Sleep fragmentation thresholds of sleep fragmentation indices

Abstract

Sleep fragmentation is one of the main problems of sleep disorders especially in respiratory failure such as obstructive sleep apnoea syndrome (OSAS) as well as for patients in intensive care units for which sleep quality is important in the recovery process of the critically ill. During this last decade, a few indices of sleep quality such as sleep fragmentation index (SFI) and sleep diversity index (SDI) were developed. However, for practical use in medical care, a sleep fragmentation threshold beyond which the patient's sleep is considered as fragmented must be provided to the sleep expert. So, the aim of this work is to determine this sleep fragmentation threshold for both SFI and SDI. Sleep fragmentation of 111 adults PSG (55 healthy and 56 patients), has been evaluated by nine sleep experts of three different specializations (three pulmonologists, three neurophysiologists and three technical experts) usually working in a sleep laboratory. Thus, by using the receiver operating characteristic (ROC) curves we have determined the fragmentation threshold value for each of the nine sleep experts for the SFI and the SDI. It follows from these results that these two sleep fragmentation indices with their corresponding fragmentation thresholds values can be used to decide whether the patient's sleep is fragmented or not.