Symptoms of sleep disordered breathing: Association with the apnea-hypopnea index and somatic arousal.

We investigated the association of typical symptoms of obstructive sleep apnea with a measure of daytime somatic arousal and with the apnea-hypopnea index. We extended the finding of an association between sleepiness, fatigue and somatic arousal previously reported in a US sleep apnea population to a German sleep apnea population (n = 374) and to other typical sleep apnea symptoms, insomnia, anxiety, daytime alertness and non-restorative sleep. Somatic arousal was measured using the body sensation questionnaire (BSQ). Correlations of apnea-hypopnea index and BSQ were computed with values of polysomnographic variables derived from overnight sleep studies and with severity of OSA symptoms. Apnea-hypopnea index and BSQ scores showed only a small negative correlation with each other; each correlated independently with the Epworth Sleepiness Scale score. Controlling for BSQ score, the apnea-hypopnea index was found to affect sleepiness only when it exceeded 50/h. Severity of all other sleep apnea symptoms did not increase with increasing apnea-hypopnea index. In contrast, severity of all symptoms of sleep apnea increased consistently with increasing BSQ scores. Thus, autonomic stress associated with obstructive sleep apnea may be the driving force behind sleep apnea symptoms rather than the sleep fragmentation associated with obstructive sleep apnea severity (apnea-hypopnea index). These findings support previously reported correlations by Gold and associates between the levels of somatic arousal, sleepiness and fatigue. Using the apnea-hypopnea index and BSQ together renders a more comprehensive assessment of sleep apnea than apnea-hypopnea index alone, which appears to impact only on sleepiness and only when it exceeds 50/h. More work is needed to elucidate the source of the chronic stress, which appears to arise endogenously in affected individuals, likely as a function of sleep disordered breathing, such as snoring/inspiratory flow limitation.

Validity of Two Consumer Multisport Activity Tracker and One Accelerometer against Polysomnography for Measuring Sleep Parameters and Vital Data in a Laboratory Setting in Sleep Patients.

Two commercial multisport activity trackers (Garmin Forerunner 945 and Polar Ignite) and the accelerometer ActiGraph GT9X were evaluated in measuring vital data, sleep stages and sleep/wake patterns against polysomnography (PSG). Forty-nine adult patients with suspected sleep disorders (30 males/19 females) completed a one-night PSG sleep examination followed by a multiple sleep latency test (MSLT). Sleep parameters, time in bed (TIB), total sleep time (TST), wake after sleep onset (WASO), sleep onset latency (SOL), awake time (WASO + SOL), sleep stages (light, deep, REM sleep) and the number of sleep cycles were compared. Both commercial trackers showed high accuracy in measuring vital data (HR, HRV, SpO2, respiratory rate), r > 0.92. For TIB and TST, all three trackers showed medium to high correlation, r > 0.42. Garmin had significant overestimation of TST, with MAE of 84.63 min and MAPE of 25.32%. Polar also had an overestimation of TST, with MAE of 45.08 min and MAPE of 13.80%. ActiGraph GT9X results were inconspicuous. The trackers significantly underestimated awake times (WASO + SOL) with weak correlation, r = 0.11−0.57. The highest MAE was 50.35 min and the highest MAPE was 83.02% for WASO for Garmin and ActiGraph GT9X; Polar had the highest MAE of 21.17 min and the highest MAPE of 141.61% for SOL. Garmin showed significant deviations for sleep stages (p < 0.045), while Polar only showed significant deviations for sleep cycle (p = 0.000), r < 0.50. Garmin and Polar overestimated light sleep and underestimated deep sleep, Garmin significantly, with MAE up to 64.94 min and MAPE up to 116.50%. Both commercial trackers Garmin and Polar did not detect any daytime sleep at all during the MSLT test. The use of the multisport activity trackers for sleep analysis can only be recommended for general daily use and for research purposes. If precise data on sleep stages and parameters are required, their use is limited. The accuracy of the vital data measurement was adequate. Further studies are needed to evaluate their use for medical purposes, inside and outside of the sleep laboratory. The accelerometer ActiGraph GT9X showed overall suitable accuracy in detecting sleep/wake patterns.

Heart Rate and Distance Measurement of Two Multisport Activity Trackers and a Cellphone App in Different Sports: A Cross-Sectional Validation and Comparison Field Study.

