Sleep apnea: clinical investigations in humans

Evidence-based recommendations for the assessment and management of sleep disorders in older persons

Sleep-related disorders are most prevalent in the older adult population. A high prevalence of medical and psychosocial comorbidities and the frequent use of multiple medications, rather than aging per se, are major reasons for this. A major concern, often underappreciated and underaddressed by clinicians, is the strong bidirectional relationship between sleep disorders and serious medical problems in older adults. Hypertension, depression, cardiovascular disease, and cerebrovascular disease are examples of diseases that are more likely to develop in individuals with sleep disorders. Conversely, individuals with any of these diseases are at a higher risk of developing sleep disorders. The goals of this article are to help guide clinicians in their general understanding of sleep problems in older persons, examine specific sleep disorders that occur in older persons, and suggest evidence- and expert-based recommendations for the assessment and treatment of sleep disorders in older persons. No such recommendations are available to help clinicians in their daily patient care practices. The four sections in the beginning of the article are titled, Background and Significance, General Review of Sleep, Recommendations Development, and General Approach to Detecting Sleep Disorders in an Ambulatory Setting. These are followed by overviews of specific sleep disorders: Insomnia, Sleep Apnea, Restless Legs Syndrome, Circadian Rhythm Sleep Disorders, Parasomnias, Hypersomnias, and Sleep Disorders in Long-Term Care Settings. Evidence- and expert- based recommendations, developed by a group of sleep and clinical experts, are presented after each sleep disorder.

Bibliometric analysis of obstructive sleep apnea research trends

BACKGROUND

This study aimed to describe current trends and areas of future research using a bibliometric evaluation of the publication output associated with research on obstructive sleep apnea (OSA) during the 16-year period of 1991-2006.

METHODS

Data encompassing the period from 1991 to 2006 were extracted from the Science Citation Index online version. We analyzed selected documents with "obstructive sleep apnea", "obstructive apnea", or "OSA" as a part of the title, abstract, or key words and reported the following parameters: trends of publication output, journal pattern, country of publication, authorship, author-generated key words, and KeyWords Plus.

RESULTS

The annual number of articles on OSA grew at a faster rate than did the number of general scientific publications, from approximately 200 in 1991 to 650 in 2006. The main subject categories in which research on OSA was conducted were the respiratory system and clinical neurology, each of which accounted for > 10% of total articles. Most of the research was conducted in the major industrial countries, with most international collaborations involving the United States and Canada. Certain terms were identified by KeyWords Plus but not by author-generated key words, and some terms increased in frequency of use over time.

CONCLUSION

This study provides a bibliometric analysis showing that the annual number of publications related to OSA has been increasing at a much faster rate than the overall scientific literature during the past 16 years in a growing number of specialized journals. Analysis of key words (KeyWords Plus) suggests research trends and areas for future research.

Review of sleep disorders

Sleep disorders are common and may result in significant morbidity. Examples of the major sleep disturbances in primary care practice include insomnia; sleep-disordered breathing, such as obstructive sleep apnea; central nervous system hypersomnias, including narcolepsy; circadian rhythm sleep disturbances; parasomnias, such as REM sleep behavior disorder; and sleep-related movement disorders, including restless legs syndrome. Diagnosis is based on meticulous inventory of the clinical history and careful physical examination. In some cases referral to a sleep laboratory for further evaluation with polysomnography, a sleep study, is indicated.

Perceived informational needs, side-effects and their consequences on adherence - a comparison between CPAP treated patients with OSAS and healthcare personnel

OBJECTIVE

To compare perceptions among continuous positive airway pressure (CPAP) treated patients with obstructive sleep apnoea syndrome (OSAS) and healthcare personnel with regard to informational needs, side-effects and their consequences on adherence.

METHODS

A cross-sectional descriptive design was used including 350 CPAP treated OSAS patients from three Swedish hospitals and 105 healthcare personnel from 26 Swedish hospitals. Data collection was performed using two questionnaires covering informational needs, side-effects and adherence to CPAP.

