The impact of sleep duration in obstructive sleep apnea patients.

PURPOSE: Obstructive sleep apnea (OSA) is a risk factor for cardiovascular disease. Strong associations have been reported among sleep duration, hypertension, obesity, and cardiovascular mortality. The authors hypothesize that sleep duration may play a role in OSA severity. The aim of this study is to analyze sleep duration in OSA patients. METHODS: Patients who underwent overnight polysomnography were consecutively selected from the Sleep Clinic of Universidade Federal de São Paulo database between March 2009 and December 2010. All subjects were asked to come to the Sleep Clinic at 8:00 a.m. for a clinical evaluation and actigraphy. Anthropometric parameters such as weight, height, hip circumference, abdominal circumference, and neck circumference were also measured. RESULTS: One hundred thirty-three patients were divided into four groups based on total sleep time, sleep efficiency, sleep latency, and wake after sleep onset: very short sleepers (n = 11), short sleepers (n = 21), intermediate sleepers (n = 56), and sufficient sleepers (n = 45). Apnea-hypopnea index (AHI) was higher in very short sleepers (50.18 ± 30.86 events/h) compared with intermediate sleepers (20.36 ± 14.68 events/h; p = 0.007) and sufficient sleepers (23.21 ± 20.45 events/h; p = 0.02). Minimal and mean arterial oxygen saturation and time spent below 90 % oxygen saturation exhibited worse values in very short sleepers. After adjustment for gender, age, AHI, and body mass index, mean oxygen saturation was significantly associated to total sleep time (p = 0.01). CONCLUSIONS: In conclusion, the present study suggests that sleep duration may be associated to low mean oxygen saturation in OSA patients.

Cardiorespiratory response to exercise in men and women with obstructive sleep apnea.

BACKGROUND: OSA severity has been associated with self-reported lack of exercise. Most of the research has been done with men recruited from sleep clinics. There is limited data on the exercise performance of women with OSA. Therefore, the aim of this study was to assess exercise performance in a prospective, consecutive sample of men and women with OSA to compare their cardio respiratory parameters, arterial blood pressure and heart rate responses during and after exercise. METHODS: Sixty-two subjects (32 men) completed the protocol. Men had a higher peak VO2, percent predicted peak VO2, VCO2, heart rate, systolic BP, and oxygen pulse than women. RESULTS: There were no differences between men and women for peak oxygen saturation, peak Borg scales for dyspnea and leg fatigue and diastolic BP. A significant negative correlation was found between severity of OSA as measured by AHI, and peak VO2 (r=-0.4) in women, but not in men. CONCLUSION: Men with OSA have higher peak VO2 and higher peak exercise heart rate than women with OSA; they also have higher end-exercise systolic BP than women and higher SBP during recovery from exercise; although this difference is not significant when adjusted for peak systolic BP. In men with OSA, there is no correlation between peak VO2 and AHI, but there is a significant correlation between these variables in women. Heart rate and blood pressure behaved similarly during exercise in both groups.

Does obstructive sleep apnea affect exercise capacity and the hemodynamic response to exercise? An individual patient data and aggregate meta-analysis.

Obstructive sleep apnea (OSA) has been linked to altered cardiovascular response to exercise. A systematic review and individual patient data (IPD) meta-analysis were conducted to assess whether OSA patients present reduced exercise capacity. PubMed, Embase and Web of Science were searched until September 2018. Studies which performed sleep recording in both OSA patients and controls and measured maximal oxygen consumption (VO2peak) via a maximal exercise test were included. IPD were provided for five trials upon the 18 eligible (N = 289) and a two-stage IPD meta-analysis model was used, allowing to standardize the apnea cutoff and adjust for confounders. IPD meta-analysis demonstrated that moderate to severe OSA patients had similar VO2peak (mean difference: -1.03 mL·kg-1 min-1; 95% CI: -3.82 to 1.76; p = 0.47) and cardiovascular response to exercise compared to mild or non-OSA patients. By contrast, aggregate data (AD) meta-analysis including the 13 trials for which IPD were unavailable (N = 605) revealed that VO2peak was reduced in OSA patients compared to controls (mean difference: -2.30 mL·kg-1 min-1; 95% CI: -3.96 to -0.63; p < 0.001) with high heterogeneity. In conclusion, IPD meta-analysis suggests that VO2peak and the cardiovascular response to exercise are preserved in moderate to severe OSA patients while AD meta-analysis suggests lower VO2peak in severe OSA.

Neurocognitive function in patients with residual excessive sleepiness from obstructive sleep apnea: a prospective, controlled study.

