Effect of supplemental nocturnal oxygen on gas exchange in patients with severe obstructive lung disease

We studied the effect of supplemental nocturnal oxygen on blood gases in 15 patients with severe but stable chronic obstructive lung disease (ratio of forced expired volume in one second to forced vital capacity, 37.2 +/- 1.8 [mean +/- S.E.] per cent of predicted; arterial oxygen tension, 50.7 +/- 1.4 mm Hg; and arterial carbon dioxide tension [PCO2], 53.1 +/- 1.5 mm Hg). Sleep variables and measures of gas exchange were determined on two consecutive nights; on the first night the subjects breathed supplemental oxygen, and on the second they breathed room air. Transcutaneous PCO2 was measured with an infrared sensor, and arterial oxygen saturation with an ear oximeter. Breathing of supplemental oxygen sufficient to keep oxygen saturation at or above 90 per cent was associated with only small increases (less than 6 mm Hg) in PCO2 throughout sleep, as compared with values while subjects were breathing room air. The increase in PCO2 occurred early in the night and was not progressive. Only three patients, who were found to have obstructive sleep apnea in addition to obstructive lung disease, had larger increases in PCO2 during sleep and reported morning headaches. We conclude that nocturnal oxygen does not induce clinically important increases in PCO2 during sleep in patients with stable obstructive lung disease and therefore can safely be used to prevent the dangerous consequences of hypoxia.     

Sleep apnea syndrome: a possible contributing factor to resistant

STUDY OBJECTIVES: There is evidence supporting an association between sleep apnea and hypertension. However, it is not clear if sleep apnea interteres with the pharmacotherapy of hypertension. To investigate this question, we studied the relationship between the effectiveness of anti-hypertensive treatment in reducing blood pressure, and severity of sleep apnea in a large group of apneic patients referred to a sleep disorders centre at St. Michael's Hospital at the University of Toronto. DESIGN: N/A SETTING: N/A PARTICIPANTS: 1,485 adult patients with sleep apnea, as defined by the apnea/hypopnea index (AHI) >10 events/hr, were analyzed. There were 393 who reported using anti-hypertensive medications on a regular basis for more than 6 months. One hundred and eighty-three patients were treated "effectively" (i.e. blood pressure lower than 140/90 mm Hg in the morning and in the evening). Seventy-four patients were treated "ineffectively," defined as blood pressure >140/90 mm Hg in the morning or in the evening. Both groups were compared with respect to clinical and demographic data using analysis of covariance with gender, age, body mass index (BMI), and neck circumference (NC) as covariates. INTERVENTIONS: N/A MEASUREMENTS AND RESULTS: Ineffectively and effectively treated patients were similar in age (57 +/- 9) vs. 57 +/- 10 years, respectively), and had similar body mass index (33.8 +/- 7.4 vs. 33.4 +/- 7.3 kg/m2, respectively). However, ineffectively treated patients had significantly higher apnea/hypopnea index (44 +/- 29 vs. 33 +/- 25 events/hr, p<.0005), despite having similar nocturnal oxygenation (percent of total sleep time spent with oxygen desaturation lower than 90% was 36 +/- 34 vs. 29 +/- 30% in the ineffective and effective groups, respectively). The difference in AHI persisted even after adjusting for age, gender, and body mass index. CONCLUSIONS: Our results demonstrate that hypertensive patients with sleep apnea whose blood pressure responds beneficially to treatment have less severe sleep apnea than those patients whose blood pressure remains elevated despite anti-hypertensive therapy. Since neither obesity nor nocturnal hypoxemia appear to be important determinants of ineffective treatment, we suggest that resistant hypertension may be caused by frequent intermittent sympathetic stimulation.     

