Symbolic dynamics marker of heart rate variability combined with clinical variables enhance obstructive sleep apnea screening.

Many sleep centres try to perform a reduced portable test in order to decrease the number of overnight polysomnographies that are expensive, time-consuming, and disturbing. With some limitations, heart rate variability (HRV) has been useful in this task. The aim of this investigation was to evaluate if inclusion of symbolic dynamics variables to a logistic regression model integrating clinical and physical variables, can improve the detection of subjects for further polysomnographies. To our knowledge, this is the first contribution that innovates in that strategy. A group of 133 patients has been referred to the sleep center for suspected sleep apnea. Clinical assessment of the patients consisted of a sleep related questionnaire and a physical examination. The clinical variables related to apnea and selected in the statistical model were age (p < 10(-3)), neck circumference (p < 10(-3)), score on a questionnaire scale intended to quantify daytime sleepiness (p < 10(-3)), and intensity of snoring (p < 10(-3)). The validation of this model demonstrated an increase in classification performance when a variable based on non-linear dynamics of HRV (p < 0.01) was used additionally to the other variables. For diagnostic rule based only on clinical and physical variables, the corresponding area under the receiver operating characteristic (ROC) curve was 0.907 (95% confidence interval (CI) = 0.848, 0.967), (sensitivity 87.10% and specificity 80%). For the model including the average of a symbolic dynamic variable, the area under the ROC curve was increased to 0.941 (95% = 0.897, 0.985), (sensitivity 88.71% and specificity 82.86%). In conclusion, symbolic dynamics, coupled with significant clinical and physical variables can help to prioritize polysomnographies in patients with a high probability of apnea. In addition, the processing of the HRV is a well established low cost and robust technique.

Tracheobronchial constriction in asthmatics induced by isocapnic hyperventilation with dry cold air.

Although it is well known that isocapnic hyperventilation (IHV) with dry cold air produces airway constriction in asthmatic subjects, the site of airway narrowing is nuclear. To address this issue, we have quantified the tracheal and bronchial response to IHV with dry cold air in 15 patients with mild asthma and 7 healthy control subjects. We employed the acoustic reflection technique to evaluate changes in airway cross-sectional areas caused by IHV with dry cold air. Airway areas were measured during tidal breathing before and 5 to 10, 30, 60, and 90 min following cold air challenge. For analysis purposes, airway areas were divided into three anatomic segments: extrathoracic tracheal segment, intrathoracic tracheal segment, and main bronchial segment. These segments were assessed at a fixed volume below total lung capacity. Maximal and partial expiratory flow-volume curves were also obtained before each set of area measurements. In normal subjects, IHV with dry cold air caused no significant changes in FEV1, flow at 30% of the vital capacity in the partial curve (V30p), or airway areas. In asthmatics, at 5 to 10 min after challenge, we found that FEV1 decreased by 22 +/- 5% (mean +/- SEM) (p < 0.0001), V30p by 33 +/- 8% (p < 0.003), intrathoracic tracheal area by 10.7% +/- 2% (p < 0.03), and main bronchial area by 14 +/- 3% (p < 0.003). At 30 min, tracheal and main bronchial areas were returned to baseline levels; however, FEV1 and V30p were still significantly decreased, by 13 +/- 3% and 16 +/- 4%, respectively. We conclude that in asthmatics, IHV with dry cold air causes both tracheal and bronchial constriction, and that recovery seems to occur first in the central airways.

One-year continuous inhaled nitric oxide for primary pulmonary hypertension.

We describe a case of long-term administration of nitric oxide (NO) in a 32-year-old man who was admitted with exertional dyspnea and anasarca. A diagnosis of primary pulmonary hypertension was made. An acute vasodilator trial with inhaled NO showed a 5% reduction of the mean pulmonary artery pressure. Long-term NO inhalation therapy was initiated. Twenty days later, the dyspnea improved, the anasarca resolved, and the PaO(2) level increased. After 12 months of NO therapy, the patient remained stable and no signs of toxicity or tachyphylaxis were observed. To our knowledge, this is the first report of 1 year of continuously inhaled NO in an adult patient with primary pulmonary hypertension. These findings suggest that prolonged NO therapy might be an effective alternative, at a lower cost, to the continuous IV infusion of epoprostenol.