OBJECTIVE: This study aimed to evaluate neurocognitive function in adult patients with residual excessive sleepiness (RES) after appropriate treatment of obstructive sleep apnea (OSA) with CPAP and good adherence to treatment. METHODS: This was a prospective controlled study. We included patients of both sexes, aged 35-60 years with OSA and an apnea-hypopnea index >20 ev/h, effectively treated with CPAP, but with a residual Epworth Sleepiness Scale score ≥11. The control group consisted of OSA patients adequately treated with CPAP who did not present with excessive sleepiness after treatment. Both groups underwent the following evaluations: polysomnography, multiple sleep latency testing, depression symptoms, and cognitive assessment. RESULTS: Regarding baseline characteristics, the data were matched for age, years of study, and body mass index. Long-term memory result did not show a significant difference between the two groups (RES group 4.7 ± 2.0; control group 6.5 ± 1.9; p = 0.08). The executive functions were the most affected, with alterations in Wisconsin test, number of categories (RES group: 1.6 ± 1.4; control group: 3.0 ± 1.4; p = 0.01), and semantic verbal fluency test (RES group: 13.6 ± 3.3; control group: 16.9 ± 4.3; p = 0.04). CONCLUSION: In summary, the mean depression scale score in the group with residual excessive sleepiness was significantly higher than that in the control group. Patients with residual excessive sleepiness showed impairment of executive functions but no impairments in other cognitive domains.

Quality-adjusted life-years gain and health status in patients with OSAS after one year of continuous positive airway pressure use.

STUDY OBJECTIVES: To estimate the health utility score and quality-adjusted life-years (QALY) index of obstructive sleep apnea syndrome (OSAS) in patients over 1 y of continuous positive airway pressure (CPAP) treatment. DESIGN: Longitudinal interventional study. SETTING: The study was carried out in Sao Paulo Sleep Institute, Brazil. PATIENTS AND PARTICIPANTS: Ninety-five patients with OSAS and with apnea-hypopnea index (AHI) > 20 of either sex, body mass index < 40 kg/m(2), and no previous contact with CPAP were included. INTERVENTIONS: The participants underwent baseline and titration polysomnographies, clinical evaluation, and ambulatory blood pressure (BP) measurement, completed Short-Form 6 Dimension Health Survey (SF-6D) and Epworth Sleepiness Scale (ESS) questionnaires, and implementation of CPAP. The patients were followed for 1 y. MEASUREMENTS AND RESULTS: The mean AHI and age were 57.6 ± 29.2 events/h and 53.3 ± 9.3 y, respectively. One year of CPAP treatment increased the health utility score from 0.611 ± 0.112 to 0.710 ± 0.121 (P < 0.01). Therefore, CPAP resulted in a mean gain of 0.092 QALY/patient. The improvements in utility scores were associated with decreases in the ESS after 1 mo, in systolic BP after 1 y, and in diastolic BP at 6 mo. BP normalization group (≤ 130/85 mmHg) showed higher QALY than that of the non-normalization group (0.10 ± 0.09 versus 0.05 ± 0.10; P = 0.03). One-year ESS score (P = 0.03), diastolic BP reduction P = 0.01) and baseline utility scores (P < 0.01) were significantly associated with QALY gain. CONCLUSION: This study showed a significant QALY/patient gain after 1 y of regular CPAP use. In addition, BP normalization was associated with higher QALY gain. Thus, utility studies can provide more complete analyses of the total benefits of CPAP treatment in patients with OSAS and should be encouraged.

Evaluation and validation of a method for determining platelet catecholamine in patients with obstructive sleep apnea and arterial hypertension.

BACKGROUND: Measurements of plasma and urinary catecholamine are susceptible to confounding factors that influence the results, complicating the interpretation of sympathetic nervous system (SNS) activity in the Obstructive sleep apnea (OSA) and arterial hypertension (HYP) conditions. OBJECTIVE: In this study, we validated a test for platelet catecholamine and compared the catecholamine levels (adrenaline and noradrenaline) in urine, plasma and platelets in patients with OSA and HYP compared with controls. METHODS: In the validation, 30 healthy, nonsmoking volunteers who were not currently undergoing treatment or medication were selected as the control group. One hundred fifty-four individuals (114 OSA, 40 non-OSA) were consecutively selected from the outpatient clinic of the Sleep Institute and underwent clinical, polysomnographic and laboratory evaluation, including the urinary, plasma and platelet levels of adrenaline (AD) and noradrenaline (NA). Patients were then allocated to groups according to the presence of OSA and/or hypertension. RESULTS: A logistic regression model, controlled for age and BMI, showed that urinary AD and urinary NA were risk factors in the OSA+HYP group and the HYP group; however, the model showed higher levels of platelet NA for OSA without HYP. After 1 year of CPAP (continuous upper airway pressure) treatment, patients (n = 9) presented lower levels of urinary NA (p = 0.04) and platelet NA (p = 0.05). CONCLUSION: Urinary NA and AD levels were significantly associated with the condition of hypertension with and without OSA, whereas platelet NA with OSA without comorbidity. These findings suggest that platelet catecholamine levels might reflect nocturnal sympathetic activation in OSA patients without hypertension.

