The present study was aimed at evaluating the effects of a specific inspiratory muscle training protocol on the structure of inspiratory muscles in patients with chronic obstructive pulmonary disease. Fourteen patients (males, FEV1, 24 +/- 7% predicted) were randomized to either inspiratory muscle or sham training groups. Supervised breathing using a threshold inspiratory device was performed 30 minutes per day, five times a week, for 5 consecutive weeks. The inspiratory training group was subjected to inspiratory loading equivalent to 40 to 50% of their maximal inspiratory pressure. Biopsies from external intercostal muscles and vastus lateralis (control muscle) were taken before and after the training period. Muscle samples were processed for morphometric analyses using monoclonal antibodies against myosin heavy chain isoforms I and II. Increases in both the strength and endurance of the inspiratory muscles were observed in the inspiratory training group. This improvement was associated with increases in the proportion of type I fibers (by approximately 38%, p < 0.05) and in the size of type II fibers (by approximately 21%, p < 0.05) in the external intercostal muscles. No changes were observed in the control muscle. The study demonstrates that inspiratory training induces a specific functional improvement of the inspiratory muscles and adaptive changes in the structure of external intercostal muscles.

Injury of the diaphragm may have clinical relevance having been reported in cases of sudden infant death syndrome or fatal asthma. However, examination of diaphragm injury after acute inspiratory loading has not been reported. The purpose of this study was to determine whether an acute inspiratory overload induces injury of the human diaphragm and to determine if diaphragm from chronic obstructive pulmonary disease (COPD) is more susceptible to injury. Eighteen patients with COPD and 11 control patients with normal pulmonary function (62 +/- 10 yr) undergoing thoracotomy or laparotomy were studied. A threshold inspiratory loading test was performed prior to surgery in a subset of seven patients with COPD and five control patients. Samples of the costal diaphragm were obtained during surgery and processed for electron microscopy analysis. Signs of sarcomere disruption were found in all diaphragm samples. The range of values of sarcomere disruption was wide (density: 2-45 abnormal areas/100 microm(2); area fractions: 1.3-17.3%), significantly higher in diaphragm from patients with COPD (p < 0.05) and with the greatest injury after inspiratory loading. We conclude that sarcomere disruption is common in the human diaphragm, is more evident in patients with COPD, and is higher after inspiratory loading, especially in the diaphragm of those with COPD.

It was hypothesised that wood smoke exposure could be a risk factor for chronic obstructive pulmonary disease (COPD) in Spain. The present study was designed as a casecontrol study of 120 females requiring hospitalisation during 2001-2003 at Hospital del Mar (Barcelona, Spain).Cases were recruited from hospital records as females who had been admitted for an exacerbation of COPD. Controls were obtained from pulmonary function test laboratory consultations prior to a surgical intervention. All patients answered a standardised questionnaire.Exposure to wood or charcoal smoke was strongly associated with COPD after adjusting for age and smoking. The association between length of exposure and COPD suggested a doseresponse pattern. Intensity of exposure in both summer and winter was also related to COPD. Wood or charcoal alone independently increased risk of COPD (odds ratio (OR) 1.8 and 1.5, respectively), but only the combination of both was statistically significant (OR 4.5).In conclusion, the present study shows a strong association between wood or charcoal smoke exposure and chronic obstructive pulmonary disease, supporting its existence not only in developing countries, but also in European countries, such as Spain. Further studies assessing whether this association also exists in other European societies are warranted.

The aims of this study were to investigate whether the impairment in endurance of limb muscles is a general finding in chronic obstructive pulmonary disease (COPD) patients, affecting even those with mild-to-moderate disease or relatively normal physical activity. In addition, this study aimed to determine the physiopathology of exhaustion in local endurance tests and whether the reduction in quadriceps endurance can be predicted from muscle strength measurements.A total of 75 volunteers were assigned to one of two groups according to pulmonary function tests: COPD patients or healthy age-matched controls. Functional assessment included both quadriceps strength (maximum voluntary contraction (QMVC)), and quadriceps endurance (contractions against a load equivalent to 10% QMVC until task failure or for up to a limiting time of 30 min (QTlim)).COPD patients showed a decrease of y43% in QMVC and y77% in QTlim compared with controls. Task failure occurred only in COPD patients and was due to muscle fatigue, since limiting symptoms were associated with a decrease in the median frequency of quadriceps electromyographical signal and a reversible decrease in QMVC. The impairment in skeletal muscle endurance was present even in patients with mild-tomoderate airflow obstruction and individuals with relatively normal physical activity, and was irrespective of lung function variables, anthropometrical data or quadriceps strength.Peripheral muscle endurance was impaired in chronic obstructive pulmonary disease patients, even in those with relatively normal physical activity and mild-to-moderate airflow obstruction. This impairment associated with an early onset of muscle fatigue and could not be predicted from the severity of the disease or the reduction in quadriceps strength. Eur Respir J 2004; 24: 129-136.

