The effect of unproductive coughing/FET on regional mucus movement in the human lungs

The role of lung volume recruitment therapy in neuromuscular disease: a narrative review

Respiratory muscle weakness results in substantial discomfort, disability, and ultimately death in many neuromuscular diseases. Respiratory system impairment manifests as shallow breathing, poor cough and associated difficulty clearing mucus, respiratory tract infections, hypoventilation, sleep-disordered breathing, and chronic ventilatory failure. Ventilatory support (i.e., non-invasive ventilation) is an established and key treatment for the latter. As survival outcomes improve for people living with many neuromuscular diseases, there is a shift towards more proactive and preventative chronic disease multidisciplinary care models that aim to manage symptoms, improve morbidity, and reduce mortality. Clinical care guidelines typically recommend therapies to improve cough effectiveness and mobilise mucus, with the aim of averting acute respiratory compromise or respiratory tract infections. Moreover, preventing recurrent infective episodes may prevent secondary parenchymal pathology and further lung function decline. Regular use of techniques that augment lung volume has similarly been recommended (volume recruitment). It has been speculated that enhancing lung inflation in people with respiratory muscle weakness when well may improve respiratory system "flexibility", mitigate restrictive chest wall disease, and slow lung volume decline. Unfortunately, clinical care guidelines are based largely on clinical rationale and consensus opinion rather than level A evidence. This narrative review outlines the physiological changes that occur in people with neuromuscular disease and how these changes impact on breathing, cough, and respiratory tract infections. The biological rationale for lung volume recruitment is provided, and the clinical trials that examine the immediate, short-term, and longer-term outcomes of lung volume recruitment in paediatric and adult neuromuscular diseases are presented and the results synthesised.

Active cycle of breathing technique for cystic fibrosis

BACKGROUND

People with cystic fibrosis (CF) experience chronic airway infections as a result of mucus buildup within the lungs. Repeated infections often cause lung damage and disease. Airway clearance therapies aim to improve mucus clearance, increase sputum production, and improve airway function. The active cycle of breathing technique (ACBT) is an airway clearance method that uses a cycle of techniques to loosen airway secretions including breathing control, thoracic expansion exercises, and the forced expiration technique. This is an update of a previously published review.

OBJECTIVES

To compare the clinical effectiveness of ACBT with other airway clearance therapies in CF.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched clinical trials registries and the reference lists of relevant articles and reviews. Date of last search: 29 March 2021.

SELECTION CRITERIA

We included randomised or quasi-randomised controlled clinical studies, including cross-over studies, comparing ACBT with other airway clearance therapies in CF.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened each article, abstracted data and assessed the risk of bias of each study. We used GRADE to assess our confidence in the evidence assessing quality of life, participant preference, adverse events, forced expiratory volume in one second (FEV1) % predicted, forced vital capacity (FVC) % predicted, sputum weight, and number of pulmonary exacerbations.

MAIN RESULTS

Our search identified 99 studies, of which 22 (559 participants) met the inclusion criteria. Eight randomised controlled studies (259 participants) were included in the analysis; five were of cross-over design. The 14 remaining studies were cross-over studies with inadequate reports for complete assessment. The study size ranged from seven to 65 participants. The age of the participants ranged from six to 63 years (mean age 18.7 years). In 13 studies follow up lasted a single day. However, there were two long-term randomised controlled studies with follow up of one to three years. Most of the studies did not report on key quality items, and therefore, have an unclear risk of bias in terms of random sequence generation, allocation concealment, and outcome assessor blinding. Due to the nature of the intervention, none of the studies blinded participants or the personnel applying the interventions. However, most of the studies reported on all planned outcomes, had adequate follow up, assessed compliance, and used an intention-to-treat analysis. Included studies compared ACBT with autogenic drainage, airway oscillating devices (AOD), high-frequency chest compression devices, conventional chest physiotherapy (CCPT), positive expiratory pressure (PEP), and exercise. We found no difference in quality of life between ACBT and PEP mask therapy, AOD, other breathing techniques, or exercise (very low-certainty evidence). There was no difference in individual preference between ACBT and other breathing techniques (very low-certainty evidence). One study comparing ACBT with ACBT plus postural exercise reported no deaths and no adverse events (very low-certainty evidence). We found no differences in lung function (forced expiratory volume in one second (FEV1) % predicted and forced vital capacity (FVC) % predicted), oxygen saturation or expectorated sputum between ACBT and any other technique (very low-certainty evidence). There were no differences in the number of pulmonary exacerbations between people using ACBT and people using CCPT (low-certainty evidence) or ACBT with exercise (very low-certainty evidence), the only comparisons to report this outcome.

