慢性间歇低氧对心脏B超和血压影响的观察

目的 探讨慢性间歇低氧对OSAHS患者左心功能的影响,以及持续气道正压通气(CPAP)治疗后左心功能和血压的变化.方法 顺序收集2007年5月至2008年12月于吉林大学第一医院就诊的、符合OSAHS诊断标准的门诊或住院患者75例(OSA组),其中非高血压者35例,合并高血压者40例.另选30名健康人为对照组,其中男20名,女10名,年龄30～65岁,与患者组年龄匹配,均为经系统检查无异常发现的健康人.对两组左心室射血分数(left ventricular ejection fraction,LVEF)、短轴缩短率(shortening fraction,FS)、E峰、A峰,并计算E/A进行比较.CPAP治疗后的血压、LVEF、E/A进行分析.结果 所有患者晨起血压(150.80±20.73/108.0±15.34)mm Hg(1 mm Hg=0.133 kPa)均较睡前血压(134.16±18.33/90.09±11.24)mm Hg明显升高.OSA组E/A明显降低(P<0.01),LVEF、FS明显降低(P<0.05);与对照组及OSA非高血压组比较,OSA合并高血压的患者左室射血分数和短轴缩短率均减少,提示高血压的出现是OSA左室收缩功能减退的重要因素;与对照组比较,OSA非高血压组E/A明显降低;非高血压组和高血压组比较,高血压组E/A下降显著,说明OSA本身可直接影响左心室舒张功能,而高血压的出现加重了左心室的舒张功能的降低.经CPAP治疗6个月后晨起血压(142.59±15.34/96.52±9.81)mmHg较治疗前(150.80±20.73/108.0±15.34) mm Hg显著下降(P<0.001);左室射血分数(59.70±11.1)%较治疗前(56.40±9.74)%增加(P<0.05);E/A值1.16±0.25较治疗前0.87±0.17明显增加(P<0.01).结论 (1)CIH可引起左心结构和功能发生改变,高血压的出现加重了这种变化.(2)CPAP对于纠正OSA患者高血压、改善左心功能,提高生活质量有重要意义.     

CPAP对高血压伴代谢综合征的OSAS患者的影响

目的探讨持续气道正压通气（Continuous positive airway pressure,CPAP）干预对有阻塞性睡眠呼吸暂停综合征（Obstructive sleep apnea syndrome,OSAS）的高血压伴代谢综合征患者的血压及异常代谢组分的影响。方法采用双盲、安慰剂对照设计,将患者随机分配接受5个月CPAP治疗或者5个月假性CPAP。在每种干预之前和之后,检测受试者的血压、空腹血糖、胰岛素抵抗指数、空腹血脂谱、糖化血红蛋白及人体测量学参数等指标。结果共128例完成研究。CPAP治疗与下列指标平均值的显著降低相关：收缩压（6.1mmHg;95%可信区间[CI]：1.3～6.2,P=0.001）,舒张压（4.5mmHg;95%CI：0.8～4.2,P〈0.001）,血清总胆固醇（16.5mg/dl;95%CI：5.2～21.4,P=0.005）,非高密度脂蛋白胆固醇（16.1mg/dl;95%CI：4.7～21.9,P=0.008）,低密度脂蛋白胆固醇（12.8mg/dl;95%CI：2.4～16.9,P=0.007）,甘油三酯（21.9mg/dl;95%CI：4.2～42.1,P=0.03）和糖化血红蛋白（0.4%;95%CI：0.1～0.5,P=0.004）。CPAP治疗后代谢综合征显著好转（128例患者中23例逆转[18%]vs.假性CPAP治疗后仅3例逆转[2%]）。结论在有中重度OSAS的高血压伴代谢综合征患者中,CPAP治疗5个月可降低血压并改善伴随的代谢异常。     

