方 舟,許 強(qiáng),盧才義
睡眠剝奪狀態(tài)下心率變異性變化的研究進(jìn)展
方 舟*,許 強(qiáng),盧才義
(解放軍總醫(yī)院心血管內(nèi)科,北京 100853)
睡眠剝奪可以導(dǎo)致自主神經(jīng)功能紊亂,而自主神經(jīng)功能對維持心血管系統(tǒng)的穩(wěn)定至關(guān)重要。心率變異性(HRV)分析是目前較為準(zhǔn)確的預(yù)測心臟自主神經(jīng)功能的無創(chuàng)性方法。近年來大量的研究著眼于采用HRV對正常睡眠以及睡眠剝奪狀態(tài)下心臟自主神經(jīng)功能進(jìn)行評價。急性以及慢性睡眠剝奪可以引起HRV時域分析與頻域分析指標(biāo)的明顯變化,且HRV指標(biāo)異常與心血管風(fēng)險明顯相關(guān)。本文對以上幾個方面進(jìn)行了綜述,并對未來的研究前景進(jìn)行了展望。
自主神經(jīng)系統(tǒng);心率變異性;睡眠;睡眠剝奪
正常的睡眠時間及節(jié)律對維持自主神經(jīng)(交感神經(jīng)和副交感神經(jīng))調(diào)節(jié)功能的穩(wěn)定具有重要意義[1]。睡眠剝奪能夠?qū)е滦难芟到y(tǒng)調(diào)節(jié)功能紊亂,其中心臟自主神經(jīng)功能紊亂是重要的機(jī)制之一[2,3]。心率變異性(heart rate variability,HRV)的分析被認(rèn)為是目前較為準(zhǔn)確地預(yù)測心臟自主神經(jīng)功能的無創(chuàng)性方法[4,5],在心肌梗死后或心力衰竭患者中,HRV的異常與患者心血管事件的發(fā)生風(fēng)險密切相關(guān)[6?8]。本文主要從HRV變化的角度綜述了各種形式的睡眠剝奪對心臟自主神經(jīng)功能的影響,以及其潛在的心血管風(fēng)險。
HRV分析方法主要有以下幾類。第一類是時域分析方法,其常用參數(shù)包括:(1)相鄰NN間期總體標(biāo)準(zhǔn)差(standard deviation between the NN period,SDNN)反映了總的HRV水平;(2)相鄰NN間期的均方根(root mean square values of the standard deviation,RMSSD)一般用來反映副交感神經(jīng)的輸出水平;(3)相鄰NN間期差值>50ms的百分比(percentage of differences exceeding 50ms between the NN period,pNN50)能夠敏感地反映迷走神經(jīng)張力的變化。第二類是頻域分析方法,常用參數(shù)包括:(1)總功率(total power,TP)的頻段≤0.14Hz,反應(yīng)總的HRV;(2)超低頻(Ultra Low Frequency,ULF)功率的頻段≤0.003Hz,反映了HRV的周期性變化;(3)極低頻(very low frequency,VLF)功率頻段在0.003~0.04Hz之間,主要受迷走神經(jīng)以及腎素?血管緊張素系統(tǒng)的支配;(4)低頻(low frequency,LF)功率頻段在0.04~0.15Hz之間,受交感神經(jīng)以及副交感神經(jīng)共同調(diào)節(jié);(5)高頻(high frequency,HF)功率頻段在0.15~0.4Hz,反映了副交感神經(jīng)的輸出水平。低頻和高頻成分的比值(LF/HF)代表了交感神經(jīng)與副交感神經(jīng)的平衡性[5,9]。近年來新發(fā)展出兩類HRV處理方法:一類為非線性分析方法,目前應(yīng)用于HRV研究的非線性指標(biāo)有近似熵、樣本熵、修正條件熵等[10];還有一類方法為心率震蕩。后兩類分析方法在睡眠剝奪研究中尚無報道。