Tracheobronchial dilation during isocapnic hypoxia in conscious humans.

To assess the effects of isocapnic hypoxia on the pharynx, glottis, extrathoracic trachea (ET), intrathoracic trachea (IT), and main bronchi (MB), we measured the cross-sectional areas of these airways by acoustic reflection technique in 15 healthy volunteers. Measurements were made during tidal volume breathing while subjects were normoxic [arterial O2 saturation (SaO2) > 95%] or were made hypoxic by a rebreathing procedure. Under hypoxemic conditions, airway cross-sectional areas increased significantly at ET, IT, and MB levels (P < 0.001). The magnitude of this dilation was similar for both levels of hypoxemia studied (SaO2 80-85% and 70-75%); at the milder of the two hypoxemic conditions, ET cross-sectional area increased by 12.4 +/- 4.2% (SE), IT by 10.2 +/- 5.9%, and MB by 19.1 +/- 3.2%. No significant changes were found in the pharyngeal or glottic areas. Dilation was not produced by normoxic isocapnic hyperventilation, and the use of hypoxic airway gas mixtures did not artifactually alter acoustic reflection measurements in a mechanical model. Vagal airway tone, as reflected by airway constriction during pauses in tidal breathing, was unaffected by isocapnic hypoxia. We conclude that isocapnic hypoxia produces dilation of the trachea and major bronchi, an effect unaccounted for by an alteration in the ventilatory pattern.

Heterogeneous airway tone in asthmatic subjects.

We examined the effect of volume history on the dynamic relationship between airways and lung parenchyma (relative hysteresis) in 20 asthmatic subjects. The acoustic reflection technique was employed to evaluate changes in airway cross-sectional areas during a slow continuous expiration from total lung capacity to residual volume and inspiration back to total lung capacity. Lung volume was measured continuously during this quasi-static maneuver. We studied three anatomic airway segments: extra- and intrathoracic tracheal and main bronchial segments. Plots of airway area vs. lung volume were obtained for each segment to assess the relative magnitude and direction of the airway and parenchymal hysteresis. We also performed maximal expiratory flow-volume and partial expiratory flow-volume curves and calculated the ratio of maximal to partial flow rates (M/P) at 30% of the vital capacity. We found that 10 subjects (group I) showed a significant predominance of airway over parenchymal hysteresis (P < 0.005) at the extra- and intrathoracic tracheal and main bronchial segments; these subjects had high M/P ratios [1.53 +/- 0.27 (SD)]. The other 10 subjects (group II) showed similar airway and parenchymal hysteresis for all three segments and significantly lower M/P ratios (1.16 +/- 0.20, P < 0.01). We conclude that the effect of volume history on the relative hysteresis of airway and lung parenchyma and M/P ratio at 30% of vital capacity in nonprovoked asthmatic subjects is variable. We suggest that our findings may result from heterogeneous airway tone in asthmatic subjects.

Massive hemoptysis as a manifestation of fistulized thoracic aortic aneurysms into the bronchial tree.

Aortobronchial fistulas are an uncommon and serious cause of hemoptysis. We present three cases of aortobronchial fistulas that were diagnosed and treated at our hospital. They were presented as massive hemoptysis. The clinical suspicion of a leaking thoracic aortic aneurysm into the bronchial tree should prompt the correct diagnostic procedures since early surgery is the only way to manage this condition.

High prevalence of asthma and atopy in the Canary Islands, Spain.

