Sleep Apnoea in Diabetic Patients with Autonomic Neuropathy

Breathing during sleep was monitored in 8 diabetic patients with objective evidence of autonomic neuropathy and in 8 diabetic patients without neuropathy. Thirty or more periods of apnoea lasting 10 seconds or longer during one night's sleep were demonstrated in 3 of the diabetic patients with autonomic neuropathy. Such apnoeic periods may be related to the high incidence of cardiorespiratory arrests reported in such patients, particularly in association with anaesthesia or pneumonia.

Use of dry powder inhalers in COPD

INTRODUCTION

This was a study of 30 chronic obstructive pulmonary disease (COPD) patients to assess the ease of use and preference of four dry powder inhalers -- accuhaler, aerolizer, handihaler, turbohaler -- the accuhaler and turbohaler are multidose devices, whereas the aerolizer and handihaler are single dose devices.

METHOD

None of the subjects had previous experience of dry powder inhalers. The correct technique for each inhaler was divided into 12 steps including one critical step that if not performed would result in no drug delivery. Subjects were shown the correct technique for each inhaler in a random order and were assessed immediately and 1 h later. Each subject was asked to rank the four devices for preference and ease of use, as well as to assess how comfortable it felt to inhale through the device using a visual analogue scale.

RESULTS

The numbers of perfect scores were not significantly different between devices, but the number of fatal errors that would result in no drug delivery was significantly more common in single dose devices (p < 0.01). There were significant differences in the rankings of each device (Friedman test, p < 0.005) with the turbohaler being ranked first most often and the handihaler last. The turbohaler scored highest for comfort of inhalation and the accuhaler lowest, but differences were small.

CONCLUSIONS

In COPD patients starting on dry powder inhalers, multidose devices appear to be preferred, have fewer problems and are easier to use effectively.

Snoring, not just a social nuisance

Snoring is a very common source of complaints from partners and neighbours. Snorers themselves are less likely to be affected, unless they have associated daytime sleepiness caused by the sleep disruption from obstructive sleep apnoea. There is increasingly firm evidence that obstructive sleep apnoea is associated with hypertension, cardiovascular, cerebrovascular and metabolic problems such as insulin resistance, even at mild levels which may not cause much daytime somnolence. In addition, the central and obstructive apnoeas found in cardiac failure affect heart muscle function. Treatment of the apnoea improves blood pressure and cardiac function and is likely to have a beneficial effect on mortality. Since obstructive sleep apnoea is common it should be sought by appropriate questioning in these patient groups. The treatments for obstructive sleep apnoea are effective but cumbersome and this remains a challenge if patients do not achieve obvious early benefits such as reduction in sleepiness or breathlessness.

Computer assisted learning is an effective way of teaching endocrinology

OBJECTIVES

Computers are a part of everyday life and offer an exciting way of learning. The aim of our study was to determine the effectiveness of teaching undergraduate endocrinology using a Computer Assisted Learning (CAL) programme.

DESIGN AND SUBJECTS

One hundred and eighty-five first year clinical medical students were randomly assigned either to attend a series of conventional lectures (n = 77) or to have the same material available through a CAL programme.

MEASUREMENTS

A multiple choice question examination was performed before and after the course. Lecture attendance and individual usage of the computer system were recorded. Students were asked to fill in an evaluation form at the end of the study.

RESULTS

There was no significant difference in the first examination scores between the groups. Both groups improved their scores after the course. Students spent longer performing CAL than attending lectures. Those who scored lowest in the first examination spent the most time on the CAL course. Those who spent the most time on the CAL course showed the largest improvement in examination score. Thirty-six out of the 42 students, who completed an evaluation of the CAL programme, rated it better than the standard lectures.

CONCLUSIONS

Computer assisted learning is an effective way of increasing knowledge in teaching undergraduate endocrinology. The course was easy to run and was valued more highly than conventional lectures. The module is now running routinely in the year 3 clinical firms at St Thomas' and has resulted in an increase in knowledge in the end of firm assessment.

Inspiratory muscle strength in acute asthma

STUDY OBJECTIVES

The aim of this study was to measure inspiratory pressure-generating capacity in patients presenting with acute asthma, as it has been suggested that inspiratory muscle fatigue may contribute to breathlessness and acute respiratory failure.

DESIGN

Descriptive study.

SETTING

Emergency departments of two inner-city hospitals.

PATIENTS

Fifty-one patients with acute asthma, and 45 patients without respiratory disease who served as control subjects.