RESULTS

Both groups perceived all surveyed informational areas as very important. Patients perceived the possibilities to learn as significantly greater in all areas (p<0.001) compared to healthcare personnel, and scored significantly higher regarding positive effects on adherence of information about pathophysiology (p<0.05), self-care (p<0.001) and troubleshooting (p<0.01). A total of 11 out of 15 surveyed side-effects were perceived to be more frequent by healthcare personnel (p<0.01-p<0.001). They also scored all side-effects to cause greater problems and decrease the CPAP use to a greater extent (p<0.001).

CONCLUSION

Knowledge about these differences between patients and healthcare personnel regarding educational needs, side-effects and their effects on adherence can be important when designing educational programmes to increase CPAP adherence.

PRACTICE IMPLICATIONS

Measurement of these parameters before, during and after educational programs are suggested.

Expenditure on health care in obese women with and without sleep apnea

STUDY OBJECTIVES

To determine the effect of obesity and sleep apnea on health care expenditure in women over 10 years.

DESIGN

Retrospective observational study

SETTING

Tertiary university-based medical center

PATIENTS AND CONTROLS

Three groups of age-matched women: 223 obese women with OSAS (body mass index: 39.3 +/- 0.6 kg/m2), and from the general population, 223 obese controls (BMI 36.3 +/- 0.4) and 223 normal weight controls (BMI 23.9 +/- 0.4).

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

We examined health care utilization in the 3 matched groups for the 10 years leading up to the documentation of OSAS. The mean physician fees and the number of physician visits were significantly higher in obese controls than in normal weight controls during the observed period. Physician fees and physician visits progressively increased in the 10 years before diagnosis in the OSAS cases and were significantly higher than in the matched obese controls. Physician fees, in Canadian dollars, one year before diagnosis in the OSAS cases were higher than in obese controls: $547.49 +/- 34.79 vs $246.85 +/- 20.88 (P<0.0001). More was spent for OSAS cases on physician fees for circulatory, endocrine and metabolic diseases, and mental disorders than the obese controls. Physician visits one year before diagnosis in the OSAS cases were more frequent than in the obese controls: 13.2 +/- 0.73 visits vs 7.26 +/- 0.49 visits (P<0.0001).

CONCLUSIONS

Obese women are heavier users of health services than normal weight controls. Obese women with OSAS use significantly more health services than obese controls. Since OSAS imposes a greater financial burden, treatment of OSAS may reduce other comorbidities and lower overall medical costs.

Normal probability testing of snore signals for diagnosis of obstructive sleep apnea

Obstructive Sleep Apnea (OSA) is a highly prevalent disease in which upper airways are collapsed during sleep, leading to serious consequences. The standard method of OSA diagnosis is known as Polysomnography (PSG), which requires an overnight stay in a specifically equipped facility, connected to over 15 channels of measurements. PSG requires (i) contact instrumentation and, (ii) the expert human scoring of a vast amount of data based on subjective criteria. PSG is expensive, time consuming and is difficult to use in community screening or pediatric assessment. Snoring is the most common symptom of OSA. Despite the vast potential, however, it is not currently used in the clinical diagnosis of OSA. In this paper, we propose a novel method of snore signal analysis for the diagnosis of OSA. The method is based on a novel feature that quantifies the non-Gaussianity of individual episodes of snoring. The proposed method was evaluated using overnight clinical snore sound recordings of 86 subjects. The recordings were made concurrently with routine PSG, which was used to establish the ground truth via standard clinical diagnostic procedures. The results indicated that the developed method has a detectability accuracy of 97.34%.

[The role of family physicians in the recognition and screening of obstructive sleep apnea]

Obstructive sleep apnea is the most frequent sleep disorder. The prevalence of sleep apnea in the general population is 2-4% and the main characteristic of the disease is the intermittent cessation or substantial reduction of airflow during sleep, caused by complete, or near complete upper airway obstruction. Decreased airflow is followed by oxygen desaturation and intermittent arousals. The clinical presentation of the disorder is complex. Loud snoring with breathing pauses and daytime sleepiness should raise the suspicion of sleep apnea, but we have to consider this disease if the patient has therapy resistant hypertension, heart failure, arrhythmias, stroke, depression or memory problems. Family physicians have an important role in recognizing sleep apnea. High risk patients can easily be identified by the main symptoms and using the Berlin sleep apnea questionnaire. These patients should be referred to a sleep laboratory for polysomnographic assessment and, if necessary, for further treatment.