Options for monitoring sports have been continuously developed by using activity trackers to determine almost all vital and movement parameters. The aim of this study was to validate heart rate and distance measurements of two activity trackers (Polar Ignite; Garmin Forerunner 945) and a cellphone app (Polar Beat app using iPhone 7 as a hardware platform) in a cross-sectional field study. Thirty-six moderate endurance-trained adults (20 males/16 females) completed a test battery consisting of walking and running 3 km, a 1.6 km interval run (standard 400 m outdoor stadium), 3 km forest run (outdoor), 500/1000 m swim and 4.3/31.5 km cycling tests. Heart rate was recorded via a Polar H10 chest strap and distance was controlled via a map, 400 m stadium or 50 m pool. For all tests except swimming, strong correlation values of r > 0.90 were calculated with moderate exercise intensity and a mean absolute percentage error of 2.85%. During the interval run, several significant deviations (p < 0.049) were observed. The swim disciplines showed significant differences (p < 0.001), with the 500 m test having a mean absolute percentage error of 8.61%, and the 1000 m test of 55.32%. In most tests, significant deviations (p < 0.001) were calculated for distance measurement. However, a maximum mean absolute percentage error of 4.74% and small mean absolute error based on the total route lengths were calculated. This study showed that the accuracy of heart rate measurements could be rated as good, except for rapid changing heart rate during interval training and swimming. Distance measurement differences were rated as non-relevant in practice for use in sports.

Predictors for treating obstructive sleep apnea with an open nasal cannula system (transnasal insufflation).

BACKGROUND: Obstructive sleep apnea (OSA) is a disorder that is associated with increased morbidity and mortality. Although continuous positive airway pressure effectively treats OSA, compliance is variable because of the encumbrance of wearing a sealed nasal mask throughout sleep. In a small group of patients, it was recently shown that an open nasal cannula (transnasal insufflation [TNI]) can treat OSA. The aim of this larger study was to find predictors for treatment responses with TNI. METHODS: Standard sleep studies with and without TNI were performed in 56 patients with a wide spectrum of disease severity. A therapeutic response was defined as a reduction of the respiratory disturbance index (RDI) below 10 events/h associated with a 50% reduction of the event rate from baseline and was used to identify subgroups of patients particularly responsive or resistant to TNI treatment. RESULTS: For the entire group (N = 56), TNI decreased the RDI from 22.6 +/- 15.6 to 17.2 +/- 13.2 events/h (P < .01). A therapeutic reduction in the RDI was observed in 27% of patients. Treatment responses were similar in patients with a low and a high RDI, but were greater in patients who predominantly had obstructive hypopneas or respiratory effort-related arousals and in patients who predominantly had rapid eye movement (REM) events. The presence of a high percentage of obstructive and central apneas appears to preclude efficacious treatment responses. CONCLUSION: TNI can be used to treat a subgroup of patients across a spectrum from mild-to-severe sleep apnea, particularly if their sleep-disordered breathing events predominantly consist of obstructive hypopneas or REM-related events but not obstructive and central apneas.

Reaction time performance in upper airway resistance syndrome versus obstructive sleep apnea syndrome.

BACKGROUND: Patients with obstructive sleep apnea syndrome (OSAS) are known to have an increased risk for motor vehicle crashes. They suffer from sleep-related respiratory abnormality causing repetitive arousal leading to daytime sleepiness. In turn, it has been demonstrated that sleepiness can impair human psychomotor performance causing slowing of reaction times (RTs). Patients with OSAS present with RTs comparable to young adults under the influence of blood alcohol concentrations above the legally permitted level to drive a motor vehicle. Vigilance related risk levels in patients with upper airway resistance syndrome (UARS) and potential deficits in psychomotor performance are unknown. METHODS: We designed a study to compare psychomotor performance in UARS and compared it to patients with OSAS. Forty-seven UARS patients were matched by gender and age with 47 OSAS patients. All subjects completed a standardized vigilant attention task utilizing reaction time before undergoing polygraphic sleep studies. RESULTS: Patients with UARS presented worse psychomotor performance on most test metrics than patients with OSAS. CONCLUSIONS: Our study results may suggest that patients with UARS may also present an increased risk for motor vehicle crashes as previously demonstrated in OSAS patients.