MEASUREMENTS AND RESULTS

Maximum inspiratory pressure-generating capacity was measured soon after presentation by the sniff nasal inspiratory pressure (SNIP) method. The mean (SD) SNIP was 110 cm H(2)O (23 cm H(2)O) in men with asthma (mean for control subjects, 126 cm H(2)O [25 cm H(2)O]; p < 0.05) and 80 cm H(2)O [24 cm H(2)O] in women with asthma (mean for control subjects, 105 cm H(2)O (26 cm H(2)O); p < 0.01). In a second study of simultaneous SNIP and intrathoracic pressure measurements in a group of patients with acute asthma (n = 10) and control subjects (n = 11), the effect of airways obstruction on SNIP was assessed. The measurement of sniff esophageal pressure was more negative than SNIP by approximately 16% in asthmatic patients and by 4% in control subjects. Taking account of the likely effect of airways obstruction on SNIP, the reduction in inspiratory pressure-generating capacity that was observed in these patients with moderately severe acute asthma was minor and was consistent with the modest hyperinflation observed.

CONCLUSIONS

This study did not find evidence of inspiratory muscle weakness or fatigue in patients with moderately severe acute asthma presenting to the emergency department.

Pulmonary echinococcosis with chest wall involvement in a patient with no apparent risk factors

Pulmonary hydatid disease is rare in the U.K., and chest wall involvement has to our knowledge not previously been described in this country. We report the case of a 72-year-old man who was found to have a left upper lobe opacity on his chest radiograph. He declined further investigation at the time, but 2 years later developed a palpable mass over his left lateral chest wall. Fine-needle aspiration-biopsy of this mass revealed the diagnosis of pulmonary hydatid disease. Despite thorough questioning, no risk factor could be identified for the development of the disease. Hydatid disease should be remembered as a rare cause of mass lesions identified on chest radiographs even in non-endemic regions. Spread to the chest wall may mimic malignancy.

Clinical safety of SonoVue, a new contrast agent for ultrasound imaging, in healthy volunteers and in patients with chronic obstructive pulmonary disease

RATIONALE AND OBJECTIVES

To evaluate the safety profile of SonoVue, a new echo-contrast agent based on stabilized sulfur hexafluoride (SF6) microbubbles, in healthy volunteers and in patients with chronic obstructive pulmonary disease (COPD).

METHODS

Safety and tolerability of SonoVue were evaluated in 66 healthy volunteers during two placebo-controlled phase I studies (a single intravenous ascending-dose study in 36 volunteers given SonoVue doses of 0.003 to 0.12 mL/kg and a multiple-dose study in 30 subjects given cumulative doses of 0.15 to 0.6 mL/kg) and in 12 patients with COPD of various degrees of clinical severity, who were given SonoVue at a dosage of 4 mL (corresponding to 0.057 mL/kg in a 70-kg patient). Adverse events were monitored up to 48 to 72 hours after administration. All volunteers underwent extensive safety assessments (monitoring of vital signs, electrocardiogram, blood oxygen saturation, laboratory assessments, and Mini-Mental test) up to 24 to 72 hours after administration. In addition, patients with COPD underwent specific lung function tests, such as forced expiratory volume, forced vital capacity, and forced midexpiratory flow.

RESULTS

No serious adverse events occurred throughout the study. All nonserious adverse events were minor, mild, and rapidly self-resolving. No difference in the incidence of adverse events was observed among the various dosages of SonoVue and between SonoVue and placebo. There were no clinically significant changes in any of the safety assessments. No statistically significant differences between SonoVue and placebo were observed in mean forced expiratory volume, forced vital capacity, or forced midexpiratory flow levels. No substantial changes from baseline in blood oxygen saturation were observed for either study agent at any postinjection time point.

CONCLUSIONS

SonoVue showed a good safety profile both in healthy subjects and in patients with COPD.

Current treatment of asthma--focus on leukotrienes

Since their identification in 1979, the cysteinyl leukotrienes (cysLTs) have been shown to be prominent in many inflammatory conditions, including asthma, allergic rhinitis, rheumatoid arthritis, psoriasis, cystic fibrosis and inflammatory bowel disease. They are potent pro-inflammatory agents, as well as causing bronchoconstriction, and undoubtedly have a role in asthma. The cysLTs are products of arachidonic acid metabolism and have been shown to have effects via a cysteinyl leukotriene receptor (CysLTR1) on vascular permeability, mucus production, chemotaxis and bronchial smooth muscle. Their detection in certain body fluids in allergic, aspirin-sensitive and exercise-induced asthma is well documented and potential roles in pathogenesis, proposed. The development of agents affecting production or action offers an exciting new approach to the treatment of asthma. Two approaches to antileukotriene therapy have been developed: blocking their production by inhibiting the action of 5-lipoxygenase enzyme or blocking the CysLTR1. Both approaches have been tried in studies in asthma and overall the results are encouraging, with a decrease in both daytime and nocturnal symptoms, a decrease in additional beta 2 agonist usage and improvement in lung function. The changes, however, are small in some studies. This may be a reflection of disease severity in the study subjects, but of note is a heterogeneity of response to these treatments that may be genetically determined. Antileukotriene therapy has been shown to have an effect in specific types of asthma where the role of cysLTs seems well established--aspirin-sensitive/intolerant asthma and exercise-induced asthma. Longer term studies are needed in other areas such as severe asthma and chronic persistent asthma in both children and adults to provide evidence for the appropriate placement of antileukotriene treatment in current asthma guidelines, in comparison with other established treatments.