Treatment of sleep apnea in heart failure

Obstructive and central sleep apnea are common in heart failure, and may participate in its progression by exposing the heart to intermittent hypoxia, increased preload and afterload, sympathetic activation, and vascular endothelial dysfunction. Treatment of sleep apnea in patients with heart failure may reverse these detrimental effects, in addition to alleviating symptoms of sleep apnea. In patients with heart failure and obstructive sleep apnea, short-term randomized trials have demonstrated that continuous positive airway pressure (CPAP) improves cardiac function, and lowers sympathetic activity and blood pressure. However, there are no data on whether treating obstructive sleep apnea in patients with heart failure improves morbidity and mortality. Various treatments have been tested in heart failure patients with central sleep apnea, particularly oxygen and CPAP. Both reduce the frequency of central respiratory events, and lower sympathetic activity. In addition, CPAP improves cardiac function. However, the largest randomized trial did not demonstrate any beneficial effect of CPAP on the rate of mortality and cardiac transplantation (32 vs. 32 events in the control and treatment groups, respectively; p=0.54), but ultimately lacked power to conclude with certainty whether CPAP has an effect on morbidity and mortality in such patients. Thus, although there are data to indicate that treating both obstructive and central sleep apnea in patients with heart failure improves cardiovascular function, larger randomized trials involving interventions such as oxygen, CPAP, or other forms of positive airway pressure will be required to determine whether treating these sleep-related breathing disorders reduces clinically important outcomes such as morbidity and mortality.     

Effect of continuous positive airway pressure therapy on 24-hour blood pressure in patients with obstructive sleep apnea syndrome

BACKGROUND: Patients with obstructive sleep apnea syndrome (OSAS) are subject to an increased cardiovascular morbidity including systemic hypertension. Little is known about the effects of treatment with nasal continuous positive airway pressure (CPAP) on systemic hypertension. METHODS: Automated ambulatory 24-h blood pressure (BP) monitoring was performed in 88 consecutive patients who were referred for evaluation of snoring or suspected OSAS. In addition, the long-term effects of CPAP therapy on 24-h BP were assessed. RESULTS: A total of 62 patients had OSAS and 26 habitual snoring. Patients with OSAS had significantly higher mean arterial BP values than snorers (102.7 +/- 10.7 v 94.0 +/- 10.2 mm Hg; P < .01). Multiple stepwise linear regression analysis disclosed that the degree of systemic hypertension was independently associated with the severity of OSAS as determined by the apnea/hypopnea index (R = 0.43; P < .001), but not with age, body mass index, or smoking habits. Of the 62 patients with OSAS, 52 were treated with CPAP and reevaluated after 9 months. The CPAP resulted in a significant decrease in mean arterial BP (from 103.7 +/- 10.4 to 99.1 +/- 10.8 mm Hg; P < .05). For those patients with systemic hypertension whose BP improved with CPAP therapy, 24-h mean pulse pressure at baseline (r = -0.36; P < .05) as well as average heart rate during the day (r = -0.35; P < .05) turned out as predictors. CONCLUSIONS: Obstructive sleep apnea syndrome contributes, at least in part, to the development of systemic hypertension, and CPAP may improve BP values in treated OSAS patients. Predictors of a beneficial CPAP effect on BP are a high heart rate and a high pulse pressure before treatment.     

Obstructive sleep apnea: the most common secondary cause of hypertension associated with resistant hypertension

