[Can cough peak flow be used to assess cough capacity in severe obstructive respiratory diseases?] / ¿Se puede utilizar la determinación del pico flujo de tos para valorar la capacidad tusígena en enfermedades respiratorias obstructivas graves?

INTRODUCTION: Cough capacity is assessed by measuring cough peak flow (CPF). However, this assessment could be altered by obstructive airway diseases. The aim was to assess measurement of cough capacity by CPF in patients with chronic obstructive pulmonary disease (COPD), as well as correlations with pulmonary, respiratory muscle, and oropharyngeal function. METHODS: Patients with COPD, and with neuromuscular disease, were selected as well as healthy subjects who had undergone respiratory muscle strength measurement in a healthcare setting. From this population, respiratory function values and lung and oropharyngeal muscle function were analysed. A subgroup of COPD patients underwent a videofluoroscopic swallow study. RESULTS: Three hundred and seven subjects were included (59.3% COPD, 38.4% neuromuscular diseases, and 2.3% healthy). CPF was found to be statistically significantly decreased in the COPD group compared to both the healthy and neuromuscular disease groups. Of the COPD patients, 70% had a pathological decrease in CPF. There was only a direct correlation between CPF with the degree of bronchial obstruction and expiratory muscle strength. No alteration of inspiratory or oropharyngeal muscle function was found. CONCLUSIONS: The use of CPF in COPD patients does not reflect cough capacity as it is influenced by the degree of bronchial obstruction. Therefore, new diagnostic tests to measure cough capacity should be considered, especially in patients with coexisting neuromuscular diseases and severe bronchial obstructive disease.

[Effects of high frequency chest wall oscillatory (HFCWO) therapy on gas exchange and ventilation in healthy participants]. / Efectos en población sana de la terapia con oscilación de alta frecuencia sobre la pared torácica (HFCWO) a nivel de la dinámica de gases pulmonares y de la mecánica respiratoria.

INTRODUCTION: Chest physiotherapy is an essential part of the treatment of respiratory diseases with increased respiratory secretion and ineffective cough. To date, there have been no studies on the effect of high frequency chest wall oscillatory (HFCWO) therapy on respiratory muscle strength, ventilation and gas exchange. The aim of this study was therefore to assess these three factors in healthy participants. METHODS: Respiratory muscle strength was measured before and immediately after HFCWO therapy in 25 healthy participants. During the treatment, we continuously measured ventilation parameters, gas exchange, oxygen saturation and heart rate. All participants underwent HFCWO sessions twice (with 24hours difference) with the same procedure. Symptoms during the session and discomfort were measured with the visual analog scale (VAS). RESULTS: HFCWO therapy produced a change in breathing pattern with increased ventilation associated with altered gas exchange. Heart rate also increased, with no changes in oxygenation. There was no effect, either beneficial or deleterious, on the strength of respiratory muscles. Up to 20% of participants reported substantial discomfort (VAS≥5/10) during the session. CONCLUSIONS: This study shows that, during the application of HFCWO therapy in healthy participants, ventilation and heart rate increased. However, there were undesirable effects on gas exchange with a high degree of intolerance among volunteers, with no effects on respiratory muscle strength.

Muscle dysfunction and exercise limitation in adolescent idiopathic scoliosis.

Adolescent idiopathic scoliosis (AIS) can lead to ventilatory restriction, respiratory muscle weakness and exercise limitation. However, both the causes and the extent of muscle dysfunction remain unclear. The aim of our study is to describe muscle weakness and its relationship to lung function and tolerance to exercise in AIS patients. Lung and muscle function, together with exercise capacity, were assessed in 60 patients with pronounced spinal deformity (>40 degrees) and in 25 healthy volunteers. Patients with AIS had only mild to moderate abnormal ventilatory patterns, the most frequent of which were restrictive abnormalities. The function of respiratory and limb muscles and exercise capacity were below normal limits in AIS patients, and were significantly lower than in controls. Exercise capacity was found to correlate with the function of inspiratory, expiratory, upper limb and lower limb muscles which, in addition, were reciprocally interrelated. Multivariate analysis showed that lower limb muscle function is the main contributor to exercise intolerance. There appeared to be no connection between spinal deformity and lung function, muscle function or exercise capacity. We conclude that AIS patients show generalised muscle dysfunction which contributes to the reduction in their exercise capacity, even in the absence of severe ventilatory impairment.

[Low-weight syndrome associated with COPD in our setting]. / Síndrome de bajo peso asociado a la EPOC en nuestro medio.