1991年Ewing等[11]發(fā)現(xiàn)24h睡眠剝奪期間,會出現(xiàn)夜間的pNN50明顯降低,提示急性睡眠剝奪期間存在副交感神經(jīng)輸出水平的損害。隨后Tochikubo等[12]發(fā)現(xiàn)急性部分睡眠剝奪后,次日24h HRV的LF水平及LF/HF比值均明顯增高,提示急性部分睡眠剝奪后次日出現(xiàn)交感神經(jīng)亢進(jìn)。鐘旭等[13]對18例健康青年男性進(jìn)行了整夜完全睡眠剝奪(36h睡眠剝奪),結(jié)果發(fā)現(xiàn)HRV的LF與LF/HF顯著增加,指標(biāo)HF顯著降低,整夜完全睡眠剝奪可導(dǎo)致健康青年男性心血管交感神經(jīng)輸出增加,副交感神經(jīng)輸出明顯下降。Sgoifo等[14]對大鼠進(jìn)行了48h睡眠剝奪,隨后對大鼠施加再次應(yīng)激刺激,結(jié)果顯示,大鼠心率在睡眠剝奪后明顯增加,HRV的時域分析指標(biāo)(SDNN、RMSDD)明顯下降,提示總HRV降低伴隨副交感神經(jīng)輸出抑制;大鼠再次接受應(yīng)激刺激時HRV指標(biāo)顯示交感神經(jīng)輸出水平過度激活;且出現(xiàn)室性早搏發(fā)生率明顯增加。以上實驗均提示,急性完全睡眠剝奪可能導(dǎo)致HRV降低伴隨交感神經(jīng)輸出成分相對增加,副交感神經(jīng)抑制,可能是誘發(fā)心律失常的潛在機(jī)制。Vaara等[15]探討了更長時間的睡眠剝奪對HRV的影響,發(fā)現(xiàn)經(jīng)過60h的睡眠剝奪,受試者的HRV雖然降低,但是心臟自主神經(jīng)的輸出水平趨向于副交感輸出為主,伴隨受試者的困倦感,這可能是一種保護(hù)機(jī)制。但受試者在睡眠剝奪后進(jìn)行直立試驗時,仍表現(xiàn)出了LF/HF比值增高的趨勢,提示在應(yīng)激下仍出現(xiàn)了交感神經(jīng)輸出相對亢進(jìn)。以上的結(jié)果顯示急性完全睡眠剝奪導(dǎo)致了HRV的減低,伴有心臟自主神經(jīng)功能調(diào)節(jié)明顯受損,且在應(yīng)激狀態(tài)下交感神經(jīng)輸出進(jìn)一步亢進(jìn),可能誘發(fā)心血管事件的發(fā)生。
不同睡眠時相的急性睡眠剝奪也對HRV的影響存在明顯的差異。Sayk等[16]對11名健康人進(jìn)行了整夜的單純非快速動眼(non-rapid eye movement,NREM)睡眠剝奪,受試者次日的HRV無明顯變化,同時肌肉交感活性及血壓也未受影響,提示短期NREM睡眠剝奪可能對次日的心臟自主神經(jīng)功能調(diào)節(jié)無明顯影響;而快速動眼(rapid eye movement,REM)睡眠剝奪,常見于焦慮、創(chuàng)傷后應(yīng)激以及反復(fù)噩夢驚醒的人群。Nielsen等[17]通過對反復(fù)出現(xiàn)噩夢驚醒的人群與普通人群進(jìn)行了比較,對以上兩類人群進(jìn)行REM睡眠剝奪,會導(dǎo)致剝奪次日再次睡眠時REM比例的明顯增高,且伴有REM過程中HRV的LF標(biāo)準(zhǔn)值及LF/HF比值的明顯增加,反復(fù)噩夢驚醒的受試者以上表現(xiàn)更為明顯,提示急性REM睡眠剝奪會導(dǎo)致心臟交感神經(jīng)輸出亢進(jìn),可能與焦慮癥或者創(chuàng)傷后應(yīng)激(精神緊張性)障礙(post-traumatic stress disorder,PTSD)患者心血管事件風(fēng)險增加有關(guān)。
慢性睡眠剝奪的形式多樣,參與機(jī)制繁多,作用機(jī)制復(fù)雜,目前的研究結(jié)論非常不一致。慢性睡眠剝奪的一種形式是睡眠限制,即長期每天睡眠<5h。Spiegel等[18]對11名青年男性進(jìn)行6d睡眠時間<4h的睡眠限制后,受試者在睡眠限制期間日間交感神經(jīng)的輸出明顯增加,表現(xiàn)為LF/HF比值的增高;伴隨應(yīng)激相關(guān)的糖耐量及內(nèi)分泌激素(促甲狀腺激素、皮質(zhì)醇類激素)水平的異常,提示慢性睡眠限制可以導(dǎo)致機(jī)體處于應(yīng)激狀態(tài)。