Hemofiltration in chronic heart failure

30 patients with severe congestive heart failure (NYHA IV) unresponsive to medical management were treated by continuous hemofiltration (CHF). 57% of patients received arteriovenous CHF and 43% of patients venovenous, machine assisted CHF over 95 +/- 31 hours. A reduction of body edemas was achieved. The removal of body fluid by CHF between 2 and 40 kg led to a reduction of body edemas and short-term clinical improvement. Furthermore CHF treatment induced hemodynamic improvement with a reduction of central venous pressure (18 +/- 6 cm H2O pre CHF vs 8 +/- 4 cm H2O post CHF p less than 0.01) and a reduction of left ventricular filling pressure (22 +/- 6 mm Hg vs 14 +/- 5 mm Hg, p less than 0.01), while the left ventricular ejection fraction remained unchanged. Patients with low serum sodium levels (less than 132 mval/l) benefited most. While 28/30 of patients has short-term clinical improvement between 2 and 8 weeks, 38% of patients had long-term benefits.     

Increased homeostatic response to behavioral sleep fragmentation in morning types compared to evening types

STUDY OBJECTIVES: To evaluate the influence of chronotype on sleep stages and quantitative sleep EEG when sleep pressure is increased and sleep schedule remains constant. DESIGN: A 5-day session comprising an adaptation night, a baseline night, two nights of sleep fragmentation, and a recovery night. SETTING: Chronobiology laboratory. PARTICIPANTS: Twenty-four healthy subjects aged 19-34 years: 12 morning types and 12 evening types selected by questionnaire. Each group included 6 men and 6 women with a habitual sleep duration of 7 to 9 hours. Interventions: Two nights of behavioral sleep fragmentation induced by forced 5-min awakenings every half-hour. MEASUREMENTS AND RESULTS: Each night of polysomnography recording lasted 8 hours and was based on each subject's preferred sleep schedule. On both nights of sleep fragmentation, stage 1 sleep increased, while both total sleep time and minutes of slow wave sleep decreased. No difference was observed in sleep architecture between morning types and evening types during sleep fragmentation nights or during recovery night. Spectral analysis of all-night NREM sleep EEG showed that during the recovery night, morning types had a larger fronto-central increase in low frequency activities and a larger centro-parietal decrease in 14-15 Hz activity than evening types. The largest group difference was for slow wave activity in the fronto-central area during the first part of the sleep episode. CONCLUSIONS: These results add further support to a postulated difference in homeostatic sleep regulation between morning types and evening types, with morning types showing indications of a higher homeostatic response to sleep disruption.     

Chronotype and sex effects on sleep architecture and quantitative sleep EEG in healthy young adults

STUDY OBJECTIVES: To evaluate the influence of chronotype (morning types and evening types) on sleep stages and quantitative sleep electroencephalograms when constraints on the sleep schedule are minimal and when sex difference is taken into account. DESIGN: A 48-hour session in the laboratory, including 2 nights of polysomnography, preceded by 7 days of ambulatory actigraphy. SETTING: Chronobiology laboratory. PARTICIPANTS: Twenty-four healthy young subjects: 12 morning types and 12 evening types selected by questionnaire. Each group included 6 men and 6 women. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: A polysomnography night of 8 hours in duration was recorded according to preferred sleep schedule. Sleep-stage analysis revealed that morning types and evening types did not differ in sleep architecture. However, morning-type men showed a higher percentage of stage 1 sleep and lower sleep efficiency than evening-type men. Electroencephalogram spectral analysis was conducted in non-rapid eye movement sleep for 6 frequency bands. Morning types had more spectral power in low sigma (12-14 Hz) compared with evening types. The most robust difference between women and men was found in high sigma (14-16 Hz) and was not present between chronotypes. The decay rate of slow-wave activity (1-5 Hz) tended to be faster in morning types compared with evening types (P = .06). This rate was almost identical for women and men. CONCLUSIONS: These results agree with the hypothesis that homeostatic sleep regulation differs between morning types and evening types, with morning types showing indications of a higher rate of dissipation of sleep pressure during the night. Morningness-eveningness seems to affect sleep in a sex-specific manner, with men being more affected by their chronotype.     

