经鼻持续性气道正压对阻塞性睡眠呼吸暂停综合征患者呼吸中枢驱动性的影响

为了解经鼻持续性气道正压（ｎＣＰＡＰ）通气治疗对阻塞性睡眠呼吸暂停综合征（ＯＳＡＳ）患者呼吸中枢驱动性的影响，研究了２０例无二氧化碳（ＣＯ＿２）储留的ＯＳＡＳ患者（Ｏ组）及２０例单纯鼾症患者（Ｓ组）夜间睡眠前后呼吸方式及口腔阻断压（Ｐ＿（０．１））的改变，并观察了ｎＣＰＡＰ治疗对ＯＳＡＳ，患者呼吸方式及Ｐ＿（０．１）的影响。结果显示：Ｏ组患者睡前的Ｐ＿（０．１）、呼吸频率、有效吸气阻抗明显高于Ｓ组，潮气量则显著低于Ｓ组。ｎＣＰＡＰ治疗组患者经一夜睡眠后的Ｐ＿（０．１）、每分通气量、潮气量、呼吸频率等较睡前显著增高。经ｎＣＰＡＰ治疗后Ｏ组的呼吸紊乱指数较治疗前明显降低，夜间最低氧饱和度明显提高，Ｐ＿（０．１）较睡前则无明显升高。提示ＯＳＡＳ患者睡前的呼吸中枢驱动性高于单纯鼾症患者，其呼吸形式为浅快呼吸；经过一夜睡眠后，其呼吸中枢驱动水平较睡前明显增高，呼吸形式更为浅快；ｎＣＰＡＰ治疗可以有效地解除睡眠呼吸暂停及其继发的低氧血症，从而逆转睡眠前后呼吸方式和呼吸中枢驱动性的改变。     

Influence of nasal resistance on initial acceptance of continuous positive airway pressure in treatment for obstructive sleep apnea syndrome

BACKGROUND: Continuous positive airway pressure (CPAP) is considered as the standard therapy for obstructive sleep apnea syndrome (OSAS), but some patients with OSAS are unable to accept CPAP due to nasal obstruction and poor nasal airflow. OBJECTIVES: We assessed the influence of nasal resistance before beginning CPAP treatment on the initial acceptance of CPAP in OSAS patients. METHODS: The study subjects comprised 77 patients (74 males, 3 females) with primary OSAS, all of whom received CPAP treatment with nasal masks. Before trials, all subjects underwent overnight polysomnography, and nasal resistance was measured with active anterior rhinomanometry in the seated position on the first day of CPAP trial. RESULTS: The CPAP treatment was accepted by 56 patients after the initial trials with overnight polysomnography. Body mass index, the number of apnea/hypopnea episodes per hour (apnea/hypopnea index; AHI), and the number of episodes per hour with an oxygen desaturation of >3% (oxygen desaturation index) were significantly higher (p<0.01) and nasal resistance was lower (p=0.003) in patients who accepted CPAP than in those who did not. Logistic regression analysis, with patient age, body mass index, Epworth sleepiness scale score, AHI, oxygen desaturation index, and nasal resistance before CPAP treatment as explanatory variables, showed that nasal resistance (OR+0.1 Pa/cm3/s: 1.48; p=0.002) and AHI (OR+1 event/h: 0.93; p=0.003) were significant factors for CPAP non-acceptance. CONCLUSIONS: Nasal resistance before the beginning of CPAP treatment has a significant effect on the acceptance of CPAP in OSAS patients, and hence, could be a predictive parameter for the initial acceptance of CPAP.     