Subepithelial immunopathology of the large airways in smokers with and without chronic obstructive pulmonary disease

Previous work has shown an increase in CD8+ T-cells, neutrophils and eosinophils in small airway subepithelium in smokers. The authors have now investigated whether similar changes occur in the large airways. Immunohistochemistry on frozen sections of bronchial biopsies were obtained at bronchoscopy in 11 nonsmokers, eight asymptomatic smokers and 11 smokers with chronic bronchitis and chronic obstructive pulmonary disease (COPD). There was an increase in the number of CD8+ cells infiltrating the bronchial subepithelium in the COPD group compared to the asymptomatic smokers (305 (109-400) versus 92 (41-550) cells x mm(-2), p=0.030). There was a negative correlation between the number of CD8+ cells and the forced expiratory volume in one second (FEV1) %predicted (p=0.005, r=-0.62), and a positive correlation between the number of CD8+ cells and the number of pack years smoked (p=0.017, r=0.42). There was a negative correlation between the activated/total eosinophils ratio and the FEV1 % pred (p=0.017, r=-0.51). There was a negative correlation between pack years smoked and the number of neutrophils (p=0.022, r=-0.36). Smokers who develop chronic obstructive pulmonary disease have increased numbers of CD8+ T-cells in large airways when compared to asymptomatic smokers. Airway obstruction was associated with an increase in the proportion of eosinophils that were activated.

An unusual cause of falls in an elderly patient

Falls are common in the elderly, often causing considerable morbidity and mortality. Prevention is therefore important and is based on determining the cause. We present an elderly patient who had multiple falls during the day due to recurrent daytime sleep episodes, an entity we believe has not previously been reported.

A case of severe reversible lung disease caused by sulphasalazine

Various lung problems have been reported in patients with inflammatory bowel disease. Some of these can be drug related. We report an unusual case of upper lobe infiltration which appeared to be caused by sulphasalazine.

Drug treatment of asthma in the 1990s: achievements and new strategies

Asthma is an inflammatory condition of the airways. First-line therapy involves the use of inhaled corticosteroids as anti-inflammatory agents to control the underlying process. Bronchodilators are used for symptom relief. Short-acting beta-agonists provide rapid relief of bronchoconstriction, whereas long-acting beta-agonists control the symptoms and reduce the frequency of exacerbations when combined with inhaled corticosteroids. Anticholinergic bronchodilators have a minor role in acute exacerbations and in patients troubled by adverse effects from beta-agonists. Theophylline has a bronchodilator action in asthma, but its role as an anti-inflammatory agent needs to be examined further. Because of their toxicity, corticosteroid-sparing agents have a limited role, being restricted to patients with severe uncontrolled asthma. New selective phosphodiesterase IV inhibitors show both anti-inflammatory and bronchodilator characteristics with fewer adverse effects. Other new approaches to the control of inflammation come from the antileukotriene drugs, which improve pulmonary function in patients with chronic asthma. The antileukotrienes have shown promising results, especially in the treatment of asthma caused by aspirin (acetylsalicylic acid), exercise and cold air. Other new therapies being studied include anti-immunoglobulin E, antitryptase and anti-CD4 agents. These newer possibilities suggest that the range of available treatment options will expand significantly over the next decade.

Immunopathology of the small-airway submucosa in smokers with and without chronic obstructive pulmonary disease

The airflow obstruction in chronic obstructive pulmonary disease (COPD) occurs mainly at the level of the small airways. In order to investigate the effect of smoking on small-airway submucosal immunopathology, we used immunohistochemistry in peripheral lung sections obtained at surgery from a group of smokers (n = 22) and from a group of nonsmokers (n = 22) that contained both ex-smokers (n = 17) and lifelong nonsmokers (n = 5). Subjects were also divided into those with (n = 19) and those without (n = 20) airflow obstruction. We found an increase in total eosinophils (p = 0.001) and activated eosinophils (p = 0.010), an increase in the CD8(+)/CD3(+) cell ratio (p = 0.003), and a decrease in the CD4(+)/CD8(+) cell ratio (p = 0.005) among cells infiltrating the small-airway submucosa in an area 50 micrometers deep to the basement membrane in smokers as compared with nonsmokers. There was also an increase in neutrophils (p = 0.019) when smokers were compared with lifelong nonsmokers. Neutrophil numbers correlated with numbers of eosinophils (p = 0.0003, r = 0.58). Furthermore, the CD8(+)/CD3(+) cell ratio was related to pack-years smoked (p = 0.016, r = 0.36), months since smoking cessation (p = 0.003, r = 0.47), and number of infiltrating eosinophils (p = 0.007, r = 0.43) and neutrophils (p = 0.004, r = 0.44). These findings suggest that smoking induces movement of an inflammatory infiltrate into the submucosa of the small airway, the location of the increased resistance to airflow in COPD.