Long-term treatment of primary pulmonary hypertension with aerosolized iloprost, a prostacyclin analogue

BACKGROUND: Continuous intravenous infusion of epoprostenol (prostacyclin) is an effective treatment for primary pulmonary hypertension. This approach requires the insertion of a permanent central venous catheter, with the associated risk of serious complications. Recently, aerosolized iloprost, a stable prostacyclin analogue, has been introduced as an alternative therapy for severe pulmonary hypertension. METHODS: We evaluated the effects of aerosolized iloprost on exercise capacity and hemodynamic variables over a one-year period in patients with primary pulmonary hypertension. RESULTS: Twenty-four patients with primary pulmonary hypertension received aerosolized iloprost at a daily dose of 100 or 150 microg for at least one year. The mean (+/-SD) distance covered in the six-minute walk test increased from 278+/-96 m at base line to 363+/-135 m after 12 months (P<0.001). During the same period, the mean pulmonary arterial pressure before the inhalation of iloprost declined from 59+/-10 mm Hg to 52+/-15 mm Hg (P=0.006), cardiac output increased from 3.8+/-1.4 liters per minute to 4.4+/-1.3 liters per minute (P=0.02), and pulmonary vascular resistance declined from 1205+/-467 dyn x sec x cm(-5) to 925+/-469 dyn x sec x cm(-5) (P<0.001). The treatment was generally well tolerated, except for mild coughing, minor headache, and jaw pain in some patients. CONCLUSIONS: Long-term treatment with aerosolized iloprost is safe and has sustained effects on exercise capacity and pulmonary hemodynamics in patients with primary pulmonary hypertension.     

Differential effects of permanent and rotating shifts on self-report sleep length: a meta-analytic review

STUDY OBJECTIVES: The current study used the meta-analytic technique to quantitatively assess the effects of permanent and rotating shift-work schedules on sleep length. DESIGN: A meta-analysis was completed on 36 primary studies resulting in 165 effect sizes. Effect sizes comparing shift-workers to a permanent day shift control group were calculated for permanent evening shifts, permanent night shifts, and morning, evening, and night shifts worked as part of slowly and rapidly rotating shift systems. SETTING: NA PATIENTS OR PARTICIPANTS: NA INTERVENTIONS: NA RESULTS: Permanent night shifts resulted in a decrease, whereas permanent evening shifts resulted in an increase in sleep length. The shifts within rotating schedules followed the same pattern, with the addition of morning shifts having a moderate detrimental effect on sleep length. Furthermore, the speed of shift rotation had an impact. Slowly rotating shifts, in general, had the least detrimental effect on sleep length of the permanent and rotating shift-work schedules studied here. The pattern of effects among morning, evening, and night shifts was the same for rapidly and slowly rotating shifts, with night shifts having the greatest detrimental effect, morning shifts having a moderate detrimental effect and evening shifts having a positive effect on sleep length. In addition, nights on rotating shifts had a greater negative effect on sleep length than permanent night shifts. CONCLUSIONS: Slowly rotating shifts have the least negative impact on sleep length of shift-work schedules including a night shift. However, permanent night shifts could be an alternative shift-work schedule in operational settings that require many workers at night.     

Diagnosis of sleep-disordered breathing in patients with chronic heart failure: evaluation of a portable limited sleep study system

Sleep-disordered breathing (SDB) is common in chronic heart failure (CHF), affects disease progression and presents a potential therapeutic target. This study was designed to test the hypothesis that there would be good agreement in diagnostic outcome between home limited sleep studies and in-laboratory polysomnography (PSG) in the identification of SDB in patients with CHF. We performed synchronous in-laboratory Embletta and PSG, and home Embletta studies, prospectively in 20 consecutive patients with stable symptomatic CHF (ejection fraction 33 +/- 12%) on optimal medical therapy. Sleep efficiency was poor at 57 +/- 21%. Unlike synchronous in-laboratory Embletta (kappa coefficient 0.63, P < 0.01), home Embletta showed poor agreement with PSG (kappa coefficient 0.27, P = 0.06). Positive and negative predictive values for home Embletta in detecting SDB were 83% and 57% respectively. In this relatively small study, agreement in diagnostic outcome between home Embletta and PSG, and negative predictive value for the home Embletta, were poor. We explore possible explanations for this, both technical and situational, which should be taken into consideration when considering potential screening or diagnostic tools for SDB in patients with CHF.     

