Factors associated with systemic hypertension in asthma.

PURPOSE: Asthmatics have unique characteristics that may influence cardiovascular morbidity. We tested the association of lower airway caliber, obstructive sleep apnea (OSA), and other asthma-related factors, with systemic hypertension (HTN). METHODS: Asthma individuals at specialty clinics completed the Sleep Apnea scale of the Sleep Disorders Questionnaire (SA-SDQ). Medical records were reviewed for diagnosed HTN, OSA and comorbidities, spirometry, and current medications. FEV1% predicted was categorized as ≥ 80 (reference), 70-79, 60-69, and < 60. SA-SDQ ≥ 36 for men and ≥ 32 for women defined high OSA risk. RESULTS: Among 812 asthmatics (mean age ± standard deviation: 46 ± 14 years), HTN was diagnosed in 191 (24%), OSA in 65 (8%), and OSA or high OSA risk (combined OSA variable) in 239 (29%). HTN was more prevalent in lower FEV1% categories (p < 0.0001), in subjects with OSA, and those with combined OSA variable (55 vs. 21% and 46 vs. 14%, respectively, both p < 0.0001). With adjustment for covariates, associations with HTN remained significant for some FEV1% categories (70-79% odds ratio = 1.60 [95% CI 0.90-2.87]; 60-69% 2.73 [1.28-5.79]; < 60% 0.96 [0.43-2.14]), and for OSA (2.20 [1.16-4.19]). The combined OSA variable in comparison with OSA alone demonstrated a stronger association with HTN (3.17 [1.99-5.04]) in a reiteration of this model. Inhaled corticosteroids (ICS) at lowest doses, in comparison to no ICS use had an independent "protective" association with HTN (0.44 [0.22-0.90]). CONCLUSIONS: In this young population, worse lower airways obstruction and OSA were associated with HTN. In contrast, lower ICS doses attenuated likelihood for HTN. Adequate control of airway inflammation at appropriate ICS doses, and screening for OSA may reduce the burden of HTN in asthma.

Sleep duration, asthma and obesity.

BACKGROUND: Obesity is more prevalent in asthmatics. Sleep duration is a novel risk factor for obesity in general populations. OBJECTIVE: We tested the association of sleep duration and asthma characteristics with obesity. METHODS: Adults at tertiary clinics were surveyed on asthma symptoms and habitual sleep duration. Medical records were used to assess asthma severity step (1-4), extract height and weight, current medications and diagnosed comorbid conditions. BMI ≥30 kg/m(2) defined obesity. Habitual sleep was categorized as <6 (very short), 6 to <7 h (short), 7-8 h (normal), >8 to ≤9 h (long) and >9 h (very long). Inhaled corticosteroid doses were categorized as low, moderate and high. RESULTS: Among 611 participants (mean BMI 30 ± 8), 249 (41%) were obese. After adjustment for covariates, obesity was associated with short and very long sleep: as compared to normal sleepers, the odds of being obese were on an average 66% higher ([95% CI: 1.07-2.57], p = 0.02) among short and 124% higher ([1.08-1.65], p = 0.03) among very long sleepers, and the association with very short sleep approached significance (1.74 [0.96-3.14], p = 0.06). Obesity was also significantly related to highest asthma step (1.87 [1.09-3.21], p = 0.02) and psychopathology (1.64 [1.08-2.48], p = 0.02), and a trend was seen with high-dose inhaled corticosteroids (1.82 [0.93-3.56], p = 0.08). CONCLUSIONS: Obesity in asthmatics is associated with shorter and very long sleep duration, worse asthma severity, psychopathology and high-dose inhaled corticosteroids. Although this cross-sectional study cannot prove causality, we speculate that further investigation of sleep may provide new opportunities to reduce the rising prevalence of obesity among asthmatics.

Association of obstructive sleep apnea risk or diagnosis with daytime asthma in adults.

OBJECTIVE: Obstructive sleep apnea (OSA) worsens nocturnal asthma, but its potential impact on daytime asthma remains largely unassessed. We investigated whether the sleep disorder is associated with daytime, in addition to nighttime, asthma symptoms. METHODS: Asthma patients at tertiary-care centers completed the Sleep Apnea scale of the Sleep Disorders Questionnaire (SA-SDQ), and an asthma control questionnaire. SA-SDQ scores ≥36 for males and ≥32 for females defined high OSA risk. Medical records were reviewed for established diagnosis of OSA and continuous positive airway pressure (CPAP) use. RESULTS: Among 752 asthma patients, high OSA risk was associated similarly with persistent daytime and nighttime asthma symptoms (p < .0001 for each). A diagnosis of OSA was robustly associated with persistent daytime (p < .0001) in addition to nighttime (p = .0008) asthma symptoms. In regression models that included obesity and other known asthma aggravators, high OSA risk retained associations with persistent daytime (odds ratio [OR] = 1.96 [95% confidence interval [CI] = 1.31-2.94]) and nighttime (1.97 [1.32-2.94]) asthma symptoms. Diagnosed OSA retained an association with persistent daytime (2.08 [1.13-3.82]) but not with nighttime (1.48 [0.82-2.69]) asthma symptoms. CPAP use was associated with lower likelihood of persistent daytime symptoms (0.46 [0.23-0.94]). CONCLUSIONS: Questionnaire-defined OSA risk and historical diagnosis were each associated with persistent daytime asthma symptoms, to an extent that matched or exceeded associations with nighttime asthma symptoms. Unrecognized OSA may be a reason for persistent asthma symptoms during the day as well as the night.

Sleep medicine content of major medical textbooks continues to be underrepresented.

OBJECTIVE: Sleep-related material in medical textbooks may be the only method by which physicians educate themselves about sleep. In the last decade significant progress in sleep research has been made, but how textbooks in relevant fields reflect it has not been examined. Our purpose was to review and compare (2005 with 1998) sleep content in representative medical textbooks. METHODS: Sleep content of the latest edition of textbooks in four specialties was evaluated. Present sleep content in seven textbooks was compared with that found in 1998. Numbers of pages devoted to sleep were counted and reported for the subjects covered and for the specialty of the textbook. RESULTS: Thirty-one textbooks were examined for current content and seven textbooks for content comparison. Sleep coverage in medical textbooks uniformly received less than 2% of the text volume. Focus of topics covered varied with specialty. Compared with 1998, the proportion of pages devoted to sleep remained the same or decreased. Coverage of new topics remained minimal. CONCLUSIONS: Major medical textbooks present small amounts of sleep content and few provide a comprehensive overview of sleep medicine. In comparison to textbook editions from the 1990s, current editions still devote little attention to sleep, and the diversity of topics has not improved.

Effects of stabilizing or increasing respiratory motor outputs on obstructive sleep apnea.

To determine how the obstructive sleep apnea (OSA) patient's pathophysiological traits predict the success of the treatment aimed at stabilization or increase in respiratory motor outputs, we studied 26 newly diagnosed OSA patients [apnea-hypopnea index (AHI) 42 ± 5 events/h with 92% of apneas obstructive] who were treated with O2 supplementation, an isocapnic rebreathing system in which CO2 was added only during hyperpnea to prevent transient hypocapnia, and a continuous rebreathing system. We also measured each patient's controller gain below eupnea [change in minute volume/change in end-tidal Pco2 (ΔVe/ΔPetCO2)], CO2 reserve (eupnea-apnea threshold PetCO2), and plant gain (ΔPetCO2/ΔVe), as well as passive upper airway closing pressure (Pcrit). With isocapnic rebreathing, 14/26 reduced their AHI to 31 ± 6% of control (P < 0.01) (responder); 12/26 did not show significant change (nonresponder). The responders vs. nonresponders had a greater controller gain (6.5 ± 1.7 vs. 2.1 ± 0.2 l·min(-1)·mmHg(-1), P < 0.01) and a smaller CO2 reserve (1.9 ± 0.3 vs. 4.3 ± 0.4 mmHg, P < 0.01) with no differences in Pcrit (-0.1 ± 1.2 vs. 0.2 ± 0.9 cmH2O, P > 0.05). Hypercapnic rebreathing (+4.2 ± 1 mmHg PetCO2) reduced AHI to 15 ± 4% of control (P < 0.001) in 17/21 subjects with a wide range of CO2 reserve. Hyperoxia (SaO2 ∼95-98%) reduced AHI to 36 ± 11% of control in 7/19 OSA patients tested. We concluded that stabilizing central respiratory motor output via prevention of transient hypocapnia prevents most OSA in selected patients with a high chemosensitivity and a collapsible upper airway, whereas increasing respiratory motor output via moderate hypercapnia eliminates OSA in most patients with a wider range of chemosensitivity and CO2 reserve. Reducing chemosensitivity via hyperoxia had a limited and unpredictable effect on OSA.

Asthma Control and Its Relationship with Obstructive Sleep Apnea (OSA) in Older Adults.

Background/Objectives. Asthma in older individuals is poorly understood. We aimed to characterize the older asthma phenotype and test its association with obstructive sleep apnea (OSA). Design. Cross-sectional. Setting. Pulmonary and Asthma/Allergy clinics. Participants. 659 asthma subjects aged 18-59 years (younger) and 154 aged 60-75 (older). Measurements. Sleep Apnea scale of Sleep Disorders Questionnaire (SA-SDQ), asthma severity step (1-4, severe if step 3 or 4), established OSA diagnosis, continuous positive airway pressure (CPAP) use, and comorbidities. Results. Older versus younger had worse control, as assessed by asthma step, lung function, and inhaled corticosteroid use. Among older subjects, after controlling for known asthma aggravators, OSA diagnosis was the only factor robustly associated with severe asthma: on average, OSA was associated with nearly 7 times greater likelihood of severe asthma in an older individual (OR = 6.67). This relationship was of greater magnitude than in younger subjects (OR = 2.16). CPAP use attenuated the likelihood of severe asthma in older subjects by 91% (P = 0.005), much more than in the younger asthmatics. Conclusion. Diagnosed OSA increases the risk for worse asthma control in older patients, while CPAP therapy may have greater impact on asthma outcomes. Unrecognized OSA may be a reason for poor asthma control, particularly among older patients.

Association of obstructive sleep apnea risk with asthma control in adults.

BACKGROUND: Unrecognized obstructive sleep apnea (OSA) may lead to poor asthma control despite optimal therapy. Our objective was to evaluate the relationship between OSA risk and asthma control in adults. METHODS: Patients with asthma seen routinely at tertiary-care clinic visits completed the validated Sleep Apnea Scale of the Sleep Disorders Questionnaire (SA-SDQ) and Asthma Control Questionnaire (ACQ). An ACQ score of >or= 1.5 defined not-well-controlled asthma, and an SA-SDQ score of >or= 36 for men and >or= 32 for women defined high OSA risk. Logistic regression was used to model associations of high OSA risk with not-well-controlled asthma (ACQ full version and short versions). RESULTS: Among 472 subjects with asthma, the mean +/- SD ACQ (full version) score was 0.87 +/- 0.90, and 80 (17%) subjects were not well controlled. Mean SA-SDQ score was 27 +/- 7, and 109 (23%) subjects met the definition of high OSA risk. High OSA risk was associated, on average, with 2.87-times higher odds for not-well-controlled asthma (ACQ full version) (95% CI, 1.54-5.32; P = .0009) after adjusting for obesity and other factors known to worsen asthma control. Similar independent associations were seen when using the short ACQ versions. CONCLUSIONS: High OSA risk is significantly associated with not-well-controlled asthma independent of known asthma aggravators and regardless of the ACQ version used. Patients who have difficulty achieving adequate asthma control should be screened for OSA.