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At least 1,387 records · Page 77Linked to original sources
PubMed2002

Detection of wheezing during maximal forced exhalation in patients with obstructed airways.

STUDY OBJECTIVES: Wheezing is a common clinical finding in patients with asthma and COPD during episodes of severe airway obstruction, and can also be heard in normal subjects during forced expiratory maneuvers; however, the properties of wheezing are difficult to perceive and quantify during auscultation. We therefore developed and evaluated a new technique for recording and analyzing wheezing during forced expiratory maneuvers in a group of patients with obstructed airways (asthma, COPD) and a control group of healthy subjects. MATERIAL AND METHODS: Sixteen patients with asthma (9 men and 7 women), 6 patients with COPD (6 men), and 15 healthy subjects (7 men and 8 women) were enrolled. The patients had moderate-to-severe obstruction (FEV(1) of 40 to 53% predicted). A contact sensor on the trachea was used to record sound during forced expiratory maneuvers. Wheeze detection was carried out by a modified algorithm in a frequency-time space after applying the fast Fourier transform. RESULTS: More wheezes were recorded in patients with obstructed airways than in control subjects: asthma patients, 8.4 +/- 6.4 wheezes; COPD patients, 10.4 +/- 6.1 wheezes; and control subjects, 2.9 +/- 2.0 wheezes (mean +/- SD). The mean frequency of all detected wheezes was higher in control subjects than in patients with obstructed airways (asthma patients, 560.9 +/- 140.8 Hz; COPD patients, 669.4 +/- 250.1 Hz; and control subjects, 750.7 +/- 175.7 Hz). The total number of wheezes after terbutaline inhalation changed more in patients with obstructed airways than in control subjects. CONCLUSIONS: The new method that we describe for studying airway behavior during forced expiratory maneuvers is able to identify and analyze wheeze segments generated in patients with obstructed airways, as evidenced by the greater number of wheezes detected in the patient group, the main finding of this study. This method clearly and objectively identifies the presence of obstructive disease.

Analysis of Variance↗
PubMed2005

Clinical implications of the ethane in exhaled breath in patients with acute paraquat intoxication.

STUDY OBJECTIVES: Pulmonary fibrosis due to lipid peroxidation is a major symptom of paraquat intoxication. Ethane in the expired breath (exEth) reflects lipid peroxidation and may be a measure of the damage effected by oxygen radicals in acute lung injury. The purpose of this study was to evaluate the clinical efficacy of exEth as a measure of exposure to paraquat and as an indicator of lung damage. DESIGN: Exposure levels were evaluated by the amount ingested, semiquantitative measurement of urine paraquat levels, and plasma paraquat concentration. End-tidal breath was collected for measurement of ethane 24 h after paraquat ingestion. Renal function and blood gas analyses were conducted on the same day as the breath collection, and the final clinical outcome was defined as either recovery or death. Associations between exEth and paraquat exposure profiles and clinical outcomes were assessed using linear regression models. PATIENTS: Twenty-one patients poisoned by paraquat were selected for the study during 2001 and 2002. RESULTS: exEth could not be used as a predictor of laboratory parameters such as Pa(O2), Pa(CO2), serum creatinine, and lung injury (as graded by high-resolution CT). A logistical analysis revealed that only the amount of paraquat ingested was a significant predictor of fatality (p = 0.021). The strength of the association between exEth and fatality was unaffected by the addition of potential confounders such as age, sex, and time interval and paraquat concentration. CONCLUSION: exEth cannot be used as either an independent predictor of survival or a specific marker of lung injury in patients with acute paraquat poisoning.

Adult↗
PubMed2000

Increased exhalation of hydrogen peroxide in healthy subjects following cigarette consumption.

CONTEXT: Increased hydrogen peroxide has been described in the expired breath condensate (H2O2-E) of several lung conditions, such as acute respiratory distress syndrome, chronic obstructive pulmonary disease and asthma. This technique has been advocated as being a simple method for documenting airway inflammation. OBJECTIVE: To evaluate H2O2-E in healthy cigarette smokers, and to determine the acute effects of the consumption of one cigarette on H2O2-E levels. TYPE OF STUDY: Prospective, controlled trial. SETTING: A pulmonary function laboratory in a University Hospital. PARTICIPANTS: Two groups of healthy volunteers: individuals who had never smoked (NS; n=10; 4 men; age = 30.6 +/- 6.2 years) and current cigarette smokers (S; n=12; 7 men; age = 38.7 +/- 9.8). None of the volunteers had respiratory symptoms and all showed normal spirometric tests. INTERVENTION: Expired air was collected from all volunteers through a face mask and a plastic collecting system leading into a flask with dry ice and pure ethanol. Samples from the group S were collected twice, before and half an hour after the combustion of one cigarette. MAIN MEASUREMENTS: Expired hydrogen peroxide using the Gallati and Pracht method. RESULTS: The S and NS groups showed comparable levels of H2O2-E at basal conditions [NS = 0.74 microM (DP 0.24) vs. S = 0.75 microM (DP 0.31)]. The smokers showed a significant increase in H2O2-E levels half an hour after the consumption of only one cigarette [0.75 microM (DP 0.31) vs. 0. 95 microM (DP 0.22)]. CONCLUSION: The present results are consistent with the concept that smokers increase oxidative stress with elevated production of reactive oxygen species, contributing to the development of smoking-related disorders.

