Nocturnal worsening of asthma and sleep-disordered breathing

Sleep and allergic diseases among young Chinese adults from the Singapore/Malaysia Cross-Sectional Genetic Epidemiology Study (SMCGES) cohort

BACKGROUND AND OBJECTIVE

Sleep disruption has been shown to affect immune function and thus influence allergic disease manifestation. The specific effects of sleep on allergic diseases, however, are less well-established; hence, in a unique population of young Chinese adults, we investigated the association between sleep and allergic disease.

METHODS

Young Chinese adults recruited from Singapore in the Singapore/Malaysia Cross-Sectional Genetic Epidemiology Study (SMCGES) were analyzed. We used the International Study of Asthma and Allergies in Childhood (ISAAC) protocol and a skin prick test to determine atopic dermatitis (AD), allergic rhinitis (AR), and asthma status. Information regarding total sleep time (TST) and sleep quality (SQ) was also obtained.

RESULTS

Of 1558 participants with a mean age of 25.0 years (SD = 7.6), 61.4% were female, and the mean total sleep time (TST) was 6.8 h (SD = 1.1). The proportions of AD, AR, and asthma were 24.5% (393/1542), 36.4% (987/1551), and 14.7% (227/1547), respectively. 59.8% (235/393) of AD cases suffered from AD-related sleep disturbances, 37.1% (209/564) of AR cases suffered from AR-related sleep disturbances, and 25.1% (57/227) of asthma cases suffered from asthma-related sleep disturbances. Only asthma cases showed a significantly lower mean TST than those without asthma (p = 0.015). Longer TST was significantly associated with lower odds of AR (OR = 0.905, 95% CI = 0.820-0.999) and asthma (OR = 0.852, 95% CI = 0.746-0.972). Linear regression analyses showed that lower TST was significantly associated with asthma (β =  - 0.18, SE = 0.076, p-value = 0.017), and AR when adjusted for AR-related sleep disturbances (β =  - 0.157, SE = 0.065, p-value = 0.016). Only sleep disturbances due to AR were significantly associated with a poorer SQ (OR = 1.962, 95% CI = 1.245-3.089).

CONCLUSIONS

We found that sleep quality, but not sleep duration was significantly poorer among AD cases, although the exact direction of influence could not be determined. In consideration of the literature coupled with our findings, we posit that TST influences allergic rhinitis rather than vice versa. Finally, the association between TST and asthma is likely mediated by asthma-related sleep disturbances, since mean TST was significantly lower among those with nighttime asthma symptoms. Future studies could consider using objective sleep measurements coupled with differential expression analysis to investigate the pathophysiology of sleep and allergic diseases.

Evaluation of obesity and asthma as risk factors for moderate to severe obstructive sleep apnea in children

STUDY OBJECTIVES

Asthma and obesity are risk factors for obstructive sleep apnea (OSA) in children but their link to OSA severity is uncertain. We aimed at determining whether asthma or obesity were associated with an increased risk of moderate/severe OSA.

METHODS

Children undergoing a one-night polysomnography for suspicion of OSA were retrospectively included. Univariate and multivariate analyses were conducted to assess the clinical and demographic characteristics linked to moderate/severe OSA (obstructive apnea-hypopnea index ≥ 5/h of sleep) with odds ratio (OR) and 95% confidence interval reported.

RESULTS

490 children (311 (64%) boys) were included with a median [25th; 75th percentile] age of 8.7 [5.4; 12.9] years, 164 (33%) non-asthmatics non-obese, 122 (25%) obese non-asthmatics, 125 (26%) asthmatics non-obese, 79 (16%) asthmatics and obese. Moderate/severe OSA was present in 157 (32%) children (75/157 (48%) obese and 52/157 (33%) asthmatics). Independent factors associated with increased or decreased risk of moderate/severe OSA were: obesity and male sex (OR 1.82 [1.16; 2.87], P = 0.01, and 1.55 [1.02; 2.36], P = 0.04, respectively), and current asthma, age >6 years or behavioral disorders (OR 0.45 [0.29; 0.70], P < 0.001; 0.44 [0.27; 0.73], P < 0.001; and 0.55 [0.33; 0.92], P = 0.02, respectively). Abnormal resistance of the respiratory system (measured in 241 children), but not abnormal spirometry (measured in 213 children), increased the risk of moderate/severe OSA (OR 2.95 [1.46-5.96], P = 0.003).

CONCLUSIONS

In our cohort enriched in obese and asthmatic children, obesity was associated with higher risk of moderate/severe OSA whereas current asthma was not.

Circadian Rhythms in Environmental Health Sciences

PURPOSE OF REVIEW

This review aims to explore how circadian rhythms influence disease susceptibility and potentially modify the effect of environmental exposures. We aimed to identify biomarkers commonly used in environmental health research that have also been the subject of chronobiology studies, in order to review circadian rhythms of relevance to environmental health and determine if time-of-day is an important factor to consider in environmental health studies. Moreover, we discuss opportunities for studying how environmental exposures may interact with circadian rhythms to structure disease pathology and etiology.

RECENT FINDINGS

In recent years, the study of circadian rhythms in mammals has flourished. Animal models revealed that all body tissues have circadian rhythms. In humans, circadian rhythms were also shown to exist at multiple levels of organization: molecular, cellular, and physiological processes, including responding to oxidative stress, cell trafficking, and sex hormone production, respectively. Together, these rhythms are an essential component of human physiology and can shape an individual's susceptibility and response to disease. Circadian rhythms are relatively unexplored in environmental health research. However, circadian clocks control many physiological and behavioral processes that impact exposure pathways and disease systems. We believe this review will motivate new studies of (i) the impact of exposures on circadian rhythms, (ii) how circadian rhythms modify the effect of environmental exposures, and (iii) how time-of-day impacts our ability to observe the body's response to exposure.

"Severe-controlled" asthma 4 years later: is it still controlled?

BACKGROUND

Controlled severe asthma is based on needing regular medication and 4 markers of good asthma control. This study reevaluated a community sample defined 4 years earlier as "severe-controlled" based on electronic medical records of medications dispensed over 12 months.

OBJECTIVES

Determine the current extent of clinically-controlled asthma and asthma-related quality-of-life among patients previously considered "severe-controlled".