Differences in clinical features of upper airway resistance syndrome, primary snoring, and obstructive sleep apnea/hypopnea syndrome.

BACKGROUND: The clinical features of patients with upper airway resistance syndrome (UARS) have previously been compared to patients with obstructive sleep apnea/hypopnea syndrome (OSAHS). No data regarding differences between patients with primary snoring (PS) or patients with obstructive sleep apnea/hypopnea without daytime sleepiness (OSAH) are available. We conducted a study to investigate clinical features of UARS, comparing them to those in patients with PS, OSAH, and OSAHS. METHODS: Retrospective chart analysis of 157 patients with PS, 424 patients with UARS, 562 patients with OSAH, and 1610 patients with OSAHS seen in two sleep disorders clinics between 1996 and 2006. All patients had a diagnostic polysomnography (PSG) and a comprehensive clinical history taken by board-certified sleep specialists. RESULTS: PS and UARS patients were significantly younger, less overweight and had lower weight gain during the past 5years. The female-to-male ratio was highest in the UARS group. UARS patients had significantly less stage non-rapid eye movement sleep (NREM) 1 and NREM 2 and significantly more NREM 3 and NREM 4 sleep than OSAH and OSAHS patients. Arousal indices between PS/UARS and OSAH/OSAHS patients were significantly lower, with no significant difference within these diagnostic categories. Patients with UARS presented the highest degree of subjective impairment. CONCLUSIONS: UARS patients share some clinical features of patients with OSAHS and PS, although these two groups differ in their presentation of clinical sleepiness. Patients with UARS were most impaired in terms of their daily functioning and perception of sleep quality. This finding could not be corroborated by objective measures.

Vascular endothelial dysfunction in patients with mild obstructive sleep apnea syndrome.

BACKGROUND: We investigated endothelial dysfunction, an early manifestation of atherosclerosis, in patients with mild obstructive sleep apnea syndrome (OSAS) (5/h < AHI < 15/h). PATIENTS AND METHODS: Endothelium-dependent and -independent vasodilatory function was tested in 10 patients with mild OSAS, 12 healthy controls and 20 subjects with moderate to severe OSAS using the hand vein compliance technique. RESULTS: Maximum endothelium-dependent vasodilation to bradykinin (Emax) was significantly blunted in patients with mild OSAS (68.6 +/- 30.2 %) compared to healthy controls (94.8 +/- 9.5 %; p < 0.05; moderate to severe OSAS: 57.1 +/- 23.4 %; p = 0.33). Mean endothelium-independent venodilation was not altered. After 160.7 +/- 82.2 nights of CPAP therapy, mean Emax was significantly improved to 90.8 +/- 23.8 % (p < 0.01 vs. baseline; p = 0.7 vs. healthy controls) in 7 patients with mild OSAS. CONCLUSIONS: Systemic endothelium-dependent venodilation is markedly reduced in subjects with mild OSAS, which may imply adverse cardiovascular consequences. CPAP-treatment leads to a sustained restoration of endothelial dysfunction in these patients and is thus highly recommended.

Antihypertensive treatment and endothelium-dependent venodilation in sleep-disordered breathing.

Sleep-disordered breathing (SDB) is associated with nitric oxide-mediated endothelial dysfunction and increased risk and prevalence of cardiovascular disease, namely, arterial hypertension. A substantial number of patients do not comply with nasal continuous positive airway pressure (nCPAP) treatment. These individuals have a persisting increased cardiovascular risk. Antihypertensive drugs have shown to improve nitric oxide-mediated endothelial dysfunction. We therefore designed a study to test the hypothesis that antihypertensive drug treatment in hypertensive patients with SDB can have beneficial effects on nitric oxide-mediated endothelial function in the absence of treatment with nCPAP. Six patients with SDB and treated arterial hypertension, six normotensive patients with SDB, and six healthy controls received sleep studies and an assessment of venodilation using the dorsal hand vein technique. Polygraphic measures using standard overnight sleep studies and dose-response curves to the endothelium-dependent vasodilator bradykinin were obtained. Maximum nitric-oxide-mediated dilation to bradykinin was significantly higher in patients with SDB who had received antihypertensive drug treatment compared to normotensive SDB patients. Nitric oxide-mediated dilation in hypertensive patients with SDB was similar to nitric oxide-mediated dilation in healthy controls. After treatment of normotensive patients with SDB using nCPAP, nitric oxide-mediated dilation in normotensive SDB patients was comparable to nitric oxide-mediated dilation in SDB patients with antihypertensive drug treatment and normal controls. Hypertensive patients with SDB present a normal nitric oxide-mediated endothelial function under antihypertensive treatment.