AUTHORS' CONCLUSIONS

There is little evidence to support or reject the use of the ACBT over any other airway clearance therapy and ACBT is comparable with other therapies in outcomes such as participant preference, quality of life, exercise tolerance, lung function, sputum weight, oxygen saturation, and number of pulmonary exacerbations. Longer-term studies are needed to more adequately assess the effects of ACBT on outcomes important for people with cystic fibrosis such as quality of life and preference.

Active cycle of breathing technique for cystic fibrosis

BACKGROUND

People with cystic fibrosis experience chronic airway infections as a result of mucus build up within the lungs. Repeated infections often cause lung damage and disease. Airway clearance therapies aim to improve mucus clearance, increase sputum production, and improve airway function. The active cycle of breathing technique (also known as ACBT) is an airway clearance method that uses a cycle of techniques to loosen airway secretions including breathing control, thoracic expansion exercises, and the forced expiration technique. This is an update of a previously published review.

OBJECTIVES

To compare the clinical effectiveness of the active cycle of breathing technique with other airway clearance therapies in cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles and reviews.Date of last search: 25 April 2016.

SELECTION CRITERIA

Randomised or quasi-randomised controlled clinical studies, including cross-over studies, comparing the active cycle of breathing technique with other airway clearance therapies in cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened each article, abstracted data and assessed the risk of bias of each study.

MAIN RESULTS

Our search identified 62 studies, of which 19 (440 participants) met the inclusion criteria. Five randomised controlled studies (192 participants) were included in the meta-analysis; three were of cross-over design. The 14 remaining studies were cross-over studies with inadequate reports for complete assessment. The study size ranged from seven to 65 participants. The age of the participants ranged from six to 63 years (mean age 22.33 years). In 13 studies, follow up lasted a single day. However, there were two long-term randomised controlled studies with follow up of one to three years. Most of the studies did not report on key quality items, and therefore, have an unclear risk of bias in terms of random sequence generation, allocation concealment, and outcome assessor blinding. Due to the nature of the intervention, none of the studies blinded participants or the personnel applying the interventions. However, most of the studies reported on all planned outcomes, had adequate follow up, assessed compliance, and used an intention-to-treat analysis.Included studies compared the active cycle of breathing technique with autogenic drainage, airway oscillating devices, high frequency chest compression devices, conventional chest physiotherapy, and positive expiratory pressure. Preference of technique varied: more participants preferred autogenic drainage over the active cycle of breathing technique; more preferred the active cycle of breathing technique over airway oscillating devices; and more were comfortable with the active cycle of breathing technique versus high frequency chest compression. No significant difference was seen in quality of life, sputum weight, exercise tolerance, lung function, or oxygen saturation between the active cycle of breathing technique and autogenic drainage or between the active cycle of breathing technique and airway oscillating devices. There was no significant difference in lung function and the number of pulmonary exacerbations between the active cycle of breathing technique alone or in conjunction with conventional chest physiotherapy. All other outcomes were either not measured or had insufficient data for analysis.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or reject the use of the active cycle of breathing technique over any other airway clearance therapy. Five studies, with data from eight different comparators, found that the active cycle of breathing technique was comparable with other therapies in outcomes such as participant preference, quality of life, exercise tolerance, lung function, sputum weight, oxygen saturation, and number of pulmonary exacerbations. Longer-term studies are needed to more adequately assess the effects of the active cycle of breathing technique on outcomes important for people with cystic fibrosis such as quality of life and preference.