Nasal CPAP effect on patterns of sleep apnea

To evaluate the effect of continuous positive airway pressure via nasal mask (nasal CPAP) on occlusive, mixed, and central apneas (OA, MA, and CA, respectively), we performed nocturnal polysomnography without and with nasal CPAP on 21 patients with sleep apnea. Three patients were unable to tolerate nasal CPAP. The remaining 18 patients had significant reductions in the overall apnea frequency when using nasal CPAP (52.9 +/- 5 per hour slept vs 3.3 +/- 1 per hour slept, mean +/- SE, p less than 0.001). The use of nasal CPAP significantly reduced the frequency of OAs during both nonrapid eye movement (non-REM) and REM sleep (p less than 0.001). It also reduced the frequency of MAs during both non-REM and REM sleep (p less than 0.05). Nasal CPAP did not increase the frequency of CAs in patients who had MAs when sleeping without nasal CPAP indicating that both the "central" and obstructive portions of MA were eliminated. In those patients who had CAs while sleeping without nasal CPAP, the CA frequency was unchanged by nasal CPAP although there was a good deal of interindividual variability. We conclude that nasal CPAP is well tolerated and effective in reducing the frequency of OAs and MAs. The variability of the response of CA to nasal CPAP suggests that the pathogenesis of CA may not be homogeneous.     

The effect of 1 week of continuous positive airway pressure treatment in obstructive sleep apnea patients with concomitant gastroesophageal reflux

STUDY OBJECTIVES: Patients with obstructive sleep apnea (OSA) have a very high incidence of gastroesophageal reflux (GER). Previous studies have shown that the use of continuous positive airway pressure (CPAP) reduces the frequency of reflux events, but these studies only assessed the effect of a single night of treatment. The aim of this study was to assess the effect of 1 week of CPAP treatment on reflux in patients with OSA and GER. DESIGN: Sixteen patients with OSA and GER were recruited. Polysomnography followed by 24-h, continuous esophageal pH monitoring were performed at baseline. Patients with an apnea-hypopnea index (AHI) > 20/h and 24-h acid contact time (ACT) of at least 6% were included. As part of the polysomnography-qualifying evaluation, all patients underwent CPAP titration to reduce the AHI to < 10/h. Patients were then sent home receiving nasal CPAP for 1 week; after 1 week, esophageal pH monitoring was repeated while receiving CPAP. MEASUREMENTS AND RESULTS: The AHI fell from 63.3 +/- 38.5 to 3.2 +/- 2.2/h (mean +/- SD) [p < 0.001]. Total ACT fell from 13.9 +/- 11.6 to 5.6 +/- 2.7% (p < 0.001). The upright ACT was reduced from 12.4 +/- 6.8 to 6.8 +/- 3.8% (p = 0.01), and the supine (during the sleeping interval) ACT was reduced from 16.3 +/- 18.8 to 3.8 +/- 7.6% (p < 0.01). Eighty-one percent of the patients had a reduction in supine ACT to within the normal range (< 4%). CONCLUSIONS: In OSA patients with significant heartburn complaints, CPAP would appear to be an efficacious approach to the treatment of both disorders.     

Mechanisms of nocturnal gastroesophageal reflux events in obstructive sleep apnea

Purpose  

Obstructive sleep apnea (OSA) is associated with increased nocturnal gastroesophageal reflux (nocturnal GER) events and symptoms. Treatment of OSA with continuous positive airway pressure (CPAP) reduces nocturnal GER in patients with OSA. This study sought to determine the: (1) relationship of nocturnal GER events with apnea/hypopnea and arousal, (2) effect of upper airway obstruction on the barrier function of the lower esophageal sphincter (LES), (3) mechanism of LES failure for each nocturnal GER event and (4) effect of CPAP on LES function during sleep.     

Continuous positive airway pressure treatment improves baroreflex control of heart rate during sleep in severe obstructive sleep apnea syndrome