The effect of CNS activation versus EEG arousal during sleep on heart rate response and daytime tests.

OBJECTIVE: To induce a heart rate change in normal subjects using auditory stimulation without inducing EEG arousals and to assess the effects on daytime functioning and compare results to auditory stimulation leading to short EEG arousals. METHODS: Six normal young men initially randomized into two groups (A and B) underwent 4 nights of nocturnal polysomnography (normal sleep on night 1, auditory stimulation without EEG arousal or normal sleep on nights 2 and 3 using Latin square design, and auditory stimulation with EEG arousal on night 4). MSLT and PVT were performed during days following nights 2-4. RESULTS: MSLT and PVT results showed significant differences after EEG arousal compared to stimulation without EEG arousal and to normal sleep; there were no significant differences after normal sleep compared to stimulation without EEG arousal. RR interval showed significant differences during undisturbed sleep compared to stimulation without EEG arousal and to stimulation with EEG arousal; RR interval without EEG arousal also differed significantly from RR interval with EEG arousal. CONCLUSION: Activation of the brain-stem can lead to autonomic nervous system (ANS) response without objective consequences the next day. SIGNIFICANCE: ANS responses induced by auditory stimulation during sleep without EEG arousal do not have the same effects on daytime sleepiness and performance as sleep fragmentation associated with EEG arousals.

Comparison of pleural pressure and transcutaneous diaphragmatic electromyogram in obstructive sleep apnea syndrome.

STUDY OBJECTIVES: Based on studies of the impact of esophageal pressure on cardiovascular variables during sleep, this signal can be used to refine the severity level in the clinical diagnosis of obstructive sleep apnea syndrome. We hypothesized that relative changes in diaphragmatic electromyogram (EMG) can reflect short-term changes in esophageal pressure durng obstructive apneas and hypopneas. DESIGN: Diaphragmatic EMG was sampled at 0.25 kHz; diaphragmatic EMG waveform was band-pass filtered and digitally converted; the electrocardiogram artifact was eliminated; using a gating procedure, the waveform was fast-Fourier transformed and digitally rectified; and a moving average of 200 milliseconds was calculated. For each inspiratory effort during apnea or hypopnea, we calculated maximum diaphragmatic EMG and esophageal pressure. Data were normalized calculating the percentage difference between the first obstructed and each subsequent inspiratory effort during the respiratory event. SETTING: Sleep disorders laboratory. PATIENTS: 9 patients with moderate obstructive sleep apnea syndrome presenting with apneas and hypopneas during sleep. INTERVENTION: None. MEASUREMENTS AND RESULTS: 861 respiratory events were scored, and the evolution between esophageal pressure and diaphragmatic EMG were compared. Normalized data showed a good correlation between the 2 measures during apneas and hypopneas. There was a significant difference between the percentage increase in esophageal pressure and diaphragmatic EMG for apneas and hypopneas (esophageal pressure, apnea: 118.1% +/- 118.5%, hypopnea: 76.1% +/- 74.3%, P = .000; diaphragmatic EMG, 123.5% +/- 131.7%, hypopnea: 73.3% +/- 74.2%, P = .000). No significant differences for apnea or hypopnea were noted between the 2 measures under investigation. CONCLUSION: Diaphragmatic EMG may be clinically useful to describe relative changes in respiratory effort under conditions of apnea and hypopnea during sleep and to reliably dissociate central from obstructive events where esophageal pressure monitoring is not readily available.

Long-term effects of nasal continuous positive airway pressure on vasodilatory endothelial function in obstructive sleep apnea syndrome.