Active cycle of breathing technique for cystic fibrosis

BACKGROUND

People with cystic fibrosis experience chronic airway infections as a result of mucus build up within the lungs. Repeated infections often cause lung damage and disease. Airway clearance therapies aim to improve mucus clearance, increase sputum production, and improve airway function. The active cycle of breathing technique (ACBT) is an airway clearance method that uses a cycle of techniques to loosen airway secretions including breathing control, thoracic expansion exercises, and the forced expiration technique.

OBJECTIVES

To compare the clinical effectiveness of ACBT with other airway clearance therapies in cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles and reviews.Date of last search: 02 August 2012.

SELECTION CRITERIA

Randomised or quasi-randomised controlled clinical studies, including cross-over studies, comparing ACBT with other airway clearance therapies in cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened each article, abstracted data and assessed the risk of bias of each study.

MAIN RESULTS

Sixty studies were identified of which 18 (375 participants) met the inclusion criteria. Five randomised controlled studies (127 participants) were included in the meta-analysis; four were of cross-over design. The 13 remaining studies were cross-over studies with inadequate reports for complete assessment.Included studies compared ACBT to autogenic drainage, airway oscillating devices, high frequency chest compression devices, conventional chest physiotherapy, and positive expiratory pressure. Patient preference varied: more patients preferred autogenic drainage over ACBT; more preferred ACBT over airway oscillating devices; and more were comfortable with ACBT versus high frequency chest compression. No significant difference was seen in sputum weight, lung function, or oxygen saturation between ACBT and autogenic drainage or between ACBT and airway oscillating devices. There was no significant difference in lung function and the number of pulmonary exacerbations between ACBT and ACBT plus conventional chest physiotherapy. All other outcomes were either not measured or had insufficient data for analysis.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or reject the use of ACBT over any other airway clearance therapy. Five studies, with five different comparators, found that ACBT was comparable to other therapies in outcomes such as patient preference, lung function, sputum weight, oxygen saturation, and number of pulmonary exacerbations. Longer-term studies are needed to more adequately assess the effects of ACBT on outcomes important for patients such as quality of life and patient preference.

WITHDRAWN: Bronchopulmonary hygiene physical therapy for chronic obstructive pulmonary disease and bronchiectasis

BACKGROUND

Bronchopulmonary hygiene physical therapy is a form of chest physical therapy including chest percussion and postural drainage to remove lung secretions. These are applied commonly to patients with both acute and chronic airway diseases. Despite controversies in the literature regarding its efficacy, it remains in use in a variety of clinical settings. The various forms of this therapy are labour intensive and need to be evaluated.

OBJECTIVES

The objective of this review was to assess the effects of bronchial hygiene physical therapy in people with chronic obstructive pulmonary disease and bronchiectasis.

SEARCH STRATEGY

We searched the Cochrane Airways Group trials register and reference lists of articles up to January 2007. We also wrote to study authors.

SELECTION CRITERIA

Randomised trials in which postural drainage, chest percussion, vibration, chest shaking, directed coughing or forced exhalation technique was compared to other drainage or breathing techniques, placebo or no treatment.

DATA COLLECTION AND ANALYSIS

Two reviewers applied the inclusion and exclusion criteria on masked publications independently. They assessed the trial quality independently. Only data from the first arm of crossover trials were included.

MAIN RESULTS

The seven included trials involved six comparisons and a total of 126 people. The trials were small and not generally of high quality. The results could not be combined as trials addressed different patient groups and outcomes. In most comparisons, bronchial hygiene physical therapy produced no significant effects on pulmonary function, apart from clearing sputum in chronic obstructive pulmonary disease and in bronchiectasis. An update search carried out in January 2007 did not identify any new studies for inclusion.