The cholinergic system may play a role in the pathophysiology of residual excessive sleepiness in patients with obstructive sleep apnea.

Obstructive sleep apnea (OSA) is a prevalent condition characterized by momentary cessations in breathing during sleep due to intermittent obstruction of the upper airway. OSA has been frequently associated with a number of medical comorbidities. CPAP (continuous positive airway pressure) is the gold standard treatment and is known to improve OSA symptoms, including excessive sleepiness. However, 12-14% of CPAP-treated patients continue to complain of sleepiness despite normalization of ventilation during sleep, and 6% after exclusion of other causes of EDS. This is of great concern because EDS is strongly associated with systemic health disorders, lower work performance, and a high risk of accidents. We hypothesized that decreased central cholinergic activity plays a role in the pathophysiology of residual excessive sleepiness in patients with OSA treated with CPAP. Acetylcholine (Ach) plays a large role in wakefulness physiology, and its levels are reduced in sleepiness. Herein, we discuss the potential role of the cholinergic system in this new clinical condition.

Does obstructive sleep apnea impair the cardiopulmonary response to exercise?

STUDY OBJECTIVES: The aim of this study was to evaluate cardiopulmonary exercise performance in lean and obese patients with obstructive sleep apnea (OSA) compared with controls. DESIGN: Case-control study. SETTING: The study was carried out in Sao Paulo Sleep Institute, Sao Paulo, Brazil. PATIENTS AND PARTICIPANTS: INDIVIDUALS WITH SIMILAR AGES WERE ALLOCATED INTO GROUPS: 22 to the lean OSA group, 36 to the lean control group, 31 to the obese OSA group, and 26 to the obese control group. INTERVENTIONS: The participants underwent a clinical evaluation, polysomnography, a maximum limited symptom cardiopulmonary exercise test, two-dimensional transthoracic echocardiography, and spirometry. MEASUREMENTS AND RESULTS: The apnea-hypopnea index, arousal index, lowest arterial oxygen saturation (SaO2) and time of SaO2 < 90% were different among the groups. There were differences in functional capacity based on the following variables: maximal oxygen uptake (VO2max), P < 0.01 and maximal carbon dioxide production (VCO2max), P < 0.01. The obese patients with OSA and obese controls presented significantly lower VO2max and VCO2max values. However, the respiratory exchange ratio (RER) and anaerobic threshold (AT) did not differ between groups. Peak diastolic blood pressure (BP) was higher among the obese patients with OSA but was not accompanied by changes in peak systolic BP and heart rate (HR). When multiple regression was performed, body mass index (P < 0.001) and male sex in conjunction with diabetes (P < 0.001) independently predicted VO2max (mL/kg/min). CONCLUSIONS: The results of this study suggest that obesity alone and sex, when associated with diabetes but not OSA, influenced exercise cardiorespiratory function.

Exercise capacity and obstructive sleep apnea in lean subjects.

BACKGROUND: Conflicting data regarding exercise capacity and obstructive sleep apnea (OSA) have been published, which may be partially explained by the difficulty of controlling all of the confounding factors. The aim of this study is to evaluate the exercise, anthropometric, and blood parameters in lean, sedentary patients with OSA compared with controls. METHODS: Fifty-four lean subjects (including 27 patients with OSA and 27 controls) were selected. The control group was matched for age and gender. All subjects underwent polysomnography, anthropometric measures, a cardiorespiratory exercise test, two-dimensional transthoracic echocardiography, and spirometry. RESULTS: The mean age was 52.9 +/- 7.9 years in subjects with OSA and 52.8 +/- 8.1 years in controls (P = .95). The cervical circumference was greater in the lean OSA group when compared with the controls (33.7 +/- 3.5 cm vs 31.4 +/- 2.8 cm; P = .01). There were statistical differences in the apnea-hypopnea index, minimal oxygen saturation, and mean oxygen saturation in the lean patients with OSA. Glycemia was higher in the lean OSA group (115.1 +/- 50.1 mg/dL vs 94.2 +/- 9.8 mg/dL; P = .04). There were no differences between groups in the peak oxygen consumption (Vo(2)), anaerobic threshold (AT), respiratory exchange ratio (RER), BP, and heart rate. CONCLUSION: High glycemia and cervical circumference enlargement are the main characteristics of lean patients with OSA. Exercise performance is similar between groups, considering the peak Vo(2), AT, and RER. These results suggest that OSA does not impair functional capacity in lean subjects and that obesity probably participates in the diminished cardiopulmonary capacity observed in patients with OSA.