Adult↗
PubMed1999

[Exhaled nitric oxide of childhood asthma].

Chronic airway inflammation is a central feature of pathology of bronchial asthma. In order to evaluate inflammatory status in asthma, examinations such as bronchoscope or induced sputum test can be done. Because of difficulty of those examinations we need non-invasive and simple measures for childhood asthma. Here we investigated eNO in childhood asthma. Twenty-six of atopic asthma, 13 non-asthmatic atopic children and 12 normal children were enrolled in this study. eNO was measured by chemiluminescence analyzer. eNO was significantly collerated with % FEV 1.0 and blood eosinophil counts (R = -0.494, R = 0.416, respectively). Geometrical mean of eNO in normal, non-asthmatic atopic, asthma without inhaled corticosteroid (ICS) and asthma with ICS was 16.3, 23.7, 71.6, 43.6 ppb, respectively. eNO was significantly higher in asthma than in normals. eNO in patients without ICS were significantly higher than in non-asthmatic atopic. We concluded that eNO might be useful marker for evaluation of airway inflammation in asthmatic children.

Asthma↗
PubMed1999

Exhaled nitric oxide increases during high frequency oscillatory ventilation in rabbits.

This study compared the effects of high frequency oscillatory ventilation (HFOV) and intermittent mandatory ventilation (IMV) on the homeostasis of nitric oxide (NO) in the lower respiratory tract of healthy rabbits. The mechanisms underlying a putative stretch response of NO formation in the airways were further elucidated. Male New Zealand White rabbits were anaesthetized, tracheotomized and ventilated with IMV or HFOV in random order. Total NO excretion increased from 9.6 +/- 0.8 nl min-1 (mean +/- S.E.M.) during IMV to 22.6 +/- 2.7 nl min-1 during HFOV (P < 0.001). This increase was not explained by changes of functional residual capacity ([Delta]FRC). A similar increase in NO excretion during HFOV was seen in isolated buffer-perfused lungs under constant circulatory conditions (P < 0. 05, n = 4). Intratracheal mean CO2 and NO concentrations, measured at 2.5, 5, 7.5 and 10 cm below tracheostomy, increased significantly with increasing distance into the lung during both IMV and HFOV (P < 0.001 for each comparison). At every intratracheal location of the sampling catheter, particularly low in the airways, both CO2 and NO concentrations were significantly higher during HFOV than during IMV (P < 0.01 for each comparison). We conclude that HFOV increases pulmonary NO production in healthy rabbits. Increased stretch activation of the respiratory system during HFOV is suggested as a possible underlying mechanism. The increase in mean airway NO concentrations may have biological effects in the respiratory tract. Whether it can account for some of the benefits of HFOV treatment needs to be considered.

Animals↗
PubMed1999

[Parameters of oxidative metabolism, neuro-humoral and hormonal regulation in the condensed exhaled air in early stages of anthracosilicosis].

For early diagnosis of anthracosilicosis, the authors studied oxidation parameters, neuromediators and hormones in expired air condensate in coal miners. Premorbid stage of anthracosilicosis is characterized by activated lipids peroxidation, high levels of neuromediators (acetylcholine, catecholamines), tissue hormones (histamine, serotonine) and lower contents of adaptive hormones (cortisol, triiodothyronine, thyroxine).

Air↗
PubMed2000

On-line measurement of exhaled [11C]CO2 during PET.

UNLABELLED: The purpose of this study was to develop and evaluate a system for the continuous on-line measurement of expired 11CO2 during 11C PET studies. METHODS: A detector system was developed that allowed continuous sampling of expired air during PET. Healthy volunteers (n = 4) underwent PET with [11C]CO2 during which expired air, tomographic tissue activity, and blood data were collected. The measured expired-air 11CO2 radioactivity time courses were filtered, and an envelope was extracted and compared with the time course of 11CO2/H11CO3 in blood. RESULTS: Good agreement was found between the shapes of the expired-air envelope and the time course in blood, enabling quantitative calibration against discrete blood samples. CONCLUSION: A system for the continuous monitoring of expired radioactivity during PET has been developed and evaluated with [11C]CO2. This monitoring enables the quantitative continuous measurement of 11CO2/H11CO3- in blood.

Carbon Dioxide↗