Biomedical subjects

L Lehtimäki

Publications and source records attributed to L Lehtimäki.

9 recordsLinked to original sources

PubMed2002

Increased alveolar nitric oxide concentration in asthmatic patients with nocturnal symptoms.

Nocturnal asthma symptoms and impaired lung function at night are related to inflammatory activity in the peripheral lung compartment. Exhaled nitric oxide (NO) measurement at multiple exhalation flow rates can be used to separately assess alveolar and bronchial NO production and inflammation. The authors hypothesised that asthmatic patients with nocturnal symptoms have a higher alveolar NO concentration than those with only daytime symptoms. The authors asked 40 patients with newly-diagnosed steroid-naïve asthma about their nocturnal asthma symptoms through the use of a written questionnaire. Alveolar NO concentration and bronchial NO flux were assessed in the 40 asthmatics and 40 healthy controls. Nineteen of the 40 patients reported nocturnal symptoms. Patients with nocturnal symptoms had a higher alveolar NO concentration (1.7+/-0.3 (mean+/-SEM) parts per billion (ppb)) than patients without nocturnal symptoms (0.8+/-0.3 ppb, p=0.012) or healthy controls (1.0+/-0.1 ppb, p=0.032). Bronchial NO flux was higher both in patients with (2.4+/-0.4 nL x s(-1), p<0.001) and without (2.6+/-0.4 nL x s(-1), p<0.001) nocturnal symptoms, compared to controls (0.7+/-0.1 nL x s(-1)). Nocturnal symptoms in asthmatic patients are related to a higher alveolar nitric oxide concentration. The results suggest that assessment of alveolar nitric oxide concentration can be used to detect the parenchymal inflammation in asthmatic patients with nocturnal symptoms.

Adult↗

PubMed2001

Extended exhaled NO measurement differentiates between alveolar and bronchial inflammation.

Lower respiratory tract inflammation can be detected by measuring exhaled nitric oxide (NO) concentration at a single exhalation flow rate, but this does not differentiate between alveolar and bronchial NO production. We assessed alveolar NO concentration and bronchial NO flux with an extended method of measuring exhaled NO at several exhalation flow rates in 40 patients with asthma, 17 patients with alveolitis, and 57 healthy control subjects. Bronchial NO flux was higher in asthma (2.5 +/- 0.3 nl/s, p < 0.001) than in alveolitis (0.7 +/- 0.1 nl/s) and healthy control subjects (0.7 +/- 0.1 nl/s). Alveolar NO concentration was higher in alveolitis (4.1 +/- 0.3 ppb, p < 0.001) than in asthma (1.1 +/- 0.2 ppb) and healthy control subjects (1.1 +/- 0.1 ppb). In asthma, bronchial NO flux correlated with serum level of eosinophil protein X (EPX) (r = 0.60, p < 0.001) and bronchial hyperresponsiveness (r = 0.55, p < 0.001). In alveolitis, alveolar NO concentration correlated inversely with pulmonary diffusing capacity (r = -0.55, p = 0.022) and pulmonary restriction. Glucocorticoid treatment or allergen avoidance normalized bronchial NO flux in asthma and decreased alveolar NO concentration toward normal in alveolitis. In conclusion, extended exhaled NO measurement can be used to separately assess alveolar and bronchial inflammation and to assess disease activity/severity in asthma and alveolitis.

Adult↗

PubMed2001

Inhaled fluticasone decreases bronchial but not alveolar nitric oxide output in asthma.

Exhaled nitric oxide (NO) concentration is a noninvasive measure of airway inflammation and is increased in asthma. Inhaled glucocorticoids decrease exhaled NO concentration, but the relative contributions of alveolar and bronchial levels to the decrease in exhaled NO concentration are unknown. Alveolar NO concentration and bronchial NO flux can be separately approximated by measuring exhaled NO at several exhalation flow rates. The effect of steroid treatment on alveolar and bronchial NO output in asthma was studied. Alveolar NO concentration and bronchial NO flux were assessed in 16 patients with asthma before and during treatment with inhaled fluticasone for 8 weeks and in 16 healthy controls. Before the treatment, asthmatics had increased bronchial NO flux (mean+/-SEM: 3.6+/-0.4 versus 0.7+/-0.1 nL x s(-1), p<0.001) but normal alveolar NO concentration (1.2+/-0.5 versus 1.0+/-0.2 parts per billion (ppb), p>0.05) compared with controls. Inhaled fluticasone decreased bronchial NO flux from 3.6+/-0.4 to 0.7+/-0.1 nL x s(-1) (p<0.01) but had no effect on alveolar NO concentration (before: 1.2+/-0.5; after: 1.2+/-0.1 ppb, p>0.05). The forced expiratory volume in one second improved, whereas asthma symptom score and serum levels of eosinophil cationic protein and eosinophil protein X decreased during the treatment. In conclusion, inhaled fluticasone decreases bronchial but not alveolar nitric oxide output simultaneously with clinical improvement in patients with asthma.

Administration, Inhalation↗

PubMed2000

Increased bronchial nitric oxide production in patients with asthma measured with a novel method of different exhalation flow rates.

The concentration of nitric oxide (NO) in exhaled air is increased in patients with asthma, suggesting that measuring fractional exhaled NO concentration (FE(NO)) may be used to monitor asthmatic airway inflammation. However, increased FE(NO) is not specific for asthma, as other inflammatory lung diseases may also increase FE(NO). To augment the specificity of FE(NO) measurement, we tested a novel theoretical modelling of pulmonary NO dynamics that allows the approximation of alveolar NO concentration and bronchial NO flux separately by measuring FE(NO) at several exhalation flow rates. We measured FE(NO) at four exhalation flow rates in 10 steroid-naive asthmatics, 5 patients with extrinsic allergic alveolitis, and in 10 healthy controls. Both the asthmatics and the patients with alveolitis had significantly higher FE(NO) than the healthy controls. The increased NO concentration originated from the bronchial level in the asthmatics and from the alveolar level in the patients with alveolitis. In the second part of the study we assessed the repeatability of FE(NO) test, within-day and day-to-day (during two weeks) variation in FE(NO), and the effects of mouth pressure and cigarette smoking on FE(NO) in healthy volunteers. Repeatability of 10 subsequent measurements was high (coefficient of variation (CV) 4.6% +/- 0.4%), and no diurnal variation was found. The day-to-day variation during a 2-week period gave a CV of 10.6% +/- 1.0%. The magnitude of mouth pressure (5-20 cmH2O in adults, 5-40 cmH2O in children) during measurement had no effect on FE(NO). Smoking a cigarette caused a small and transient but statistically significant increase in FE(NO) at 1 and 5 min after smoking. In conclusion, FE(NO) measurement is highly repeatable with low day-to-day variation among healthy subjects. Our results also suggest that the present novel method of measuring FE(NO) at several exhalation flow rates can be used to approximate alveolar and bronchial contributions to FE(NO) separately and thus increase the clinical value of this test.

Adult↗

PubMed1977