Exhaled nitric oxide in paediatric asthma

Mediators in exhaled breath condensate after hypertonic saline challenge

BACKGROUND

Airway narrowing after hypertonic saline challenge (HSC) is postulated to be mediated by bronchoconstrictors and inflammatory mediators.

OBJECTIVE

To study the mechanism of this challenge by using exhaled breath condensate (EBC).

METHODS

Fifty-six subjects (9 to 72 years of age) performed an HSC, with EBC collection and exhaled nitric oxide (FENO) measurements before and after the challenge. Bronchial hyper-reactivity (BHR) was defined if forced expiratory volume in 1 second (FEV1) decreased by 10% compared with baseline (PD10). EBC volume was recorded and was analyzed for mucin, histamine, nitrite/nitrate, and pH.

RESULTS

Those with BHR had a significant rise in EBC volume/5-minute collection period after challenge (286.3 +/- 25.6 microl vs 402.2 +/- 31.3 microl, p = 0.0002), while BHR(-) subjects did not show this change (387.6 +/- 29.7 microl vs 364.1 +/- 30.1 microl, p = 0.55). FENO showed a significant decrease in both BHR(+) and BHR(-) groups after challenge (p = < 0.0001). In BHR(+) subjects histamine increased significantly (1.3 +/- 0.1 microM vs 1.5 +/- 0.1 microM, p = 0.006) compared with baseline, while EBC pH and mucin increased significantly after HSC in both groups. EBC nitrite did not change in either group.

CONCLUSION

EBC analysis suggests that HSC causes an increase in pH and mucin in both groups, but EBC volume and histamine only increased in the BHR(+) group. This suggests that mast cells are activated and fluid flux is associated with the positive response, while mucin release is independent of BHR in HSC.

Pediatric asthma and related allergic and nonallergic diseases: patient-oriented evidence-based essentials that matter

Asthma is the most common medical diagnosis among hospitalized children. In the USA, asthma has accounted for approximately 15% of nonsurgical admissions to hospital in the pediatric age group. Asthma is also one of the leading causes for emergency care requirements, one of the leading causes for missed school, and a cause for considerable morbidity, disability and occasional mortality at all ages. Despite these discouraging statistics, convincing data indicate that this failure of asthma management is not the result of inadequate therapeutic potential, but instead represents ineffective delivery of medical care. Management of asthma and its major co-morbidities, allergic and nonallergic rhinitis, and atopic dermatitis requires a knowledge of the alternative therapies, natural history, and educational techniques for providing patients and families with the ability to manage these troublesome chronic disorders.

Exhaled breath condensate nitrite/nitrate and pH in relation to pediatric asthma control and exhaled nitric oxide

BACKGROUND

Combining exhaled breath condensate (EBC) and exhaled nitric oxide (eNO) may be a useful, non-invasive method to assess airway inflammation in pediatric asthma. This cross-sectional study evaluated the relationship of both EBC nitrite/nitrate (NOx) and EBC pH with asthma control and eNO in asthmatic, normal, and atopic children.

METHODS

A total of 92 children were recruited, comprising 62 with asthma, 14 with atopy only, and 16 who were normal and non-atopic. All completed a questionnaire for asthma symptoms and control. Variables measured were spirometry, EBC NOx, pH, and eNO.

RESULTS

EBC NOx in those with asthma (mean 8.4 microM, CI 7.5-9.4) was significantly elevated when compared with normal (4.8 microM, CI 3.4-6.2, P = 0.0007) and atopic children (6.5 microM, CI 4.0-9.1, P = 0.02). The mean level of eNO was significantly higher in those with asthma (43.7 ppb, CI 34.7-51.1, P < 0.001) and atopy (24 ppb, CI 16.7-31.2, P < 0.05) when compared with normal children (11.5 ppb, CI 6.7-16.2). There was a significantly lower pH in those with asthma and a FEV(1) < 80% predicted (P = 0.03), but no significant overall differences in EBC pH between the three groups of children. There was a significant correlation between eNO and EBC NOx in the group as a whole, but not between eNO and EBC pH.

CONCLUSIONS

Mean EBC NOx levels differ between children with asthma, atopy, and those who are normal, but it is not interchangeable with eNO. EBC pH may be an additional marker of asthma control.