Pulmonary Medicine

Research Article

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

Table 1

Clinical and functional characteristics of study subjects.


Parameters	Control group ()		OSA ()		value
Parameters	Mean ± SD	95% CI	Mean ± SD	95% CI	value

Clinical characteristics
Age, years	54.23 ± 14.19	48.93–59.50	53.98 ± 12.81	50.72–57.13	0.936
Height, cm	158.77 ± 7.48	156.16–161.24	161.08 ± 6.90	159.32–163.07	0.171
Weight, kg	54.33 ± 7.94	51.73–56.99	62.31 ± 12.04	59.24–65.46	0.001
BMI, kg/m²	21.58 ± 2.98	20.58–22.60	23.85 ± 3.43	22.96–24.78	0.002
, cm	32.43 ± 2.71	31.54–33.27	35.23 ± 3.92	34.23–36.23	<0.001
, cm	78.60 ± 8.28	75.47–81.40	86.96 ± 10.16	84.13–89.72	<0.001
Epworth score	10.10 ± 4.54	8.00–11.50	10.83 ± 6.05	10.00–13.00	0.539
Gender, M : F	1 : 1		1.2 : 1		NS
Smoker, %	10.0		13.5		NS
Snoring, %	76.7		76.9		NS
Lung function
FEV₁, % pred.	89 ± 11	85.06–92.94	88 ± 12	84.74–91.26	0.96
FVC, % pred.	91 ± 10	87.42–94.58	89 ± 11	86.01–91.99	0.90
FEV₁/FVC, %	78 ± 7	75.49–80.50	79 ± 8	76.83–81.17	0.93
TLC, % pred.	94 ± 8	91.13–96.86	94 ± 8	91.83–96.17	1.00
PSG parameters
TST, min	531.94 ± 62.43	508.35–553.04	523.74 ± 59.85	506.39–539.29	0.563
AHI, /h	3.03 ± 1.39	2.46–3.51	25.61 ± 15.94	21.80–29.74	<0.001
ARI, /h	23.37 ± 15.39	17.67–28.69	37.10 ± 18.83	31.94–42.58	0.001
SpO₂, %	92.43 ± 2.51	91.57–93.30	88.67 ± 4.20	87.52–89.73	<0.001
Nadir SpO₂, %	89.93 ± 3.29	88.80–91.03	79.83 ± 9.31	77.27–82.08	<0.001
Before PSG
FENO at 50 mL/s, ppb	9.4 ± 6.6	7.5–12.0	16.7 ± 11.4	14.2–20.0	0.003
FENO at 100 mL/s, ppb	6.9 ± 4.0	5.7–8.3	13.1 ± 8.0	11.1–15.3	0.002
FENO at 150 mL/s, ppb	5.6 ± 2.6	4.7–6.6	11.3 ± 6.7	9.6–13.3	0.001
FENO at 350 mL/s, ppb	3.9 ± 1.6	3.3–4.5	8.6 ± 4.7	7.4–9.9	0.001
J’awNO, nL/min	26.6 ± 19.2	20.6–33.5	38.3 ± 26.1	31.5–45.2	0.028
CANO, ppb	2.2 ± 0.7	1.9–2.4	4.0 ± 1.7	3.5–4.5	0.001
After PSG
FENO at 50 mL/s, ppb	12.0 ± 5.9	10.0–14.3	22.1 ± 16.8	18.2–26.9	0.015
FENO at 100 mL/s, ppb	8.9 ± 3.6	7.6–10.3	17.3 ± 11.3	14.7–20.5	0.003
FENO at 150 mL/s, ppb	7.4 ± 2.9	6.4–8.6	15.3 ± 8.5	13.0–17.9	0.001
FENO at 350 mL/s, ppb	5.4 ± 2.2	4.6–6.2	11.2 ± 5.3	9.8–12.7	0.001
J’awNO, nL/min	31.7 ± 20.6	25.0–39.0	39.1 ± 23.6	33.1–45.4	0.150
CANO, ppb	3.2 ± 1.1	2.8–3.6	5.3 ± 1.9	4.8–5.8	0.001

Note: OSA: obstructive sleep apnea; BMI: body mass index; : neck circumference; : abdomen circumference; M : F: male : female; FEV₁: forced expiratory volume in 1 second; FVC: forced vital capacity; TLC: total lung capacity; PSG: polysomnography; TST: total sleep time; AHI: apnea-hypopnea index; ARI: arousal index. FENO: fractional exhaled nitric oxide (measured at expiratory flows of 50, 100, 150, and 350 mL/s); CANO: alveolar nitric oxide concentration; J’awNO: maximal bronchial flux of nitric oxide (using the two-compartment model). 95% CI: bootstrap confidence interval is based on 1000 replications; NS: no significant difference.