Effect of expiratory positive airway pressure on sleep disordered breathing

STUDY OBJECTIVES: We sought to determine the effect of expiratory positive airway pressure on end expiratory lung volume (EELV) and sleep disordered breathing in obstructive sleep apnea patients. DESIGN: Observational physiology study PARTICIPANTS: We studied 10 OSA patients during sleep wearing a facial mask. We recorded 1 hour of NREM sleep without treatment (baseline) and 1 hour with 10 cm H2O EPAP in random order, while measuring EELV and breathing pattern. RESULTS: The mean EELV change between baseline and EPAP was only 13.3 mL (range 2-25 mL). Expiratory time was significantly increased with EPAP compared to baseline 2.64 +/- 0.54 vs 2.16 +/- 0.64 sec (P = 0.002). Total respiratory time was longer with EPAP than at baseline 4.44 +/- 1.47 sec vs 3.73 +/- 0.88 sec (P = 0.3), and minute ventilation was lower with EPAP vs baseline 7.9 +/- 4.17 L/min vs 9.05 +/- 2.85 L/min (P = 0.3). For baseline (no treatment) and EPAP respectively, the mean apnea+hypopnea index (AHI) was 62.6 +/- 28.7 and 56.8 +/- 30.3 events per hour (P = 0.4). CONCLUSION: In OSA patients during sleep, the application of 10 cm H2O EPAP led to prolongation of expiratory time with only marginal increases in FRC. These findings suggest important mechanisms exist to avoid hyperinflation during sleep.     

N-terminal pro-brain natriuretic peptide for detection of cardiovascular stress in patients with obstructive sleep apnea syndrome

Patients with obstructive sleep apnea syndrome (OSAS) have an elevated incidence of cardiovascular events that may be related to an increased ventricular load and hypoxemia caused by apneas and hypopneas. N-terminal pro-brain natriuretic peptide (NTproBNP) appears to be an excellent marker of myocardial stretch and could serve as an indicator of subclinical cardiac stress, thereby identifying a patient population at risk for cardiac effects from OSAS. Adult patients presenting with suspected OSAS and scheduled for nocturnal polysomnography were recruited. Patients with heart or renal failure or severe lung disease were excluded. NTproBNP was measured the evening before and the morning after sleep. Blood pressure (BP) was monitored intermittently throughout the night. Fifteen male and 15 female subjects with a mean +/- SD body mass index of 38.2 +/- 9.8 were studied. Mean Apnea-Hypopnea Index (AHI) was 38.4 +/- 26, with 17 subjects having severe OSAS (AHI > 30). No subject had a significant rise in BP. NTproBNP values overnight decreased in 19 patients and rose in 11 (mean change 3.8 +/- 33 pg mL(-1)), but only one patient had an abnormal morning value. Three patients had an abnormal NTproBNP value prior to sleep, but their levels decreased with sleep. No correlations were detected between the evening baseline or postsleep NTproBNP levels and OSAS. Monitoring pre- and postsleep NTproBNP levels revealed no association with the occurrence or degree of OSAS, making it unlikely that NTproBNP could serve as a marker of cardiac stress in OSAS patients with stable BP and without overt heart failure.     

Postoperative sleep disturbance: influences of opioids and pain in humans

STUDY OBJECTIVES: To test the hypothesis that opioids and pain contribute independently to postoperative sleep disturbance, 10 women undergoing surgery requiring a low abdominal incision for treatment of benign gynecologic conditions were randomized to receive either epidural opioid (fentanyl) (n=6) or epidural local anesthetic (bupivacaine) (n=4) for intraoperative and postoperative analgesia. DESIGN: N/A SETTING: N/A PATIENTS OR PARTICIPANTS: N/A INTERVENTIONS: N/A MEASUREMENTS: Polysomnography was performed in a standard patient room on the preoperative and first three postoperative nights. Pain at rest and with coughing was evaluated using a visual-analogue pain scale each evening and morning. RESULTS: On the first postoperative night, rapid eye movement (REM) sleep was abolished in all patients. On the third postoperative night, the mean +/- SE REM sleep time increased significantly (p=.003) to 9.8% +/- 3.1% in the fentanyl group, and 12.9% +/- 3.8% in the bupivacaine group. Conversely, light non-REM (NREM) sleep (%stage 1 + %stage 2) was higher on the first postoperative night and significantly lower on the third postoperative night (p=0.011). Between group comparison revealed only that the mean % slow-wave sleep (SWS) in the fentanyl group (6.0%, 2.0%, and 14.7%) was different from the bupivacaine group (7.8%, 9.1%, and 10.6%) in the postoperative period after adjusting for the preoperative night % SWS (p=0.021). Pain was well controlled in all patients, but was slightly better controlled in the fentanyl group than in the bupivacaine group on postoperative night 2 (p=0.024). There was no statistically significant association between pain score and any polysomnographically defined stage. CONCLUSION: Postoperative patients suffer a profound sleep disturbance even when opioids are avoided and pain is well controlled.     