Recognition and treatment of secondary causes of hypertension among patients with resistant hypertension may help to control blood pressure and reduce cardiovascular risk. However, there are no studies systematically evaluating secondary causes of hypertension according to the Seventh Joint National Committee. Consecutive patients with resistant hypertension were investigated for known causes of hypertension irrespective of symptoms and signs, including aortic coarctation, Cushing syndrome, obstructive sleep apnea, drugs, pheochromocytoma, primary aldosteronism, renal parenchymal disease, renovascular hypertension, and thyroid disorders. Among 125 patients (age: 52±1 years, 43% males, systolic and diastolic blood pressure: 176±31 and 107±19 mm Hg, respectively), obstructive sleep apnea (apnea-hypopnea index: >15 events per hour) was the most common condition associated with resistant hypertension (64.0%), followed by primary aldosteronism (5.6%), renal artery stenosis (2.4%), renal parenchymal disease (1.6%), oral contraceptives (1.6%), and thyroid disorders (0.8%). In 34.4%, no secondary cause of hypertension was identified (primary hypertension). Two concomitant secondary causes of hypertension were found in 6.4% of patients. Age >50 years (odds ratio: 5.2 [95% CI: 1.9-14.2]; P<0.01), neck circumference ≥41 cm for women and ≥43 cm for men (odds ratio: 4.7 [95% CI: 1.3-16.9]; P=0.02), and presence of snoring (odds ratio: 3.7 [95% CI: 1.3-11]; P=0.02) were predictors of obstructive sleep apnea. In conclusion, obstructive sleep apnea appears to be the most common condition associated with resistant hypertension. Age >50 years, large neck circumference measurement, and snoring are good predictors of obstructive sleep apnea in this population.     

阻塞性睡眠呼吸暂停综合征与高血压的相关性分析

目的探讨阻塞性睡眠呼吸暂停综合征(OSAS)与其所导致高血压的相关性。方法对白天嗜睡、打鼾和憋气为主诉的门诊或住院患者行多导睡眠图(PSG)监测,且血压增高达诊断标准患者为研究对象。对睡眠检测结果中的呼吸暂停和低通气指数(AHI)、夜间最低血氧饱和度(SaO2)及睡前、晨起、治疗后的血压进行分析。结果OSAS患者晨起血压较睡前血压增高(P<0.001),并与SaO2呈负相关(P<0.05);SaO2与AHI呈负相关(P<0.05)。体重指数与SaO2呈负相关(P<0.05)与晨起舒张压呈正相关(P<0.05)。经持续气道正压通气(CPAP)治疗、纠正睡眠呼吸暂停6~8周后,晨起血压较治疗前明显下降(P<0.001)。结论OSAS患者肥胖及反复睡眠呼吸暂停与其高血压具有相关性,因此OSAS高血压是一种继发性高血压,CPAP治疗对这种高血压有效。     

Effects of renal sympathetic denervation on blood pressure, sleep apnea course, and glycemic control in patients with resistant hypertension and sleep apnea

Percutaneous renal sympathetic denervation by radiofrequency energy has been reported to reduce blood pressure (BP) by the reduction of renal sympathetic efferent and afferent signaling. We evaluated the effects of this procedure on BP and sleep apnea severity in patients with resistant hypertension and sleep apnea. We studied 10 patients with refractory hypertension and sleep apnea (7 men and 3 women; median age: 49.5 years) who underwent renal denervation and completed 3-month and 6-month follow-up evaluations, including polysomnography and selected blood chemistries, and BP measurements. Antihypertensive regimens were not changed during the 6 months of follow-up. Three and 6 months after the denervation, decreases in office systolic and diastolic BPs were observed (median: -34/-13 mm Hg for systolic and diastolic BPs at 6 months; both P<0.01). Significant decreases were also observed in plasma glucose concentration 2 hours after glucose administration (median: 7.0 versus 6.4 mmol/L; P=0.05) and in hemoglobin A1C level (median: 6.1% versus 5.6%; P<0.05) at 6 months, as well as a decrease in apnea-hypopnea index at 6 months after renal denervation (median: 16.3 versus 4.5 events per hour; P=0.059). In conclusion, catheter-based renal sympathetic denervation lowered BP in patients with refractory hypertension and obstructive sleep apnea, which was accompanied by improvement of sleep apnea severity. Interestingly, there are also accompanying improvements in glucose tolerance. Renal sympathetic denervation may conceivably be a potentially useful option for patients with comorbid refractory hypertension, glucose intolerance, and obstructive sleep apnea, although further studies are needed to confirm these proof-of-concept data.     