METHODS

69 patients considered "severe-controlled" 4 years earlier answered a questionnaire that included the asthma control test (ACT), demographics, education, comorbidities, medications, asthma-related healthcare utilization, atopy history, environmental exposures, and follow-up. Patients underwent spirometry, eosinophil count, total IgE, and skin-prick testing for airborne allergens.

RESULTS

Ninety-seven percent reported using combined inhalers (ICS + LABA) regularly. Only 4% visited the ER and none was hospitalized in the last year. Average predicted FEV₁ was 80%. Average ACT score was 19; 51% reported recurrent heartburn, 46% night awakenings and 70% recurrent rhinitis. Skin-prick testing was positive in 72%, average IgE was 376 IU/ml. Eosinophil counts were ≥300/ml in 42% and ≥400/ml in 25%. ACT < 20 was strongly related to recurrent heartburn. Formal education was related to ACT ≥ 20 (p = 0.045) and perception of good asthma control the previous month (p < 0.001). Eosinophil count, recurrent heartburn, total IgE, and recurrent rhinitis were interrelated.

CONCLUSIONS

Among severe asthmatics, good drug compliance, low use of relievers and low rates of exacerbations do not necessarily reflect asthma-related quality-of-life and optimal control. We urge physicians and HMOs to address asthma control in terms of quality-of-life based on validated questionnaires, and offer all patients asthma education; perhaps more to those with low formal education.

Tidal breathing flow profiles during sleep in wheezing children measured by impedance pneumography

For the first time, impedance pneumography (IP) enables a continuous analysis of the tidal breathing flow volume (TBFV), overnight. We studied how corticosteroid inhalation treatments, sleep stage, and time from sleep onset modify the nocturnal TBFV profiles of children. Seventy children, 1-5 years old and with recurrent wheezing, underwent three, full-night TBFVs recordings at home, using IP. The first recorded one week before ending a 3-months inhaled corticosteroids treatment, and remaining two, 2 and 4 weeks after treatment. TBFV profiles were grouped by hour from sleep onset and estimated sleep stage. Compared with on-medication, the off-medication profiles showed lower volume at exhalation peak flow, earlier interruption of expiration, and less convex middle expiration. The differences in the first two features were significant during non-rapid eye movement (NREM), and the differences in the third were more prominent during REM after 4 h of sleep. These combinations of TBFV features, sleep phase, and sleep time potentially indicate airflow limitation in young children.

Tidal breathing flow volume profiles during sleep in wheezing infants measured by impedance pneumography

Overnight analysis of tidal breathing flow volume (TBFV) loops, recorded by impedance pneumography (IP), has been successfully applied in the home monitoring of children with wheezing disorders. However, little is known on how sleep physiology modifies the relationship between TBFV profiles and wheeze. We studied such interactions in wheezing infants. Forty-three infants recruited because of recurrent lower airway symptoms were divided into three groups based on their risk of asthma: high (HR), intermediate (IR), or low (LR). Sedated patients underwent infant lung function testing including assessment of airway responsiveness to methacholine at the hospital and a full-night recording of TBFV profiles at home with IP during natural sleep. Overnight TBFV indexes were estimated from periods of higher and lower respiration variability, presumably belonging to active [rapid eye movement (REM)] and quiet [non-REM (NREM)] sleep, respectively. From 35 valid recordings, absolute time indexes showed intrasubject sleep phase differences. Peak flow relative to time and volume was lower in HR compared with LR only during REM, suggesting altered expiratory control. Indexes estimating the concavity/convexity of flow decrease during exhalation suggested limited flow during passive exhale in HR compared with IR and LR, similarly during NREM and REM. Moreover, during REM convexity was negatively correlated with maximal flow at functional residual capacity and methacholine responsiveness. We conclude that TBFV profiles determined from overnight IP recordings vary because of sleep phase and asthma risk. Physiological changes during REM, most likely decrease in respiratory muscle tone, accentuate the changes in TBFV profiles caused by airway obstruction. NEW & NOTEWORTHY Impedance pneumography was used to investigate overnight tidal breathing flow volume (TBFV) indexes and their interactions with sleep phase [rapid eye movement (REM) vs. non-REM] at home in wheezing infants. The study shows that TBFV indexes vary significantly because of sleep phase and asthma risk of the infant and that during REM the changes in TBFV indexes caused by airway obstruction are accentuated and better associated with lung function of the infant.

Effects of physical exercise training on nocturnal symptoms in asthma: Systematic review

INTRODUCTION

Nocturnal worsening of asthma symptoms is a common feature of asthma. Physical exercise training improves general asthma control; however, there is no evidence showing the effects of physical exercise on nocturnal asthma symptoms. Indeed, asthma patients with daytime and nighttime symptoms are physiologically different, and thus the effects of physical exercise on asthma may also be different in these two groups. The objective of this systematic review is to explore the effects of physical exercise on nocturnal asthma symptoms.

METHODS

Searches were conducted in MEDLINE, Embase, Cochrane Central Register of Controlled Trials, CINAHL and SPORTdiscus (last search on November 2017). Authors from studies that did not report nocturnal symptoms but used questionnaires and/or diaries were contacted for detailed information. Studies that provided results on nocturnal symptoms before and after physical activity intervention were included. Prevalence of nocturnal symptoms was calculated for each study from the percentage of study participants with nocturnal symptoms before and after intervention.

RESULTS

Eleven studies were included (5 with children and 6 with adults). The prevalence of nocturnal symptoms at baseline ranged from 0% to 63% among children and from 50-73% among adults. In children and adults with nocturnal asthma, aerobic physical exercise reduced the prevalence and frequency of nocturnal symptoms.

CONCLUSIONS

Aerobic physical exercise improves nocturnal asthma in children and adults by reducing the prevalence and frequency of nocturnal symptoms. Physical exercise training could be used with conventional treatments to improve quality of life and asthma control in patients with nocturnal worsening of asthma.

Association between allergic disease, sleep-disordered breathing, and childhood nocturnal enuresis: a population-based case-control study

BACKGROUND

Little is known about the associations between allergic disease, sleep-disordered breathing (SDB), and childhood nocturnal enuresis (NE). We examined whether allergic disease and SDB were associated with childhood NE.

