The effect of nocturnal oxygen therapy in patients with sleep apnea syndrome and chronic airflow limitation

Oxygen therapy for patients with sleep apnea-hypopnea syndrome (SAHS) usually causes significant side effects. The aim of this study was to assess the effect of short-term nocturnal oxygen therapy in patients with SAHS and chronic obstructive pulmonary disease. Ten patients with diagnoses of SAHS were enrolled. The patients' mean age was 63 (10) years, mean apnea-hypopnea index (AHI) was 58 +/- 17, mean FVC was 59 +/- 8% of reference and mean FEV1 was 40 +/- 14% of reference. Using a random, single blind design, two polysomnographic studies were performed on two consecutive nights. Oxygen was administered on one night at a mean flow rate of 1.3 +/- 04 l/min and on the other night air was administered at the same rate. Arterial blood gases were analyzed at the end of each study. Oxygen administration improved nocturnal hypoxia and reduced the AHI, which was 40 +/- 20 with oxygen and 58 +/- 17 with air (p < 0.005). Improvement was achieved at the expense of a reduction in the number of hypopneic episodes. No significant differences were observed in apneic episodes and only a slight increase in the duration of hypopneic episodes was observed (21 +/- 7 s with air and 27 +/- 8 s with oxygen [p < 0.01]). Neither quality of sleep nor heart rate changed. Slight respiratory acidosis was observed in 50% of the patients. In conclusion, nocturnal oxygen administration in patients with SAHS and COPD improved nocturnal hypoxia and reduced the total number of respiratory events. However, in these patients oxygen should be administered with care, even when the rate of flow is low, given the tendency for pCO2 and respiratory acidosis to increase.     

Relationship between clinical symptoms and nocturnal oxygen desaturation in sleep apnea syndrome and chronic lung disease]

Nocturnal oxygen desaturation (NOD) is commonly seen not only in sleep apnea syndrome (SAS) but also in chronic lung disease (CLD) including chronic obstructive lung disease even without sleep apnea. However, the relationship of NOD to clinical symptoms such as morning headache, sleep deprivation due to breathlessness, and daytime sleepiness is not known. In this study, we examined by polysomnography the relationship between several NOD indexes, parameters of apnea, and subjective symptoms in 25 patients with SAS and 22 patients with CLD. In addition, the relation between daytime arterial blood gas data and NOD indexes, parameters of apnea, was examined. In the SAS group, there were no differences in any parameters of NOD and apnea between patients with subjective symptoms and those without symptoms. However, in the CLD group, symptomatic patients had significantly lower lowest SaO2, higher mean SaO2, and longer total desaturation time. In both groups, daytime PaCO2 had a significant correlation with several NOD parameters such as mean SaO2, lowest SaO2, and total desaturation time. In the SAS group, daytime PaCO2 was also correlated with the parameters of apnea. On the other hand, daytime PaO2 was significantly correlated with mean SaO2 only in the CLD group. From these data, we conclude that in patients with SAS, daytime PaCO2 is a variable that is related to the degree of NOD, and that in patients with CLD, subjective symptoms and daytime PaO2 in addition to daytime PaCO2 are associated with NOD.     

Effects of nocturnal oxygen therapy in patients with chronic heart failure and central sleep apnea: CHF-HOT study

It was previously reported that nocturnal home oxygen therapy (HOT) significantly improved not only sleep disordered breathing (SDB), but also quality of life (QOL) and left ventricular ejection fraction (LVEF) in two trials. To strengthen the statistical reliability of the above efficacies of HOT and to assess the effects of 12-week nocturnal HOT on suppression of ventricular arrhythmias, we combined the two trials and undertook a post hoc analysis. Ninety-seven patients with chronic heart failure (CHF) and central sleep apnea were assigned to receive HOT (45 patients) or not (52 patients). HOT resulted in greater reduction in the apnea–hypopnea index (AHI) (?11.4 ± 11.0 vs. ?0.2 ± 7.6 events/h, p < 0.01), which is associated with greater improvement in the Specific Activity Scale (0.8 ± 1.2 vs. 0.0 ± 0.6, p < 0.01), New York Heart Association (NYHA) functional class (p < 0.01), and LVEF (p = 0.06). Median number of premature ventricular contraction (PVC) at baseline was 17 beats per hour in both the HOT and the control groups. Overall improvements of PVCs were not different either in the HOT group or in the control. However, in 12 patients with NYHA >III and AHI >20 events/h, PVC was significantly improved by HOT with a marked reduction in AHI and a substantial increase in LVEF. In conclusion, among patients with CHF and CSA, HOT improves SDB, QOL, and cardiac function. The effectiveness of HOT for ventricular arrhythmias was not observed in the overall analysis, but only in a limited number of patients with severe CHF and SDB. To clarify the effects of HOT on ventricular arrhythmias in patients with CHF and SDB, a further study is needed.     