Diagnostic and therapeutic approach to nonsleepy apnea

Epidemiological and observational studies suggest that sleep-disordered breathing is associated with the subsequent development of hypertension and ultimately with cardiovascular consequences. It may therefore be assumed that continuous positive airway pressure (CPAP) not only avoids sleep-related symptoms but could also mitigate cardiovascular consequences. Short-term studies have revealed a drop in blood pressure, especially in more severe, symptomatic cases of obstructive sleep apnea. Two recent studies have reported that nonsleepy obstructive sleep apnea is associated with an absence of reduced blood pressure after CPAP treatment. This suggests that this group of patients is less susceptible to the consequences of apneas, even those with mild-moderate hypertension or other cardiovascular disorders. However, in patients with severe cardiovascular disease or a higher number of obstructive events, CPAP treatment should be seriously considered.     

Effect of nasal valve dilation on effective CPAP level in obstructive sleep apnea

Nasal problems are frequent at high continuous positive airway pressure (CPAP). We hypothesized that a reduction of the nasal resistance reduces CPAP and investigated the effect of a nasal valve dilator (Nozovent) on CPAP in patients with obstructive sleep apnea. In a randomized cross-over design Nozovent was inserted in 38 patients during one of two nights using AutoSet T. CPAP differences > 1 cm H2O were considered as clinically relevant. With Nozovent the median CPAP pressure was reduced from 8.6 cm H2O to 8.0 H2O (P = 0.023) in all patients, but the number of patients with a reduction of CPAP by 1 cm H2O was not significant. The median CPAP level among 20 patients requiring a CPAP level of above 9 cm H2O was reduced from 10.3 to 9.1 cm H2O, P < 0.05. A clinical improvement with Nozovent was seen in 10 of 20 patients requiring a pressure of above 9 cm H2O compared with 4 of 18 patients who needed lower pressures, P = 0.025. Nozovent reduces the CPAP level 1 cm H2O in 50% of patients requiring a high pressure (> 9 cm H2O). Future studies should identify possible patients benefiting from a nasal dilator during CPAP therapy.     

Relationship between overnight rostral fluid shift and obstructive sleep apnea in drug-resistant hypertension

Obstructive sleep apnea occurs frequently in patients with drug-resistant hypertension. The factors accounting for this observation, however, are unclear. Both conditions demonstrate clinical features suggestive of extracellular fluid volume overload. The aims of this study were to examine whether the spontaneous overnight fluid shift from the legs to the upper body is associated with obstructive sleep apnea in hypertensive subjects and whether its magnitude is greater in drug-resistant hypertension. Leg fluid volume and the circumference of the calf and neck were measured before and after sleep in drug-resistant hypertensive (n = 25) and controlled hypertensive (n=15) subjects undergoing overnight polysomnography. The severity of obstructive sleep apnea was greater in the drug-resistant hypertensive group than in the controlled hypertensive group (apnea-hypopnea index: 43.0 ± 5.4 versus 18.1 ± 4.2 events per hour of sleep; P = 0.02, case-mix adjusted). In both groups, the apnea-hypopnea index strongly related to the amount of leg fluid volume displaced (R2 = 0.56; P < 0.0001), although the magnitude of change was greater in the drug-resistant hypertensive group (346.7 ± 24.1 versus 175.8 ± 31.3 mL; P = 0.01, propensity-score adjusted). The overnight reduction in calf circumference and increase in neck circumference were also greater in drug-resistant hypertension (both P ≤ 0.02). In hypertensive subjects, rostral fluid displacement strongly relates to the severity of obstructive sleep apnea with its magnitude being greater in drug-resistant hypertension. Our findings support the concept that fluid redistribution centrally during sleep accounts for the high prevalence of obstructive sleep apnea in drug-resistant hypertension.     