METHODS

Data were assessed from the 2007-2012 Taiwan National Health Insurance Research Database. We enrolled 4308 children aged 5-18 years having NE diagnosis and age- and sex-matched 4308 children as the control group. The odds ratios of NE were calculated to determine an association with preexisting allergic disease and SDB.

RESULTS

A total of 8616 children were included in the analysis. Prevalence of allergic diseases and SDB was significantly higher for the NE group than the control group (all p < 0.001). After adjusting odds ratios for potential confounding factors, except asthma, children with allergic rhinitis, atopic dermatitis, allergic conjunctivitis, and obstructive sleep apnea (OSA) had significantly higher odds of NE compared with children never diagnosed. With stratification for sex, girls with allergic rhinitis, atopic dermatitis, allergic conjunctivitis, OSA, and snoring had significantly higher odds of NE, compared with girls never diagnosed. Only boys with allergic rhinitis and OSA were associated with increased odds of NE. With stratification for age, children aged 5-12 years with allergic rhinitis, atopic dermatitis, allergic conjunctivitis, and OSA had significantly higher odds of NE compared with those never diagnosed. Odds of NE increased with the number of comorbid allergic diseases.

CONCLUSIONS

Allergic diseases and SDB are associated with increased odds of childhood NE. The odds of NE increased with the number of comorbid allergic diseases present.

Association between Asthma and Primary Nocturnal Enuresis in Children

PURPOSE

Enuresis, sleep respiratory disorders and asthma compromise the quality of sleep in children and may occur in association with each other. An association between sleep respiratory disorders and enuresis has already been demonstrated. According to united airways disease abnormalities of the upper and lower airways may coexist. A child who wheezes has a greater chance of snoring and having obstructive sleep apnea. Since asthma and sleep respiratory disorders may be associated, and sleep respiratory disorders are associated with enuresis, we determined the possibility of an association between asthma and enuresis.

MATERIALS AND METHODS

Between August 20 and March 2015 parents/guardians of children 6 to 14 years old from 16 elementary schools in our area were randomly chosen for study. Children with nonmonosymptomatic enuresis and urological or neurological disease were excluded. The Tucson and ISAAC (International Study of Asthma and Allergies in Childhood) questionnaires were used to assess sleep respiratory disorders and asthma, respectively.

RESULTS

A total of 523 children (283 males and 240 females) with a mean ± SD age of 9.42 ± 2.46 years were included in analysis. The overall prevalence of enuresis was 15.87% (95% CI 12.98-19.26). Asthmatic children with wheezing in the last 12 months were 2.33 times more likely to have had enuresis at some point in life (OR 2.33, 95% CI 1.37-3.95, p = 0.0017). If enuresis was present, the chance increased to 2.78 (95% CI 1.38-5.61, p = 0.0041). Enuretic children were 5.34 times more prone to have apnea reported by parents (95% CI 2.19-13.03, p = 0.0002).

CONCLUSIONS

These findings demonstrate that asthma as well as sleep respiratory disorders is associated with primary nocturnal enuresis.

Sleep duration, sleep hygiene, and insomnia in adolescents with asthma

BACKGROUND

There is a need to understand more about modifiable health behaviors that may be related to asthma control. Sleep is one such health behavior that has received little attention in pediatric asthma research.

OBJECTIVE

To examine sleep duration, sleep hygiene, and insomnia in adolescents with and without asthma.

METHODS

Adolescents (n = 298; 51% boys; age range, 12-17 years; 48% with asthma) from the general community completed an online survey that included the International Study of Asthma and Allergies in Childhood questionnaire, the Children's Report of Sleep Patterns, and the Insomnia Severity Index.

RESULTS

Sleep duration did not differ between the asthma severity groups, yet more adolescents with severe asthma reported insufficient weekday sleep (44%) versus adolescents without asthma (31%). Significant asthma group differences were found for sleep hygiene, with adolescents with severe asthma reporting poorer sleep hygiene. Almost twice as many adolescents with severe asthma reported clinically significant insomnia than adolescents with mild or no asthma. Sleep hygiene variables were correlated with insomnia, although these associations did not differ between adolescents with and without severe asthma. Finally, both insomnia severity and asthma severity were significant predictors of daytime sleepiness; however, asthma severity accounted for only 2% of the variance compared with 28% of the variance accounted for by insomnia severity.

CONCLUSIONS

Many adolescents with severe asthma regularly obtain insufficient sleep, have poor sleep hygiene, and experience clinically significant insomnia. It is important to ask adolescents with asthma about sleep duration, sleep hygiene, and insomnia because there are effective interventions that can improve sleep for these youths.

Brown Norway and Zucker Lean rats demonstrate circadian variation in ventilation and sleep apnea

STUDY OBJECTIVES

Circadian rhythms influence many biological systems, but there is limited information about circadian and diurnal variation in sleep related breathing disorder. We examined circadian and diurnal patterns in sleep apnea and ventilatory patterns in two rat strains, one with high sleep apnea propensity (Brown Norway [BN]) and the other with low sleep apnea propensity (Zucker Lean [ZL]).

DESIGN/SETTING

Chronically instrumented rats were randomized to breathe room air (control) or 100% oxygen (hyperoxia), and we performed 20-h polysomnography beginning at Zeitgeber time 4 (ZT 4; ZT 0 = lights on, ZT12 = lights off). We examined the effect of strain and inspired gas (twoway analysis of variance) and analyzed circadian and diurnal variability.

MEASUREMENTS AND RESULTS

Strain and inspired gas-dependent differences in apnea index (AI; apneas/h) were particularly prominent during the light phase. AI in BN rats (control, 16.9 ± 0.9; hyperoxia, 34.0 ± 5.8) was greater than in ZL rats (control, 8.5 ± 1.0; hyperoxia, 15.4 ± 1.1, [strain effect, P < 0.001; gas effect, P = 0.001]). Hyperoxia reduced respiratory frequency in both strains, and all respiratory pattern variables demonstrated circadian variability. BN rats exposed to hyperoxia demonstrated the largest circadian fluctuation in AI (amplitude = 17.9 ± 3.7 apneas/h [strain effect, P = 0.01; gas effect, P < 0.001; interaction, P = 0.02]; acrophase = 13.9 ± 0.7 h; r (2) = 0.8 ± 1.4).

