Study of Exhaled Nitric Oxide in Subjects with Suspected Obstructive Sleep Apnea: A Pilot Study in Vietnam

Abstract

Background and Objective. The concentration of exhaled nitric oxide (eNO), reflecting the activity of inducible NO synthase in airway epithelium, has been found to increase in patients with obstructive sleep apnea (OSA). This study aimed to measure eNO concentration in patients with suspected OSA and to correlate different eNO parameters with clinical and sleep apnea characteristics. Methods. In this cross-sectional study, all patients underwent in-lab overnight polysomnography (PSG) and eNO measurement using a method of multiple flow rates before and after PSG (pre- and post-PSG). Results. According to the result of PSG, 82 persons were divided into two groups: control subjects (n = 30; 54 ± 14 years) and patients with OSA defined as apnea-hypopnea index (AHI) ≥ 5/hour (n = 52; 53 ± 12 years). Body mass index (BMI) and neck and abdomen circumferences of OSA patients were significantly higher than those from control subjects. In OSA group, post-PSG alveolar NO concentration (CANO) (5.3 ± 1.9 ppb) was significantly higher than pre-PSG CANO (4.0 ± 1.7 ppb; P < 0.001). Significant correlations have been found between CANO and AHI (P < 0.001) and between CANO and nadir SpO2 (P < 0.05). The daytime CANO value of more than 4.1 ppb can be used to screen symptomatic subjects for the presence of OSA with a high specificity of 93.3%. Conclusion. Our findings indicate CANO as a surrogate marker for OSA in persons with suggestive symptoms.

Study of nasal exhaled nitric oxide levels in diagnosis of allergic rhinitis in subjects with and without asthma

“…Previous studies using different techniques (electrochemical and chemiluminescence analyzers) have demonstrated elevated NO in the lower airways in obstructive sleep apnea and asthma 23–25. The present study showed using electrochemical-based analyzer that the levels of nasal FENO were significantly higher in subjects with AR and AR-asthma than in control subjects, but they were not significantly different between AR and AR-asthma subjects (Table 1).…”

Measurement of exhaled nitric oxide concentration in patients with obstructive sleep apnea

“…Among the included studies, 7 also analyzed the effects of continuous positive airway pressure (CPAP) treatment on airway inflammation: 2 [24,31] evaluated the effects of short-term (2 nights) CPAP therapy while the other 5 [21,22,26,30,33] followed CPAP treatment for more than 1 month. A total of 5 studies [21,24,25,29,31] including 359 subjects were pooled for CANO analysis, and 4 studies [21,24,25,29] with 296 subjects were pooled for J’awNO analysis.…”

“…In 5 studies, [16,22,25,28,29] exhaled NO was measured separately before and after overnight PSG to evaluate the variation of FENO levels in the morning and in the evening. For these studies, 2 analyses were performed.…”

“…Thirdly, there was also heterogeneity across the sample populations. We could not perform meta-regression for other confounding factors—snoring [25] or time of measurement [19] —since we did not have enough data on these variables. These factors have previously been found to be associated with eNO levels.…”

Study of the Correlation Between Bronchial Hyperresponsiveness and Exhaled Nitric Oxide in Subjects with Suspected Symptoms of Asthma

“…Technical measurement of exhaled NO was conducted according to manufacturer's instructions, as recommended by the ATS/ERS guideline [6]. The maximal bronchial production rate of NO (J'awNO) and alveolar concentration of NO (CANO) were automatically determined using the two-compartment model and had been reported via Expair's software (Medisoft) as described previously [12,13].…”