Foresi Antonio, Leone Clementina, Olivieri Dario, Cremona George
Unit of Respiratory Medicine, Sesto San Giovanni Hospital, Sesto San Giovanni, Italy.
Chest. 2007 Sep;132(3):860-7. doi: 10.1378/chest.06-3124. Epub 2007 Jul 23.
Obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular diseases, in particular systemic arterial hypertension. We postulated that intermittent nocturnal hypoxia in OSAS may be associated to decreased fractional exhaled nitric oxide (FENO) levels from distal airspaces.
Multiple flow rate measurements have been used to fractionate nitric oxide (NO) from alveolar and bronchial sources in 34 patients with OSAS, in 29 healthy control subjects, and in 8 hypertensive non-OSAS patients. The effect of 2 days of treatment with nasal continuous positive airway pressure (nCPAP) on FENO was examined in 18 patients with severe OSAS.
We found that the mean [+/- SE] concentrations of exhaled NO at a rate of 50 mL/s was 21.8 +/- 1.9 parts per billion (ppb) in patients with OSAS, 25.1 +/- 3.3 ppb in healthy control subjects, and 15.4 +/- 1.7 ppb in hypertensive control patients. The mean fractional alveolar NO concentration (CANO) in OSAS patients was significantly lower than that in control subjects (2.96 +/- 0.48 vs 5.35 +/- 0.83 ppb, respectively; p < 0.05). In addition, CANO values were significantly lower in OSAS patients with systemic hypertension compared to those in normotensive OSAS patients and hypertensive patients without OSAS. The mean values of CANO significantly improved after nCPAP therapy (2.67 +/- 0.41 to 4.69 +/- 0.74 nL/L, respectively; p = 0.01).
These findings suggest that alveolar FENO, and not bronchial FENO, is impaired in patients with OSAS and that this impairment is associated with an increased risk of hypertension. NO production within the alveolar space is modified by treatment with nCPAP.
阻塞性睡眠呼吸暂停综合征（OSAS）与心血管疾病相关，尤其是系统性动脉高血压。我们推测，OSAS患者夜间间歇性缺氧可能与远端气腔呼出一氧化氮分数（FENO）水平降低有关。
采用多次流速测量法，对34例OSAS患者、29例健康对照者和8例高血压非OSAS患者的肺泡和支气管来源的一氧化氮（NO）进行分离。对18例重度OSAS患者进行了为期2天的经鼻持续气道正压通气（nCPAP）治疗对FENO影响的研究。
我们发现，OSAS患者以50 mL/s的流速呼出的NO平均[+/- SE]浓度为21.8 +/- 1.9十亿分之一（ppb），健康对照者为25.1 +/- 3.3 ppb，高血压对照患者为15.4 +/- 1.7 ppb。OSAS患者的平均肺泡NO分数浓度（CANO）显著低于对照者（分别为2.96 +/- 0.48 vs 5.35 +/- 0.83 ppb；p < 0.05）。此外，与血压正常的OSAS患者和无OSAS的高血压患者相比，患有系统性高血压的OSAS患者的CANO值显著更低。nCPAP治疗后CANO的平均值显著改善（分别从2.67 +/- 0.41至4.69 +/- 0.74 nL/L；p = 0.01）。
这些发现表明，OSAS患者的肺泡FENO而非支气管FENO受损，且这种损害与高血压风险增加相关。nCPAP治疗可改善肺泡内NO的生成。
