated by enhanced leukotriene B4 release within the airways.

Home hospitalisation of exacerbated chronic obstructive pulmonary disease patients.

It was postulated that home hospitalisation (HH) of selected chronic obstructive pulmonary disease (COPD) exacerbations admitted at the emergency room (ER) could facilitate a better outcome than conventional hospitalisation. To this end, 222 COPD patients (3.2% female; 71+/-10 yrs (mean+/-SD)) were randomly assigned to HH (n=121) or conventional care (n=101). During HH, integrated care was delivered by a specialised nurse with the patient's free-phone access to the nurse ensured for an 8-week follow-up period. Mortality (HH: 4.1%; controls: 6.9%) and hospital readmissions (HH: 0.24+/-0.57 controls: 0.38+/-0.70) were similar in both groups. However, at the end of the follow-up period, HH patients showed: 1) a lower rate of ER visits (0.13+/-0.43 versus 0.31+/-0.62); and 2) a noticeable improvement of quality of life (delta St George's Respiratory Questionnaire (SGRQ), -6.9 versus -2.4). Furthermore, a higher percentage of patients had a better knowledge of the disease (58% versus 27%), a better self-management of their condition (81% versus 48%), and the patient's satisfaction was greater. The average overall direct cost per HH patient was 62% of the costs of conventional care, essentially due to fewer days of inpatient hospitalisation (1.7+/-2.3 versus 4.2+/-4.1 days). A comprehensive home care intervention in selected chronic obstructive pulmonary disease exacerbations appears as cost effective. The home hospitalisation intervention generates better outcomes at lower costs than conventional care.

2002: un buen año capicúa para la EPOC / 2002: a good year for turning approach to COPD around

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Physiological responses to the 6-min walk test in patients with chronic obstructive pulmonary disease.

The 6-min walking test (6MWT) is frequently used to assess functional capacity in chronic cardiopulmonary disorders because of its simplicity. The study examines the physiological responses during encouraged 6MWT in patients with chronic obstructive pulmonary disease. Pulmonary oxygen (O2) uptake (V'O2) was measured in 20 male patients (age 66+/-6 yrs, forced expiratory volume in one second 45+/-14% predicted) during 6MWT and incremental cycling, in random order. O2 tension in arterial blood, carbon dioxide tension in arterial blood and arterial lactate concentration ([La]art) were obtained in the last 10 patients. During the 6MWT, V'O2 showed a plateau after the 3rd min (1.39+/-0.28, 1.42+/-0.31, and 1.40+/-0.30 L x min(-1), 4th, 5th and 6th min, respectively), and minute ventilation (V'E) (42+/-8 L x min(-1)) was 91% maximal voluntary ventilation. No differences were shown between 6MWT (6th min) and peak cycling exercise in V'O2 (1.40+/-0.30 versus 1.41+/-0.28 L x min(-1), respectively), cardiac frequency (126+/-13 versus 130+/-12 beats x min(-1)), or arterial respiratory blood gases. The two tests were significantly different in V'E (42+/-8 versus 47+/-8 L x min(-1), 6MWT versus cycling, respectively), carbon dioxide production (1.30+/-0.31 versus 1.45+/-0.18 L x min(-1)) and [La]art (2.9+/-1.99 versus 5.9+/-1.51 M). The study demonstrates that an encouraged 6-min walking test generates a high but sustainable oxygen uptake. Since the oxygen uptake plateau reflects the integrated response of the system, it may explain the high prognostic value of the 6-min walking test.

Response to hypoxia of pulmonary arteries in chronic obstructive pulmonary disease: an in vitro study.

Patients with chronic obstructive pulmonary disease (COPD) show impaired hypoxic pulmonary vasoconstriction that might contribute to abnormal gas exchange and could be related to endothelial dysfunction in pulmonary arteries. The aim of the study was to investigate the response of PA to hypoxic stimulus in vitro in COPD, and the role of endothelium-derived nitric oxide (NO) in this response. The pulmonary arteries of 25 patients who underwent lung resection were studied. Patients were divided into controls, COPD+normoxaemia (COPDN) and COPD+ hypoxaemia (COPDH). Hypoxic vasoconstriction (HV) was evaluated before and after stimulation or inhibition of the endothelial release of NO, and in the presence of exogenous NO. Compared with the other groups, HV was reduced in COPDH. The magnitude of HV correlated with the oxygen tension in arterial blood. The hypoxic stimulus induced greater contraction after stimulating endothelial release of NO, whereas its inhibition practically abolished HV. Exogenous NO completely inhibited HV. Maximal relaxation induced by endothelium-dependent vasodilators correlated with the magnitude of HV. In conclusion, pulmonary arteries of patients with chronic obstructive pulmonary disease and hypoxaemia have an impaired response to hypoxic stimulus, and the endothelial release of nitric oxide modulates hypoxic vasoconstriction. The depressed response of pulmonary arteries to hypoxia may contribute to abnormal gas exchange in chronic obstructive pulmonary disease.

Characterization of pulmonary vascular remodelling in smokers and patients with mild COPD.

Intimal enlargement of pulmonary arteries is an early change in chronic obstructive pulmonary disease (COPD). The cellular and extracellular components that are involved in this enlargement are unknown. The present study was designed to characterize the structural changes occurring in pulmonary muscular arteries in the initial disease stages. Lung specimens from patients with moderate COPD (n=8; forced expiratory volume in one second (FEV1), 66 +/- 10% predicted) and smokers without airflow obstruction (n=7; FEV1, 86 +/- 6% pred), were investigated by histochemistry to characterize extracellular matrix proteins and by immunohistochemistry to identify intrinsic cells of the vascular wall. In both COPD patients and smokers, the majority of cells present in the enlarged intimas were stained by specific smooth muscle cell (SMC) markers. No staining with endothelial or fibroblast markers was shown. A proportion of SMCs did not stain with desmin, suggesting cellular heterogeneity in this population. Elastin was the most abundant extracellular matrix protein and collagen was seen in a lower proportion. The amount of collagen was related to the intimal thickness (p<0.001). The findings demonstrated smooth muscle cell proliferation, as well as elastin and collagen deposition, in the thickened intimas of pulmonary arteries in moderate chronic obstructive pulmonary disease patients and smokers, suggesting that these abnormalities may originate at an early stage in cigarette smoke-induced respiratory disease.

Fluticasone propionate attenuates platelet-activating factor-induced gas exchange defects in mild asthma.

Inhaled glucocorticosteroids may reduce airway mucosal oedema in acute asthma. Inhaled platelet-activating factor (PAF) provokes pulmonary gas exchange disturbances, similar to those shown in severe asthma, which may be due to increased airway plasma leakage. This randomized, double-blind, placebo-controlled, crossover study investigated the effects of high doses of inhaled fluticasone propionate (FP) in 12 patients with mild asthma before and after PAF inhalation. Patients were studied before and 12 h after inhaling FP (6 mg) or placebo (P), and then at 5, 15 and 45 min after PAF challenge. Compared with vehicle, FP inhaled before PAF improved forced expiratory volume in one second and respiratory system resistance (Rrs), increased peripheral blood neutrophils and reduced eosinophil counts. After PAF, FP enhanced transient neutropenia at 5 min and facilitated the recovery of oxygen tension in arterial blood (FP: 93+/-4 mmHg; P: 83+/-4 mmHg) at 45 min, without influencing the increases in Rrs. In conclusion, the improvement of platelet-activated factor-induced oxygen tension in arterial blood disturbances after fluticasone proprionate suggests that inhaled glucocorticosteroids may possess vasoconstrictor properties in the pulmonary circulation.