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| 2. |
- Heijkenskjöld-Rentzhog, Charlotte, et al.
(författare)
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Alveolar and exhaled NO in relation to asthma characteristics : effects of correction for axial diffusion
- 2014
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Ingår i: Allergy. European Journal of Allergy and Clinical Immunology. - : Wiley. - 0105-4538 .- 1398-9995. ; 69:8, s. 1102-1111
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Tidskriftsartikel (refereegranskat)abstract
- Background: Inflammation in the small airways might contribute to incomplete asthma disease control despite intensive treatment in some subgroups of patients. Exhaled NO (FeNO) is a marker of inflammation in asthma and the estimated NO contribution from small airways (Calv(NO)) is believed to reflect distal inflammation. Recent studies recommend adjustments of Calv(NO) for trumpet model and axial diffusion (TMAD-adj). This study aimed to investigate the clinical correlates of Calv(NO), both TMAD-adjusted and unadjusted. Methods: Asthma symptoms, asthma control, lung function, bronchial responsiveness, blood eosinophils, atopy and treatment level were assessed in 410 subjects, aged 10-35 years. Exhaled NO was measured at different flow-rates and Calv(NO) calculated, with TMAD-adjustment according to Condorelli. Results: Trumpet model and axial diffusion-adjusted Calv(NO) was not related to daytime wheeze (P = 0.27), FEF50 (P = 0.23) or bronchial responsiveness (P = 0.52). On the other hand, unadjusted Calv(NO) was increased in subjects with daytime wheeze (P < 0.001), decreased FEF50 (P = 0.02) and with moderate-to-severe compared to normal bronchial responsiveness (P < 0.001). All these characteristics correlated with increased FeNO (all P < 0.05). Unadjusted Calv(NO) was positively related to bronchial NO flux (J'aw(NO)) (r = 0.22, P < 0.001) while TMAD-adjCalv(NO) was negatively related to J'awNO (r = -0.38, P < 0.001). Conclusions: Adjusted Calv(NO) was not associated with any asthma characteristics studied in this large asthma cohort. However, both FeNO and unadjusted Calv(NO) related to asthma symptoms, lung function and bronchial responsiveness. We suggest a potential overadjustment by current TMAD-corrections, validated in healthy or unobstructed asthmatics. Further studies assessing axial diffusion in asthmatics with different degrees of airway obstruction and the validity of proposed TMAD-corrections are warranted.
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| 3. |
- Heijkenskjöld-Rentzhog, Charlotte, et al.
(författare)
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New method for single-breath fraction of exhaled nitric oxide measurement with improved feasibility in preschool children with asthma
- 2015
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Ingår i: Pediatric Allergy and Immunology. - : Wiley. - 0905-6157 .- 1399-3038. ; 26:7, s. 662-667
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Respiratory societies recommend use of standardized methodologies for fraction of exhaled nitric oxide (FeNO) measurements in adults and children, but in preschoolers, feasibility remains a problem. The exhalation time needed to obtain steady-state FeNO is unclear. Our primary aim was to study the feasibility of an adapted single-breath FeNO method with age-adjusted exhalation times. We also studied the association between time to steady-state NO level and height, as well as FeNO in relation to asthma and current treatment with inhaled corticosteroids (ICS).METHODS: Sixty-three children aged 3-10 years performed FeNO measurements with a hand-held electrochemical device with a newly developed flow-control unit. Exhalation times were pre-adapted to age. Exhaled air was simultaneously sampled to a chemiluminescence analyzer to measure time to steady-state NO level.RESULTS: Eighty-one percent of the children achieved at least one approved measurement. From 4 years upwards, success rate was high (96%). Time to steady-state [NO] (median and interquartile range) was 2.5 s (2.4-3.5) at the age of 3-4 years and 3.5 s (2.7-3.8) at the age of 5-6 years. Height was associated with time to steady state (r(2) = 0.13, p = 0.02). FeNO (geometric mean [95% CI]) was higher in ICS-naïve asthmatic children (n = 19): 15.9 p.p.b. (12.2-20.9), than in both healthy controls (n = 8) 9.1 p.p.b. (6.6-12.4) and asthmatic subjects on treatment (n = 24) 11.5 p.p.b. (9.7-13.6).CONCLUSION: We found this adapted single-breath method with age-adjusted exhalation times highly feasible for children aged 4-10 years. ICS-naïve asthmatic children had FeNO levels under the current guideline cutoff level (20 p.p.b.), highlighting the importance of taking age into account when setting reference values.