Long-acting inhaled beta 2-agonists in the management of asthma: recent advances and current recommendations

Salmeterol and formoterol belong to a new class of inhaled beta 2-agonists with a prolonged duration of action. At the time these agents were introduced, there was uncertainty regarding the safety of beta 2-agonist therapy in asthma and concern that they might lead to a deterioration in asthma control. Recent studies, in contrast, have demonstrated both their safety and therapeutic efficacy. The aims of this review are to highlight these new developments and to consider the place of these long-acting beta 2-agonists in asthma management strategies.

An outbreak of multi-drug-resistant tuberculosis in a London teaching hospital

We describe the epidemiology and control of a hospital outbreak of multi-drug-resistant tuberculosis (MDR-TB). A human immunodeficiency virus (HIV)-negative patient with drug-sensitive tuberculosis developed MDR-TB during a period of unsupervised therapy. She was admitted to an isolation room in a ward with HIV-positive patients, but the room, unbeknown to hospital staff, was at positive-pressure relative to the main ward. Seven HIV-positive contacts developed MDR-TB. The diagnosis in the second patient was delayed, partly because acid-fast bacilli in his sputum were assumed to be Mycobacterium avium-intracellulare. All the available Mycobacterium tuberculosis isolates were indistinguishable by molecular typing. Nearly 1400 staff and patient contacts were offered screening, but the screening programme detected only one of the cases. Despite therapy, the index patient and two of the contacts died. HIV-positive patients are more likely than others to develop tuberculosis after exposure, and the disease may progress more rapidly. In these patients the possibility that acid-fast bacilli may represent M. tuberculosis must always be considered. Patients with tuberculosis (suspected or proven) should not be nursed in the same wards as immunosuppressed patients, and should be isolated. MDR-TB cases must be isolated in negative-pressure rooms. Hospital side-rooms may be positive-pressure as a fire safety measure; infection control teams must be aware of the airflows in all isolation rooms, and must be consulted during the design of hospital buildings. Good communication between infection control teams and clinicians is important, and all medical and nursing staff must be aware of the principles of management of patients with proven or suspected tuberculosis and MDR-TB.

The effect of oral corticosteroids on bronchodilator responses in COPD

There have been suggestions that corticosteroid treatment might improve bronchodilator responses in chronic obstructive pulmonary disease (COPD). We have studied bronchodilator responses to salbutamol and to oxitropium bromide in 20 patients with stable moderate to severe COPD. Dose responses to the two bronchodilators were tested before and after 3 week courses of placebo and 30 mg prednisolone. Thirteen patients were taking inhaled corticosteroids. There were no significant changes in numbers of responses or maximum bronchodilator effects from either bronchodilator, although there was a trend towards higher maximum levels after 3 weeks of prednisolone. Spirometry measured at home each morning before and after oxitropium bromide showed no difference between prednisolone and placebo periods. This study provides no evidence for a significant effect on bronchodilator responses to beta-agonists or anticholinergic agents from 3 weeks of oral prednisolone in moderately severe COPD.

Home nebulized therapy for patients with COPD: patient compliance with treatment and its relation to quality of life

STUDY OBJECTIVES

To assess compliance with home nebulized therapy in patients with COPD.

DESIGN

Patients' home nebulizers were replaced with nebulizers that recorded the date and time of each treatment over a period of 4 weeks. Poor compliance was defined as taking <70% of the prescribed dose (or <60% for those prescribed treatments five or more times daily).

SETTING

Patients were seen at the hospital COPD outpatient clinic. The compliance data obtained were recorded while they were at home.

PATIENTS

Ninety-three patients aged 44 to 76 years (mean, 64.9 years) were recruited from the hospital nebulizer database.

MEASUREMENTS

Patients completed a self-reported quality of life scale, the St. George's Respiratory Questionnaire (SGRQ), both before (SGRQ1) and after (SGRQ2) the 4-week study period to look at whether quality of life was either predictive of or subsequent to level of compliance.

RESULTS

Data were obtained from 82 patients. Mean compliance was 57% (range, 0 to 124%). Thirty-six (44%) patients were compliant and 46 (56%) were poorly compliant. There was no difference between the two groups in age or sex distribution. Compliance was negatively correlated with the total score on the SGRQ2 (p=0.03).

CONCLUSION

The study shows that levels of compliance with nebulized therapy are low in a large proportion of patients with COPD and that patients with low levels of compliance report greater impairment in their quality of life.

