Clinical application of nasal nitric oxide measurement in pediatric airway diseases

Abstract

Nitric oxide plays an important role in several physiological and pathophysiological processes in the respiratory tract. Different ways to measure nasal nitric oxide levels in children are currently available. The possibility of obtaining nasal nitric oxide measurement from relatively young children, combined with the availability of portable devices that can be used even in the office setting, opens new perspectives for nasal nitric oxide analysis in the pediatric daily practice. This review presents a synopsis about the current clinical applications of nasal nitric oxide measurement in the pediatric clinical practice. A total of 3,775 articles on the topic were identified, of which 883 duplicates were removed, and 2,803 were excluded based on review of titles and abstracts. Eighty-nine full text articles were assessed for eligibility and 32 additional articles were obtained from the reference lists of the retrieved studies. Since very low nasal nitric oxide levels are found in the majority of patients with primary ciliary dyskinesia, most publications support a central role for nasal nitric oxide to screen the disease, and indicate that it is a very helpful first-line tool in the real-life work-up in all age groups. Decreased nasal nitric oxide concentration is also typical of cystic fibrosis, even though nasal nitric oxide is not as low as in primary ciliary dyskinesia. In other upper airway disorders such as allergic rhinitis, rhinosinusitis, nasal polyposis, and adenoidal hypertrophy, clinical utility of nasal nitric oxide is still critically questioned and remains to be established. Since nNO determination is flow dependent, a general consensus from the major investigators in this area is highly desirable so that future studies will be performed with the same flow rate. A shared nNO methodology will enable to overcome the challenges that lie ahead in incorporating nNO measurement into the mainstream clinical setting of pediatric airway diseases.

Establishing normative nasal nitric oxide values in infants

“…Many of these methods require patient cooperation to exhale against a resistance or phonate to close the velum during sampling. However, quiet tidal breathing has been validated in younger children unable to cooperate [7,8,11]. Nasal NO values obtained by such tidal breath sampling has shown good reliability, sensitivity, and high within-subject repeatability [11e14].…”

Nasal nitric oxide in allergic rhinitis in children and its relationship to severity and treatment

“…A number of studies have shown that nNO is decreased in conditions in which the sinus becomes blocked (nasal polyps adenoidal hypertrophy), ciliary function is compromised (ciliary dyskinesia) or inducible NO synthase in the airway epithelium is reduced (cystic fibrosis) [8–12]. A few studies have shown nNO to be increased in AR [4, 10, 13] and one study has reported that anti-histamine treatment decreased the elevated nNO levels seen in AR patients [14]. …”

“…nNO is a non-invasive marker of inflammation that is increased in AR, and can easily be measured during a routine office visit [9, 10]. We wished to see whether nNO measurement might be useful clinically in determining AR severity and following the patient’s response to treatment.…”

New Developments in the Diagnosis and Therapy of Allergic Rhinitis

“…Aynı zamanda ağır nazal obstrüksiyon ve primer silyer diskinezi varlığında nNO düzeyleri çok düşük ve kistik fibrozda ise orta derecede düşük bulunmaktadır (22). Bu nedenle nNO düzeyinin nazal inflamasyonun hatta AR'nin tanısında kullanılabilecek bir test olabileceği düşünülmektedir (23).…”