CONCLUSIONS

Inherited, environmental, and circadian factors all are important elements of underlying sleep related breathing disorder. Our method to examine sleep related breathing disorder phenotypes in rats may have implications for understanding vulnerability for sleep related breathing disorder in humans.

Effects of inhaled fluticasone on upper airway during sleep and wakefulness in asthma: a pilot study

STUDY OBJECTIVE

Obstructive sleep apnea is prevalent among people with asthma, but underlying mechanisms remain unknown. Inhaled corticosteroids may contribute. We tested the effects of orally inhaled fluticasone propionate (FP) on upper airway (UAW) during sleep and wakefulness.

STUDY DESIGN

16-week single-arm study.

PARTICIPANTS

18 (14 females, mean [ ± SD] age 26 ± 6 years) corticosteroid-naïve subjects with mild asthma (FEV1 89 ± 8% predicted).

INTERVENTIONS

High dose (1,760 mcg/day) inhaled FP.

MEASUREMENTS

(1) UAW collapsibility (passive critical closing pressure [Pcrit]); (2) tongue strength (maximum isometric pressure-Pmax, in KPa) and endurance-time (in seconds) able to maintain 50% Pmax across 3 trials (Ttot)-at anterior and posterior locations; (3) fat fraction and volume around UAW, measured by magnetic resonance imaging in three subjects.

RESULTS

Pcrit overall improved (became more negative) (mean ± SE) (-8.2 ± 1.1 vs. -12.2 ± 2.2 cm H2O, p = 0.04); the response was dependent upon baseline characteristics, with older, male gender, and worse asthma control predicting Pcrit deterioration (less negative). Overall, Pmax increased (anterior p = 0.02; posterior p = 0.002), but Ttot generally subsided (anterior p = 0.0007; posterior p = 0.06), unrelated to Pcrit response. In subjects studied with MRI, fat fraction and volume increased by 20.6% and 15.4%, respectively, without Pcrit changes, while asthma control appeared improved.

CONCLUSIONS

In this study of young, predominantly female, otherwise healthy subjects with well-controlled asthma and stiff upper airways, 16-week high dose FP treatment elicited Pcrit changes which may be dependent upon baseline characteristics, and determined by synchronous and reciprocally counteracting local and lower airway effects. The long-term implications of these changes on sleep disordered breathing severity remain to be determined.

Pain as a predictor of sleep problems in youth with autism spectrum disorders

Evidence suggests that pain interferes with sleep in youth with developmental disabilities. This study examined the relationship between pain and sleep problems in a sample of youth with parent-reported autism spectrum disorder (N = 62). Mothers reported on standardized measures of pain and sleep problems. Youth demonstrated atypically high levels of both observed pain and sleep problems. Pain predicted overall sleep disturbance and three specific sleep problems: sleep duration, parasomnias, and sleep-disordered breathing. These specific sleep problems were predicted by specific modalities of nonverbal pain communication (e.g. sleep duration problems were predicted by social communication of pain). Effects were consistent across probing of relevant moderators. These findings suggest that comprehensive assessment of both pain and sleep problems may provide important information for medical and behavioral treatment planning for youth with autism spectrum disorder.

Obstructive sleep apnea and asthma: associations and treatment implications

Obstructive sleep apnea (OSA) and asthma are highly prevalent respiratory disorders and are frequently co-morbid. Risk factors common to the two diseases include obesity, rhinitis, and gastroesophageal reflux (GER). Observational and experimental evidence implicates airways and systemic inflammation, neuromechanical effects of recurrent upper airway collapse, and asthma-controlling medications (corticosteroids) as additional explanatory factors. Therefore, undiagnosed or inadequately treated OSA may adversely affect control of asthma and vice versa. It is important for clinicians to be vigilant and specifically address weight-control, nasal obstruction, and GER in these populations. Utilizing validated screening instruments to affirm high risk of co-morbid OSA or asthma in persistently symptomatic patients will allow clinicians to cost-effectively test and treat appropriate patients, potentially improving outcomes. While non-invasive ventilation in acute asthma improves outcomes, the role of chronic continuous positive airway pressure (CPAP; the first-line treatment for OSA) in improving long-term asthma control is not known. Future research should focus on the impact of optimal CPAP therapy and adherence on asthma symptoms and outcomes.

Associations of moderate to severe asthma with obstructive sleep apnea

PURPOSE

This study aimed to evaluate the correlation between associating factors of moderate to severe asthma with obstructive sleep apnea (OSA).

MATERIALS AND METHODS

One hundred and sixty-seven patients who visited the pulmonary and sleep clinic in Severance Hospital presenting with symptoms of sleep-disordered breathing were evaluated. All subjects were screened with ApneaLink. Thirty-two subjects with a high likelihood of having OSA were assessed with full polysomnography (PSG).

RESULTS

The mean age was 58.8±12.0 years and 58.7% of subjects were male. The mean ApneaLink apnea-hypopnea index (AHI) was 12.7±13.0/hr. The mean ApneaLink AHI for the 32 selected high risk patients of OSA was 22.3±13.2/hr, which was lower than the sleep laboratory-based PSG AHI of 39.1±20.5/hr. When OSA was defined at an ApneaLink AHI≥5/hr, the positive correlating factors for OSA were age, male gender, and moderate to severe asthma.

CONCLUSION

Moderate to severe asthma showed strong correlation with OSA when defined at an ApneaLink AHI≥5/hr.

Asthma and Sleep

Asthma significantly affects quality of sleep. Asthma physiology follows a diurnal pattern with peak flow at its lowest during early morning hours. The type and timing of release of inflammatory mediators also varies during the day and nighttime. Nocturnal symptoms are common in poorly controlled asthma. Hence, these nighttime symptoms play a significant role in the assessment of asthmatic patients as demonstrated in validated asthma control and quality of life questionnaires. Comorbid conditions may include allergic rhinitis, obesity, obstructive sleep apnea, and gastroesophageal reflux, all of which may worsen asthma symptoms, especially during sleep. In addition, exposure to greater loads of allergens in susceptible individuals during sleep is a significant problem and must be addressed to break the cycle of poor asthma control. Thus, asthma education for better symptom control should address these particular issues surrounding sleep.