Adaptive servoventilation versus noninvasive positive pressure ventilation for central, mixed, and complex sleep apnea syndromes

RATIONALE: Although continuous positive airway pressure (CPAP) is most often effective in patients with obstructive sleep apnea, optimal treatment of patients with predominantly mixed apneas, central sleep apnea syndrome/Cheyne-Stokes respiration (CSA/CSR), or complex sleep apnea (CompSAS) is less straightforward, and may require alternative ventilatory assist modalities. OBJECTIVES: To compare the efficacy of noninvasive positive pressure ventilation (NPPV) with adaptive servoventilation (ASV) in treating patients with centrally mediated breathing abnormalities. We hypothesized that NPPV and ASV would be equivalently efficacious in improving the apnea/hypopnea index (AHI) and respiratory arousal index (RAI). METHODS: Prospective randomized crossover clinical trial comparing NPPV with ASV in patients with CSA/CSR, predominantly mixed apneas, and CompSAS in an acute setting. MEASUREMENTS AND MAIN RESULTS: 21 patients (6 with CSA/CSR, 6 with predominantly mixed apneas, and 9 with CompSAS) with initial diagnostic AHI +/- standard deviation 51.9 +/- 22.8/hr and RAI 45.5 < or = 26.5/hr completed the study. Following optimal titration with CPAP (N = 15), disturbed breathing and disturbed sleep remained high with mean AHI = 34.3 +/- 25.7 and RAI = 32.1 +/- 29.7. AHI and RAI were markedly reduced with both NPPV (6.2 +/- 7.6 and 6.4 +/- 8.2) and ASV (0.8 +/- 2.4 and 2.4 +/- 4.5). Treatment AHI and RAI were both significantly lower using ASV (P < 0.01). CONCLUSION: These data confirm that in patients with CSA/CSR, mixed apneas, and CompSAS, both NPPV and ASV are effective in normalizing breathing and sleep parameters, and that ASV does so more effectively than NPPV in these types of patients.     

Improvement of sleep apnea in patients with chronic renal failure who undergo nocturnal hemodialysis

BACKGROUND: Sleep apnea is common in patients with chronic renal failure and is not improved by either conventional hemodialysis or peritoneal dialysis. With nocturnal hemodialysis, patients undergo hemodialysis seven nights per week at home while sleeping. We hypothesized that nocturnal hemodialysis would correct sleep apnea in patients with chronic renal failure because of its greater effectiveness. METHODS: Fourteen patients who were undergoing conventional hemodialysis for four hours on each of three days per week underwent overnight polysomnography. The patients were then switched to nocturnal hemodialysis for eight hours during each of six or seven nights a week. They underwent polysomnography again 6 to 15 months later on one night when they were undergoing nocturnal hemodialysis and on another night when they were not. RESULTS: The mean (+/-SD) serum creatinine concentration was significantly lower during the period when the patients were undergoing nocturnal hemodialysis than during the period when they were undergoing conventional hemodialysis (3.9+/-1.1 vs. 12.8+/-3.2 mg per deciliter [342+/-101 vs. 1131+/-287 micromol per liter], P<0.001). The conversion from conventional hemodialysis to nocturnal hemodialysis was associated with a reduction in the frequency of apnea and hypopnea from 25+/-25 to 8+/-8 episodes per hour of sleep (P=0.03). This reduction occurred predominantly in seven patients with sleep apnea, in whom the frequency of episodes fell from 46+/-19 to 9+/-9 per hour (P= 0.006), accompanied by increases in the minimal oxygen saturation (from 89.2+/-1.8 to 94.1+/-1.6 percent, P=0.005), transcutaneous partial pressure of carbon dioxide (from 38.5+/-4.3 to 48.3+/-4.9 mm Hg, P=0.006), and serum bicarbonate concentration (from 23.2+/-1.8 to 27.8+/-0.8 mmol per liter, P<0.001). During the period when these seven patients were undergoing nocturnal hemodialysis, the apnea-hypopnea index measured on nights when they were not undergoing nocturnal hemodialysis was greater than that on nights when they were undergoing nocturnal hemodialysis, but it still remained lower than it had been during the period when they were undergoing conventional hemodialysis (P=0.05). CONCLUSIONS: Nocturnal hemodialysis corrects sleep apnea associated with chronic renal failure.     