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| 5. |
- Heijkenskjöld Rentzhog, Charlotte, et al.
(författare)
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Overall and peripheral lung function assessment by spirometry and forced oscillation technique in relation to asthma diagnosis and control.
- 2017
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Ingår i: Clinical and Experimental Allergy. - : Wiley. - 0954-7894 .- 1365-2222. ; 47:12, s. 1546-1554
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Classic spirometry is effort dependent and of limited value in assessing small airways. Peripheral airway involvement, and relation to poor control, in asthma, has been highlighted recently. Forced oscillation technique (FOT) offers an effort-independent assessment of overall and peripheral lung mechanics. We studied the association between lung function variables, obtained either by spirometry or multifrequency (5, 11 and 19 Hz) FOT, and asthma diagnosis and control.METHODS: ), resistance difference between 5-19 Hz (R5-R19) and Asthma Control Test scores were determined in 234 asthmatic and 60 healthy subjects (aged 13-39 years). We used standardized lung function variables in logistic regression analyses, unadjusted and adjusted for age, height, gender and weight.RESULTS: and R5-R19) were associated with uncontrolled asthma (P-values < .05).CONCLUSIONS: /FVC, supporting a complementary role for FOT. Asthma control was related to FOT measures of peripheral airways, suggesting a potential use in identifying such involvement. Further studies are needed to determine a clinical value and relevant reference values in children, for the multifrequency FOT measurements.
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| 7. |
- Heijkenskjöld-Rentzhog, Charlotte, et al.
(författare)
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The fraction of NO in exhaled air and estimates of alveolar NO in adolescents with asthma : methodological aspects
- 2012
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Ingår i: Pediatric Pulmonology. - : Wiley. - 8755-6863 .- 1099-0496. ; 47:10, s. 941-949
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Tidskriftsartikel (refereegranskat)abstract
- RationaleThis study investigated the oral contribution to exhaled NO in young people with asthma and its potential effects on estimated alveolar NO (CalvNO), a proposed marker of inflammation in peripheral airways. Secondary aims were to investigate the effects of various exhalation flow-rates and the feasibility of different proposed adjustments of (CalvNO) for trumpet model and axial diffusion (TMAD).MethodsExhaled NO at flow rates of 50–300 ml/sec, and salivary nitrite was measured before and after antibacterial mouthwash in 29 healthy young people (10–20 years) and 29 with asthma (10–19 years). CalvNO was calculated using the slope–intercept model with and without TMAD adjustment.ResultsExhaled NO at 50 ml/sec decreased significantly after mouthwash, to a similar degree in asthmatic and healthy subjects (8.8% vs. 9.8%, P = 0.49). The two groups had similar salivary nitrite levels (56.4 vs. 78.4 µM, P = 0.25). CalvNO was not significantly decreased by mouthwash. CalvNO levels were similar when flow-rates between 50–200 or 100–300 ml/sec were used (P = 0.34 in asthmatics and P = 0.90 in healthy subjects). A positive association was found between bronchial and alveolar NO in asthmatic subjects and this disappeared after the TMAD-adjustment. Negative TMAD-adjusted CalvNO values were found in a minority of the subjects.ConclusionsYoung people with and without asthma have similar salivary nitrite levels and oral contributions to exhaled NO and therefore no antibacterial mouthwash is necessary in routine use. TMAD corrections of alveolar NO could be successfully applied in young people with asthma and yielded negative results only in a minority of subjects.