Habitual snoring and asthma comorbidity among pregnant women

BACKGROUND

Obstructive sleep apnea (OSA) or habitual snoring and asthma are known comorbid conditions in men and non-pregnant women. This comorbidity has not been evaluated among pregnant women. We assessed the habitual snoring-asthma relationship among pregnant women.

METHODS

A cohort of women (N = 1335) were interviewed during pregnancy, and we ascertained participants' asthma status and collected information about habitual snoring, before and during pregnancy. Logistic regression procedures were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Compared with non-asthmatics, the adjusted OR among asthmatics for snoring before pregnancy was 2.13 (95% CI 1.10-4.12). The odds of snoring during early pregnancy was 1.79-fold (OR = 1.79; 95% C; 1.07-3.01). Associations were more pronounced among overweight (≥ 25 kg/m(2)) asthmatics (OR = 5.39; 95% CI 2.27-12.75).

CONCLUSIONS

We report a cross-sectional association of habitual snoring and asthma among pregnant women. If confirmed, pregnant asthmatics may benefit from more vigilant screening and management of OSA or habitual snoring during pregnancy.

Influence of the Circadian System on Disease Severity

The severity of many diseases varies across the day and night. For example, adverse cardiovascular incidents peak in the morning, asthma is often worse at night and temporal lobe epileptic seizures are most prevalent in the afternoon. These patterns may be due to the day/night rhythm in environment and behavior, and/or endogenous circadian rhythms in physiology. Furthermore, chronic misalignment between the endogenous circadian timing system and the behavioral cycles could be a cause of increased risk of diabetes, obesity, cardiovascular disease and certain cancers in shift workers. Here we describe the magnitude, relevance and potential biological basis of such daily changes in disease severity and of circadian/behavioral misalignment, and present how these insights may help in the development of appropriate chronotherapy.

Predictors of habitual snoring and obstructive sleep apnea risk in patients with asthma

BACKGROUND

A high prevalence of obstructive sleep apnea (OSA) symptoms was reported in patients with asthma. Our goal was to evaluate factors associated with habitual snoring and OSA risk in these patients.

METHODS

Patients with asthma were surveyed at specialty clinics with the Sleep Apnea scale of the Sleep Disorders Questionnaire (SA-SDQ) and questions about the frequency of asthma symptoms (National Asthma Education and Prevention Program guidelines), followed by medical record review. SA-SDQ scores >or= 36 for men and >or= 32 for women defined high OSA risk. Logistic regression was used to model associations with habitual snoring and high OSA risk.

RESULTS

Among 244 patients, 37% snored habitually and 40% demonstrated high OSA risk. Independent predictors of habitual snoring included gastroesophageal reflux disease (GERD) [odds ratio (OR), 2.19; 95% confidence interval (CI), 1.19 to 4.02] and use of an inhaled corticosteroid (ICS) [OR, 2.66; 95% CI, 1.05 to 6.72]. High OSA risk was predicted by asthma severity step (OR, 1.59; 95% CI, 1.23 to 2.06), GERD (OR, 2.70; 95% CI, 1.51 to 4.83), and ICS use (OR, 4.05; 95% CI, 1.56 to 10.53). Linear, dose-dependent relationships of ICS with habitual snoring and high OSA risk were seen (p = 0.004 and p = 0.0006, respectively). Women demonstrated a 2.11 times greater odds for high OSA risk (95% CI, 1.10 to 4.09) when controlling for the above covariates.

CONCLUSIONS

Symptoms of OSA in patients with asthma are predicted by asthma severity, coexistent GERD, and use of an ICS in a dose-dependent fashion. The well-recognized male gender predominance for OSA symptoms is not apparent in these patients. Further exploration of these relationships may help to explain the increased prevalence of OSA in asthma and provide new insights into the reported female predominance of asthma morbidity.

Assessing sleep quality and daytime wakefulness in asthma using wrist actigraphy

This study evaluated the sleep/wake cycle of individuals with asthma in relation to asthma control, daytime sleepiness, and daytime activity. Ten persons with mild to moderate persistent asthma monitored their sleep quality and daytime wakefulness for 7 consecutive days using 24-hours wrist actigraphy. Degree of asthma control strongly correlated with sleep quality. Individuals whose asthma was not well controlled took longer to fall asleep, awoke more often, and spent more time awake during the night compared to those with well controlled asthma. Poor asthma control, use of rescue medications, and asthma symptoms were associated with daytime sleepiness and limitations in physical activity and emotional function. Forty percent of subjects reported clinically significant daytime sleepiness. Evaluating asthma throughout a 24-hour cycle provides valuable information on variations in the sleep/wake cycle associated with asthma control, use of rescue medications, and asthma symptoms.

Obstructive sleep apnea and history of asthma in snoring children

Asthma has been identified as a possible risk factor for Obstructive Sleep Apnea (OSA) in children. It is not known whether parent-reported asthma increases the likelihood of the diagnosis of OSA in snoring children. We hypothesized that snoring children with asthma are more likely to have OSA than snoring children without asthma. This study is a 1-year retrospective review of polysomnogram and questionnaire data collected on 236 patients referred to the University of Maryland Pediatric Sleep laboratory for evaluation of snoring. Of the 236 patients, 58% (137/236) were boys, and 79% (173/219 reporting race) were African-American (AA). The age at referral was 7.2 +/- 3.7 years (mean +/- S.D.). Mean body mass index (BMI) percentile was 73.4 +/- 32.3%, with 43.2% (54/125) >95th percentile. A history of asthma was reported by 31.4% (74/236); no subject was symptomatic on the night of the study. We found no increased risk for polysomnographically diagnosed OSA for asthmatics. To the contrary, by logistic regression analysis, a parent/guardian report of asthma decreased the odds of having OSA by 34% (p = 0.027), controlling for individual and socioeconomic factors and assessment results. Polysomnographic (PSG) differences between asthmatic and non-asthmatic children were found in only the arousal index (11.0 vs.9.3 +/- 6.5/h, p = 0.099) and total sleep time (337.1 +/- 64.3 vs. 347 +/- 65.2 min, p = 0.1) In a referral-based group of predominantly AA inner-city snoring children, asymptomatic asthma decreased the likelihood of OSA.

Effect of body position on lung sounds in healthy young men

BACKGROUND

The effect of body position on the generation of abnormal respiratory sounds (eg, snoring and stridor) is well recognized. Postural effects on normal lung sounds have been studied in less detail but need to be clarified if respiratory acoustic measurements are to be used effectively in clinical practice.