Behavioral correlates of sleep-disordered breathing in older women

STUDY OBJECTIVES: To examine the association between SDB and subjective measures of daytime sleepiness, sleep quality, and sleep related quality of life in a large cohort of primarily community-dwelling older women, specifically considering the relative importance of sleep duration in mediating these associations. DESIGN: Cross-sectional. The functional outcome measures of interest were daytime sleepiness (using the Epworth Sleepiness Scale, ESS), sleep-related symptoms (Pittsburgh Sleep Quality Index, PSQI), and sleep related quality of life (Functional Outcomes of Sleep Questionnaire, FOSQ). ANOVA and regression analyses examined the association between SDB severity (measured by indices of breathing disturbances and overnight oxygen saturation) and sleep time (by actigraphy) and these outcome measures. Regression models were adjusted for age, body mass index (BMI), and a medical comorbidity index. We specifically explored whether associations with indices of SDB were mediated by sleep deprivation by adjusting models for actigraphy-determined average total sleep time (TST) during the night. SETTING: Community-based sample examined in home and outpatient settings. PARTICIPANTS: 461 surviving older women from the multicenter Study of Osteoporotic Fractures were examined during Visit 8 from 2002-03. All participants underwent in-home overnight polysomnography for one night and wrist actigraphy for a minimum of 3 24-h periods and completed the above functional outcomes questionnaires. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Participants were aged 82.9 +/- 3.5 (mean +/- SD) years, had BMI of 27.9 +/- 5.1 kg/m2, and had an apnea-hypopnea index (AHI) of 15.7 +/- 15.1. AHI and TST demonstrated a weak correlation (r = -0.15). ESS score individually demonstrated a modest association with AHI, oxygen desaturation, and TST. The association of ESS score and AHI--but not oxygen desaturation-was attenuated to some extent by adjustment for TST. PSQI and FOSQ scores were not associated with measures of SDB severity or TST. CONCLUSIONS: After adjustment for TST, SDB severity in community-dwelling older women was not independently associated with self-reported daytime sleepiness, although there may be a modest association that is mediated through reduced TST. In older women, SDB severity was not associated with indices of sleep related symptoms or sleep related quality of life.     

Behavioral and psychological correlates of a difference in chronic sleep duration.

The relationship between chronic differences in sleep duration and waking behaviors was explored by comparing two groups of 10 healthy male university students who regularly slept nocturnally for 7-8 h or for 9.5-10.5 h. Measurements were obtained of sublingual temperature, from a 45 min Wilkinson auditory vigilance task and a mood adjective check list 30 min after awakening in the morning, at midday ind in the early evening following an electroencephalographically recorded night of sleep. In both subject groups body temperature increased from morning to early evening, while misses on the vigilance task correspondingly declined during the day. The average daily level of oral temperature and performance were significantly lower in the 7-8 h (control) group than in the long sleepers. Positive mood states (Cheerful, Energetic, General Activation, High Activation) were significantly greater and negative affects (Anger-Hostility, Depression) significantly less in the long sleepers. As a result of the mean difference in total sleep time existing between groups control subjects averaged significantly less stage 2, and stage REM sleep. It was postulated that there were behavioral deficits in the control group attirbutable either to selective sleep stage deprivation or to the general consequence of reduced sleep per se or to both of these factors.     