阻塞性睡眠呼吸暂停低通气综合征患者夜间缺氧程度的评估

目的 评估阻塞性睡眠呼吸暂停低通气综合征（OSAHS）患者的夜间缺氧程度。方法对疑诊有睡眠呼吸障碍的患者215例进行夜间睡眠呼吸监测,计算平均血氧饱和度（AO2）、最低血氧饱和度（LO2）、氧减指数（ODI）、平均氧减饱和度、血氧饱和度低于90％占整个记录时间的百分比（T〈90％）,并进行相关分析。结果 依据所有患者的呼吸暂停低通气指数（AHI）分为AHI正常组（AHI〈5次／h）、轻度OSAHS组（5次／h≤AHI〈15次／h）、中度OSAHS组（15次／h≤AHI〈30次／h）、重度OSAHS组（AHI≥30次／h）,4组A02、L02、ODI、T〈90％差异有统计学意义（P〈0．001）。AHI与A02、ODI、L02、平均氧减饱和度、T〈90％显著相关（r分别为-0．610、0．983、-0．789、0．782、0．821,P=0．001）。结论 OSAHS患者缺氧严重程度的评估需结合ODI、LO2、T〈90％三个指标综合判断．不能仅考虑单一指标．     

Clinical efficacy and cost-benefit analysis of nocturnal home oxygen therapy in patients with central sleep apnea caused by chronic heart failure.

BACKGROUND: There is increasing evidence that both obstructive and central sleep apnea contribute to the progression and prognosis in patients with chronic heart failure (CHF). In the main study of nocturnal home oxygen therapy (HOT) in patients with central sleep apnea because of CHF (CHF-HOT), significant improvements in oxygen desaturation index, apnea - hypopnea index, left ventricular ejection fraction, and specific activity scale were reported following 12 weeks of nocturnal HOT in these patients. METHODS AND RESULTS: The present study is designed to further evaluate the clinical efficacy and cost - benefit of nocturnal HOT according to the results of a follow-up survey on changes in frequencies of hospitalization, emergency visits, and regular outpatient visits by 53 patients undergoing nocturnal HOT for more than 6 month periods. Medical costs were estimated from the DPC-MDC5 charge for hospitalization because of worsening heart failure (HF), and from the standard model case estimation for emergency and regular outpatient visits for HF. To reveal the time-saving benefit following nocturnal HOT, the influence on estimated days spent for hospital-care was also analyzed. The present study revealed significant reduction in frequencies and length of hospitalization (2.1 to 0.5 times/year, 38.7 to 34.6 days, medical cost: -2,686,267 yen), emergency visit (2.5 to 0.7 times/year, -15,984 yen), and regular outpatient visit (17.7 to 12.6 times/year, -6,324 yen) as compared with those before the induction of nocturnal HOT, which resulted in a total medical cost-reduction of 1,854,175 yen/patient/year, even with the additional charge for nocturnal HOT (854,400 yen/patient/year). Furthermore, nocturnal HOT produced a remarkable decline in estimated days spent for hospital-care (88.2 to 21.2 days/patient/year). CONCLUSION: The present analysis calculated a remarkable cost-benefit (1,854,175 yen/patient/year) from the reduction in hospitalization and emergency visits, and also time-saving benefits from an increase in expected days free from hospital-care (67 days/patient/year).     

Effect of metabolic acidosis upon sleep apnea

The effects of metabolic acidosis upon the pattern of apnea during sleep were assessed in ten sleep apnea patients. Four had pure obstructive apnea, two pure central apnea, and four had mixed apnea. Acidosis was induced with acetazolamide. Acid-base shifts had little effect in pure obstructive and pure central apnea, but had a significant effect in mixed apnea. In two of the mixed apneic patients, metabolic acidosis converted predominantly central apnea into nearly pure obstructive apnea, prolonging apneic periods and worsening hypoxemia. A suggested explanation for this is the greater stimulating effect of acidosis upon the lower bellows muscles than upon the muscles which act to maintain patency of the upper airways. The observation that some patients with mixed sleep apnea appear to have central apnea while relatively alkalotic and obstructive apnea while acidotic emphasizes the need for more careful and detailed characterization of apneic disorders with respect to their responses to body states and therapeutic agents.     