Sleep disorders in patients with congestive heart failure

PURPOSE OF REVIEW: This review of recent literature pertains to the growing evidence that obstructive sleep apnea contributes to the development of systemic hypertension and congestive heart failure. RECENT FINDINGS: There is irrefutable evidence that OSA causes systemic hypertension and that continuous positive airway pressure (CPAP) treatment of OSA causes a reduction in blood pressure. Moreover there is evidence that untreated OSA is associated with left ventricular diastolic and systolic failure and that treatment with CPAP improves systolic function. SUMMARY: OSA should be considered in patients with systemic hypertension or heart failure.     

Effects of continuous positive airway pressure versus supplemental oxygen on 24-hour ambulatory blood pressure

Obstructive sleep apnea (OSA) is associated with recurrent episodes of nocturnal hypoxia and increased risk for development of systemic hypertension. Prior studies have been limited, however, in their ability to show reduction in blood pressure after continuous positive airway pressure (CPAP) therapy, and the effect of supplemental oxygen alone on blood pressure in OSA has not been evaluated. We performed a randomized, double-blind, placebo-controlled study comparing the effects of 2 weeks of CPAP versus sham-CPAP versus supplemental nocturnal oxygen on 24-hour ambulatory blood pressure in 46 patients with moderate-severe OSA. We found that 2 weeks of CPAP therapy resulted in a significant reduction in daytime mean arterial and diastolic blood pressure and nighttime systolic, mean, and diastolic blood pressure (all Ps <0.05). Although nocturnal supplemental oxygen therapy improved oxyhemoglobin saturation, it did not affect blood pressure. We conclude that CPAP therapy reduces both daytime and nighttime blood pressure in patients with OSA, perhaps through mechanisms other than improvement of nocturnal oxyhemoglobin saturation.     

Pulmonary hypertension in obstructive sleep apnoea: effects of continuous positive airway pressure: a randomized, controlled cross-over study.

AIMS: We tested the hypothesis that: (i) obstructive sleep apnoea (OSA) by itself originates pulmonary hypertension (PH); and (ii) the application of continuous positive airway pressure (CPAP) can reduce pulmonary pressure. METHODS AND RESULTS: In this randomized and cross-over trial, 23 middle-aged OSA (apnoea-hypopnoea index, 44.1 +/- 29.3 h(-1)) and otherwise healthy patients and 10 control subjects were included. OSA patients randomly received either sham or effective CPAP for 12 weeks. Echocardiographic parameters, blood pressure recordings, and urinary catecholamine levels were obtained at baseline and after both treatment modalities. At baseline, OSA patients had higher pulmonary artery systolic pressure than control subjects (29.8 +/- 8.8 vs. 23.4 +/- 4.1 mmHg, respectively, P = 0.036). Ten out of 23 patients [43%, (95% CI: 23-64%)] and none of the control subjects had PH at baseline (P = 0.012). Two patients were removed from the study because of inadequate CPAP compliance. Effective CPAP induced a significant reduction in the values for pulmonary systolic pressure (from 28.9 +/- 8.6 to 24.0 +/- 5.8 mmHg, P < 0.0001). The reduction was greatest in patients with either PH or left ventricular diastolic dysfunction at baseline. CONCLUSION: Severe OSA is independently associated with PH in direct relationship with disease severity and presence of diastolic dysfunction. Application of CPAP reduces pulmonary systolic pressure levels.     