Obstructive sleep apnea syndrome (OSAS) is associated with a dysfunction of vascular endothelial cells. The aim of this study was to investigate long-term improvement of endothelial dysfunction in OSAS with nasal continuous positive airway pressure (nCPAP) treatment. We investigated endothelium-dependent and endothelium-independent vasodilatory function in patients with OSAS using the hand vein compliance technique. Dose-response curves to endothelium-dependent vasodilator bradykinin were obtained in 16 subjects with OSAS before and after 6 months of nCPAP therapy and in 12 control subjects without OSAS. Maximum dilation (Emax) to bradykinin, being impaired in all OSAS patients, was completely restored with nCPAP. Mean Emax to bradykinin rose from 54.9+/-18.5 to 108.2+/-28.7% with 164.4+/-90.0 nights of nCPAP therapy (p<0.0001; Emax healthy controls, 94.8+/-9.5%). At treatment follow-up, endothelium-dependent vasodilatory capacity was not significantly different in nCPAP-treated OSAS patients vs healthy controls. Mean vasodilation with endothelium independently acting nitroglycerin was not altered initially and did not change with nCPAP therapy indicating that nCPAP restored endothelial cell function and not unspecific, endothelium-independent factors. These results suggest that regular nocturnal nCPAP treatment leads to a sustained restoration of OSAS-induced impaired endothelium-dependent nitric oxide-mediated vasodilation, suggesting an improvement of systemic endothelial dysfunction in patients studied.

Abnormal blood pressure in prepubertal children with sleep-disordered breathing.

The purpose of this study was to investigate the association between low blood pressure (BP) with mild symptoms of orthostatism, sleep-disordered breathing (SDB) and tilt test results in 7- to 12-y-old children. A retrospective chart review of 301 children, ages 7 to 12 y, was initially performed to evaluate the frequency of abnormal BP measurements. Then a prospective study was performed on 7- to 12-y-old prepubertal children with SDB, looking for both abnormal BP and mild orthostatism. All children had polysomnography. Those identified with abnormal (high or low) BP measurements (called "BP outliers") were studied with a new polysomnogram followed by a head-up tilt test as an indicator of autonomic activity. Four of the children with low BP were treated with nasal continuous positive airway pressure and received a second head-up tilt test 3.5 to 7 mo after starting treatment. The prospective study included 78 children, eight of whom were BP outliers. Seven of these outliers had low BP. Compared with all of the SDB subjects, SDB subjects with low BP and indicators of mild orthostatic hypotension had a significantly higher incidence of craniofacial dysmorphism, symptoms of SDB early in life, chronically cold extremities, and dizziness on standing up (chi2, p = 0.01 to 0.0001). They had a significantly greater drop in BP without evidence of autonomic neuropathy than all other children on head-up tilt testing (Kruskal-Wallis ANOVA with Bonferroni adjustment, p = 0.001 to 0.0001). However, the normotensive SDB controls also had significantly different BP drops than the normal controls (p = 0.0001). The four children placed on nasal continuous positive airway pressure had a nonsignificant trend toward normalization of tilt test response. SDB in prepubertal children can lead to different abnormal stimulation of the autonomic nervous system, with different impacts on BP. The severity and frequency of oxygen saturation drops during sleep, nonhypoxic increases in respiratory effort, and the duration of abnormal breathing are suspected of playing a role in the difference in autonomic nervous system stimulation.

Effect of iron depletion in carbohydrate-intolerant patients with clinical evidence of nonalcoholic fatty liver disease.

BACKGROUND & AIMS: Increased body iron, genetic hemochromatosis (GH) mutations, and nonalcoholic fatty liver disease (NAFLD) tend to cluster in carbohydrate-intolerant patients. In an attempt to further clarify the interrelationships among these conditions, we studied 42 carbohydrate-intolerant patients who were free of the common GH mutations C282Y and H63D, and had a serum iron saturation lower than 50%. METHODS: We measured body iron stores, and induced iron depletion to a level of near-iron deficiency (NID) by quantitative phlebotomy. RESULTS: In the 17 patients with clinical evidence of NAFLD, we could not demonstrate supranormal levels of body iron (1.6 +/- 0.2 vs. 1.4 +/- 0.2 g; P = 0.06). However, at NID, there was a 40%-55% improvement (P = 0.05-0.0001) of both fasting and glucose-stimulated plasma insulin concentrations, and near-normalization of serum alanine aminotransferase activity (from 61 +/- 5 to 32 +/- 2 IU/L; P < 0.001). CONCLUSIONS: These results reflect the insulin-sparing effect of iron depletion and indicate a key role of iron and hyperinsulinemia in the pathogenesis of NAFLD.