Sleep studies for sleep‐related breathing disorders

Abstract

SUMMARY Our understanding of sleep-related breathing disorders is still in a period of rapid change. Considerable uncertainty exists in several major areas of patient assessment. Although early definitions of sleep apnoea enshrined the concept of rigid guidelines, such an approach is no longer helpful, and may constrain potential advances. The recognition of the basic pathophysiological events in obstructive sleep apnoea (OSA) has evolved from purely apnoeas, to include hypopnoeas, and now to increased upper airway resistance alone. Our view as to the significant consequences of such respiratory events has also evolved from alterations to the classic sleep architecture, to hypoxic events, and now to micro-arousals and cardio-vascular events. The exact nature of a significant arousal is also far from clear, with the suggestion that perhaps even EEG based approaches to their measurement may not be telling us the whole story. Finally, the frequency of such respiratory events and their consequences, that lead to significant symptoms and long-term damage, is not known either. Thus, given this situation, the best we can achieve is broad guidelines that stress the main important physiological events and their consequences that need to be assessed, and then interpreted in conjunction with the patient's symptoms. This will not necessarily be the same for all patients and this report offers some general guidance, based on the experience of several centres throughout Europe.

A new approach to the analysis of the human sleep/wakefulness continuum

“…This means that by subtracting the value of the deep sleep output from that of the wakefulness output all three outputs can be combined, without significunt loss of information, into the single trace shown in Compared to the hypnogram, therefore, the network's outputs provide a much more accurate assessment of both sleep fragmentation and quality of sleep. Such an assessment is crucial to the study of sleep-related breathing disorders, where rule-based sleep staging has been shown to be unsuitable (Stradling 1992). Fig.…”

Value of beat-to-beat blood pressure changes, detected by pulse transit time, in the management of the obstructive sleep apnoea/hypopnoea syndrome

“…Daytime sleepiness results from the many transient arousals that fragment sleep in OSAHS and that are believed to be a response to the increases in inspiratory effort being made in an attempt to maintain adequate ventilation through a narrowed or collapsed upper airway [3,4].A respiratory sleep study to investigate OSAHS should therefore include either a measure of ventilatory effort or upper airway narrowing, and a measure of arousals as a marker of the resulting sleep fragmentation [5]. Because OSAHS is a relatively common disorder affecting 1-5% of the adult male population [6], and the financial resources for healthcare are limited, such respiratory sleep studies should also be cost-effective and, preferably, domiciliary [7].…”

“…A respiratory sleep study to investigate OSAHS should therefore include either a measure of ventilatory effort or upper airway narrowing, and a measure of arousals as a marker of the resulting sleep fragmentation [5]. Because OSAHS is a relatively common disorder affecting 1-5% of the adult male population [6], and the financial resources for healthcare are limited, such respiratory sleep studies should also be cost-effective and, preferably, domiciliary [7].…”

Accuracy of thermistors and thermocouples as flow-measuring devices for detecting hypopnoeas

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aaBreathing airflow is a physiological variable commonly monitored for assessing respiratory patterns and nocturnal events in studies aimed at diagnosing sleep disorders [1][2][3]. Given that in sleep studies the use of a pneumotachograph, which is the reference transducer for measuring flow, is rather cumbersome, airflow is routinely assessed by means of thermally sensitive devices such as thermistors and thermocouples.

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