[Can cough peak flow be used to assess cough capacity in severe obstructive respiratory diseases?]

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]

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.

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.

[Low-weight syndrome associated with COPD in our setting]

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.