Airway smooth muscle in health and disease; methods of measurement and relation to function.
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Smooth muscle is present and probably functional in the airways in utero and increases in absolute area during growth with little further change during adulthood. It encircles the entire airway below the level of the main bronchus, in a roughly circular orientation, except at high lung volumes. It occupies relatively more of the airway wall in the peripheral airways, reaching a maximum in the membranous bronchioles. Measurement of smooth muscle area in the airway wall is confounded by clinical classification of cases, methods of tissue retrieval and preparation, staining and orientation of sections, magnification, image analysis and statistical methods of comparison between groups. Airway smooth muscle area is pathologically increased in inflammatory conditions of the airways such as chronic obstructive pulmonary disease, in relation to airways obstruction, and asthma, in relation to severity and airway size (between 25 and 250% compared with control cases). It is increased in sudden infant death syndrome, but there are few studies in other conditions such as bronchiectasis. In asthma, smooth muscle must shorten (not necessarily to an abnormal degree) for the structural abnormalities of the airway to manifest as excessive airway narrowing. Not surprisingly there is renewed interest in the relationships between the mechanical and contractile properties of smooth muscle, parenchymal properties and lung volume and how these interact to determine smooth muscle length. The relative importance of smooth muscle area and mechanical properties, altered airway structure and airway inflammation in disease are yet to be determined. (+info)
Computed tomographic scan of the chest, latex agglutination test and plasma (1AE3)-beta-D-glucan assay in early diagnosis of invasive pulmonary aspergillosis: a prospective study of 215 patients.
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BACKGROUND AND OBJECTIVES: Blood and radiologic tests are frequently used for diagnosis of invasive pulmonary aspergillosis, but it remains unknown which is more useful for its early diagnosis. Aim of the study was to compare usefulness of computed tomographic (CT) scan of chest, latex agglutination (LA) test and determination of plasma (1-->3)-beta-D-glucan (BDG) levels for early diagnosis of invasive pulmonary aspergillosis (IPA). DESIGN AND METHODS: We treated 215 consecutive patients who underwent cytotoxic chemotherapy. From initiation of chemotherapy until death or discharge, blood samples were taken weekly and subjected to LA and BDG tests. We performed chest CT scans when patients had any signs of pulmonary infection or an antibiotic-resistant fever. RESULTS: Of the 215 patients, 30 (14. 0%) were diagnosed as having IPA. In sixteen cases the diagnosis was definite and in 14 it was suspected. In patient-based analysis, sensitivities of LA and BDG were 44% and 63%, respectively. Sensitivity tended to be lower in patients with IPA localized to the lung than those with disseminated invasive aspergillosis. Specificities were 93% and 74%, respectively. Either a halo or an air-crescent was observed in 7 of the 16 patients with IPA, and all of the IPA patients showed some abnormal signs on chest CT scans. On average, CT scan signs preceded a positive LA test by 7.1 days and a positive BDG assay by 11.5 days. In 6 of the 11 patients who became positive for either LA or BDG assay, CT scan signs preceded the positive results by more than seven days. INTERPRETATION AND CONCLUSIONS: Chest CT scan is more beneficial than the blood tests and X-ray for early diagnosis of IPA. (+info)
The validity of a sore throat score in family practice.
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BACKGROUND: Reducing the number of antibiotic prescriptions given for common respiratory infections has been recommended as a way to limit bacterial resistance. This study assessed the validity of a previously published clinical score for the management of infections of the upper respiratory tract accompanied by sore throat. The study also examined the potential impact of this clinical score on the prescribing of antibiotics in community-based family practice. METHODS: A total of 97 family physicians in 49 Ontario communities assessed 621 children and adults with a new infection of the upper respiratory tract accompanied by sore throat and recorded their prescribing decisions. A throat swab was obtained for culture. The sensitivity and specificity of the score approach in this population were compared with previously published results for patients seen at an academic family medicine centre. In addition, physicians' prescribing practices and their recommendations for obtaining throat swabs were compared with score-based recommendations. RESULTS: Of the 621 cases of new upper respiratory tract infection and sore throat, information about prescriptions given was available for only 619; physicians prescribed antibiotics in 173 (27.9%) of these cases. Of the 173 prescriptions, 109 (63.0%) were given to patients with culture-negative results for group A Streptococcus. Using the score to determine management would have reduced prescriptions to culture-negative patients by 63.7% and overall antibiotic prescriptions by 52.3% (both p < 0.01). Culturing of throat samples would have been reduced by 35.8% (p < 0.01). There was no statistically significant difference in the sensitivity or specificity of the score approach between this community-based population (sensitivity 85.0%, specificity 92.1%) and an academic family medicine centre (sensitivity 83.1%, specificity 94.3%). INTERPRETATION: An explicit clinical score approach to the management of patients presenting with an upper respiratory tract infection and sore throat is valid in community-based family practice and could substantially reduce the unnecessary prescribing of antibiotics for these conditions. (+info)
Efficacy of transthoracic needle aspiration in community-acquired pneumonia.
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OBJECTIVE: To evaluate the indications, efficacy, and safety of transthoracic needle aspiration (TNA) in diagnosing community-acquired pneumonia (CAP). METHODS: TNA procedure was performed using an ultrathin needle with ultrasonography and/or computed tomography. The aspirate samples were Gram-stained and sent for cultures. The results were compared with those from conventional microbiological studies. PATIENTS: Sixty patients with CAP who were admitted to the hospital and were studied prospectively between July 1994 and June 1999 were included in the study. RESULTS: TNA culture was positive in 30 cases (50.0%). Streptococcus pneumoniae was the most frequently isolated pathogen, followed by the Streptococcus milleri group, and anaerobes. The results of TNA were consistent with those of quantitative sputum cultures in 9 patients and with those of blood cultures in 4. Complications arose in 3 patients who developed small to moderate pneumothorax. CONCLUSIONS: TNA is a safe procedure with a good diagnostic yield. In particular, anaerobes or microaerophils such as the S. milleri group were highly detectable by TNA. The results obtained by TNA were highly consistent with those obtained by the gold standard methods. Combined with conventional methods, TNA is considered highly useful for determining the etiology of CAP. (+info)
Expiratory flow limitation during exercise in COPD: detection by manual compression of the abdominal wall.