Endothelial dysfunction in obstructive sleep apnea measured by peripheral arterial tone response in the finger to reactive hyperemia

STUDY OBJECTIVE: The aim of this study was to investigate endothelial functioning in sleep apnea patients using a novel plethysmographic device that monitors peripheral arterial tone response in the finger to reactive hyperemia induced by forearm ischemia. PARTICIPANTS: Forty-six sleep apnea patients, 74.0% men, mean age 46.8 +/- 9.3 years, and 17 control subjects without sleep apnea, 64.7% men, mean age 47.1 +/- 6.7 years. SETTING: Eight-bed Technion Sleep Medicine Center in Haifa, Israel. DESIGN: Endothelial functioning assessed by the reactive hyperemia peripheral arterial tone index was measured twice, before sleep and after waking from sleep monitored by polysomnography in the laboratory. The reactive hyperemia peripheral arterial tone index was calculated as the average amplitude of the peripheral arterial tone signal after the cuff deflation divided by the average amplitude before the cuff inflation. RESULTS: Morning index of endothelial functioning was significantly lower in patients with moderate to severe sleep apnea (apnea-hypopnea index > or = 30) than in patients with mild sleep apnea (30 < apnea-hypopnea index < or = 10) and in the control group without sleep apnea (apnea-hypopnea index < 10). The morning index was significantly inversely correlated with apnea-hypopnea index. Patients with a history of hypertension or cardiovascular disease had significantly lower morning and evening indexes of endothelial functioning than patients without such a history. Multivariate analysis revealed that apnea-hypopnea index and sleep efficiency were significant predictors of the morning index. CONCLUSION: Measurements of the response of the peripheral arterial tone in the finger to reactive hyperemia can be used as a substitute for the brachial artery ultrasound technique to measure endothelial functioning in patients with sleep apnea.     

Adaptive servo-ventilation and deadspace: effects on central sleep apnoea

Central Sleep Apnoea (CSA) occurs commonly in heart failure. Adaptive servo-ventilation (ASV) and deadspace (DS) have been shown in research settings to reverse CSA. The likely mechanism for this is the increase of PaCO(2) above the apnoeic threshold. However the role of increasing FiCO(2) on arousability remains unclear. To compare the effects of ASV and DS on sleep and breathing, in particular effects on Arousal Index (ArI), ten male patients with heart failure and CSA were studied during three nights with polysomnography plus measurements of PetCO(2). The order of the interventions control (C), ASV and DS was randomized. ASV and DS caused similar reductions in apnoea-hypopnoea index [(C) 30.0 +/- 6.6, (ASV) 14.0 +/- 3.8, (DS) 15.9 +/- 4.7 e h(-1); both P < 0.05]. However, DS was associated with decreased total sleep time compared with C (P < 0.02) and increased spontaneous ArI compared to C and ASV (both P < 0.01). Only DS was associated with increased DeltaPetCO(2) from resting wakefulness to eupnic sleep [(C) 2.1 +/- 0.9, (ASV) 1.3 +/- 1.0, (DS) 5.6 +/- 0.5 mmHg; P = 0.01]. ASV and DS both stabilized ventilation however DS application also increased sleep fragmentation with negative impacts on sleep architecture. We speculate that this effect is likely to be mediated by increased PetCO(2) and respiratory effort associated with DS application.     