Inhaler use in chronic obstructive pulmonary disease

Inhaler technique is a common problem, particularly in the elderly. We have assessed the ability to use seven common inhaler devices in 20 patients with chronic obstructive pulmonary disease (COPD). Techniques were taught in a standard fashion in random order and assessed immediately and one hour later by two observers. Fourteen patients had a fault that would result in no drug delivery at some time during the study, and such a fault occurred at some point for each inhaler device. These faults were most common with the diskhaler. Accuhaler, autohaler and turbohaler scored highest and diskhaler lowest. Overall scores declined by one hour after instruction. Patients ranked the metered dose inhaler and accuhaler highest for ease of use and preference. These results show that it is useful to have a small range of devices for patients with COPD and that it is important to review inhaler technique regularly.

Psychological factors associated with use of home nebulized therapy for COPD

This study examined the relationship between adherence to domiciliary nebulized therapy and psychological factors; patient attitudes, anxiety, depression, and quality of life. Ninety three patients aged 45-77 yrs with chronic obstructive pulmonary disease (COPD) and using domiciliary nebulizers were recruited from a hospital database. They completed the St George's respiratory questionnaire (SGRQ)-1 and the hospital anxiety and depression scale (HADS) and attended a semistructured interview. Their usual nebulizers were replaced by Dataloggers, which record the date, time and duration of each treatment, to use for 4 weeks. The SGRQ was then repeated (SGRQ-2). Eighty two patients completed the study. Fifty six percent were poorly adherent; taking less than 70% of the dose prescribed (or less than 60% on regimens of > or = 5 times daily). The total scores on the SGRQ-2 were negatively correlated with percentage adherence. Multiple regression analysis showed that the SGRQ-2 total score was associated with percentage adherence, depression score, feeling supported by clinic staff, and patients feeling that they tried to ignore their chest disease. Patients who report poor quality of life are more likely to be depressed, feel unsupported by clinic staff and be poorly adherent to treatment. Increased levels of clinic support, with the addition of psychological treatments, may be of benefit to some patients with chronic obstructive pulmonary disease.

A case of Churg-Strauss syndrome: tissue diagnosis established by sigmoidoscopic rectal biopsy

A case is presented of Churg-Strauss syndrome in a young man in whom the definitive diagnostic procedure was a full thickness sigmoidoscopic rectal biopsy, with submucosal sampling. Gastrointestinal changes in Churg-Strauss syndrome, a rare systemic illness characterised by asthma, blood and tissue eosinophilia, vasculitis, and granulomatous inflammation are common but poorly reported. The endoscopic and histopathological features of a case are described and emphasise the potential value of a limited sigmoidoscopy in establishing the diagnosis, when lower gastrointestinal symptoms are present.

Amiodarone pneumonitis: no safe dose

Pneumonitis is a serious adverse effect of amiodarone therapy, which is related to the average daily dose. A case of pneumonitis is described which developed after exposure to a low dose of amiodarone. This challenges the concept that low dose amiodarone therapy is safe.

Tuberculosis: current issues in diagnosis and treatment

The incidence of tuberculosis began to decline in 1801, which was probably due to improving socioeconomic conditions (certainly not the efforts of the medical profession). Patients cannot be treated unless they are detected, which underlines the importance of notification and case finding. Full multiagent chemotherapy is necessary to give the best chance of permanent cure and to prevent the emergence of resistance; compliance with treatment is increased by making it readily accessible and increasing the degree of supervision. With the resurgence of interest in tuberculosis since the rising incidence of the late 1980s a review of the state of diagnosis and treatment is due. This one covers some areas of current interest: the role of vaccination, chemoprophylaxis, tuberculosis and HIV, new methods of diagnosis, drug resistance and alternative approaches to treatment.

High-dose nedocromil sodium as an addition to inhaled corticosteroids in the treatment of asthma

In a double-blind placebo-controlled trial nedocromil sodium in a dose of 8 mg four times daily or matching placebo was added to the treatment of 29 asthmatic patients. All patients were taking inhaled corticosteroids in a dose of up to 1000 micrograms daily. The trial agents were given for 6 weeks after a 2-week run-in period. Twenty-four patients completed the study, three withdrew because of adverse effects, two on placebo. Daytime asthma symptoms were significantly reduced on nedocromil compared to placebo (-0.46 vs. +0.09, P = 0.03). Night-time asthma and morning tightness were not changed significantly. Bronchodilator use in the night and day were lower on nedocromil but the differences were not significant. Morning peak flow rates were higher on nedocromil (+22.2 vs. +0.08, P = 0.06) and physicians opinions of overall effectiveness favoured nedocromil (U = 35.0, P = 0.04). These results confirm that nedocromil sodium may be a useful addition in asthma to low to medium doses of inhaled corticosteroids. The effects of 32 mg nedocromil daily were comparable to previous reports with lower doses.