OBJECTIVE: To evaluate the prevalence of and risk factors for asthma and related conditions in the Canaries, Spain. METHODS: From a randomised sample of 9506 adults aged 20-44 years who answered a short questionnaire, a random sample corresponding to 20% of the original was taken. Subjects classified as symptomatic in the previous survey and who were not included in the random sample were also invited to participate. The subjects completed a respiratory questionnaire, and underwent spirometry, bronchial hyperresponsiveness (BHR) test, skin tests and immunoglobulin E (IgE) measurements. RESULTS: The random sample included 593 subjects. The prevalence of skin sensitisation to mites was 30.3% (95%CI 26.7-34.2) and the prevalence of IgE to mites 30.5% (95%CI 26.2-35.2). A prevalence of 40.6% (95%CI 35.9-45.5) was found for atopy, 14.1% (95%CI 11.1-17.1) for BHR and 4.2% (95%CI, 2.5-5.9) for asthma. The risk factors most strongly associated with asthma were atopy (OR 4.89, 95%CI 3.07-7.78) and respiratory infection before the age of 5 years (OR 2.78, 95%CI 1.66-4.67). CONCLUSION: This study shows a high prevalence of sensitisation to mites, atopy, BHR and asthma in the Canaries, similar to that observed in English-speaking countries. We suggest that these findings could partially result from climatic conditions.

High prevalence of asthma symptoms in the Canary Islands: climatic influence?

The worldwide variation in asthma prevalence prompted us to carry out a study to assess the variability of asthma-related symptoms in young adults on the islands of Gran Canaria and Tenerife. We used the questionnaire used in the European Community Respiratory Health Survey with the addition of two questions on smoking and ancestors from the Canary Islands. In each island, this questionnaire was distributed to a random sample of 5000 subjects aged 20-44 years. Of the 10,000 subjects, 9,506 (95.06%) were considered eligible. We obtained 7,132 (75.03%) responses. The prevalence of the different symptoms was wheezing 25.3%, nocturnal thoracic tightness 18.0%, awakened by an attack of shortness of breath 13.1%, attack of nocturnal coughing 33.3%, attack of asthma 4.3%, current asthma treatment 6.2%, and nasal allergies 18.0%. Women and smokers showed a significantly higher prevalence of asthma symptoms. No significant difference in symptoms was found between subjects whose ancestors were of Canarian origin and those with ancestors born outside the Canaries. As has been observed on other islands (Great Britain and New Zealand), asthma is common in individuals from 20 to 44 years of age in the Canaries. We hypothesize that climatic conditions play an important role in the prevalence of asthma symptoms.

DNA analysis of bronchoalveolar lavage in the diagnosis of pulmonary lymphoma.

Lung lymphomas frequently present a diagnostic challenge. The diagnosis of malignant lymphoma is possible when lymphocyte subpopulations show aneuploidy or a definable monoclonal surface marker or both. We present a case of lymphoma of the lung in which DNA analysis of bronchoalveolar lavage fluid was the first successful method in the time course of diagnosis.

Absence of central microtubules and transposition in the ciliary apparatus of three siblings.

We studied the cases of three siblings with a history of chronic bronchitis and infertility. The electron-microscopic investigation of the tracheal and bronchial biopsies showed a ciliary defect consisting in the absence of the central microtubules and the transposition of a peripheral doublet. This is a rare and infrequently reported abnormality included in the primary ciliary diskinesia syndrome.

Value of DNA analysis in addition to cytological testing in the diagnosis of malignant pleural effusions.