老年阻塞性睡眠呼吸暂停低通气综合征患者持续气道正压通气治疗的依从性

目的 评价65岁以上老年阻塞性睡眠呼吸暂停低通气综合征(OSAHS)患者接受持续气道正压通气(CPAP)治疗的依从性是否与年龄<65岁患者有所不同;并探讨影响OSAHS患者接受CPAP治疗依从性的因素.方法 将147位经过多导睡眠仪(PSG)诊断的OSAHS患者分为两组,其中年龄≥65岁组为46例,年龄<65岁组101例,147例OSAHS患者的临床资料及PSG检查结果均被前瞻性的输入数据库,随访所有患者CPAP治疗压力水平及呼吸机使用时间.结果 与年龄<65岁OSAHS组比较,年龄≥65岁OSAHS组中合并慢性阻塞性肺疾病(COPD)较高(16%对4%,P=0.02),心血管疾患患病率较高(23%对10%,P=0.04),长期饮酒者所占比例较高(61%对38%,P=0.007).打鼾者比例较低(31%对54%,P=0.03);睡眠时间较短(378 min对423 min,P=0.001),入睡后的醒觉时间延长(162 min对115 min,P=0.004),睡眠效率减低(69%对77%,P<0.001),1期睡眠时间延长(29%对20%,P=0.001),3～4期睡眠(6%对9%,P=0.016)与快速眼动相(REM)睡眠时间(12%对15%,P=0.001)缩短.在3个月、6个月、1年、2年、3年期间接受CPAP治疗的患者在≥65岁组中为91%、89%、84%、82%、82%,而在<65岁组中为92%、86%、81%、72%、67%.CPAP的平均使用时间在年龄≥65岁组为(5.1±1.5)h/d,在年龄<65岁组中为(3.9±1.2)h/d.多元回归分析结果表明,相对较高的CPAP治疗压力是较好CPAP治疗依从性的唯一因素.结论 与年龄<65岁患者比较,年龄≥65岁OSAHS患者接受CPAP治疗的依从性并未见降低;相对较高的CPAP治疗压力与较好的治疗依从性有关.     

The PHARAO study: prevention of hypertension with the angiotensin-converting enzyme inhibitor ramipril in patients with high-normal blood pressure: a prospective, randomized, controlled prevention trial of the German Hypertension League

BACKGROUND: The prevention of hypertension with the angiotensin-converting enzyme inhibitor ramipril in patients with high-normal blood pressure study addresses the issue of whether progression to manifest hypertension in patients with high-normal blood pressure can be prevented with treatment. METHODS: A total of 1008 participants with high-normal office blood pressure were randomized to ramipril treatment group (n = 505) and a control group (n = 503). The patients were followed up for 3 years. Primary endpoint was to prevent or delay the progression to manifest hypertension. Secondary endpoints were reduction in the incidence of cerebrovascular and cardiovascular events, as well as the development of hypertension as defined by ambulatory blood pressure monitoring. FINDINGS: One hundred and fifty-five patients (30.7%) in the ramipril group, and 216 (42.9%) in the control group reached the primary endpoint (relative risk reduction 34.4%, P = 0.0001). Ramipril also proved to be more effective in reducing the incidence of manifest office hypertension in patients with baseline ambulatory blood pressure monitoring high-normal blood pressure. The incidence of cerebrovascular and cardiovascular events showed no statistically significant differences between the two groups. Cough was more frequent in the ramipril group (4.8 vs. 0.4%). INTERPRETATION: There is now good clinical evidence that patients with high-normal blood pressure (prehypertension) are more likely to progress to manifest hypertension than patients with optimal or normal blood pressure. Additional ambulatory blood pressure monitoring seems to be essential to achieve correct diagnosis. Treatment of patients with high-normal office blood pressure with the angiotensin-converting enzyme inhibitor was well tolerated, and significantly reduced the risk of progression to manifest hypertension.     

Pressure-relief continuous positive airway pressure vs constant continuous positive airway pressure: a comparison of efficacy and compliance