The role of the arterial baroreflex in the cardiovascular changes associated with the obstructive sleep apnea syndrome (OSAS), and the effect of nasal continuous positive airway pressure (CPAP) treatment on baroreflex function during sleep are unknown. Baroreflex control of heart rate was studied in 29 normotensive patients with OSAS under no treatment, in 11 age-matched control subjects, and in 10 patients at CPAP withdrawal after 5.5 +/- 3.7 (range 3-14) months of treatment. Baroreflex control of heart rate was assessed by "sequence method" analysis of continuous blood pressure recordings (Finapres) obtained during nocturnal polysomnography. In untreated OSAS, baroreflex sensitivity (BRS) was low during wakefulness and non-rapid eye movement (REM) stage 2 sleep compared with control subjects, and correlated inversely with mean lowest Sa(O(2)) and the blood pressure increase after apneas. After CPAP treatment, the apnea-hypopnea index was lower, and mean lowest Sa(O(2)) higher than before treatment. After CPAP, patients were more bradycardic, blood pressure and its standard deviation decreased as Sa(O(2)) improved in non-REM stage 2 sleep, and BRS increased (nocturnal wakefulness: +59%; non-REM stage 2 sleep: +68% over pretreatment values). Our data suggest that baroreflex dysfunction in OSAS may be at least partly accounted for by nocturnal intermittent hypoxemia, and can be reversed by long-term CPAP treatment.     

Sleep structure correlates of continuous positive airway pressure variations during application of an autotitrating continuous positive airway pressure machine in patients with obstructive sleep apnea syndrome

STUDY OBJECTIVES: To evaluate the relationship between sleep structure and continuous positive airway pressure (CPAP) delivered by an automatic CPAP (auto-CPAP) machine in patients with obstructive sleep apnea syndrome (OSAS). DESIGN: Nocturnal polysomnography was performed during CPAP administration by an auto-CPAP machine (Autoset Clinical 1; ResMed; Sydney, Australia). SETTING: Sleep-disorders center in a research institute. PATIENTS: Fifteen subjects with newly diagnosed OSAS deserving home CPAP treatment. Measurements and results: During the night, in most cases, the lowest CPAP level was recorded during a prolonged nonrapid eye movement (NREM) sleep period uninterrupted by arousals, whereas the highest level during wake-sleep transitions or NREM sleep fragmented by arousals. In four subjects, rapid eye movement sleep was always associated with increasing CPAP. Sleep efficiency was negatively correlated with CPAP variability, evaluated as the SD of the mean nocturnal CPAP level averaged epoch by epoch (r = 0.63, p < 0.02). Eighty-eight percent of rapid CPAP augmentations (increases by at least 2 cm H(2)O in less-than-or-equal 2 min) were observed during sleep-wake transitions or after arousals/awakenings (Ar/Aw); 63% of such Ar/Aw were not preceded by any detectable respiratory abnormality. CONCLUSIONS: CPAP levels and variations during auto-CPAP application may be mainly related to sleep continuity and efficiency. The recording of a highly variable pressure during auto-CPAP administration in an unattended environment must raise the question whether the patient's sleep quality was acceptable. A poor sleep quality during an autotitration night could lead to an undesirable overestimation of the CPAP level needed for use with fixed-level CPAP machines.     

The effect of short-term nasal CPAP therapy in cases of obstructive sleep apnea syndrome

Recent studies have shown that nasal CPAP is very effective in the treatment of patients with obstructive sleep apnea syndrome (OSA). To clarify the characteristics of pulmonary function testing and to evaluate the effect of short term nasal CPAP therapy in 13 cases of OSA patients, nasal CPAP was used for 10 to 14 days and polysonography was performed on two consecutive nights without nasal CPAP and at one night with nasal CPAP. Pulmonary function tests and the Uchida-Kraepelin test were performed before the initiation of nasal CPAP therapy and also 7 to 14 days after the nasal CPAP therapy. Apnea index reduced significantly in all cases from 5.10 +/- 19.6 episodes/hour without therapy to 3.1 +/- 3.5 with nasal CPAP (p less than 0.001). Nasal CPAP significantly reduced the frequency of obstructive (p less than 0.001) and mixed apnea (p less than 0.01), but the frequency of central apnea did not change with nasal CPAP. During the nasal CPAP, mean nadir SaO2 rose from 87.3 +/- 2.9% to 92.7 +/- 1.1% (p less than 0.001) and the lowest SaO2 rose from 73.3 +/- 6.4% to 92.0 +/- 2.1% (p less than 0.001). Before the nasal CPAP therapy, daytime PaO2 was 80.6 +/- 6.4 Torr and closing capacity (CC)/FRC ratio was higher when patients were in a supine than in a sitting position. After short term nasal CPAP therapy, daytime PaO2 increased significantly (p less than 0.001), and FRC/TLC in a supine position increased and CC/FRC in a supine position decreased in some patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Continuous positive airway pressure intolerance associated with elevated nasal resistance is possible mechanism of complex sleep apnea syndrome