AUTHORS' CONCLUSIONS

There is not enough evidence to support or refute the use of bronchial hygiene physical therapy in people with chronic obstructive pulmonary disease and bronchiectasis.

Mucociliary and cough clearance as a biomarker for therapeutic development

A workshop/symposium on “Mucociliary and Cough Clearance (MCC/CC) as a Biomarker for Therapeutic Development” was held on October 21–22, 2008, in Research Triangle Park, NC, to discuss the methods for measurement of MCC/CC and how they may be optimized for assessing new therapies designed to improve clearance of airway secretions from the lungs. The utility of MCC/CC as a biomarker for disease progression and therapeutic intervention is gaining increased recognition as a valuable tool in the clinical research community. A number of investigators currently active in using MCC/CC for diagnostic or therapeutic evaluation presented details of their methodologies. Attendees participating in the workshop discussions included those interested in the physiology of MCC/CC, some of who use in vitro or animal methods for its study, pharmaceutical companies developing muco-active therapies, and many who were interested in establishing the methods in their own clinical laboratory. This review article summarizes the presentations for the in vivo human MCC/CC methods and the discussions both at and subsequent to the workshop between the authors to move forward on a number of questions raised at the workshop.

Active cycle of breathing technique for cystic fibrosis

BACKGROUND

People with cystic fibrosis (CF) experience chronic airway infections as a result of mucus build up within the lungs. Repeated infections often cause lung damage and disease. Airway clearance therapies aim to improve mucus clearance, increase sputum production, and improve airway function. The active cycle of breathing technique (ACBT) is an airway clearance method that uses a cycle of techniques to loosen airway secretions including breathing control, thoracic expansion exercises, and the forced expiration technique.

OBJECTIVES

To compare the clinical effectiveness of ACBT with other airway clearance therapies in CF.

SEARCH STRATEGY

We searched the Cochrane CF Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the reference lists of relevant articles and reviews.Last search: 05 August 2010.

SELECTION CRITERIA

Randomised or quasi-randomised controlled clinical studies, including crossover studies, comparing ACBT with other airway clearance therapies in CF.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened each article, abstracted data and assessed the risk of bias of each study.

MAIN RESULTS

Fifty-eight studies were identified of which 17 (346 participants) met the inclusion criteria. Four randomised controlled studies (98 participants) were included in the meta-analysis; three were of crossover design. The 13 remaining studies were crossover studies with inadequate reports for complete assessment.Included studies compared ACBT to autogenic drainage, airway oscillating devices, high frequency chest compression devices, and conventional chest physiotherapy. Patient preference varied: more patients preferred autogenic drainage over ACBT, more preferred ACBT over airway oscillating devices, and more were comfortable with ACBT versus high frequency chest compression. No significant difference was seen in sputum weight between ACBT and autogenic drainage or between ACBT and airway oscillating devices. There was no significant difference in lung function and the number of pulmonary exacerbations between ACBT and ACBT plus conventional chest physiotherapy. All other outcomes were either not measured or had insufficient data for analysis.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or reject the use of ACBT over any other airway clearance therapy. Four studies, with four different comparators, found that ACBT was comparable to other therapies in outcomes such as patient preference, lung function, sputum weight, oxygen saturation, and number of pulmonary exacerbations. Longer-term studies are needed to more adequately assess the effects of ACBT on outcomes important for patients such as quality of life and patient preference.