BACKGROUND: Aneuploidy appears to be a highly specific marker for cancer, and measurement of cellular DNA content by flow cytometry is rapid and reliable. This study was undertaken to determine if the addition of DNA analysis improved the sensitivity of cytological diagnosis of malignancy in pleural fluid. METHODS: Pleural effusions from 92 patients were studied by cytological examination and flow cytometry. RESULTS: In 41 patients the final diagnosis was malignancy, there were 40 cases of benign effusions including 22 with pleural tuberculosis, and in the remaining 11 patients with biopsy proven cancer the presence of malignant cells was not found by cytological and histological means in the pleural fluid. Aneuploidy and cytological malignancy were found in 14 samples. There were seven cases with abnormal flow cytometry and negative cytological results. In 12 patients the cytological test results were positive but DNA analysis was normal. Thirty six samples of fluid were both diploid and cytologically negative. Of the 22 tuberculous effusions seven contained aneuploid cells. The sensitivity of DNA and cytological analysis was 51.2% and 63.4%, respectively. The specificity of DNA analysis was 74.5%. CONCLUSIONS: DNA analysis of cells in malignant pleural effusions is both less sensitive and specific than the cytological diagnosis. Flow cytometric analysis is not recommended for routine use in the diagnosis of pleural effusions.

Assessment of airway tone in asthma. Comparison between double lung transplant patients and healthy subjects.

We investigated the hypothesis that asthmatic patients have an increased cholinergic tone by measuring tracheobronchial cross-sectional areas during transient voluntary apnea. This allowed us to assess bronchomotor tone without the influence of changes in lung recoil or lung volume. Three groups of subjects with potentially different levels of tracheobronchial tone were studied: 14 healthy volunteers (N), 18 stable asthmatic patients (A), and 10 double lung transplant recipients (T). Using the acoustic reflection technique, we measured changes in tracheobronchial cross-sectional areas during short periods (5 to 10 s) of voluntary apnea. In a subset of subjects, studies were repeated before and after the inhalation of the muscarinic antagonist ipratropium. During breath-holding, glottis and extrathoracic trachea remained unchanged but intrathoracic tracheal area decreased by 30 +/- 8% (mean +/- standard error of the mean) in N, by 27 +/- 3% in A, and by 9 +/- 4% in the T group. Bronchial areas decreased by 24 +/- 8% in N, by 45 +/- 3% in A, and by 10 +/- 4% in T. These differences among groups were statistically significant at the tracheal and bronchial levels (p < 0.05), and ipratropium significantly inhibited this airway constriction (p < 0.05) only in the asthmatic group. Assuming that changes in cross-sectional airway areas voluntary apnea reflect airway tone, these results support the view that in humans this tone is mainly vagally controlled and that it is significantly increased in asthmatic compared with nonasthmatic subjects.

Do quantitative cultures of protected brush specimens modify the initial empirical therapy in ventilated patients with suspected pneumonia?

The real contribution of the protected specimen brush (PSB) to guide the choice of antimicrobial therapy in ventilated patients with severe pneumonia is not well established. This study aimed to assess how data obtained by PSB changed the initial empirical therapy. One hundred and ten ventilated patients with suspected pneumonia were entered into a prospective study. All patients underwent fibreoptic bronchoscopy within the first 24 h after clinical suspicion of pneumonia. Specimens were obtained by PSB and were processed for quantitative cultures using standard methods. When patients were started on empirical antibiotics, a standard therapeutic regimen was followed. The decision to introduce, withdraw, maintain, or modify antibiotic therapy, according to the PSB culture results, was left to the attending physician. Pneumonia was the final diagnosis in 45 (41%) of the 110 patients. Pneumonia was excluded in 47 (43%) patients and in the remaining 18 (16%) the diagnosis was uncertain. The initial therapeutic plans were considered to be adequate in 40 patients (36%) and inadequate in 37 cases (34%). In 17 patients (15%), therapeutic changes were made based on the results of PSB cultures. In one case appropriate antibiotics were introduced; in nine cases the therapeutic regimen was reduced to select a narrower and rational therapy; and in seven patients therapy was changed because the prescribed antimicrobial agents were ineffective against the organisms recovered. This study shows that therapeutic changes were made based on the results of PSB cultures in 38% of the patients with pneumonia. In contrast, the PSB technique has no impact on antimicrobial therapy of patients without pneumonia.