Purpose

Complex sleep apnea syndrome (CompSAS) is diagnosed after an elimination of obstructive events with continuous positive airway pressure (CPAP), when a central apnea index ??5/h or Cheyne?CStokes respiration pattern emerges in patients with obstructive sleep apnea syndrome (OSAS). However, the pathophysiology of CompSAS remains controversial.

Methods

Of the 281 patients with suspected OSAS, all of whom underwent polysomnography conducted at Nagoya University Hospital, we enrolled 52 patients with apnea?Chypopnea index ??15/h (age 51.4?±?13.3?years). The polysomnographic findings, left ventricular ejection fraction (LVEF), and nasal resistance were compared between the CompSAS patients and OSAS patients.

Results

Forty-three patients were diagnosed with OSAS and nine patients with central sleep apnea syndrome by natural sleep PSG. Furthermore, 43 OSAS patients were classified into the OSAS patients (OSAS group, n?=?38) and the CompSAS patients (CompSAS group, n?=?5) by the night on CPAP PSG. The nasal resistance was significantly higher in CompSAS group than in OSAS group (0.30?±?0.10 vs. 0.19?±?0.07?Pa/cm³/s, P?=?0.004). The arousal index, percentage of stage 1 sleep, and oxygen desaturation index were significantly decreased, and the percentage of stage REM sleep was significantly increased in the OSAS group with the initial CPAP treatment, but not in the CompSAS group. In addition, the patients with CompSAS showed normal LVEF.

Conclusion

CPAP intolerance secondary to an elevated nasal resistance might relate to frequent arousals, which could presumably contribute to an increase in central sleep apnea. Further evaluation in a large study is needed to clarify the mechanism of CompSAS.     

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。     

正压通气对阻塞性睡眠呼吸暂停综合征夜间室性心律失常的作用

目的 探讨阻塞性睡眠呼吸暂停综合征(OSAS)严重程度与夜间室性心律失常间的关系以及经鼻持续气道正压通气(nCPAP)对室性心律失常的作用.方法 197例OSAS者按呼吸紊乱指数分轻、中、重3组,观察夜间室性心律失常发生率,比较组间差异性,并观察各组行nCPAP前后宣性心律失常发生率的变化.结果 OSAS者夜间室性心律失常发生率随着病情加重而明显增加、室性心律失常增多.治疗后各组夜间室性心律失常发生率较治疗前显著下降.结论 随着OSAS者病情加重,夜间室性心律失常发生率增多,nCPAP能有效降低OSAS者夜间室性心律失常发生率.     

Effects of nasal continuous positive airway pressure (NCPAP) on nocturnal renal function in obstructive sleep apnea syndrome (OSAS)

Nocturnal renal function was examined in 8 patients with obstructive sleep apnea syndrome (OSAS) and the effects of nasal CPAP (NCPAP) on renal function were also studied. Nocturia was observed more than twice in all cases when no treatment was performed, but it disappeared after initiation of NCPAP. Fractional nocturnal urine volume and creatinine clearance decreased significantly from 1.36 +/- 0.15 ml/min to 0.75 +/- 0.20 ml/min (p less than 0.01) and from 116.8 +/- 46.5 ml/min to 101.1 +/- 33.0 ml/min (p less than 0.05), respectively, after initiation of NCPAP. Although the serum Na and creatinine did not change following NCPAP, the urine Na and creatinine changed significantly after NCPAP therapy. The serum renin, aldosterone, and ADH did not change after NCPAP therapy. The significant positive correlation (p less than 0.05) between the fractional nocturnal urine volume and DI, and also significant inverse correlation (p less than 0.05) between the fractional urine volume and %FRC were observed. These results suggest that the abnormal renal function seen in cases of OSAS is related to the hypoxemia during sleep. It was concluded that the nocturnal renal function in cases of OSAS was different from those in normal controls and NCPAP therapy induced the recovery of these abnormalities.     