The effect of huffing and directed coughing on energy expenditure in young asymptomatic subjects

Coughing and huffing have been shown to be effective airway clearance techniques and some authors have anecdotally reported that a huff requires less energy than a series of coughs commencing and finishing at the same lung volume. The aim of this study was to determine whether there is a difference in the energy expenditure between periods of huffing and directed voluntary coughing commencing from the same initial lung volume in young asymptomatic subjects. Energy expenditure was measured using open-circuit indirect calorimetry equipment. Twenty-four non-smoking asymptomatic subjects (12 male, 12 female, aged 18-24 years), without any form of disease and within 10% of their predicted pulmonary function, completed the study. Energy expenditure was measured over three 10min, randomly ordered sessions of huffing, directed coughing and rest. The forced expiratory sessions comprised a single huff or double-barrel cough (both starting at total lung capacity) at the end of every two minutes. Each session was separated by a 5min washout period. No significant difference in energy expenditure was found between the huffing and directed coughing periods (mean difference 0.003 mL/kg/min (95% CI -0.160 to 0.114) and both produced significantly greater energy expenditure than rest (rest and huff mean difference 0.309 mL/kg/min (95% CI 0.080 to 0.549) and rest and cough mean difference 0.306 mL/kg/min (95% CI 0.074 to 0.508)). The suggested benefits of huffing versus coughing in terms of energy conservation are yet to be shown.

Effect of manually assisted cough and mechanical insufflation on cough flow of normal subjects, patients with chronic obstructive pulmonary disease (COPD), and patients with respiratory muscle weakness

BACKGROUND

It has been suggested that cough effectiveness can be improved by assisted techniques. The effects of manually assisted cough and mechanical insufflation on cough flow physiology are reported in this study.

METHODS

The physiological actions and patient self-assessment of manually assisted cough and mechanical insufflation were investigated in 29 subjects (nine normal subjects, eight patients with chronic obstructive pulmonary disease (COPD), four subjects with respiratory muscle weakness (RMW) with scoliosis, and eight subjects with RMW without scoliosis).

RESULTS

The peak cough expiratory flow rate and cough expiratory volume were not improved by manually assisted cough and mechanical insufflation alone or in combination in normal subjects. The median increase in peak cough expiratory flow in subjects with RMW without scoliosis with manually assisted cough alone or in combination with mechanical insufflation of 84 l/min (95% confidence interval (CI) 19 to 122) and 144 l/min (95% CI 14 to 195), respectively, reflects improvement in the expulsive phase of coughing by these techniques. Manually assisted cough and mechanical insufflation in combination raised peak expiratory flow rate more than either technique alone in this group. The abnormal chest shape in scoliotic subjects and the fixed inspiratory pressure used made effective manually assisted cough and mechanical insufflation difficult in this group and no improvements were found. In patients with COPD manually assisted cough alone and in combination with mechanical insufflation decreased peak expiratory flow rate by 144 l/min (95% CI 25 to 259) and 135 l/min (95% CI 30 to 312), respectively.

CONCLUSIONS

Manually assisted cough and mechanical insufflation should be considered to assist expectoration of secretions in patients with RMW without scoliosis but not in those with scoliosis.

Effect of manually assisted cough and mechanical insufflation on cough flow of normal subjects, patients with chronic obstructive pulmonary disease (COPD), and patients with respiratory muscle weakness

BACKGROUND

It has been suggested that cough effectiveness can be improved by assisted techniques. The effects of manually assisted cough and mechanical insufflation on cough flow physiology are reported in this study.

METHODS

The physiological actions and patient self-assessment of manually assisted cough and mechanical insufflation were investigated in 29 subjects (nine normal subjects, eight patients with chronic obstructive pulmonary disease (COPD), four subjects with respiratory muscle weakness (RMW) with scoliosis, and eight subjects with RMW without scoliosis).