Energy expenditure and respiratory diseases: is there a link?

Recent studies have suggested that respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea syndrome (OSAS), influence energy expenditure (EE). This influence on energy balance may be responsible for the weight changes that are often seen in individuals suffering from OSAS and COPD. However, even though EE has been assessed in several studies, be it in OSAS or COPD, there are still controversies regarding these potential relationships. Thus, the objective of this review is to describe some of the potential mechanisms that may affect EE in respiratory diseases and, thereby discuss whether there seems to be an explanation for the aforementioned relationship. The primary focus is on the oxygen transport system, which may be an important determinant for the relationship between both of these respiratory diseases and EE.

Symptom screening in detection of occupational solvent-related encephalopathy

OBJECTIVES

Sensitive and easily applicable methods are needed for early detection of central nervous system adverse effects related to occupational solvent exposure. The present study evaluates how symptom screening works in practice.

METHODS

A cross-sectional questionnaire survey was conducted on 2,000 construction workers, including painters and carpenters, in Finland. Scores were calculated for symptoms relevant for chronic solvent encephalopathy (CSE). Responses on exposure and health were compared between subjects with high score (N = 28) and all other respondents. The respondents with the highest scores, regardless of their occupation and exposure, were invited for clinical examination to investigate the aetiologies of the symptoms. If the examination resulted in a suspicion of CSE, a multidisciplinary differential diagnostic follow-up procedure was performed.

RESULTS

The respondents with highest symptom scores were more exposed to solvents than those with lower scores (P < 0.001) and reported more often physician-diagnosed diseases, especially psychiatric disorders (P < 0.001). They also consumed more alcohol (P = 0.005) and were more often unemployed or unable to work (P < 0.001). In the clinical examination, sleep disturbances, somatic disorders, depression, unemployment, and alcohol use were commonly found in addition to considerable solvent exposure history and clinical neurological findings. Further examinations and a diagnostic follow-up verified three cases of encephalopathy. One case was a CSE, an occupational disease. The other two encephalopathy cases had multifactorial aetiology including solvents.

CONCLUSIONS

Screening in active workforce for symptoms of cognitive dysfunction identifies highly solvent-exposed workers and also reveals occupational and non-occupational cases of encephalopathy. Evaluation of differential diagnostic conditions is essential in the detection of CSE. A stepwise model is proposed.

Determination of reference ranges for transcutaneous oxygen and carbon dioxide tension and the oxygen challenge test in healthy and morbidly obese subjects

BACKGROUND

Transcutaneous monitoring of oxygen and carbon dioxide tension emerged decades ago as reliable, indirect measurements of arterial pressure of oxygen and carbon dioxide in neonates. Investigators have since found other valuable roles for this modality, particularly in critically ill adults. This investigation was undertaken to further characterize these measurements in normal and in obese adults, who are contributing to a rising proportion of intensive care unit admissions.

MATERIALS AND METHODS

Transcutaneous sensors were adjusted for barometric pressure and calibrated to reference gases. The following were measured: equilibration time; oxygen saturation; transcutaneous oxygen tension; and transcutaneous carbon dioxide tension on room air and after administering fraction of inspired oxygen of 1.0 for 5 min (Oxygen Challenge Test).

RESULTS

One hundred three healthy and 47 obese subjects were enrolled. Oxygen Challenge Test values were 131.5 +/- 57.4 and 171.6 +/- 65.9 mm Hg for obese and healthy subjects, respectively (P value <0.001). Smoking status, respiratory rate, and transcutaneous oxygen tension on room air best predicted the Oxygen Challenge Test response. A negative correlation was found between transcutaneous oxygen on room air and the Oxygen Challenge Test versus body mass index (P < 0.001).

CONCLUSIONS

Reference ranges were determined for transcutaneous oxygen and carbon dioxide tension and the Oxygen Challenge Test in obese and in normal, healthy subjects. Increasing body mass index was associated with a lower baseline transcutaneous oxygen tension, but it was not an independent predictor of the Oxygen Challenge Test response in multivariate analysis.