AimsThe purpose of this study was to evaluate the effectiveness, feasibility, and safety of a 4-week high-intensity inspiratory muscle training (hi-IMT) in patients with chronic heart failure (CHF). Methods and resultsA double-blind randomized clinical trial was carried out in 22 patients with CHF. Participants were assigned to the hi-IMT or sham-IMT group. The trainer device was a prototype of the Orygen-Dual Valve w . The training workloads were adjusted weekly at the inspiratory pressure which allowed the performance of 10 consecutive maximal repetitions (10RM). Main outcomes were strength and endurance of the respiratory muscles assessed by maximal respiratory pressures (PI max and PE max ) and a 10RM manoeuvre, respectively. Twenty-one patients presented impairment in respiratory muscle strength and endurance. Patients in the hi-IMT group showed a significant improvement in both strength and endurance: inspiratory muscle strength in the intervention group increased 57.2% compared with 25.9% in the control group (P ¼ 0.001). The percentage change in endurance was 72.7% for the hi-IMT group compared with 18.2% in the sham-IMT group (P , 0.001). No adverse effects occurred during the intervention. ConclusionA 4-week hi-IMT with the use of the Orygen-Dual Valve w is shown to be an effective, feasible, and safe tool to improve weakness and fatigue of the inspiratory muscles. The key point of this study is to discuss immediate practical implications in terms of respiratory muscle dysfunction postulated as a potential prognostic factor and as an additional therapeutic target. Trials registration

The aim of this study was to evaluate the effect of two body positions (supine and semirecumbency) on the dynamics of gastroesophageal reflux (GER) in 15 patients requiring mechanical ventilation and having a nasogastric tube in place. Samples of gastric contents, pharyngeal and bronchial secretions, and blood were obtained at baseline and every hour during a period of 5 h after nasogastric tube isotopic instillation of 37 megabecquerels of Tc99m. Radioactivity counting (RAc) was performed using a gamma counter with correction for decay. Irrespective of the body position, all patients showed at 3, 4, and 5 h after the isotope instillation a significant increase in RAc of the oropharyngeal contents (p < 0.05, each), indicating GER. Although RAc values in the pharynx were higher in supine from 1 through 4 h (p < 0.05), at the end of the study (5 h) the values did not differ between each position. Likewise, the slopes of the regression lines of sequential oropharyngeal RAc values were not different between each position (0.39 +/- 0.09 versus 0.45 +/- 0.11, respectively). In contrast, RAc values in bronchial secretions were higher at 5 h in the supine position compared with baseline (p < 0.05) and to semirecumbency (p < 0.01). These results strongly support that GER in mechanically ventilated patients with a nasogastric tube is a feature occurring irrespective of body position. Semirecumbent position does not protect completely from GER and subsequently from oropharyngeal colonization from gastric origin.

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Pulmonary hyperinflation impairs the function of the diaphragm in patients with chronic obstructive pulmonary disease (COPD). However, it has been recently demonstrated that the muscle can counterbalance this deleterious effect, remodelling its structure (i.e. changing the proportion of different types of fibres). The aim of this study was to investigate whether the functional impairment present in COPD patients can be associated with structural subcellular changes of the diaphragm.Twenty individuals (609 yrs, 11 COPD patients and 9 subjects with normal spirometry) undergoing thoracotomy were included. Nutritional status and respiratory function were evaluated prior to surgery. Then, small samples of the costal diaphragm were obtained and processed for electron microscopy analysis.COPD patients showed a mean forced expiratory volume in one second (FEV1) of 609% predicted, a higher concentration of mitochondria (n mit ) in their diaphragm than controls (0.620.16 versus 0.460.16 mitochondrial transections (mt) . mm -2 , p<0.05). On the other hand, subjects with air trapping (residual volume (RV)/total lung capacity (TLC) >37%) disclosed not only a higher n mit (0.630.17 versus 0.430.07 mt . mm -2 , p<0.05) but shorter sarcomeres (L sar ) than subjects without this functional abnormality (2.080.16 to 2.270.15 mm, p<0.05). Glycogen stores were similar in COPD and controls. The severity of airways obstruction (i.e. FEV1) was associated with n mit (r=-0.555, p=0.01), while the amount of air trapping (i.e. RV/TLC) was found to correlate with both n mit (r=0.631, p=0.005) and L sar (r=-0.526, p<0.05). Finally, maximal inspiratory pressure (PI,max) inversely correlated with n mit (r-0.547, p=0.01).In conclusion, impairment in lung function occurring in patients with chronic obstructive pulmonary disease is associated with subcellular changes in their diaphragm, namely a shortening in the length of sarcomeres and an increase in the concentration of mitochondria. These changes form a part of muscle remodelling, probably contributing to a better functional muscle behaviour. Eur Respir J 1999; 13: 371±378. Chronic obstructive pulmonary disease (COPD) is a respiratory condition mainly characterized by persistent airflow limitation [1]. It affects >5% of the general population [2], is a cause of permanent disability and constitutes one of the leading and increasing causes of death in developed countries [3].The function of the diaphragm, the main respiratory muscle, can be impaired in patients with COPD owing to both airways obstruction and pulmonary hyperinflation (air trapping) [4±6]. However, it has been demonstrated that this deleterious effect can be partially counterbalanced by the muscle [7]. TAMAOKI [8] found that fibres were hypertrophic in the diaphragm of guinea-pigs with elastaseinduced emphysema. Recently, LEVINE et al.[9] have demonstrated that patients with severe COPD show a higher percentage of type I fibres in their diaphragm than subjects with normal lung function or mild COPD. These and other chan...