Archive of Medical Research

[The effect of chronic intermittent hypoxia caused by obstructive sleep apnea hypopnea syndrome on blood pressure.]

OBJECTIVE: To explore the effect of chronic intermittent hypoxia caused by obstructive sleep apnea hypopnea syndrome (OSAHS) and chronic continuous hypoxia caused by chronic obstructive pulmonary disease (COPD) on blood pressure and levels of nitric oxide (NO)/endothelin (ET). METHODS: A total of 85 cases were selected, including OSAHS patients over 18 years old visited this hospital from June to August 2006, stable COPD patients and healthy volunteers. According to the results of clinical questionnaire, pulmonary function test and polysomography (PSG), they were divided into 4 groups: non-smoking OSAHS patients (n = 26), smoking OSAHS patients (n = 22), patients with stable COPD (n = 17) and healthy control subjects (n = 20). Blood pressure measurement was performed before and after the PSG examination while the subjects were resting. The levels of ET and NO in blood samples and exhaled breath condensates (EBC) were measured by radioimmunoassay and nitrate reductase, respectively. Measurement data were analyzed by ANOVA, numeration data were analyzed by chi-square test, data of normal distribution were analyzed by Pearson correlation analysis, and non-normal data were analyzed by Spearman correlation analysis. Multiple linear regression analysis was also performed. RESULTS: Regardless of the smoking status, the difference of morning-evening diastolic blood pressure (DBP) in the morning of patients with OSAHS [non-smoking OSAHS: (88 +/- 10) mm Hg, 1 mm Hg = 0.133 kPa; smoking OSAHS: (95 +/- 17) mm Hg] was higher than that of patients with COPD [(76 +/- 7) mm Hg] and healthy subjects [(70 +/- 6) mm Hg]. The difference of morning-evening NO level in EBC of patients with OSAHS [non-smoking OSAHS: (-4.5 +/- 7.9) micromol/L; smoking OSAHS: (-3.4 +/- 5.5) micromol/L] was lower than that of patients with COPD [(1.4 +/- 6.1) micromol/L] and healthy subjects [(3.1 +/- 4.0) micromol/L]. The ratio of NO to ET in serum of the smoking OSAHS group (1.0 +/- 0.5) was lower than that of the COPD group (1.4 +/- 0.7). After adjustment for sex, age, BMI, waist circumference, history of smoking and alcohol, level of hypertension, and category of antihypertensive drugs, the morning-evening difference of NO level in EBC was negatively associated with the morning-evening difference of DBP (r = -0.301, P = 0.021), and was positively associated with apnea hypopnea index (AHI) (r = 0.116, P < 0.05). The morning-evening difference of DBP was associated with AHI (r = -0.303, P = 0.011), amplitude of oxygen desaturation with pulse oxygen saturation (SpO(2)) less than 90% (OLA90%, r = -0.281, P = 0.018), and gradient of oxygen desaturation with SpO(2) less than 90% (OLG90%, r = 0.286, P = 0.035). Multiple linear regression analysis showed that, if AHI increased by 1/h, the morning-evening difference of DBP would increase 0.41 mm Hg; if the morning-evening difference of NO level in EBC increased by 1 micromol/L, the morning-evening difference of DBP would decrease 0.27 mm Hg; and if AHI increased by 1/h, the morning-evening difference of NO level in EBC would increase 0.40 micromol/L. CONCLUSION: The DBP of OSAHS patients in the morning is significantly higher than that in the evening. The morning-evening difference of NO level in EBC reflects indirectly the consumption of NO in the body, and is associated with the degree of OSAHS and the morning-evening difference of DBP.

Mo L, Gai J, He QY.

Department of Respiratory Medicine, Peking University People\’s Hospital, Beijing 100044, China.

[A multi-center study on the association between sleep apnea and prevalence of hypertension.]

OBJECTIVE: To investigate the prevalence of hypertension among sleep apnea patients and the associated factors. METHODS: A total of 2297 patients (male 1310, female 211) from 20 teaching hospitals were enrolled in this study. Medical history interview, blood pressure measurement and an in-hospital polysomnogram were performed for all the patients. Questionnaires of sleep apnea and hypertension were finished by all the patients. SPSS 11.0 software package was used for data analyzing, and prevalence rates of hypertension were compared by chi-square test. RESULTS: The prevalence of hypertension in the apnea hypopnea index (AHI) < 5/h group was 23.5%, but in AHI >/= 5/h group was 49.3%, the difference being significant. The prevalence of hypertension in the group with obstructive sleep apnea hypopnea syndrome (OSAHS) was 56.2%, but was 63.7% and 39.4% in the groups with and without hypertension family history, respectively. The odds ratio of hypertension in AHI >/= 5/h group was 3.167 times higher than in the AHI < 5/h group (OR = 3.167, 95% CI 2.953 - 5.426, P < 0.01). The prevalence of hypertension increased with AHI increases, and it was the highest in subjects with AHI of 16 - 20/h, but deceased slowly in subjects with AHI of 66 - 70/h. Two equations were formulated to show the relationship between AHI and the prevalence of hypertension: the prevalence of hypertension = 0.3199 + 0.0042 x AHI, and OR of the prevalence of hypertension = 1.018 + 0.017 x AHI. The AHI was an independent risk factor for the prevalence of hypertension after control for age, sex, BMI and family history of hypertension. CONCLUSIONS: The prevalence of hypertension in subjects with sleep apnea was higher than those without sleep apnea. There was a close relationship between sleep apnea syndrome and the prevalence of hypertension. Sleep apnea was an independent factor for hypertension after control for the confounding factors.

Sleep Breathing Disorder Group of Respiratory Diseases Branch, Chinese Medical Association, Chen BY, He QY.

Department of Respiratory Medicine, Tianjin Medical University General Hospital, Tianjin 300052, China.

[Obstructive sleep apnea hypopnea and metabolic syndromes.]

Zhang XL.

[Continuous positive airway pressure treatment for obstructive sleep apnea hypopnea syndrome.]

Luo YM.

[The clinical recognition and simple diagnostic procedures for obstructive sleep apnea and hypopnea syndrome.]

Liu HG, Xu YJ.

[In Process Citation]

[The relationship between obstructive sleep apnea hypopnea syndrome and cerebrovascular diseases.]

Han F.

[To further study the pathogenesis of obstructive sleep apnea-hypopnea syndrome.]

Wang GF.

[Emphasis on the research of sleep apnea pattern intermittent hypoxia.]

Chen BY, He QY.

Hypoxemia with high alveolar-arterial oxygen gradient but no lung involvement in a patient with Churg-Strauss syndrome: case report.

Churg-Strauss syndrome (CSS) is characterized by asthma and/or a history of allergy, eosinophilia and an often life-threatening systemic necrotizing vasculitis. We describe a patient with CSS and hypoxemia with a high alveolar-arterial oxygen gradient (AaDO2), but no pulmonary parenchymal involvement. The patient also had a low diffusion capacity with normal lung volume and a high level of serum thrombomodulin, a marker of endothelial cell injury. Treatment for CSS, such as corticosteroid, improved both hypoxemia and AaDO2 consistent with amelioration of diffusion capacity and serum thrombomodulin level, suggesting that this pathosis involves microangiopathy with endothelial cell damage induced by vasculitis in pulmonary blood vessels.

Utsugi M, Ishizuka T, Hisada T, Sato K, Ishizuka T, Dobashi K, Mori M.

Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan.