Similar Apnea-hypopnea Index Research Articles

Does AHI Value Enough for Evaluating the Obstructive Sleep Apnea Severity?

Obstructive sleep apnea/hypopnea syndrome (OSAHS) is an important and more common public health problem with increasing incidence. Polysomonography (PSG) is the gold standard test in OSAHS diagnosis. Apnea-hypopnea index (AHI) is the main parameter of PSG, which is correlated with OSAHS severity. The main complaint of OSAHS patients is daytime sleepiness and the Epworth Sleepiness Scale (ESS) used for evaluation of disease severity. The correlation of AHI with daytime sleepiness and ESS is well known. But there are many patients, which have uncorrelated daytime sleepiness with AHI. This data calls this hypothesis; Are there any other parameters which may affect daytime sleepiness. 648 patients with complaining of snoring and apnea were evaluated by polysomnography and anthropometric measurements. The cut-off value of ESS was accepted 10 as an indicator of severe daytime sleepiness. Patients were divided to groups with the aim of homogenization, according to AHI values. The patients with similar AHI values were analyzed according to their ESS scores. BMI and neck circumference were elevated in daytime sleepiness patients. The nocturnal hypoxemia markers; apnea number/index, maximum duration of apnea, at least SO2 concentration, duration of SO2 less than 90% were much effected in the group of daytime sleepiness. Beside the fact that our research, AHI is not enough for predicting the daytime sleepiness; anthropometric measurements and the nocturnal hypoxemia markers should be evaluated.

Prevalence of the upper airway resistance syndrome in the general population

Background : Upper airway resistance syndrome (UARS) shares common clinical features with obstructive sleep apnea and hypopnea (OSAH). It is characterized by repetitive respiratory effort-related arousal (RERA), which may lead to daytime sleepiness and functional impairment. Little is known about the prevalence of UARS in the general population. Objectives : To determine the prevalence of UARS in the general population and to compare its characteristics to matched control subjects without UARS. 2020 subjects (50.0% women, 57.3 ± 10.7 years old, BMI 25.5 ± 4.3 kg/m 2 ) participating in an ongoing population-based sleep cohort study (HypnoLaus, Lausanne, Switzerland) underwent complete polysomnographic recordings at home. Respiratory events were scored according to the AASM Chicago criteria. UARS was present if the RERA index was ⩾5/h and accounted for more than 50% of the respiratory disturbance index (RDI), which is defined by the sum of the apnea–hypopnea index (AHI) and RERA index. Characteristics of each subject with confirmed UARS were compared with 5 age and sex matched control subjects with similar AHI but no RERA. The prevalence of UARS was 0.84% of this general population sample. Median AHI and RDI were respectively 4.4/h (IQ range 3.5–6.8/h) and 10.7/h (IQ range 9.1–15.6/h). Mean Epworth Sleepiness Score was 6.6 ± 3.2; male-to-female ratio was 0.7. There were no significant differences between UARS subjects and the control subjects regarding BMI (24.7 ± 3.1 vs. 24.0 ± 3.3, p = 0.46) and the Epworth Sleepiness Score (6.6 ± 3.2 vs. 7.4 ± 2.5, p = 0.15). Also, the same prevalence of hypertension (29.4 ± 47.0% vs. 25.9 ± 19.7%, p = 0.77), diabetes (5.9 ± 24.2% vs. 5.9 ± 11.8%, p = 1.0) and metabolic syndrome (29.4 ± 47.0% vs. 12.9 ± 12.1%, p = 0.16) were found in UARS and control subjects. In our middle-aged population-based cohort, the prevalence of UARS is lower than previously reported. There was no significant difference between UARS and control subjects in terms of BMI, daytime sleepiness, hypertension, diabetes and metabolic syndrome. Funding: Ligue pulmonaire vaudoise, Fondation Leenaards, Fond national Suisse and GSK.

The severity of individual obstruction events is related to increased mortality rate in severe obstructive sleep apnea

Obstructive sleep apnea (OSA) is linked to an increased mortality rate. However, the severity of individual obstruction events is rarely considered quantitatively in clinical practice. We hypothesized that OSA with especially severe obstruction events would predispose a patient to greater health risks than OSA with a similar apnea-hypopnea index (AHI), but lower severity of individual events. This hypothesis was tested in a follow-up (198.2±24.7months) of a population of 1068 men referred for ambulatory polygraphic recording due to suspected OSA. The recordings were analysed according to the guidelines of the American Academy of Sleep Medicine. Furthermore, a novel obstruction severity parameter was determined; this was defined as the product of duration of the individual obstruction event and area of the related desaturation event. Patients treated with continuous positive airway pressure (CPAP) were omitted. We identified 125 deceased patients from our original population and for 113 of these a matching alive patient with similar AHI, age, body mass index (BMI), smoking habits and follow-up time could be found. The deceased patients with severe OSA (based on conventional AHI) showed higher obstruction severity values than their AHI-matched alive controls. Based on the multivariate logistic regression analysis, obstruction severity was the only parameter which was related statistically significantly to mortality in the severe OSA category. Furthermore, 59% of all deceased patients and 83% of those who had severe OSA displayed higher obstruction severity than the AHI-matched alive counterparts. To conclude, the obstruction severity parameter provided valuable prognostic information supplementing AHI. The obstruction severity parameter might improve recognition of the patients with the highest risk.

Novel parameters indicate significant differences in severity of obstructive sleep apnea with patients having similar apnea–hypopnea index

Sleep apnea-hypopnea syndrome (SAHS) causes impairment of daytime functions and increases risk of cardiovascular diseases. Apnea-hypopnea index (AHI), currently used for the estimation of the severity of SAHS, does not contain information on the morphology or duration aspects of the breathing cessations and related oxygen desaturations. Longer breathing cessations and deeper desaturations may have more severe consequences than shorter and shallower ones. To address these issues, novel parameters containing information on the duration and morphology of breathing cessations and oxygen desaturations were calculated and evaluated on 160 male patients (40 patients in normal, mild, moderate and severe AHI severity categories). Obstruction and desaturation duration parameters consist of sum of event durations normalized with the total analysed time. Desaturation severity is a sum of desaturation event areas normalized with total analysed time and obstruction severity parameter is a sum of the products of apnea and hypopnea durations and related desaturation areas normalized with total analysed time. The median follow-up time of the patients was 183months (range 154-215months). The 40 patients in each category were further divided into subgroups A and B with lowest and highest novel parameter values, respectively. AHI showed no differences between the subgroups. Mortality was increased in subgroups B compared to subgroups A. The correlation of the novel parameters with AHI was only moderate and the parameter values were partially overlapping between the AHI severity categories. This suggests that patients with similar AHI may in fact suffer from SAHS of very different severity. Thus, the present results suggest that the novel parameters could bring new insight to the individual estimation of the severity of SAHS.

Novel parameters for evaluating severity of sleep disordered breathing and for supporting diagnosis of sleep apnea-hypopnea syndrome

Sleep apnea-hypopnea syndrome (SAHS) is a complex public health problem causing increased risk of cardiovascular diseases. Traditionally, evaluation of the severity of the disease is based on Apnea-Hypopnea Index (AHI). It is defined as the average number of apnea and hypopnea events per hour during sleep. However, e.g. the total duration and the morphology of the recorded events are not considered when evaluating the severity of the disease. This is surprising, as increasing the length of apnea and hypopnea events will most likely lead to longer and deeper oxygen desaturation events. Obviously, this is physiologically more stressful and may have more severe health consequences than shorter and shallower desaturation events. Paradoxically, the lengthening of apnea and hypopnea events may even lead to a decrease in AHI and oxygen desaturation index (ODI). This raises the question of whether additional information is needed besides AHI and ODI for the evaluation of the severity of SAHS and its potential cardiovascular consequences. In the present paper, several novel parameters are introduced to bring additional information for evaluation of the severity of SAHS. Besides the number of events per hour, that AHI and ODI takes into account, the duration of the breathing cessations and the morphology of the oxygen desaturation events are considered as important factors that may influence the daytime fatigue and also the related cardiovascular problems. In this study diagnostic ambulatory polygraphy recordings of 19 male patients were retrospectively analysed. Importantly, the novel parameters showed significant variation amongst patients with similar AHI. For example, the correlation between AHI and the Obstruction severity-parameter was only moderate (r2 = 0.604, p < 0.001). This suggests that patients with similar AHI may exhibit significantly different cardiovascular stress related to the disease. It is suggested that the present novel parameters might provide additional information over the currently used parameters and support the evaluation of the severity of SAHS.