METHODS

Lung sounds and airflow were recorded in six healthy male subjects. Two acoustic sensors were placed over corresponding sites of the right and left chest, first anteriorly and then on the back. Subjects were studied in sitting, supine, prone, and lateral decubitus positions. Lung sound intensity (LSI) was determined at flows of 0.4 to 0.6 L/s and 0.8 to 1.2 L/s within frequency bands of 150 to 300 Hz and 300 to 600 Hz.

RESULTS

LSI was greater over the dependent lungs in the lateral decubitus positions. In the sitting position, LSI was greater on the left compared with the right posterior lung at the same airflow within the same frequency bands. Compared with sitting, neither the supine nor prone positions caused a significant change in LSI.

CONCLUSIONS

Our study confirms previously reported asymmetries of normal lung sounds. The insignificant change of flow-specific LSI between the upright and horizontal positions in healthy subjects is encouraging for the clinical use of respiratory acoustic measurements. Further studies should address postural effects on lung sounds in patients with acute lung injury and other lung pathologies.

Findings of a Berlin Questionnaire survey: comparison between patients seen in an asthma clinic versus internal medicine clinic

BACKGROUND

Obstructive sleep apnea (OSA) and asthma are common and share similar nocturnal symptoms. We hypothesized that the prevalence of OSA symptoms would be greater in asthmatics compared to a general internal medicine population.

METHODS

Patients in the Asthma Clinics (n=177) and Internal Medicine Clinics (n=328) at MetroHealth Medical Center, an urban academic institution, were surveyed for OSA risk. Patients completed the Berlin Questionnaire, a validated questionnaire with a positive predictive value (ppv) of 0.89 for determining the presence of OSA in primary care populations. All asthmatics had spirometry performed.

RESULTS

The asthma group had more females (p=0.01) and a higher mean body mass index (33.2 vs. 31.2 kg/m(2), p=0.02). However, the percentage with a body mass index >30 kg/m(2) was not different between the groups (p=0.19). The internal medicine group had a much higher rate of hypertension (p=0.002) and diabetes (p<0.001). Asthmatics were more likely to report frequent snoring (18.5% vs. 8.0%, p<0.001) and chronic sleepiness (46.1% vs. 34.3%, p=0.01). OSA risk, as determined by the Berlin Questionnaire, was higher in the asthma group than in the internal medicine group (39.5% vs. 27.2%, p=0.004). In the asthma group, risk for OSA did not correlate with asthma severity (p=0.183).

CONCLUSIONS

This study suggests a possible association between asthma and OSA. There is a higher prevalence of OSA symptoms in an asthmatic population when compared to a primary care population, independent of the severity of the asthma.

Le ronflement habituel. Prévalence et facteurs de risque dans un échantillon de la population masculine française

INTRODUCTION

As there are important differences in the prevalence of snoring in the literature we have studied this prevalence and the risk factors in a sample of the active male population of Lorraine.

METHODS

850 men, aged 22 to 66 tears, volunteered for the study and completed a questionnaire on the frequency of snoring, their lifestyle and their personal and family histories. The usual anthropomorphic measurements were made together with a non-invasive examination of the upper airways.

RESULTS

The prevalence of habitual snoring was 34.6%, increasing with age, weight and the derived indices. We identified, by logistic regression, the factors independently associated with habitual snoring in univariate analysis. These were age, weight, nocturnal nasal obstruction, a medical diagnosis of obstructive sleep apnoea, and hypertrophy of the soft palate and uvula. There was evidence that height had a protective effect but exercise activity did not appear to be significant.

CONCLUSION

The 35% prevalence of habitual snoring in our sample of middle aged men is similar to other studies in the literature using the same methods. The present study confirmed that age, weight, girth, nasal obstruction and nasopharyngeal abnormalities are risk factors. The protective effect of height was a new finding not identified in previous studies.

Nocturnal asthma

PURPOSE OF REVIEW

To examine recent advancements of the epidemiology, pathophysiology, and treatment of nocturnal asthma.

RECENT FINDINGS

In a large cross-sectional survey, the prevalence of nocturnal symptoms was 60%. Forty-two percent of patients who completed the study did not declare nocturnal symptoms that were detected by physicians. A recent study including 47 individuals with nocturnal and nonnocturnal asthma showed that allele genotype Gly16 was significantly higher in the nocturnal asthma group (72%) compared with the nonnocturnal asthma group (54%). A randomized double-blind study of nocturnal asthma with esomeprazole improved the peak expiratory flow rate in individuals with both nocturnal asthma and gastroesophageal reflux disease. Of patients with nocturnal asthma and snoring, 48% had obstructive sleep apnea. After continuous positive airway pressure treatment, there was significant improvement of asthma nighttime symptom scores; however, no significant difference in lung functions was observed.

SUMMARY

Nocturnal symptoms in asthma are frequently underdiagnosed. Obstructive sleep apnea may be prevalent in nocturnal asthma. The Gly16 polymorphism of the beta2-receptor is common in nocturnal asthma. Gastric suppression treatment in patients with both gastroesophageal reflux disease and nocturnal asthma improved the peak expiratory flow rate. Continuous positive airway pressure improves nocturnal symptoms but not lung function tests.

Potential mechanisms connecting asthma, esophageal reflux, and obesity/sleep apnea complex--a hypothetical review

Obstructive sleep apnea (OSA) and asthma are potentially linked at several levels. The pathophysiology of these two conditions seems to overlap significantly, as airway obstruction, inflammation, obesity, and several other factors are implicated in the development of both diseases. Gastroesophageal reflux disease (GERD), cardiovascular complications, obesity itself, and the underlying inflammatory processes are all complex contributory factors that provide hypothetical links. Furthermore, a collateral rise in prevalence of both OSA and asthma has been noticed during the past few years, occurring in association with the emerging epidemic of obesity, a common risk factor for both conditions. OSA and asthma share many other risk factors as well. We propose a hypothetical OSA-asthma relationship that has implications on the diagnosis and management of patients presenting with either condition singly. Clinicians should be aware that OSA might complicate asthma management. Based on this hypothesis, we suggest that the treatment of the individual patient who experiences both asthma and OSA needs to be multidisciplinary and comprehensive. This hypothetical association of asthma and OSA, though described anecdotally, has not been systematically studied. In particular, the influence of continuous positive airway pressure therapy (for sleep apnea) on asthma outcomes (such as quality of life, steroid utilization, emergency room visits) and fatality needs to be studied further.