Theophylline. Current thoughts on the risks and benefits of its use in asthma

Theophylline and its derivatives have been used in the treatment of asthma for over 50 years, but since the advent of more potent bronchodilators their use has become cloaked in controversy. Their continued existence results from their undoubted usefulness in severe acute asthma, nocturnal asthma, childhood asthma and moderate to severe chronic airflow limitation, and because of habitual use by physicians in other situations. The precise mechanism of action of theophylline remains uncertain. The role of phosphodiesterase inhibition and adenosine antagonism has been reviewed and the clinical significance of the anti-inflammatory action of theophylline discussed. Theophylline has unpredictable metabolism when first administered, and continued monitoring of drug concentrations is essential. Commonly encountered adverse effects may occur at therapeutic serum concentrations, frequently necessitating drug withdrawal. The overlapping therapeutic and toxic theophylline serum ranges can lead to life-threatening adverse effects at the upper end of the therapeutic range, especially in the elderly in whom special precaution is required.

Alveolar macrophage accessory cell function in bronchial asthma

The capacity of peripheral blood monocytes and alveolar macrophages (AM) obtained by bronchoalveolar lavage (BAL) to present recall antigens, namely, tuberculin purified protein derivative (PPD) or streptokinase-streptodornase (SKSD), to highly purified autologous T-cells has been studied in 11 asthmatic and 11 healthy, nonatopic normal subjects. In the asthmatic group, AM accessory cell function was variable, and most subjects were unable to present either recall antigen as effectively as blood monocytes, although one asthmatic subject demonstrated larger proliferative responses than blood monocytes for both antigens. AM accessory cell activity was not antigen-specific, and there was a correlation between accessory cell efficacy for the two antigens (r = 0.92; confidence interval, 0.53 to 0.98). Furthermore, a correlation existed between the percentage lymphocyte count in the BAL fluid and the ratio of macrophage to monocyte antigen-presenting capability for both PPD (r = 0.92; 95% confidence interval, 0.83 to 0.99) and SKSD (r = 0.90; 95% confidence interval, 0.45 to 0.98). In the normal subjects, AM were also unable to act effectively as accessory cells for the presentation of PPD and SKSD in the majority of subjects. No correlation existed between the percentage lymphocytes in BAL fluid and the ratio of AM to monocyte accessory cell function. These results suggest an association between AM accessory function and the presence of BAL lymphocytes in bronchial asthma.

Effect of changes in inspiratory flow rate on cough responses to inhaled capsaicin

1. Twelve non-smoking subjects inhaled capsaicin at three different inspiratory flow rates: 50, 100 and 150 litres/min. Capsaicin was delivered by a breath-actuated dosimeter; inhalations consisted of 0.21-13.6 nmol of capsaicin in doubling amounts given in random order. 2. The mean number of coughs per challenge decreased with increasing inspiratory flow rate. The difference in cough numbers were significant: 7.7 (95% confidence interval 2.5-12.8) for 50 versus 100 litres/min and 10.9 (95% confidence interval 5.0-16.9) for 100 versus 150 litres/min. 3. On a separate day, a cough threshold was measured by giving increasing doses of citric acid that were inhaled at 50 litres/min. There was a positive correlation between the sensitivity to capsaicin and the cough threshold to citric acid (r = 0.69, P = 0.01), and also between the cough latencies (r = 0.67, P = 0.02). 4. The negative relationship between the cough response and the inspiratory flow rate may be caused by increased laryngeal deposition at lower inspiratory flow rates. 5. These results are compatible with a similar anatomical distribution of cough receptors for capsaicin and citric acid. 6. These results suggest that changes in inspiratory flow rate may affect the results of cough challenges.

The effects of osmotic challenge on bronchial responsiveness to methacholine in non-asthmatic subjects

We have measured the airway responses to methacholine on three days in sixteen non-asthmatic subjects. On the first day the methacholine challenge alone was performed. The other two days were randomized between pretreatment with distilled water or hypertonic saline administered by ultrasonic nebulizer. Distilled water and hypertonic saline did not affect baseline specific conductance (sGaw). Provocative dose producing a 35% fall in sGaw (PD35sGaw) was slightly reduced by both distilled water and hypertonic saline (15.83 to 8.55 mumol with distilled water and to 11.80 mumol with hypertonic saline). Six out of 16 subjects reached a plateau of maximal response with methacholine. The level of this plateau was not affected by pretreatment with distilled water or hypertonic saline. These results show that distilled water and 3.6% saline produced small increases in non-specific reactivity in normal subjects and confirm that substantial osmotic challenge does not change airway calibre in non-asthmatic subjects.