Total duration of apnea and hypopnea events and average desaturation show significant variation in patients with a similar apnea–hypopnea index

Obstructive sleep apnea (OSA) is commonly diagnosed based on the apnea-hypopnea index (AHI). Presently, novel indices were introduced for sleep apnea severity: total duration of sleep apnea and hypopnea events (TAHD%) and a combined index including duration and severity of the events (TAHD% × average desaturation). Two hundred and sixty-seven subjects were divided based on their AHI into four categories (normal, mild, moderate, severe OSA). In the most severe cases TAHD% exceeded 70% of the recorded time. This is important as excessive TAHD% may increase mortality and cerebro-vascular complications. Moreover, simultaneous increase in duration and frequency of apnea and hypopnea events leads to a paradoxical situation where AHI cannot increase along severity of the disease. Importantly, the combined index including duration and severity of the events showed significant variation between patients with similar apnea-hypopnea indices. To conclude, the present results suggest that the novel parameters could give supplementary information to AHI when diagnosing the severity of OSA.

The Relationship Between Mouth Opening and Sleep Stage-Related Sleep Disordered Breathing

To evaluate mouth opening during sleep and the possible correlations between mouth opening and specific patient characteristics. A total of 55 patients consecutively referred to assess snoring and suspected obstructive sleep apnea (OSA) were included. Sensors to record mouth opening were attached to each patient's face and synchronized with a standard polysomnogram. Mouth opening data were evaluated for each sleep stage as a percentage of maximum mouth opening. The patients were divided into 2 groups: patients with REM apnea hypopnea index (AHI) > NREM AHI (REM-dependent group = RD group), and patients with NREM AHI > REM AHI (NREM-dependent group = ND group). A total of 42 patients (male 69.0%, mean age 51.4 ± 12.9 years) underwent successful data collection. The amount of mouth opening during stage 1 (18.8% ± 14.6%) was significantly smaller than stage 2 (23.7% ± 16.4%, p < 0.01) and REM (29.2% ± 20.3%, p < 0.01). Age, body mass index (BMI), Epworth Sleepiness Scale (ESS) score, and AHI exhibited no correlation with mouth opening. The RD and the ND groups exhibited similar age, BMI, ESS, and AHI variables, but the ND group opened their mouths significantly more than the RD group during total sleep time (28.3% ± 13.6% vs 17.8% ± 17.3%, p < 0.01), stage 1 (23.2% ± 13.5% vs 12.9% ± 14.3%, p < 0.01), stage 2 (28.1% ± 17.9% vs 17.9% ± 17.4%, p < 0.01), and REM (34.7% ± 19.2% vs 21.9% ± 19.8%, p < 0.05). The ND patients opened their mouths wider than the RD patients during most sleep stages. The relationship between REM-dependent AHI and the amount of mouth opening may be a factor in the pathogenesis of OSA.

Blood Pressure Evolution After Acute Ischemic Stroke in Patients With and Without Sleep Apnea