Perennial non-infectious rhinitis--an independent risk factor for sleep disturbances in Asthma

AIM OF THE STUDY

To evaluate if perennial non-infectious rhinitis is associated with sleep disturbances in asthma.

MATERIALS AND METHODS

This is a questionnaire based study in a random population sample from Denmark, Estonia, Iceland, Norway and Sweden aged 30-54yr. A total of 1127 individuals reporting asthma from an original random population sample of 16,191 were analysed regarding their quality of sleep in relation to perennial non-infectious rhinitis. Perennial non-infectious rhinitis was defined as having nasal symptoms such as nasal blockage and secretion in the absence of common cold, always. Asthma was defined as both ever having had asthma and having physician diagnosed asthma. Odds ratios (OR) for difficulties inducing sleep, difficulties maintaining sleep, early morning awakenings and daytime sleepiness were calculated in a multiple logistic regression controlling for other risk factors for sleep disturbances such as snoring, wheeze, obesity and smoking.

RESULTS

The response rate was 74%. A total of 189 (17%) of the subjects with asthma reported perennial non-infectious rhinitis. Perennial non-infectious rhinitis was associated with an increased OR for difficulties maintaining sleep (1.6 (95% confidence interval (CI) 1.1-2.3)), early morning awakenings (1.5 (95% CI 1.1-2.2)) and daytime sleepiness (1.8 (95% CI 1.2-2.9)). The result show that perennial non-infectious rhinitis is an independant risk factor for sleep disturbances in asthma.

Correlates of daytime sleepiness in patients with asthma

BACKGROUND AND PURPOSE

Patients with asthma often complain of daytime sleepiness, which is usually attributed to a direct effect of asthma on nocturnal sleep quality. We investigated this and other potential explanations for daytime sleepiness among asthmatics.

PATIENTS AND METHODS

One hundred fifteen adult asthmatics were assessed for perceived daytime sleepiness (one question item), subjective sleepiness (Epworth Sleepiness Scale score, ESS), obstructive sleep apnea risk (Sleep Apnea scale score within Sleep Disorders Questionnaire, SA-SDQ), asthma severity step, relevant comorbid conditions, and current asthma medications.

RESULTS

Among all subjects, 55% perceived excessive daytime sleepiness and 47% had ESS>10. Most subjects reported snoring (n=99, or 86%) and many snored habitually (n=44, 38%). The ESS correlated with SA-SDQ (P<0.0001), male gender (P=0.01), and asthma severity step (P=0.04). In a multiple regression model, the ESS was independently associated with SA-SDQ (P=0.0003) and male gender (P=0.02), but not with asthma severity step (P=0.51). There were no correlations between ESS and age, body mass index (BMI), forced expiratory volume in one second as percent of predicted value (FEV(1)%), comorbidities, or medication used to treat asthma.

CONCLUSIONS

Sleepiness is common in asthmatics and may reflect occult obstructive sleep apnea more often than effects of asthma itself, other comorbid conditions, or asthma medications.

Non-rapid eye movement sleep parasomnias

Parasomnias are unpleasant or undesirable behavioral or experiential phenomena that occur during sleep. Once believed unitary phenomena related to psychiatric disorders, it is now clear that parasomnias result from several different phenomena and usually are not related to psychiatric conditions. Parasomnias are categorized as primary (disorders of the sleep states) and secondary (disorders of other organ systems that manifest themselves during sleep). Primary sleep parasomnias can be classified according to the sleep state of origin: rapid eye movement sleep, non-rapid eye movement sleep, and miscellaneous (those not respecting sleep state). Secondary sleep parasomnias are classified by the organ system involved.

CNS determinants of sleep-related worsening of airway functions: implications for nocturnal asthma

This review summarizes the recent neuroanatomical and physiological studies that form the neural basis for the state-dependent changes in airway resistance. Here, we review only the interactions between the brain regions generating quiet (non-rapid eye movement, NREM) and active (rapid eye movement, REM) sleep stages and CNS pathways controlling cholinergic outflow to the airways. During NREM and REM sleep, bronchoconstrictive responses are heightened and conductivity of the airways is lower as compared to the waking state. The decrease in conductivity of the lower airways parallels the sleep-induced decline in the discharge of brainstem monoaminergic cell groups and GABAergic neurons of the ventrolateral periaqueductal midbrain region, all of which provide inhibitory inputs to airway-related vagal preganglionic neurons (AVPNs). Withdrawal of central inhibitory influences to AVPNs results in a shift from inhibitory to excitatory transmission that leads to an increase in airway responsiveness, cholinergic outflow to the lower airways and consequently, bronchoconstriction. In healthy subjects, these changes are clinically unnoticed. However, in patients with bronchial asthma, sleep-related alterations in lung functions are troublesome, causing intensified bronchopulmonary symptoms (nocturnal asthma), frequent arousals, decreased quality of life, and increased mortality. Unquestionably, the studies revealing neural mechanisms that underlie sleep-related alterations of airway function will provide new directions in the treatment and prevention of sleep-induced worsening of airway diseases.

Obstructive sleep apnea

BACKGROUND

Patients with undiagnosed obstructive sleep apnea (OSA) represent a major public health problem, and studies suggest that the incidence of OSA may be even higher than estimated.

TYPES OF STUDIES REVIEWED

The authors reviewed current literature describing comorbidities of patients with OSA.

RESULTS

Sleep medicine is a relatively new field. Dental practitioners may lack educational exposure and, as a result, feel uncomfortable asking their patients sleep-related questions. While patients with well-controlled OSA present few difficulties for routine dental treatment, it is imperative that health care professionals understand the comorbidities associated with OSA and that untreated OSA may contribute to increased morbidity and mortality.

CLINICAL IMPLICATIONS

Dental professionals have a unique doctor-patient relationship that affords them a role in recognizing sleep disorders by exploring the history of patients who are sleepy.

Factors associated with objective (actigraphic) and subjective sleep quality in young adult women

OBJECTIVE

The aim of this study was to describe factors associated with actigraphic and subjective sleep quality in young women.

