＜REM-specific sleep apnea＞

・主としてREM sleep中にOSA (obstructive sleep apnea)が起る。

・したがって、overall AHI may be low even if the AHI during REM sleep is fairly high ��これが手がかり

・NREM sleep中には、�@heavy snoring

                                    or

                           �ARERAs (=UARS)（下記参照） を伴う。

                                                         

・EDSを説明できる他の疾患がない（下記参照）ならば治療の適応となる。CPAPで治療。

 

                                                  
＜上気道抵抗症候群UARS＝RERAs＞

・overall AHIから期待されるEDSとpatientが訴えるEDSが合わない時に考慮すべき事：

�@) normal night-to-night variation in AHI due to �@different body positions (no supine monitoring)

                                                                  �Avariable amounts of REM sleep (low amount of REM sleep)

                                                                  �Bvariations in nasal resistance (nasal congestion → nasal

                                                         resistance↑ → amount of apnea↑)

                                                                  �Ceffect of medication and bevevages

�A) alcohol (ethanol) : regular use of ethanol worsens sleep apnea considerably due to

  �@inhibitory effect on upper airway muscle activity and increasing snoring and apnea

  �Ainpairs the arousal response to airways occlusion; thus, apneas tend to be longer and associated with more

     severe desaturations

  �Bsupress REM sleep; this results in an increase in the REM latency and a shift of REM toward the morning (as

     the ethanol level drops)

�B) insufficient sleep

�C) narcolepsy

�D) idiopathic hypersomnolence

�E) depression

�F) PLMS

�G) drug abuse

�H) REM-specific sleep apnea（上述）

�I) UARS (RERAs)

11) progressive hydrocephalus

12) posttraumatic hypersomnia：hypersomnia develops 6-18 months after head trauma

・arousal index much higher than the AHI ��RERAの手がかり

・definition: RERAs are arousals following periods of high inspiratory effort that do not meet

  criteria for apnea or hypopnea. originally                       ↓

  AHI＜5/hr & RAI＞10/hr                      �@ご存じの通りobstructive apnea/hypopneaでは当たり前！

                         ↓　　　　　　　　　　　　　　　     �A正常人では-20 to -30 cmH2Oでarousal起るが、snorers and

                         ↓                                  patients with OSAでは-40 to -80 cmH2Oになるまで起らない。

                         ↓  　　　　　　　　　　　　　　　　 �Barousalを起こすか否かはmagnitude of inspiratory effort and

                     ↓                                         threshold of arousalにdepend on。

　　but RAI＜10/hrのUARSもある。RAI＞10/hrはnormal groupのmedian（中央値）

・arousalはEDSの原因になるが、一方ではarousal responseにより、apneaを終了させてairway patencyを

　保っていると解釈することも出来る。

・RAI＞10/hr plus no other reason to explain sleepiness can be used to define UARS or mild OSA.

     

・RAI (Respiratory Arousal Index)＝respiratory arousals per hour of sleep＝index of the amount of

  sleep fragmentation secondary to respiratory events

　　　　　　　　　　　　　　　　　　　　　　　　　　　　↓

         include arousals associated with the termination of apnea, hypopnea and RERAs

         in sleep lab not using nasal pressure, "snore arousals" (defined as those following heavy snoring) are

         included in the RAI.

         For detecting increased respiratory effort, esophageal pressure monitoring is the gold standard, but

         nasal pressure monitoring is gaining popularity.　　↓

　　　　　　　normal breathing respiratory effirt はa maximum of -9 cmH2Oまで（-2 to -3 cmH2O in a small women）

・eventをRERAととるかobstructive hypopneaととるかは、hypopneaの定義次第である。

  if you accept any drop in the flow (nasal pressure) for 10 or more seconds + an arousal as a hypopnea,

  there will be few RERAs because most events will be labeled hypopneas.

・nasal pressureをmonitorすれば、spontaneous arousalsはcorrectly identified as respiratory arousals

・nasal pressure monitoring reveals repetitive episode of airflow limitation (flattening of an initial peak or

  an abrupt decrease immediately after an initial peak)

  followed by an arousal and temporary reversal of the flattening (return to a normal rounded pattern).

  The flattened nasal pressure signal suggests increased respiratory effort.

・Using standard monitoring (=not using nasal pressure monitoring), the only clue that UARS may be

  present is repetitive episodes of subtle changes in airflow (thermistor) followed by arousals (or trasient

  EEG changes).

・無呼吸apnea、低呼吸hypopnea、動脈血酸素飽和度低下desaturationは伴わない。

・RERAｓ is the arousal characterizing UARS. ＝ respiratory arousals secondary to high respiratory (inspiratory) efforts（呼吸努力の亢進） → repeated arousal（覚醒） → sleep fragmentation（睡眠の分断） → EDSを生じる。（obstructive apnea/hypopneaのarousalも同様）

・主訴major complaintはfatigue rather than EDS. snoring is common but not always.

・治療はCPAP。