Sleep apnea (SA) is an independent risk factor for arterial hypertension and is present in 50% to 70% of patients with ischemic stroke. The effects of SA on blood pressure (BP) and stroke outcome in the acute stroke phase are essentially unknown. We studied 41 consecutive patients admitted within 96 hours after stroke onset. Stroke severity on admission (National Institutes of Health Stroke Scale [NIHSS]) and stroke outcome at discharge (modified Rankin Disability Scale [mRS]) were assessed. Nocturnal breathing was assessed with an ambulatory device the first night after admission. SA was defined by an apnea-hypopnea-index (AHI) > or =10/hour, and moderate-severe SA (MSSA) was defined by an AHI >30/hour. BP monitoring was performed during the first 36 hours after admission. A nondipping status (NDS) was defined by a ratio >0.9 of mean systolic BP during nights 1 to 2/mean systolic BP during day 2. SA was found in 28 (68%) and MSSA in 11 (27%) of 41 patients. A correlation was found between AHI and both NIHSS (r=0.331; P=0.035) and mRS (r=0.341; P=0.031). Patients with MSSA had higher systolic and diastolic BP values during night 1 (P=0.003), day 2 (P=0.004), and night 2 (P=0.03). NDS was found in 26 (63%) patients. Nondippers had a similar AHI but higher NIHSS (P=0.004) and mRS (P=0.005) than dippers. AHI and NDS were confirmed to be independent predictors for both stroke severity and stroke outcome in a multiple stepwise linear regression model. SA severity is associated with high 24-hour BP values but only weakly with stroke severity and outcome. Conversely, NDS is linked with a more severe stroke and a poorer evolution but not with SA severity. These data suggest different, although overlapping, pathophysiological and clinical implications of circadian and nocturnal BP values in acute stroke.

Choice of Oximeter Affects Apnea-Hypopnea Index

Current Medicare guidelines include an apnea-hypopnea index (AHI) > or = 15 events per hour, in which all hypopneas must be associated with 4% desaturation, to qualify for reimbursement for therapy with continuous positive airway pressure (CPAP). The present data demonstrate the effect of pulse oximeter differences on AHI. Prospective study, blinded analysis. Academic sleep disorder center. One hundred thirteen consecutive patients (84 men and 29 women) undergoing diagnostic sleep studies and being evaluated for CPAP based on the Medicare indications for reimbursement. Patients had two of four commonly used oximeters with signal averaging times of 4 to 6 s placed on different digits of the same hand during nocturnal polysomnography. Apneas and candidate hypopneas (amplitude reduction, > 30%) were scored from the nasal cannula airflow signal without reference to oximetry. Candidate hypopneas then were reclassified as hypopneas by each oximeter if they were associated with a 4% desaturation. Although the use of three oximeters resulted in a similar AHI (bias, < 1 event per hour), the fourth oximeter showed an overall increase in AHI of 3.7 events per hour. This caused 7 of 113 patients to have an AHI of > or = 15 events per hour (meeting the Medicare criteria for treatment) by one oximeter but not when a different oximeter was used. More importantly, when our analysis was limited to those patients whose number of candidate hypopneas made them susceptible to the threshold value of 15 events per hour, 7 of 35 patients who did not meet the Medicare AHI standard for treatment by one oximeter were reclassified when a different oximeter was used. In the present study, oximeter choice affected whether the AHI reached the critical cutoff of 15 events per hour, particularly in those with disease severity that was neither very mild nor very severe. As oximetry is not a technique that produces a generic result, there are significant limitations to basing the definition of hypopnea on a fixed percentage of desaturation in determining the eligibility for CPAP therapy.

A Comparison of Men and Women with Occlusive Sleep Apnea Syndrome

Among 118 patients with occlusive sleep apnea syndrome (OSA), defined as daytime hypersomnolence and an apnea hypopnea index (AHI) greater than ten events/h, 41 women were compared with 77 men. Body mass index, spirometric study, PaO2, PaCO2, and results from nocturnal polysomnography were examined in a two-way analysis of variance (ANOVA) for the effects of sex, age group, and a sex-age group interaction. The age groups examined were above and below 42 years, the breakpoint for menopause in the women. Younger persons tended to be more obese and to have a higher AHI. Both sexes had similar pulmonary function, AHI, and nocturnal desaturation, but women experienced significantly fewer completely occluded breathing events and had apneas of shorter mean and maximum duration than men of similar ages. No effect of menopausal status per se was observed. In OSA patients, differences in upper airway occlusion and apnea duration suggest differences between the sexes in upper airway physiology or respiratory control.