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| 8. |
- Heijkenskjöld Rentzhog, Charlotte, 1971-
(författare)
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Towards Improved Diagnostics and Monitoring in Childhood Asthma : Methodological and Clinical Aspects of Exhaled NO and Forced Oscillation Technique
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Asthma is a heterogeneous disease. Diagnosis relies on symptom evaluation and lung function tests using spirometry. Symptoms can be vague. Spirometry is effort-dependent and does not reliably evaluate small airways. Allergic asthma in preschool children is not easily separated from episodic wheeze.Exhaled NO (FeNO) is a marker of allergic Th2-cytokine-driven airway inflammation. However, FeNO is not feasible in preschoolers with current devices and algorithms. Alveolar NO is an estimate of small airway involvement. Forced oscillometry (FOT) is an effort-independent lung function test assessing both large and small airways.Aims: To study clinical and methodological aspects of FeNO, alveolar NO and lung function indices by FOT.Methods: Asthmatic children and young adults and healthy controls, were included in the studies. FeNO at 50 mL/s was performed in all studies (in study III with an adapted single-breath method with age-adjusted exhalation times). FeNO at multiple exhalation flow rates were performed in studies I, II and IV to calculate alveolar NO, as was spirometry. FOT indices were assessed in study IV.Results: The exhalation time needed to reach steady-state NO was < 4 s in subjects aged 3-4 years, and was related to subject height. FeNO was higher in ICS-naïve asthmatic children than in controls. ICS-naïve asthmatic preschool children had FeNO < 20 ppb. The oral contribution to FeNO was similar in asthmatic and healthy youths. Multiple flow rates and modelling of alveolar NO were feasible in children aged 10-18 years. Alveolar NO correlated to asthma characteristics, though not when axial diffusion correction was applied. FOT resistance measures were associated with asthma diagnosis, and small airway FOT measures were associated with asthma control, in adolescents.Conclusion: An adapted FeNO method is feasible from 4 years, and exhalation time is related to child height. Our findings emphasise the need to refine clinical cut-offs for FeNO in younger children. FOT variables discriminate between asthmatics and controls, much like spirometry. The information provided by FOT is additive to that from spirometry. Further studies of exhaled NO dynamics and FOT indices of small airways are warranted to evaluate new treatment options and possibly improve asthma control.
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| 9. |
- Johansson, Henrik, et al.
(författare)
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Prevalence of exercise-induced bronchoconstriction and exercise-induced laryngeal obstruction in a general adolescent population
- 2015
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Ingår i: Thorax. - : BMJ. - 0040-6376 .- 1468-3296. ; 70:1, s. 57-63
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Tidskriftsartikel (refereegranskat)abstract
- Background Exercise-induced respiratory symptoms are common among adolescents. Exercise is a known stimulus for transient narrowing of the airways, such as exercise-induced bronchoconstriction (EIB) and exercise-induced laryngeal obstruction (EILO). Our aim was to investigate the prevalence of EIB and EILO in a general population of adolescents. Methods In this cross-sectional study, a questionnaire on exercise-induced dyspnoea was sent to all adolescents born in 1997 and 1998 in Uppsala, Sweden (n=3838). A random subsample of 146 adolescents (99 with self-reported exercise-induced dyspnoea and 47 without this condition) underwent standardised treadmill exercise tests for EIB and EILO. The exercise test for EIB was performed while breathing dry air; a positive test was defined as a decrease of >= 10% in FEV1 from baseline. EILO was investigated using continuous laryngoscopy during exercise. Results The estimated prevalence of EIB and EILO in the total population was 19.2% and 5.7%, respectively. No gender differences were found. In adolescents with exercise-induced dyspnoea, 39.8% had EIB, 6% had EILO and 4.8% had both conditions. In this group, significantly more boys than girls had neither EIB nor EILO (64.7% vs 38.8%; p=0.026). There were no significant differences in body mass index, lung function, diagnosed asthma or medication between the participants with exercise-induced dyspnoea who had or did not have a positive EIB or EILO test result. Conclusions Both EIB and EILO are common causes of exercise-induced dyspnoea in adolescents. EILO is equally common among girls and boys and can coexist with EIB.
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