The effects of oxygen in patients with sleep apnea

The effects of 6 h of continuous low flow, nasally administered oxygen were compared with the effects of breathing air in 10 men and 2 women with obstructive sleep apnea and daytime hypersomnolence. The overall quality of sleep, sleep fragmentation, the pattern of breathing, nocturnal oxygenation, and the clinical effects on daytime hypersomnolence determined by multiple sleep latency testing were evaluated. We found that in non-REM sleep, breathing 3 L/min of oxygen increased baseline percent arterial oxyhemoglobin saturation and decreased both the rate of sleep-disordered breathing from 69 +/- 36 to 56 +/- 39 (mean +/- SD) (p less than 0.02) episodes per hour and the peak fall in arterial oxyhemoglobin saturation from 11.5 +/- 5.6% to 6.5 +/- 4.0% (p less than 0.001). In addition, oxygen significantly reduced the percentage of central and mixed sleep-disordered breathing events, thus increasing the percentage of obstructive sleep-disordered breathing events. In contrast, during REM sleep, neither the baseline nor the peak fall in oxyhemoglobin saturation during disordered breathing improved; however, there was a significant reduction in hourly sleep-disordered breeathing rate from 70 +/- 17 to 56 +/- 23 (p less than 0.02) episodes. These improvements in oxygenation and pattern of breathing were associated with improved sleep architecture characterized by a decrease in the number of awakenings from sleep and an increased total sleep time from 335 +/- 72 to 369 +/- 68 min (p less than 0.05). Although 7 of 12 patients felt more alert after oxygen therapy, there was no overall improvement in multiple sleep latency test results.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prediction of the degree of nocturnal oxygen desaturation in sleep apnea syndrome by estimating the testosterone level

We studied the influence of hypoxia due to sleep apnea on testosterone (T) secretion. It was conducted on the basis of an idea that sustained hypoxia may depress T secretion. The subjects consisted of 15 male patients with no drug administration whose complaints were snoring and/or obesity. The subjects participated in a sleep study on two consecutive nights. During the first night we collected blood samples starting every 4 hours from 10 PM via a catheter and measured T. From the data of the second night, we calculated total desaturation time with more than 4% from the baseline SaO2. According to the amount of this desaturation time, the subjects were divided into 2 groups; desaturation time less than 80 min in group 1 and longer in group 2, respectively. The peak value was seen at 6 AM in group 1 and at 10 AM in group 2. We investigated the correlation between the ratio of T10/T6, which is the ratio of T level at 10 AM to that at 6 AM, and parameters of sleep disorders related to oxygen desaturation. Total 4% desaturation time in total sleep period and non REM period significantly correlated with this ratio. From the diagram illustrating the correlation between the ratio and total 4% desaturation time in total sleep period, we could assume that if the ratio is beyond 1, the subject may have had more than about 80 min of total 4% desaturation time.     

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.     

Observation-based nocturnal sleep inventory: screening tool for sleep apnea in elderly people

OBJECTIVES: To measure the ability of the Observation‐based Nocturnal Sleep Inventory (ONSI) to detect the presence or absence of sleep apnea syndrome (SAS) in older adults. DESIGN: Cross‐sectional blinded study. SETTING: University hospital–based geriatric sleep center. PARTICIPANTS: All participants aged 70 and older were referred by physicians for suspicion of SAS. MEASUREMENTS: ONSI performed by nurses; overnight polysomnography. SAS was defined as an apnea‐hypopnea index of 15 events or more per hour of sleep. RESULTS: A total of 121 consecutive patients were evaluated for study participation. Six were excluded because of technical difficulties with polysomnography or too‐frequent awakenings related to medical conditions. One hundred eleven patients completed the validation process. Polysomnography identified 68 patients as having SAS and 43 patients as not having SAS. The nurse‐administered ONSI demonstrated good levels of sensitivity (90%), specificity (81%), positive predictive value (88%), and negative predictive value (83%) in screening older adults for SAS. CONCLUSION: The ONSI is the first valid SAS screening tool proposed for older persons in hospitals and nursing homes. This study demonstrates that the ONSI provides accurate information; is a simple, easy‐to‐use bed‐side tool; and is highly sensitive and specific in screening SAS when compared with overnight polysomnography results.     