The effects of osmotic challenge on bronchial responsiveness to methacholine in non-asthmatic subjects

We have measured the airway responses to methacholine on three days in sixteen non-asthmatic subjects. On the first day the methacholine challenge alone was performed. The other two days were randomized between pretreatment with distilled water or hypertonic saline administered by ultrasonic nebulizer. Distilled water and hypertonic saline did not affect baseline specific conductance (sGaw). Provocative dose producing a 35% fall in sGaw (PD35sGaw) was slightly reduced by both distilled water and hypertonic saline (15.83 to 8.55 mumol with distilled water and to 11.80 mumol with hypertonic saline). Six out of 16 subjects reached a plateau of maximal response with methacholine. The level of this plateau was not affected by pretreatment with distilled water or hypertonic saline. These results show that distilled water and 3.6% saline produced small increases in non-specific reactivity in normal subjects and confirm that substantial osmotic challenge does not change airway calibre in non-asthmatic subjects.

Bronchodilator responses to salbutamol followed by ipratropium bromide in partially reversible airflow obstruction

We have performed a retrospective survey on 296 patients, who attended the Respiratory Function Unit at Guy's Hospital to have their bronchodilator responses (BR) tested. The aim of the study was to see the effect of ipratropium bromide (IB) in a group of patients with incomplete reversibility after salbutamol (S). Patients were routinely given salbutamol and ipratropium bromide sequentially by inhalation, and spirometric changes were recorded after each drug. We identified two groups: Group A, 95 patients with FEV1 response greater than or equal to 0.2 l after either drug and FEV1 less than 80% predicted after salbutamol; and, Group B, 49 with change in FEV1 less than 0.02 l, FVC less than 80% predicted after salbutamol and an improvement in FVC greater than or equal to 0.33 l. Seventy-nine of the 95 patients in Group A also had an FVC response. In Group A, age was negatively correlated with response to salbutamol (r = -0.41, P less than 0.0001), and within Group B baseline FVC was negatively correlated with response to ipratropium bromide (r = -0.30, P = 0.03). There were no differences in age, sex, or doses given to each group (median dose: salbutamol, 800 micrograms, ipratropium bromide 120 micrograms). Baseline FEV1 and FVC (% predicted) were significantly higher in FEV1 responders. Mean (SD) FEV1 were 43% (14) in Group A vs. 29% (14) in Group B, while FVC were 62% (16) vs. 47% (13), P less than 0.001. Responses to ipratropium bromide were more frequent in Group B; in Group A 87% improved after salbutamol and 26% after ipratropium bromide, while in Group B 68% responded to salbutamol and 47% to ipratropium bromide (P = 0.03). Most patients responded to salbutamol, but in 33% ipratropium bromide had an additional effect. The FEV1 response to salbutamol declined with age. Isolated volume responders had more severe airflow obstruction, had less responses to salbutamol and were more likely to show a response to ipratropium bromide. These results support a trial of ipratropium bromide in patients with inadequate beta responsiveness, especially in those with severe airflow obstruction.

Importance of inspiratory flow rate in the cough response to citric acid inhalation in normal subjects

1. The cough response to inhalation of citric acid is produced mainly by irritation of the larynx and trachea. Variations in the inspiratory flow rate might lead to changes in deposition of the drug, and consequently in the cough threshold. 2. We have studied the effect of three different inspiratory flow rates in 11 normal, non-smoking subjects (nine males, aged 23-39 years), who inhaled nebulized citric acid (2.5-640 mg/l). The test finished when a cough was produced at each inhalation (cough threshold) or the maximum concentration was reached. 3. The inspiratory flow rate was limited with a fixed resistance and displayed on a screen so that the subjects could reach a constant inspiratory flow rate of 50, 100 and 150 l/min with a submaximal inspiratory effort. 4. The mean (SD) inspiratory flow rates achieved were 51.4 (5.3), 86.2 (16.6) and 134.4 (22.9) l/min. Baseline forced expiratory volume in 1 s and functional vital capacity were not different on the 3 study days. 5. The cough threshold (geometric mean and 95% confidence intervals) was 21 (9-54) mg/l at an inspiratory flow rate of 50 l/min and 43 (13-141) mg/l at 150 l/min (P less than 0.05). The amount of drug tolerated by the subjects before the cough threshold was achieved was 5.2 (2.0-13.8) mg at an inspiratory flow rate of 50 l/min and 11.6 (3.4-39.8) mg at 150 l/min (P less than 0.05). The number of coughs per inhalation was 1.6 (1.1-2.0) at an inspiratory flow rate of 50 l/min and 1.1 (0.7-1.5) at 150 l/min (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Airway responsiveness to adenosine 5' monophosphate following inhalation of hypertonic saline