Nasopharyngeal symptoms in patients with obstructive sleep apnea syndrome. Effect of nasal CPAP treatment

BACKGROUND: Nasal side effects are often reported during nasal continuous positive airway pressure (CPAP) treatment of obstructive sleep apnea syndrome (OSAS) and may make the use of nasal CPAP difficult. OBJECTIVE: The aim of this study was to evaluate the effect of nasal CPAP on nasopharyngeal symptoms in OSAS patients. METHODS: The frequency and severity of nasopharyngeal symptoms and signs were prospectively evaluated in 49 consecutive OSAS patients (37 men, 12 women, mean (SD) age 54 (7) years, body mass index 35 (6) kg/m2) immediately before and after 6 months' treatment with nasal CPAP. RESULTS: Nasopharyngeal symptoms were common already before starting nasal CPAP: 74% of patients reported dryness, 53% sneezing, 51% mucus in the throat, 45% blocked nose, and 37% rhinorrhea. During nasal CPAP treatment, severity and frequency of sneezing (75%) and rhinorrhea (57%) increased. This increase was related to the season when nasal CPAP was applied, and was more profound in winter than in summer. Mild abnormalities on rhinoscopy and paranasal sinus X-rays were common both at baseline and at follow-up with no significant change during treatment. CONCLUSIONS: Nasopharyngeal problems were found to be frequent in patients with OSAS before nasal CPAP treatment, and tended to increase during the treatment.     

Nocturnal positive pressure ventilation via nasal mask

Five patients with chronic respiratory failure from neuromuscular disease and symptomatic worsening nocturnal hypoventilation were treated with nocturnal ventilation. Home ventilation at night was provided by a volume-cycled positive pressure ventilator attached to a nasal mask originally designed to administer nasal continuous positive airway pressure (CPAP) for obstructive sleep apnea. The device was well tolerated. Symptoms of headache, insomnia/somnolence, and impaired intellectual capacity rapidly disappeared with nocturnal ventilatory support. Daytime arterial PO2 and PCO2 improved after therapy. There are several advantages over commonly used, negative pressure devices for nocturnal ventilation. These include patient synchronization of tidal volume, ease of application, less cumbersome apparatus, more nocturnal patient mobility, and absence of production of upper airway obstruction.     

Treatment of obstructive sleep apnea. A preliminary report comparing nasal CPAP to nasal oxygen in patients with mild OSA

Nasal CPAP is presently accepted as first-line therapy for obstructive sleep apnea, but a significant minority of patients do not tolerate nasal CPAP. The purpose of this study was to compare the benefits of nasal CPAP, nasal oxygen (O2), and placebo (air) using patients as their own controls. We studied eight men, aged 33 to 72 (mean 57 years), who had mild obstructive sleep apnea. To be eligible for study, patients had to have an apnea plus hypopnea index greater than or equal to 5, plus one or more of the following: blood pressure greater than 150/95 mm Hg, multiple sleep latency test mean score less than or equal to 10 minutes, or significant nocturnal cardiac ectopy. After a baseline study, patients received a month each of nocturnal O2 at 4 LPM and air at 4 LPM, presented in random order. The third month of treatment consisted of nasal CPAP (range 2.5 to 12.5 cm H2O). Patients underwent evaluation at baseline and after each month of treatment. It was concluded that oxygen was more effective in improving oxygenation and hypopneas than is nasal CPAP. However, oxygen did not reduce apneas or improve daytime hypersomnolence as well as nasal CPAP in patients with mild OSA. Oxygen might be considered as an alternate form of treatment for patients who are not hypersomnolent, or as an adjunct to nasal CPAP.     