RESULTS

The peak cough expiratory flow rate and cough expiratory volume were not improved by manually assisted cough and mechanical insufflation alone or in combination in normal subjects. The median increase in peak cough expiratory flow in subjects with RMW without scoliosis with manually assisted cough alone or in combination with mechanical insufflation of 84 l/min (95% confidence interval (CI) 19 to 122) and 144 l/min (95% CI 14 to 195), respectively, reflects improvement in the expulsive phase of coughing by these techniques. Manually assisted cough and mechanical insufflation in combination raised peak expiratory flow rate more than either technique alone in this group. The abnormal chest shape in scoliotic subjects and the fixed inspiratory pressure used made effective manually assisted cough and mechanical insufflation difficult in this group and no improvements were found. In patients with COPD manually assisted cough alone and in combination with mechanical insufflation decreased peak expiratory flow rate by 144 l/min (95% CI 25 to 259) and 135 l/min (95% CI 30 to 312), respectively.

CONCLUSIONS

Manually assisted cough and mechanical insufflation should be considered to assist expectoration of secretions in patients with RMW without scoliosis but not in those with scoliosis.

Bronchopulmonary hygiene physical therapy for chronic obstructive pulmonary disease and bronchiectasis

BACKGROUND

Bronchopulmonary hygiene physical therapy is a form of chest physical therapy including chest percussion and postural drainage to remove lung secretions. These are applied commonly to patients with both acute and chronic airway diseases. Despite controversies in the literature regarding its efficacy, it remains in use in a variety of clinical settings. The various forms of this therapy are labour intensive and need to be evaluated.

OBJECTIVES

The objective of this review was to assess the effects of bronchial hygiene physical therapy in people with chronic obstructive pulmonary disease and bronchiectasis.

SEARCH STRATEGY

We searched the Cochrane Airways Group trials register and reference lists of articles up to July 1997. We also wrote to study authors.

SELECTION CRITERIA

Randomised trials in which postural drainage, chest percussion, vibration, chest shaking, directed coughing or forced exhalation technique was compared to other drainage or breathing techniques, placebo or no treatment.

DATA COLLECTION AND ANALYSIS

Two reviewers applied the inclusion and exclusion criteria on masked publications independently. They assessed the trial quality independently. Only data from the first arm of crossover trials were included.

MAIN RESULTS

The seven included trials involved six comparisons and a total of 126 people. The trials were small and not generally of high quality. The results could not be combined as trials addressed different patient groups and outcomes. In most comparisons, bronchial hygiene physical therapy produced no significant effects on pulmonary function, apart from clearing sputum in chronic obstructive pulmonary disease and in bronchiectasis.

REVIEWER'S CONCLUSIONS

There is not enough evidence to support or refute the use of bronchial hygiene physical therapy in people with chronic obstructive pulmonary disease and bronchiectasis.

Regional lung clearance during cough and forced expiration technique (FET): effects of flow and viscoelasticity

BACKGROUND

In vitro studies have suggested that both the viscoelastic properties of lung secretions and the peak flow attained during simulated cough influence clearance. This study examines the possible association of the viscoelastic properties of sputum and maximum expiratory flow with measured effectiveness of mucus clearance induced by instructed cough and by forced expiration technique (FET) in patients with airways obstruction.

METHODS

Nineteen patients (11 men and eight women) of mean (SE) age, % predicted FEV1, and daily sputum wet weight of 64 (2) years, 52 (6)%, and 37.5 (7.9) g respectively participated in the study. Mucus movement from proximal and peripheral lung regions was measured by an objective non-invasive radioaerosol technique. Each patient underwent three assessments: control, cough, and FET. During cough and FET, maximum expiratory flow was measured at the mouth level. Apparent viscosity and elasticity of the expectorated sputum samples were measured with a viscometer.

RESULTS

Compared with the control run (mean (SE) clearance: 16 (3)%) there was an increase in clearance from the whole lung during cough (44 (5)%) and FET (42 (5)%), and also an enhanced clearance of inhaled, deposited radioaerosol from the trachea, inner and intermediate regions of the lungs, but not from the outer region. There were, however, no differences in regional clearance between cough and FET. Neither regional nor total clearance correlated with maximum expiratory flow, apparent viscosity, elasticity, or daily sputum wet weight.