We wished to determine whether the refractory period after hypertonic saline (HS) challenge is due to mast cell mediator depletion. Therefore, the airway responsiveness to adenosine 5' monophosphate (AMP), which induces bronchoconstriction via mast cell histamine release, was determined after the inhalation of HS aerosol. Nine asthmatic subjects attended the laboratory on three occasions. On day 1 HS challenge was performed followed one hour later by a second HS challenge. On day 2 an AMP challenge was performed. On day 3 an HS challenge was performed followed one hour later by an AMP challenge. Airway responsiveness (PD35 sGaw) to an initial HS challenge ranged from 12 to 315 l of aerosol (mean 47 l). Airway responsiveness to a second HS challenge ranged from 8 to 800 l (mean 102 l p = 0.035, n = 9). Airway responsiveness to AMP increased from 0.44 to 14.0 mumol (mean 2.37 mumol) at baseline to 0.3 to 15.5 (mean 1.3 mumol) (p = 0.05) after HS challenge. There was a linear correlation between baseline AMP responsiveness and baseline HS responsiveness (r = 0.911, p = 0.001). There was no correlation between the degree of refractoriness and the change in AMP responsiveness (r = 0.1, p = 0.9). Thus airway responsiveness to AMP increased significantly after inhalation of HS aerosol and this increase was independent of refractory behaviour. Our results suggest that the refractory period to HS is not due to mediator depletion.

Maximum achievable bronchodilatation in asthma

We have examined the effects of combinations of three bronchodilator drugs in 37 patients with poorly reversible asthma. In each case FEV1 was less than 90% predicted before administration of the third drug. Nineteen patients took increasing doses of salbutamol by inhalation followed by 160 micrograms ipratropium bromide and intravenous aminophylline, 5.6 mg kg-1. FEV1 increased by at least 200 ml in 18 patients after salbutamol. Subsequently, ipratropium bromide increased FEV1 by 200 ml in three patients while aminophylline did not produce a further 200 ml rise in any patient in this group. Nine patients were given aminophylline followed by ipratropium bromide and salbutamol and nine took ipratropium bromide then aminophylline and salbutamol. Eleven of the 18 patients in these latter two groups had a 200 ml increase in FEV1 using salbutamol as the third drug. Significant increases in pulse rate were only seen after aminophylline or salbutamol administered as the third drug. These results suggest that maximal bronchodilatation in poorly reversible asthma can usually be achieved by increasing doses of beta agonist up to a therapeutic plateau. A further response, if required, may be achieved in some patients with ipratropium bromide.

Airway responsiveness to adenosine 5' monophosphate following inhalation of hypertonic saline

We wished to determine whether the refractory period after hypertonic saline (HS) challenge is due to mast cell mediator depletion. Therefore, the airway responsiveness to adenosine 5' monophosphate (AMP), which induces bronchoconstriction via mast cell histamine release, was determined after the inhalation of HS aerosol. Nine asthmatic subjects attended the laboratory on three occasions. On day 1 HS challenge was performed followed one hour later by a second HS challenge. On day 2 an AMP challenge was performed. On day 3 an HS challenge was performed followed one hour later by an AMP challenge. Airway responsiveness (PD35 sGaw) to an initial HS challenge ranged from 12 to 315 l of aerosol (mean 47 l). Airway responsiveness to a second HS challenge ranged from 8 to 800 l (mean 102 l p = 0.035, n = 9). Airway responsiveness to AMP increased from 0.44 to 14.0 mumol (mean 2.37 mumol) at baseline to 0.3 to 15.5 (mean 1.3 mumol) (p = 0.05) after HS challenge. There was a linear correlation between baseline AMP responsiveness and baseline HS responsiveness (r = 0.911, p = 0.001). There was no correlation between the degree of refractoriness and the change in AMP responsiveness (r = 0.1, p = 0.9). Thus airway responsiveness to AMP increased significantly after inhalation of HS aerosol and this increase was independent of refractory behaviour. Our results suggest that the refractory period to HS is not due to mediator depletion.

Role of histamine release in hypertonic saline induced bronchoconstriction

In a study designed to determine the protective effect of the specific histamine H1 antagonist terfenadine on hypertonic saline induced bronchoconstriction, 10 asthmatic subjects underwent hypertonic saline challenge (3.6%) after premedication with placebo or terfenadine (120 mg) 12 and two hours before the challenge. Hypertonic saline was administered in a dose dependent manner and the response determined as the dose of hypertonic saline that induced a 20% fall in FEV1 (PD20 FEV1). FEV1 was on average 11% greater with terfenadine than with placebo given before the challenge with hypertonic saline. PD20 FEV1 was attenuated by a mean of 2.5 fold after terfenadine (geometric mean PD20 FEV1 was 22 litres after placebo and 56 l after terfenadine). There was substantial intersubject variation in the inhibitory effect of terfenadine on hypertonic saline induced bronchoconstriction: the ratio of the PD20 hypertonic saline after terfenadine to that after placebo ranged from 0.9 to 10.0. Terfenadine inhibited histamine induced bronchoconstriction in the eight subjects in whom it was tested, by 13 to 160 fold compared with placebo in four subjects and by greater than 2 to greater than 9 fold in the four who showed no response to the highest dose of histamine given (16 mg/ml). These results suggest that histamine release has a role in hypertonic saline induced bronchoconstriction in some individuals; other mediators or mechanisms may have a more prominent role in others.