The effects of nasal continuous positive airway pressure on platelet activation in obstructive sleep apnea syndrome

OBJECTIVE: A case-controlled study to assess the effects of nasal continuous positive airway pressure (CPAP) on platelet activation in patients with obstructive sleep apnea (OSAS) syndrome. METHODS: We recruited 65 patients with suspected OSAS for this study. Blood samples were taken with the patient in the supine position in the morning immediately after polysomnography, and 1 night and 3 months after the start of nasal CPAP therapy to measure an index of platelet activation (IPA+), which reflected both the quantity and quality of platelet activation. Significant OSAS was defined as an apnea-hypopnea index (AHI) of > or = 10 events per hour. RESULTS: There were 42 patients with significant OSAS and 23 control subjects with AHI < 10 events per hour. The mean (+/- SD) age for the OSAS patients was 48 +/- 9 years, the mean body mass index was 30.7 +/- 4.8, the mean AHI was 47 +/- 25 events per hour, the mean arousal index (AI) was 37 +/- 23 events per hour, and the mean minimum arterial oxygen saturation was 74 +/- 11%. Following multiple linear regression analyses of the clinical and polysomnography parameters, AI was the independent factor that correlated best with the baseline IPA+ (beta-coefficient, 0.386; p = 0.006). Following nasal CPAP treatment with a mean objective CPAP compliance of 3.9 +/- 1.9 h per night, there was a significant decrease in IPA+ from 15.1 +/- 12.2 U (at baseline) to 12.2 +/- 5.2 U (p < 0.001) and 9.8 +/- 4.3 U (p = 0.005), respectively, after 1 night and 3 months, whereas no significant change was noted among the control subjects. Using univariate analysis of variance to compare the changes in IPA+ between the two groups at 3 months with adjustment for the baseline value, nasal CPAP reduced IPA+ by 5.63 (SE, 1.85), whereas IPA+ increased in control subjects by 1.33 (SE, 1.27) [least-squared mean difference between groups, 3.34; 95% confidence interval, 0.42 to 6.26; p = 0.026]. CONCLUSIONS: OSAS, through repeated episodes of arousals, may lead to platelet activation, which can be reduced by nasal CPAP therapy.     

Driving simulator performance in patients with sleep apnea

Although previous studies have shown that patients with obstructive sleep apnea have a higher automobile crash rate than normal subjects, objective measurements of driving performance in patients with sleep apnea have not been reported. Therefore, we compared the driving performance of subjects with untreated, severe sleep apnea to that of control subjects on two driving simulators. Using a simulator with road films, six subjects with untreated, severe apnea performed worse than did a control group of seven normal subjects on both highway and city/rural driving (p less than 0.05). Using a personal computer program simulating a monotonous highway drive, 12 subjects with untreated sleep apnea performed worse than 12 control subjects. The patients with apnea hit a greater number of road obstacles during their 30-minute simulated drive than did the control subjects (44 +/- 52 in patients with apnea versus 9 +/- 7 in control subjects, p less than 0.05). Six patients with apnea hit fewer road obstacles after treatment with nasal continuous positive airway pressure (CPAP) than before treatment (29 +/- 19 before CPAP versus 13 +/- 8 after CPAP, p less than 0.05). We conclude that: (1) driving simulator performance of untreated subjects with severe obstructive sleep apnea is worse than that of control subjects; (2) driving simulator performance of subjects treated with nasal CPAP improves.     

IS THERE A SPECIFIC LINKAGE BETWEEN OBSTRUCTIVE SLEEP APNEA SYNDROME AND GASTROESOPHAGEAL REFLUX DISEASE?