Hormone replacement therapy reduces mean 24-hour blood pressure and its variability in postmenopausal women with treated hypertension

BACKGROUND: The rate and severity of hypertension increase dramatically after menopause. Complications seem to be more frequent and marked in hypertensive patients with greater blood pressure (BP) variability, and antihypertensive treatment does not easily reduce this variability. The effect of hormone replacement therapy (HRT) on BP and its variability is not well understood in moderate to severe hypertension, but estrogen may have calcium channel-blocking properties. Cardiovascular events occur more frequently in the morning, likely in part because of a rise in BP. DESIGN: We prospectively studied 34 postmenopausal women with treated hypertension (mean age = 53 years) and receiving a cyclic combination of estradiol and norgestrel for 19 weeks with 24-h ambulatory BP monitoring. RESULTS: Mean daily BP and its variability decreased significantly with HRT (149.3 +/- 6.1 mm Hg vs. 140.3 +/- 8.5 mm Hg [p < 0.001]; diastolic: 95.4 +/- 4.7 mm Hg vs. 92.4 +/- 7.2 mm Hg [p < 0.05]). There was also a significant decrease in the early morning BP values after HRT (154.0 +/- 6.9 mm Hg vs. 145.6 +/- 11.0 mm Hg [p < 0.001]; diastolic: 98.0 +/- 4.8 mm Hg vs. 95.1 +/- 10.0 mm Hg [p < 0.05]). Subjects who were taking calcium channel blockers (n = 11) had only half the reduction in 24-h systolic BP compared with those who were not taking calcium channel blockers (5.3 mm Hg vs. 10.5 mm Hg), and the reduction in those who were taking calcium channel blockers failed to reach statistical significance. CONCLUSIONS: Our results demonstrate that HRT may have a role in decreasing the severity of hypertension, and the mechanism of its action might be through calcium channels.     

The results of investigation by the Japanese version of Morningness-Eveningness Questionnaire

Morningness-Eveningness Questionnaire (MEQ) developed by Horne & Ostberg (1976) was translated into Japanese, and then, MEQ and Life Habits Inventory were administered to approximately 1,500 university students. The distribution of MEQ scores was essentially normal, and the reliability of this questionnaire was high (r alpha = .702). Comparing among the morning, evening, and intermediate types, it was found that the morning type retired and arose significantly earlier than other types, although there was no significant differences in sleep length. Furthermore, there were significant differences between the morning and evening types in sleep latency, mood on arising, adequate amount of sleep, frequency and duration of nap, and number of staying awake all night per month. These results suggested that the evening type had more irregular sleep-waking habits than the morning type. Since the above results were obtained only from student population, further investigation on various populations is requested.     

Association of usual sleep duration with hypertension: the Sleep Heart Health Study

STUDY OBJECTIVES: Limited experimental data suggest that sleep restriction acutely elevates blood pressure; however, little is known about the relationship between usual sleep duration and hypertension. This study assesses the relationship between usual sleep duration and hypertension in a community-based cohort. DESIGN: Cross-sectional observational study. SETTING: The Sleep Heart Health Study, a community-based prospective study of the cardiovascular consequences of sleep-disordered breathing. PARTICIPANTS: Two thousand eight hundred thirteen men and 3097 women, aged 40 to 100 years. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Usual weekday and weekend sleep durations were obtained by questionnaire, and their weighted average were categorized as less than 6, 6 to less than 7, 7 to less than 8, 8 to less than 9, and 9 or more hours per night. Hypertension was defined as a systolic blood pressure of 140 mm Hg or greater, a diastolic blood pressure of 90 mm Hg or greater, or use of medication to treat hypertension. The relationship between sleep duration and hypertension was examined using categorical logistic regression with adjustment for age, sex, race, apnea-hypopnea index, and body mass index. Compared to subjects sleeping 7 to less than 8 hours per night, those sleeping less than 6 and between 6 and 7 hours per night had adjusted odds ratios for hypertension of 1.66 (95% confidence interval 1.35-2.04) and 1.19 (1.02-1.39), respectively, whereas those sleeping between 8 and 9 and 9 or more hours per night had adjusted odds ratios for hypertension of 1.19 (1.04-1.37) and 1.30 (1.04-1.62), respectively (p < .0001 for association of sleep duration with hypertension). These associations persisted when analyses were further adjusted for caffeine and alcohol consumption, current smoking, insomnia symptoms, depression symptoms, sleep efficiency, and prevalent diabetes mellitus or cardiovascular disease. CONCLUSIONS: Usual sleep duration above or below the median of 7 to less than 8 hours per night is associated with an increased prevalence of hypertension, particularly at the extreme of less than 6 hours per night.