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Manual compression of the abdomen (MCA) during spontaneous expiration is a simple method for the detection of flow limitation in the chronic obstructive pulmonary disease (COPD) patients during resting breathing, based on comparison of flow/volume curves obtained during MCA with that of the preceding control breath. It was assessed whether this nonstandardized technique is also feasible during exercise. MCA was performed during resting breathing and constant-exercise work at one- and two-thirds maximal mechanical power output (W'max) in six normal subjects and 12 COPD patients. Changes in end-expiratory lung volume (EELV) were also studied. With the aid of inspection, abdominal palpation and lung auscultation, MCA could always be applied during expiration. Flow limitation was never detected in the six normal subjects, whereas four of the COPD patients were flow limited at rest, seven during exercise at one-third W'max and nine during exercise at two-thirds W'max. Expiratory flow limitation detected by MCA was always associated with an increase in EELV during exercise, indicating dynamic hyperinflation occurrence or increase. It is concluded that manual compression of the abdomen is a very simple and reliable method for the detection of flow limitation during exercise. (+info)
Formoterol in patients with chronic obstructive pulmonary disease: a randomized, controlled, 3-month trial.
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The aim of this study was to investigate formoterol, an inhaled long-acting beta2-agonist, in patients with chronic obstructive pulmonary disease (COPD). Six-hundred and ninety-two COPD patients, mean baseline forced expiratory volume in one second (FEV1) 54%, FEV1/forced vital capacity 75% of predicted, reversibility 6.4% pred, were treated with formoterol (4.5, 9 or 18 microg b.i.d.) or placebo via Turbuhaler for 12 weeks. Symptoms were recorded daily. Spirometry and the incremental shuttle walking test (SWT) were performed at clinic visits. Compared with placebo, 18 microg b.i.d. formoterol reduced the mean total symptom score by 13% and increased the percentage of nights without awakenings by 15%. Formoterol (9 and 18 microg b.i.d.) significantly reduced symptom scores for breathlessness (-7% and -9%, respectively) and chest tightness (-11% and -8%, respectively), reduced the need for rescue medication (-25% and -18%, respectively), and increased symptom-free days (71% and 86%, respectively). FEV1 improved significantly after all three doses of formoterol (versus placebo). No differences were found between groups in SWT walking distance. No unexpected adverse events were seen. In conclusion, 9 and 18 microg b.i.d. formoterol reduced symptoms and increased the number of symptom-free days in a dose-dependent manner in chronic obstructive pulmonary disease patients. Formoterol improved lung function at a dose of 4.5 microg b.i.d. and higher. (+info)
Evaluation of a portable device for diagnosing the sleep apnoea/hypopnoea syndrome.
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Waiting times for hospital-based monitoring of the obstructive sleep apnoea/hypopnoea syndrome (OSAHS) are rising. This study tested whether Embletta, a new portable device, may accurately diagnose OSAHS at home. A synchronous comparison to polysomnography was performed in 40 patients and a comparison of home Embletta studies with in-laboratory polysomnography was performed in 61 patients. In the synchronous study, the mean difference (polysomnography-Embletta) in apnoeas+hypopnoeas (A+H) x h(-1) in bed was 2 h(-1). In comparison to the apnoea/ hypopnoea index (AHI) x h(-1) slept, the Embletta (A+H) x h(-1) in bed differed by 8 x h(-1). These data were used to construct diagnostic categories in symptomatic patients from their Embletta results: "OSAHS" (> or = 20 (A+H) x h(-1) in bed), "possible OSAHS" (10-20 (A+H) x h(-1) in bed) or "not OSAHS" (<10 (A+H) x h(-1) in bed). In the home study, the mean difference in (A+H) x h(-1) in bed was 3 x h(-1). In comparison to the polysomnographic AHI x h(-1) slept, the Embletta (A+H) x h(-1) in bed differed by 6 +/- 14 x h(-1). Using the above classification, all nine patients categorised as not OSAHS had AHI < 15 x h(-1) slept on polysomnography and all 23 with OSAHS on Embletta had an AHI > or = 15 on polysomnography, but 18 patients fell into the possible OSAHS category potentially requiring further investigation and 11 home studies failed. Most patients were satisfactorily classified by home Embletta studies but 29 out of 61 required further investigation. The study suggested a 42% saving in diagnostic costs over polysomnography if this approach were adopted. (+info)
Diagnosing occupational asthma: how, how much, how far?
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Diagnosing occupational asthma is still a challenge because it is based on a stepwise approach in which the depth of investigative means may vary depending on resources. The authors herewith review the existing investigative means from the approach of outlining controversies and queries. There is no validated clinical questionnaire for diagnosing occupational asthma. Immunological investigation is limited by the lack of standardised extracts for skin-prick testing and specific immunoglobulin E assessments. Criteria for interpretation of changes in peak expiratory flow rates and bronchial responsiveness to pharmacological agents are still open to discussion. It is worth improving the methodology of specific inhalation challenges, either in the laboratory or in the workplace, to facilitate more extensive use of these tests. Validation of new means that assess airway inflammation, such as exhaled nitric oxide and induced sputum, needs to be performed. There is a need to increase the use of these diagnostic tests because the diagnosis is still too often based on "clinical impression". (+info)