Effectiveness of short-term treatment with nocturnal oxygen therapy for central sleep apnea in patients with congestive heart failure

OBJECTIVES. To evaluate the short term effects of inhalation of oxygen at night in 51 patients with congestive heart failure (CHF) and sleep apnea syndrome (SAS). METHODS. Fifty-one patients with stable CHF (31 males, 20 females, mean age 79.0 +/- 11.9 years; brain natriuretic peptide level of > 100 pg/ml) were evaluated between September 2003 and August 2004, using a Morpheus monitor. The complication rate of SAS in patients with CHF was assessed and apnea hypopnea index, oxygen desaturation index 3%, heart rate, and autonomic nerve activity under room air compared to supplemental O2 (2 l/min) over two consecutive nights. RESULTS. Thirty-eight (75%)of the CHF patients had SAS. Of these SAS patients, 49% suffered from central SAS and 51% had obstructive SAS. Apnea hypopnea index and oxygen desaturation index 3% improved remarkably with supplemental oxygen (p < 0.001), in particular, the central SAS group demonstrated prominent improvement (p < 0.001). Obstructive SAS patients exhibited no significant changes (p = 0.3356), but tended to exacerbate the episodes of sleep apnea. Total heart rate was decreased (p = 0.0079). Nevertheless, heart rate variability analysis showed little effect of nocturnal oxygen therapy on the autonomic nervous system during sleeping. CONCLUSIONS. Nocturnal oxygen therapy improved the number of sleep apnea episodes and decreased total heart rate during sleep time for the CHF patients with central SAS, despite little influence on the autonomic nervous system, based upon assessment of heart rate variability. Obstructive SAS might exacerbate the episodes of sleep apnea.     

Influence of apnea type and sleep stage on nocturnal postapneic desaturation

We examined the influence of apnea type and sleep stage on the severity of apnea-induced desaturations in 32 patients with a sleep apnea syndrome. The individual postapneic desaturations were evaluated by a desaturation curve; this curve was built by plotting the fall in SaO2 after an apnea against this apnea's length for each apneic event during the whole night recording. We considered only apneas where the preapneic SaO2 was greater than 90% and the lowest SaO2 value after the apnea was equal to or greater than 60% (limit of linearity of our oximeter). From the desaturation curve, we determined a desaturation surface defined as the area under the curve between 10s and a variable apnea duration. The upper bound used for the determination of the desaturation curve and the desaturation surface was the maximal length of apnea type with the shortest apnea duration between non-REM obstructive apnea and the other apnea types (i.e., obstructive and central apnea, obstructive and mixed apnea, etc.). The desaturation surface was determined separately for non-REM sleep apneas (obstructive apneas, mixed apneas, central apneas, and obstructive apneas with persistent expiratory flow) and REM sleep apnea (all obstructive in type). Non-REM obstructive apneas served as reference to evaluate the severity of apnea-induced desaturations of the other apneas. We found that the desaturation surface of obstructive apnea (OA) with expiratory flow and of REM sleep OA were significantly greater than for OA in non-REM sleep (p less than or equal to 0.005). The OA-related desaturation was significantly greater than those of central apneas (p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)     

Combined effect of obstructive sleep apnea and chronic smoking on cognitive impairment

Objectives

Little is known about combined effect of obstructive sleep apnea (OSA) and chronic smoking on cognitive impairment. We aimed to determine whether smoking synergizes with OSA in deteriorating cognitive function and whether smoking cessation contributes to cognitive benefits.

Methods

One hundred and eighteen male patients were enrolled in the study and asked to complete neurocognitive function tests including Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), clock drawing test (CDT), and verbal fluency test (VFT). Variables of those neurocognitive function tests were analyzed with two factors: OSA and smoking.

Results

After adjustment of potential confounding factors, an OSA-by-smoking interaction was found in CDT-C scores and a main smoking effect were showed in MoCA scores. Smoking patients with OSA had the worst performance in the four tests compared with the other three groups (smoking patients without OSA, non-smoking patients with and without OSA). Ex-smokers with OSA tended to perform better than current smokers, but still worse than never-smokers with OSA in those tests.

Conclusion

The results suggested that the coexistence of OSA and chronic smoking resulted in more pronounced cognitive deficits than either factor along. Smoking cessation may benefit cognitive function to some extents in patients with OSA.