另一項研究證實,慢性睡眠不足可以造成受試者在站立情況下短時程HRV頻域分析指標(biāo)向交感神經(jīng)輸出增加趨勢轉(zhuǎn)變,即LF/HF明顯升高[19]。Takase等[20]分析了男性大學(xué)生在考試期間出現(xiàn)的慢性(≥4周)睡眠不足時24h的HRV,受試者全天總HRV及時域分析指數(shù)明顯下降,循環(huán)腎上腺素水平明顯增加,提示慢性睡眠不足導(dǎo)致交感神經(jīng)輸出水平相對增加。Muenter等[21]則發(fā)現(xiàn)對健康人群進(jìn)行睡眠限制,每天<4h睡眠,持續(xù)4d,臥位測定的短時程HRV時域分析指標(biāo)無明顯變化,心率降低。Sasaki等[22]對工人的慢性睡眠剝奪與HRV的變化特點進(jìn)行了研究,結(jié)果發(fā)現(xiàn),長期日間加班的工人(存在慢性睡眠不足)其HRV的LF/HF比值明顯降低,提示副交感神經(jīng)輸出相對增加,其與白天的困倦程度相關(guān)。以上結(jié)論表面上看相互沖突,但是,仔細(xì)分析可以發(fā)現(xiàn),提示交感神經(jīng)輸出相對增加的試驗大部分是在日間全天活動或者接受測試時進(jìn)行的,而后面提示副交感神經(jīng)輸出相對亢進(jìn)的試驗多是來自于休息狀態(tài)下臥位或者坐位采集的。這些提示了慢性睡眠限制的試驗可以導(dǎo)致總HRV降低,心臟自主神經(jīng)調(diào)節(jié)功能紊亂,在休息狀態(tài)下副交感輸出相對亢進(jìn),與疲勞感相關(guān);而在應(yīng)激狀態(tài)下,交感神經(jīng)過度激活,增加心血管事件發(fā)生的風(fēng)險。
睡眠節(jié)律的紊亂是慢性睡眠剝奪的另一種形式,主要發(fā)生在夜班及輪班工作的人群中。有研究表明[23],初始參加夜班的工人24h總HRV的下降伴隨LF與HF標(biāo)準(zhǔn)值的下降,但是LF/HF升高,提示心臟自主神經(jīng)調(diào)節(jié)輸出水平受損,以副交感神經(jīng)輸出受損更為顯著,Holmes等[24]發(fā)現(xiàn)持續(xù)1周的夜班工作,日間睡眠期間的交感神經(jīng)活動水平明顯增加,而總HRV及體現(xiàn)迷走神經(jīng)輸出的RMSDD明顯下降。Su等[25]對夜班工人的研究表明,在進(jìn)行夜班工作期間,健康男性出現(xiàn)總的HRV(SDNN)降低,LF標(biāo)準(zhǔn)值及LF/HF比值明顯升高,HF標(biāo)準(zhǔn)值下降;提示夜間工作時出現(xiàn)了交感神經(jīng)輸出亢進(jìn),伴隨副交感神經(jīng)輸出水平的降低。
睡眠剝奪導(dǎo)致機(jī)體出現(xiàn)交感神經(jīng)輸出相對亢進(jìn),副交感神經(jīng)相對抑制,從而導(dǎo)致心律失常的風(fēng)險明顯增加;對大鼠接受48h睡眠剝奪后HRV的變化特點的研究提示HRV的時域分析指標(biāo)(SDNN、RMSDD)明顯下降;與大鼠再次接受應(yīng)激刺激時室性心律失常發(fā)生率明顯相關(guān)[14]。人群慢性睡眠剝奪的研究也證實,室性心律失常的發(fā)生率與HRV的LF、LF/HF指標(biāo)升高密切相關(guān)[23]。
Sauvet等[26]發(fā)現(xiàn)健康人群進(jìn)行40h的睡眠剝奪期間,HRV的LF值顯著升高,細(xì)胞間黏附分子?1及白介素?6的水平增加,伴隨皮膚血管流導(dǎo)率明顯下降,提示睡眠剝奪除交感神經(jīng)水平亢進(jìn)外還可早期伴隨血管內(nèi)皮功能異常及炎性反應(yīng);Tobaldini等[27]對內(nèi)科醫(yī)師的研究也證實,夜班工作受試者主要表現(xiàn)為HRV的LF指標(biāo)以及LF/HF比值明顯升高,HF比值明顯下降,提示出現(xiàn)基礎(chǔ)交感神經(jīng)輸出水平的亢進(jìn),但是在進(jìn)行直立傾斜試驗時,睡眠剝奪后受試者的LF標(biāo)準(zhǔn)值以及LF/HF比值增加幅度明顯降低,HF標(biāo)準(zhǔn)值下降幅度也明顯降低,提示睡眠剝奪明顯損害了健康人群的自主神經(jīng)調(diào)節(jié)能力,機(jī)體應(yīng)對重力變化的能力因而受損。同時血清學(xué)檢查也證實,夜班后體內(nèi)炎癥因子如干擾素?γ等水平明顯增加,這可能與睡眠剝奪導(dǎo)致的基礎(chǔ)交感神經(jīng)輸出水平亢進(jìn)有關(guān)。