CONCLUSIONS

These results confirm that cough and FET both promote effective clearance but suggest that, unlike in vitro studies, sputum production and viscoelasticity, as well as maximum expiratory flow, provide no guide to clearance efficacy in humans.

Regional mucus transport following unproductive cough and forced expiration technique in patients with airways obstruction

It has previously been shown that unproductive coughing in both healthy subjects and patients with airways obstruction is not effective in clearing lung secretions. This study investigates the regional mucus transport in a group of subjects with airways obstruction who failed to expectorate following instructed cough and forced expiration technique. Fourteen patients (mean +/- SEM age: 68 +/- 2 years) with airways obstruction (mean +/- SEM percent predicted. FEV1: 54 +/- 5; daily wet weight sputum: 9.1 +/- 2.0 g) took part in the study which was a randomized, three-way crossover within-patient design. Each patient underwent three treatment maneuvers: control, cough (30 coughs over a 10-min period), and forced expiration (30 forced expirations over a 10-min period). An objective radioaerosol technique was used to monitor regional mucus movement within the lungs of the patients. The lungs were divided arbitrarily into four regions of interest: tracheal, inner, intermediate, and outer. Peak expiratory flow rate during cough and forced expiration was measured at the mouth. There was no correlation between the radioaerosol clearance from all regions and (1) mean peak flow during cough and forced expiration, and (2) mean 24-h sputum production prior to the study day. There were no differences in regional radioaerosol clearance between cough and forced expiration. However, both cough and forced expiration resulted in significant clearance compared with control for all regions with the exception of the forced expiration in the outer region. To our knowledge, this study is the first to demonstrate that unproductive cough and forced expiration result in movement of secretions proximally from all regions of the lung in patients with airways obstruction.

Impairment of lung mucociliary clearance in pigeon fanciers

Lung mucociliary clearance was measured in 15 pigeon fanciers. The study group was subdivided into two: a precipitin-positive group (n = 10; mean +/- SEM age 45 +/- 5 years) with circulating blood precipitins and a precipitin-negative group (n = 5; mean +/- SEM age 40 +/- 3 years) without. Clearance was measured using an objective, noninvasive radioaerosol technique. The data for both groups were compared with those of matched control groups of healthy subjects. The mean +/- SEM area under the tracheobronchial retention curves (AUC) over the 6-h observation period was 257 +/- 27 %h for the precipitin-positive group compared with 177 +/- 16 %h for its control group (p = 0.02)--a high AUC value denoting slow clearance. That for the precipitin-negative group was 282 +/- 34 %h compared with 150 +/- 15 %h for its control group (p = 0.02). Our study illustrates in pigeon fanciers involvement of the conducting airways in that a major defense mechanism of the airways--namely, mucociliary clearance--is substantially compromised. The presence or absence of precipitins appears not to be related to the degree of mucociliary clearance impairment.

Tracheobronchial clearance in patients with pulmonary sarcoidosis

Lung mucociliary clearance was measured using an objective, noninvasive radioaerosol technique in 13 patients with pulmonary sarcoidosis and 13 matched, healthy control subjects. Four of the sarcoid patients had never received any steroid therapy, five were currently receiving oral corticosteroids, and the remaining four were using inhaled corticosteroids only. A statistically significant retardation in tracheobronchial clearance (p less than 0.02) was observed in the sarcoid patients compared to the control subjects. The sarcoid patients using inhaled corticosteroids appeared to demonstrate the greatest degree of mucociliary transport impairment. The sarcoid patients in apparent remission and those receiving oral corticosteroid therapy had clearances better than those using inhaled corticosteroids, but they were still reduced compared to the control subjects. This study demonstrates that lung mucociliary clearance is adversely affected in patients with pulmonary sarcoidosis and raises the question of the possible consequences that could follow long-term inhaled immunosuppressive therapy on the prime clearance defense mechanism within the human lungs.