Obstructive sleep apnea syndrome (OSAS) is a common condition characterized by repetitive sleep‐induced collapse of the upper airways. It is associated with increased risk for hypertension, ischemic heart disease, cerebral stroke, and traffic accidents. In contrast, gastroesophageal reflux disease (GERD) is a very common disorder defined as various symptoms or esophageal mucosal damage generated by the abnormal reflux of gastric contents into the esophagus. Patients with OSAS have been reported to have a high prevalence of gastroesophageal reflux (GER) symptoms. The increase of transdiaphragmatic pressure in parallel with the large negative intrathoracic pressure produced during apnea events may directly lead to GER. In addition, some studies have demonstrated improvement in GERD with the application of continuous positive airway pressure, most consistently effective treatment for OSAS. However, GER dose not occur with every apnea. Moreover, the common conditions observed in patients with OSAS, including obesity or alcohol ingestion, are also predisposing factors for GER. A more recent investigation in over 1000 subjects failed to show a causal link between both diseases. Thus, the potential relationship between OSAS and GERD remains controversial. Inconsistencies in definitions of both diseases or sampling biases may contribute to the confusing results.     

Long-term compliance with nasal continuous positive airway pressure therapy of obstructive sleep apnea

In an attempt to identify predictors of long-term compliance with nasal continuous positive airway pressure (CPAP), we reviewed the records of 125 patients with obstructive sleep apnea (OSA) referred to our center for nasal CPAP trials. Severity of sleep apnea, sleep staging, daytime hypersomnolence, effectiveness of nasal CPAP, previous palatal surgery, and adverse reactions were compared in compliant and noncompliant patients. Nineteen patients did not tolerate a nasal CPAP trial in the laboratory or refused home nasal CPAP therapy. Ten patients were unavailable for follow-up. Of the remaining 96 patients, 23 (24 percent) had discontinued therapy, while 73 (76 percent) were still using nasal CPAP at 14.5 +/- 10.7 months (mean +/- SD). There were no statistically significant differences between the compliant and noncompliant patients in baseline apnea plus hypopnea index (AHI), baseline sleep staging, AHI while receiving nasal CPAP, sleep staging while receiving nasal CPAP, or frequency of adverse reactions during therapy. Severe daytime sleepiness was present in 65 of the 73 compliant patients and in 12 of the 23 noncompliant patients (p less than 0.05). Ten of 43 in the compliant group had previous palatal surgery compared with ten of 23 noncompliant patients (p less than 0.05). Our data confirm earlier observations in smaller samples that compliant and noncompliant patients have equally severe sleep apnea and good initial responses to nasal CPAP. Long-term compliance with nasal CPAP may be associated with the severity of daytime hypersomnolence on presentation. Previous palatal surgery was more frequent in patients who did not tolerate long-term nasal CPAP therapy.     

Vascular reactivity in obstructive sleep apnea syndrome

The obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular disease and systemic hypertension. Because systemic arterial blood pressure is proportional to venodilation and venous return to the heart, we hypothesized that altered vascular responsiveness might exist in the veins of subjects with OSAS. We therefore investigated venodilator responses in awake, normotensive subjects with and without OSAS, using the dorsal hand vein compliance technique. Dose-response curves to bradykinin and nitroglycerin were obtained from 12 subjects with OSAS and 12 matched control subjects. Maximal dilation (E(max)) to bradykinin was significantly lower in the OSAS group (62.1% +/- 26.1%) than in the control group (94.3% +/- 10.7%) (p < 0.005). Vasodilation to nitroglycerin tended to be lower in the OSAS group (78.6% +/- 31.8%) than the control group (100.3% +/- 12.9%), but this effect did not reach statistical significance. When six of the OSAS subjects were retested after 60 d of treatment with nasal continuous positive airway pressure (CPAP), E(max) to bradykinin rose from 60.3% +/- 20. 3% to 121.4% +/- 26.9% (p < 0.01). Vasodilation to nitroglycerin also increased, but this effect did not reach statistical significance. These results demonstrate that a blunted venodilatory responsiveness to bradykinin exists in OSAS. This effect appears to be reversible with nasal CPAP therapy.