HRV是進(jìn)一步了解睡眠剝奪導(dǎo)致心血管事件的內(nèi)在機(jī)制的重要手段,一方面我們可以通過新的分析方法,如非線性分析方法及室性早搏后心率震蕩等方法進(jìn)一步探索睡眠剝奪相關(guān)HRV的變化規(guī)律;另一方面,也可以采取更多的統(tǒng)計分析手段,對不同頻段的能量譜或時域分析指標(biāo)與心血管事件的相關(guān)性進(jìn)行分析,進(jìn)一步明確HRV對睡眠剝奪導(dǎo)致心血管事件的預(yù)測價值。針對睡眠剝奪導(dǎo)致的HRV進(jìn)行干預(yù)的研究目前仍處于起步階段,具有廣闊的研究前景。
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(編輯: 劉子琪)
Research progress on sleep deprivation-induced heart rate variability changes
FANG Zhou*, XU Qiang, LU Cai-Yi
(Department of Cardiology, Chinese PLA General Hospital, Beijing 100853, China)
Sleep deprivation leads to disturbance of the autonomic nervous system, which plays an important role in maintaining the stability of the cardiovascular system. Heart rate variability (HRV) analysis is a non-invasive and reliable tool in evaluating the activities of cardiovascular autonomic nervous system. In recent years, many studies focused on the evaluation of cardiac autonomic modulation in conditions of normal sleep and sleep deprivation by means of HRV analysis. Both acute and chronic sleep deprivations were proved to evoke dramatic and complex changes in HRV time-domain and frequency-domain indices. The changes of HRV were closely related to risks of cardiac events. The present article reviewed the studies on the fields mentioned above and brought forward an agenda for future research.
autonomic nervous system; heart rate variability; sleep; sleep deprivation
R541.7
A
10.11915/j.issn.1671-5403.2015.05.091
2015?03?17;
2015?04?01
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