METHODS

Participants were 73 regularly menstruating women, 20-40 years old, who were not taking oral contraceptives, pregnant, or shift workers. Women contributed an average of 7 nights of actigraphy data during the luteal menstrual cycle phase, resulting in a total of 595 nights of data.

RESULTS

One night of actigraphy data was unreliable for measuring total sleep time, sleep onset, and time in bed (intraclass correlation < or =.15) but was acceptable for measuring sleep efficiency and total wake time (intraclass correlation [ICC]=.52). Going to bed late, medication use, employment, increased daylight hours, longer menstrual cycle length, and higher body mass index (BMI) were associated with poorer actigraphic sleep measures. Employment, age, and perceived stress were associated with subjective sleep quality.

CONCLUSION

Multiple factors were associated with sleep quality in these young women who were sleeping at home. However, the associations differed for subjectively versus actigraphically assessed sleep quality. Actigraphy is feasible for measuring sleep, but multiple recording nights may be needed to obtain reliable estimates.

Effect of nasal continuous positive airway pressure in uncontrolled nocturnal asthmatic patients with obstructive sleep apnea syndrome

The mechanisms of nocturnal asthma are intimately related to circadian rhythms, which influence inflammatory cells and mediators, hormone levels and cholinergic tone. Nocturnal airway narrowing in asthma is sometimes associated with sleep disorders, such as obstructive sleep apnea syndrome (OSAS). The aims of this study were to evaluate the association of nocturnal asthma and OSAS, and investigate the influence of continuous positive airway pressure (CPAP) therapy to improve nighttime symptoms in asthmatic patients with OSAS. Forty-three asthmatic patients who had nocturnal symptoms in spite of the optimal medical treatment according to the Global Initiative for Asthma guidelines and associated with snoring were studied. Pulmonary function tests (PFTs), asthma nighttime symptom scores, and polysomnography were performed on all patients. We treated the patients with an apnea-hypopnea index (AHI) 15 (moderate-severe OSAS) (n=16) with CPAP during 2 months. After 2 months, PFT, asthma nighttime symptom scores were reperformed. There was no significant difference in PFT values before and after CPAP treatment in OSAS patients. Asthma nighttime symptom scores were improved significantly (P<0.05) after CPAP treatment. In conclusion, in some patients with nocturnal asthma, OSAS may be responsible disease for nocturnal symptoms. In this condition, CPAP improves nocturnal symptoms without amelioration in PFT abnormalities.

Rhinitis and sleep apnea

The nose and pharynx begin the upper airway system and represent a continuum. This is the biologic basis for the mutual influences of rhinitis and obstructive sleep apnea (OSA). Sleep-disordered breathing has a large differential diagnosis that includes snoring, upper airway resistance syndrome, and severe OSA. Nasal obstruction is an independent risk factor for OSA, but there is no correlation of daytime nasal resistance with the severity of OSA. However, nasal resistance was an independent predictor of apnea-hypopnea index in a recent study of nonobese OSA patients. Rhinitis alone is associated with mild OSA, but commonly causes microarousals and sleep fragmentation. Reduction of nasal inflammation with topical treatment improves sleep quality and subsequent daytime sleepiness and fatigue. Patient compliance with the nasal continuous positive airway pressure (nCPAP) device is relatively low, in part due to adverse nasal effects.

Severe upper airway obstruction during sleep

Few disorders may manifest with predominantly sleep-related obstructive breathing. Obstructive sleep apnea (OSA) is a common disorder, varies in severity and is associated with significant cardiovascular and neurocognitive morbidity. It is estimated that between 8 and 18 million people in the United States have at least mild OSA. Although the exact mechanism of OSA is not well-delineated, multiple factors contribute to the development of upper airway obstruction and include anatomic, mechanical, neurologic, and inflammatory changes in the pharynx. OSA may occur concomitantly with asthma. Approximately 74% of asthmatics experience nocturnal symptoms of airflow obstruction secondary to reactive airways disease. Similar cytokine, chemokine, and histologic changes are seen in both disorders. Sleep deprivation, chronic upper airway edema, and inflammation associated with OSA may further exacerbate nocturnal asthma symptoms. Allergic rhinitis may contribute to both OSA and asthma. Continuous positive airway pressure (CPAP) is the gold standard treatment for OSA. Treatment with CPAP therapy has also been shown to improve both daytime and nighttime peak expiratory flow rates in patients with concomitant OSA and asthma. It is important for allergists to be aware of how OSA may complicate diagnosis and treatment of asthma and allergic rhinitis. A thorough sleep history and high clinical suspicion for OSA is indicated, particularly in asthma patients who are refractory to standard medication treatments.

Difficult-to-control asthma and obstructive sleep apnea

This study tested the hypothesis that asthma can promote obstructive sleep apnea (OSA) by looking at the prevalence of OSA among patients with difficult-to-control asthma receiving long-term oral corticosteroid (CS) therapy and examined some possible etiological factors. The study design was a prospective cohort study and was conducted in the pulmonary outpatient clinic of a tertiary care center in Haifa, Israel. Twenty-two consecutive patients with severe unstable asthma, 14 on continuous and 8 on bursts of oral CS, in addition to their standard therapy for a mean of 8.9 +/- 3.3 years, underwent a night polysomnography in a sleep laboratory regardless of sleep complaints. A standard questionnaire was completed upon attending the sleep laboratory. The OSA was defined as respiratory disturbance index (RDI) of > or = 5 and typical complaints. The correlation between RDI to asthma and morphometric parameters was tested. All but one patient had OSA [95.5% prevalence], with mean RDI of 17.7 +/- 2.5. The RDI values were significantly higher in the continuous CS therapy subgroup (21.4 +/- 3.4 vs. 11.1 +/- 1.6, p < 0.05]. The study group had above normal neck circumferences and body mass index. The former increased by 12.1% +/- 3.1% % to 29.8% +/- 1% during the oral CS therapy interval but had no significant effect on RDI as a covariant. This study showed an unexpectedly high prevalence of OSA among patients with unstable asthma receiving long-term chronic or frequent burst of oral CS therapy. It may be assumed that prolonged and especially continuous oral CS therapy in asthma increases airway collapsibility.