OBJECTIVES: To compare polysomnographic data and compliance in sleep apnea patients receiving continuous positive airway pressure (CPAP) and pressure-relief CPAP (PRCPAP) [C-flex; Respironics; Murrysville, PA] as first treatment in the sleep laboratory and subsequently at home. DESIGN: A prospective, randomized, crossover design was used in the sleep laboratory, and a prospective randomized design was used at home. PATIENTS: Data were collected from 52 sleep apnea patients for whom CPAP was used for the first time. INTERVENTIONS: Treatment with constant CPAP and PRCPAP. MEASUREMENTS AND RESULTS: Patients with a first-time diagnosis of obstructive sleep apnea syndrome (OSAS) underwent conventional CPAP titration. Thereafter, polysomnography was performed at the titrated pressure using both the fixed CPAP pressure mode and the PRCPAP mode in a randomized crossover approach. The patients were then discharged home for 7 weeks of treatment with the last-applied treatment mode, and compliance data were established at the end of that time. The average apnea-hypopnea index was 53.3/h in the "diagnostic night," 5.8/h with CPAP, and 7.0/h with PRCPAP. The native arousal index was 35.2/h, 12.6/h with CPAP, and 12.9/h with PRCPAP (not significant [NS]). The central apnea index was 0.7/h with CPAP and 1.2/h with PRCPAP (p < 0.05). Compliance after 7 weeks was, on average, 9.4 min longer with PRCPAP than with CPAP (NS). Evaluation of a 13-item questionnaire showed scores of 16.4 for PRCPAP and 18.1 for constant CPAP (NS) [the fewer the complaints, the lower the score]. With regard to oral dryness, the score with PRCPAP (1.4) was significantly lower than with constant CPAP (1.9) [p < 0.05]. This difference was no longer detectable after 7 weeks. CONCLUSION: In terms of the effectiveness in treating obstructive sleep apnea, PRCPAP and constant CPAP are comparable. During the first night of treatment, patients receiving PRCPAP had less dryness of mouth; over a period of 7 weeks, this difference disappeared. Nightly use of the device was comparable in both groups. PRCPAP is therefore a new ventilation mode that enables effective treatment of OSAS patients. Further studies should be done to investigate the effects of expiratory pressure lowering in low-compliance patients and patients requiring CPAP > 9 cm H(2)O or experiencing dry mouth with CPAP.     

Effects of obstructive sleep apnea syndrome on serum aminotransferase levels in obese patients

PURPOSE: Obesity has been associated with obstructive sleep apnea and hepatic steatosis. We investigated the effects of obstructive sleep apnea and treatment with nasal continuous positive airway pressure (CPAP) on serum aminotransferase levels in obese patients. METHODS: We studied 40 obese men with obstructive sleep apnea syndrome. None had hepatitis B antigen or C antibody, autoimmune disease, or an excessive intake of alcohol. Serum levels of aspartate aminotransferase, alanine aminotransferase, triglyceride, glucose, insulin, and leptin were determined in the afternoon and in the morning immediately after sleep, before and after nasal CPAP treatment. RESULTS: Aminotransferase levels were abnormal in 35% (n = 14) of patients. Before treatment, mean (+/- SD) aspartate aminotransferase levels were higher in the morning than in the previous afternoon (presleep, 34 +/- 20 IU/L; postsleep, 39 +/- 28 IU/L; P = 0.006). The overnight mean increases in aminotransferase levels were less marked after the first night of nasal CPAP treatment (aspartate aminotransferase: from 6 +/- 11 IU/L to 2 +/- 6 IU/L, P = 0.0003; alanine aminotransferase: from 5 +/- 9 IU/L to 2 +/- 6 IU/L, P = 0.006). Leptin levels (n = 23) decreased significantly after treatment (P = 0.0002), whereas insulin resistance (calculated by the homeostasis model assessment method) and triglyceride levels were unchanged. Improvements in aspartate and alanine aminotransferase levels were maintained after 1 and 6 months of nasal CPAP treatment. CONCLUSION: Nasal CPAP therapy may have beneficial effects on serum aminotransferase abnormalities in obese patients who have obstructive sleep apnea.     