     

睡眠呼吸暂停综合征患者氧亲和力的变化

目的 :了解睡眠呼吸暂停综合征 (SAS)患者P50 (即血红蛋白氧饱和度 5 0 %时相应的氧分压 )是否有改变 ,探讨P50 与夜间血氧饱和度的相关性以及P50 可否预测SAS患者的病情严重程度。方法 :随机选择SAS患者 5 6例 ,其平均睡眠呼吸暂停 低通气指数 (AHI)为 (3 7 5 1± 2 0 2 1)次 h ,平均夜间血氧饱和度为 86 5 2 %± 1 91% ,清醒时的血氧饱和度为 95 2 0 %± 1 40 % ,并选择正常人 42例作为对照组进行P50 水平的测试。 11例患者经持续气道正压通气 (CPAP)治疗后重复进行测试。结果 :1 SAS患者日间P50 值为 (2 9 2 7± 1 3 1)mmHg(1mmHg=0 13 3kPa) ,对照组为 (2 7 63± 1 0 1)mmHg,二者存在显著性差异 (P <0 0 5 ) ;2 SAS患者P50 与夜间平均血氧饱和度呈明显负相关 (r=- 0 962 1,P <0 0 5 ) ;3 11例SAS患者经CPAP治疗 3个月后 ,P50 水平显著下降至 (2 7 2 7± 0 63 )mmHg,与正常对照组相比无显著性差异。结论 :1 SAS患者的氧离曲线右移 ,这可能是对组织低氧的一个保护性机制 ,以延迟肺动脉高压的形成 ,红细胞的增多及其它器官系统并发症的发生。 2 P50 能够反映SAS患者夜间低氧的严重程度 ,因而可以作为一个常规指标进行检测     

The acute effects of continuous positive airway pressure and oxygen administration on blood pressure during obstructive sleep apnea.

We have measured blood pressure continuously with a digital artery blood pressure monitor in eight patients with severe obstructive sleep apnea (OSA) during 30 min each of wakefulness, OSA, OSA with added oxygen to keep saturation above 96 percent at all times (OSA+O2), and nasal continuous positive airway pressure (CPAP) therapy. Mean blood pressures were not different between wakefulness, OSA, OSA+O2, and CPAP, although the variability in blood pressure was significantly greater during OSA and OSA+O2 than during wakefulness and CPAP. The addition of oxygen did not attenuate the variability in blood pressure. Using multiple linear regression modeling to further dissect out the principal variables determining the postapneic blood pressure rise, we found that only apnea length (r2 = 0.28, p less than 0.0001) and pulse rate changes (r2 = 0.15, p less than 0.0001) remained significantly related to SBPmax, while hypoxemia did not. We found the same trends in the other variables SBPten, DBPmax, and DBPten. Hypoxemia made a small contribution to the size of DBPmax, although this was small by comparison with apnea length. We conclude that CPAP treatment of OSA does not lower mean blood pressure acutely, although it significantly reduces the large oscillations in blood pressure seen in patients with untreated OSA. The rise in blood pressure following each apnea is not primarily due to arterial desaturation but is related to apnea length and may be caused by increased sympathetic activity secondary to arousal.     

The effect of altitude descent on obstructive sleep apnea

BACKGROUND: The present requirement for "at facility" polysomnograms requires many residents in mountain communities to descend in elevation for sleep testing, which may cause misleading results regarding the severity of obstructive sleep apnea (OSA). DESIGN: Eleven patients with previously undiagnosed sleep apnea living at an altitude > 2,400 m (7,900 feet) in Colorado underwent diagnostic sleep studies at their home elevation and at 1,370 m (4,500 feet), and 5 of the 11 patients were also studied at sea level. RESULTS: The mean (SE) apnea-hypopnea index (AHI) fell from 49.1 (10.5)/h to 37.0 (11.2)/h on descent to 1,370 m (p = 0.022). In the five patients who traveled to sea level, the AHI dropped from 53.8 (13.2)/h at home elevation to 47.1 (14.8)/h at 1,370 m, and to 33.1 (12.6)/h at sea level (p = 0.018). The reduction in AHI was predominantly a reduction in hypopneas and central apneas, with little change in the frequency of obstructive apneas. Duration of the obstructive apneas lengthened with descent. Of eight patients with an AHI < 50/h at their home elevation, two patients had their AHI fall to < 5/h at 1,370 m, and a third patient dropped to < 5/h at sea level, ie, below many physicians' threshold for providing therapy. Patients with the most severe OSA had the least improvement with descent. CONCLUSIONS: Because AHI decreases significantly with descent in altitude, polysomnography is most accurately done at the home elevation of the patient. Descent to a sleep laboratory at a lower elevation may yield false-negative results in patients with mild or moderate sleep apnea.