UNLABELLED: The high prevalence of chronic obstructive pulmonary disease (COPD) has considerable economic and health-related impact. The consequences arise largely from limitations on a patient's activity and shortened life expectancy. Low body weight has recently been implicated as a factor affecting limitations. Although the reason is not clear, weight loss appears to affect many patients (from 25 to 35% in different series), at least in Europe and North America. However, the situation is thought to be different in the Mediterranean area. OBJECTIVE: To estimate the prevalence of the low weight syndrome in patients with COPD in our area. METHODS: COPD patient characteristics monitored by our laboratory over the last two years (2000 and 2001) were reviewed. RESULTS: The prevalence of a body mass index (BMI) less than 20 kg/m2 was only 6.6% among the 3,126 patients studied. That percentage fell to 3.1% with a cutoff of 18 kg/m2. The figure was even more striking if we consider that half the patients had severe disease (FEV1 < 50% of reference). BMI was directly related to FEV1/FC and CO transfer. CONCLUSIONS: These results suggest that COPD patients in our geographic area have characteristics that distinguish them from those previously described in other countries. Specifically, the prevalence of low weight syndrome in our area appears to be lower. However, larger studies should be performed to confirm this finding.

Place of death in patients with amyotrophic lateral sclerosis.

UNLABELLED: Amyotrophic lateral sclerosis (ALS) is a degenerative neurological disorder that affects motor neurons. Involvement of respiratory muscles causes the failure of the ventilator pump with more or less significant bulbar troubles. ALS course is highly variable but, in most cases, this disease entails a very significant burden for patients and caregivers, especially in the end-of-life period. In order to analyze the characteristics of ALS patients who die at home (DH) and in hospital (DHosp) and to study the variability of clinical practice, a retrospective medical records analysis was performed (n=77 from five hospitals). VARIABLES: time elapsed since the onset of symptoms and the beginning of ventilation, characteristics of ventilation (device, mask and hours/day), and support devices and procedures. RESULTS: In all, 14% of patients were ventilated by tracheotomy. From the analysis, 57% of patients were of DH. Mean time since the onset of symptoms was 35.93±25.89 months, significantly shorter in patients who DHosp (29.28±19.69 months) than DH (41.12±29.04) (p=0.044). The percentage of patients with facial ventilation is higher in DHosp (11.4% vs 39.4%, p<0.005). DH or not is related to a set of elements in which health resources, physician attitudes and support resources in the community play a role in the decision-making process. There is great variability between countries and between hospitals in the same country. Given the variability of circumstances in each territory, the place of death in ALS might not be the most important element; more important are the conditions under which the process unfolds.

Interpretation of the approximate entropy using fixed tolerance values as a measure of amplitude variations in biomedical signals.

A new method for the quantification of amplitude variations in biomedical signals through moving approximate entropy is presented. Unlike the usual method to calculate the approximate entropy (ApEn), in which the tolerance value (r) varies based on the standard deviation of each moving window, in this work ApEn has been computed using a fixed value of r. We called this method, moving approximate entropy with fixed tolerance values: ApEn(f). The obtained results indicate that ApEn(f) allows determining amplitude variations in biomedical data series. These amplitude variations are better determined when intermediate values of tolerance are used. The study performed in diaphragmatic mechanomyographic signals shows that the ApEn(f) curve is more correlated with the respiratory effort than the standard RMS amplitude parameter. Furthermore, it has been observed that the ApEn(f) parameter is less affected by the existence of impulsive, sinusoidal, constant and Gaussian noises in comparison with the RMS amplitude parameter.

Upregulation of pro-inflammatory cytokines in the intercostal muscles of COPD patients.

Muscle dysfunction is a characteristic feature of chronic obstructive pulmonary disease (COPD). Recent studies suggest that cytokines may operate as local regulators of both muscle function and regeneration. The aim of the present study was to characterise the expression of different cytokines in the external intercostal muscle of COPD. Muscle biopsies were obtained from 25 stable COPD patients and eight healthy controls. Local tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, -6 and -10 expressions (real-time PCR and ELISA), sarcolemmal damage (immunohistochemistry), and the transcript levels of CD18 were assessed. Muscle TNF-alpha and IL-6 transcripts were significantly higher in COPD patients compared with controls, and IL-1beta and sarcolemmal damage showed a strong tendency in the same direction. Similar results were observed at protein level. The CD18 panleukocyte marker was similar in COPD and controls. Respiratory muscle function was impaired in COPD patients and it correlated to both the severity of lung function impairment and TNF-alpha muscle expression. Chronic obstructive pulmonary disease is associated with the upregulation of pro-inflammatory cytokines in the intercostal muscles. This phenomenon might be involved in respiratory muscle dysfunction.