Continuous Positive Airway Pressure in Patients With Obstructive Sleep Apnea and Resistant Hypertension: A Meta‐Analysis of Randomized Controlled Trials

This study aimed to analyze the effect of continuous positive airway pressure (CPAP) on blood pressure (BP) in patients with obstructive sleep apnea (OSA) and resistant hypertension. Randomized controlled trials (RCTs) that evaluated the effect of CPAP on BP in patients with OSA and resistant hypertension, indexed in MEDLINE, Embase, and the Cochrane Library from inception until March 20, 2015, were included in the meta‐analysis. A total of five RCTs were identified to meet the inclusion criteria. The pooled changes after CPAP treatment for 24‐hour ambulatory systolic BP and diastolic BP (DBP) were −4.78 mm Hg (95% confidence interval [CI], −7.95 to −1.61) and −2.95 mm Hg (95% CI, −5.37 to −0.53) in favor of the CPAP group. CPAP was also associated with reduction in nocturnal DBP (mean difference, −1.53 mm Hg, 95% CI, −3.07 to 0). The results indicated a favorable reduction in BP with CPAP treatment in patients with OSA and resistant hypertension.     

Continuous positive airway pressure treatment rapidly improves insulin sensitivity in patients with obstructive sleep apnea syndrome

The obstructive sleep apnea syndrome is typically associated with conditions known to increase insulin resistance as hypertension, obesity, and diabetes. We investigated whether obstructive sleep apnea itself is an independent risk factor for increased insulin resistance and whether continuous positive airway pressure (CPAP) treatment improves insulin sensitivity. Forty patients (apnea-hypopnea index > 20) were treated with CPAP. Before, 2 days after, and after 3 months of effective CPAP treatment, hyperinsulinemic euglycemic clamp studies were performed. Insulin sensitivity significantly increased after 2 days (5.75 +/- 4.20 baseline versus 6.79 +/- 4.91 micromol/kg.min; p = 0.003) and remained stable after 3 months of treatment. The improvement in insulin sensitivity after 2 days was much greater in patients with a body mass index less than 30 kg/m2 than in more obese patients. The improved insulin sensitivity after 2 nights of treatment may reflect a decreasing sympathetic activity, indicating that sleep apnea is an independent risk factor for increased insulin resistance. The effect of CPAP on insulin sensitivity is smaller in obese patients than in nonobese patients, suggesting that in obese individuals insulin sensitivity is mainly determined by obesity and, to a smaller extent, by sleep apnea.     

Short-term effects of oral theophylline in addition to CPAP in mild to moderate OSAS

Theophylline is effective in the treatment of central apneas and periodic breathing. In obstructive sleep apnea syndrome (OSAS), results of pharmacological monotherapy with theophylline are inconsistent. The present study investigates whether additional theophylline in patients with OSAS and continuous positive airway pressure (CPAP) therapy might improve ventilation, lower effective CPAP pressure levels or affect sleep architecture. Patients with mild to moderate OSAS (mean apnea index [AI] 12.8+/-11.7) and CPAP therapy (Autoset system; n=16, all male) received either 900 mg of oral sustained-release theophylline (T) or placebo (P) on two separate nights, 3 days apart, using a randomized double-blind crossover study design. There was no change in AI (T: 0.7+/-1.4 vs. P: 0.7+/-0.6/h; P=0.3) or apnea-hypopnea index (AHI; T: 4.3+/-3.3 vs. P: 4.5+/-3.7/h; P=0.84) when theophylline was added to CPAP therapy. We observed no difference in mean CPAP pressure (T: 6.9+/-2.1 vs. P: 6.7+/-1.9 cm H2O; P=0.7) or 95% pressure percentiles (T: 9.7+/-2.7 vs. P: 9.3+/-2.1cm H2O; P=0.3) when nights with theophylline were compared to placebo nights. Theophylline reduced significantly total sleep time (T: 290.6+/-58.9 vs. P: 338.0+/-40.1 min; P=0.02) and thus sleep efficiency (SE; T: 70.5+/-14.9%, P: 82.0+/-70.5%; P=0.005). Rapid eye movement and slow wave sleep were not affected. Oral theophylline did not show any additional effects on ventilation parameters or pressures in patients with mild to moderate OSAS once CPAP therapy has been successfully installed. SE was reduced with theophylline with unchanged sleep architecture. The role of oral theophylline may be in patients with predominately central apneas not eligible for ventilation therapy or severe cases.