| 作者：Laurie Barclay, MD | | 出處：WebMD醫學新聞 |
December 4, 2008 — 根據發表於12月小兒科期刊的研究結果，睡眠時的血壓變化可能與發生嬰兒猝死症(SIDS)有關。
澳洲Monash大學Ritchie嬰兒健康研究中心的Nicole B. Witcombe等人寫道，早產嬰兒的SIDS風險增加，可能是因為心律與血壓自體控制不成熟；之前的研究顯示，早產嬰兒的心律和血壓與校正年齡組不一樣；不過，有關這個年紀的資訊有限。本研究的目標是確認早產者在出生後6個月內、與達到校正年齡後之心律與血壓，包括增加SIDS風險的年紀，以瞭解SIDS的病理。
研究針對25個早產兒和20個週產兒在2至4週、2至3個月、5至6個月校正年齡時進行日間多頻道睡眠記錄；在嬰兒的手腕運用光體積描繪圖訊號(Finometer, Finapres Medical Systems BV公司) 測量安靜與活動睡眠時的血壓。
研究的所有年紀中，早產組在安靜與活動睡眠時都有較低的血壓，但是兩組的心律沒有差別。對於早產組的嬰兒，校正年齡2至3個月時的平均血壓比校正年齡2至4週和5至6個月時低，各年紀安靜睡眠時的血壓都比活動睡眠時低。心律隨著年紀增加而降低。在5至6個月校正年齡時，安靜睡眠時的心律低於活動睡眠時。
研究作者寫道，睡眠狀態與年紀影響早產嬰兒校正年紀6個月內心律與血壓模式；值得注意的是，早產嬰兒之平均血壓比年紀相仿的足月嬰兒低，意味著對於早產嬰兒的心血管控制要有長期的改變。
研究限制包括研究樣本之異質性；研究中的25個嬰兒有3個生產時比懷孕週數小；根據概念年紀進行足月與早產嬰兒之配對，早產嬰兒SIDS風險最大的時期發生在比研究中的2至3個月更早的時候。
研究作者結論表示，我們在早產和足月嬰兒之間的血壓發現顯著差異，這可能是因為早產兒之SIDS風險增加。需要進行睡眠時心血管變化與檢視重覺反射反應的後續研究，以進一步瞭解早產嬰兒是否在出生後初期有不佳的心血管控制。這些研究或許可以進一步解釋早產兒SIDS風險增加的機轉，以及瞭解未來對心血管系統的影響。
澳洲國家健康與醫學研究委員會支持本研究。作者宣稱沒有相關資金上的往來。 | |
Blood Pressure Changes During Sleep May Be Related to SIDS
By Laurie Barclay, MD
Medscape Medical News
December 4, 2008 — Blood pressure changes during sleep may be related to development of sudden infant death syndrome (SIDS), according to the results of a study published in the December issue of Pediatrics.
"Preterm infants are at an increased risk of [SIDS], which may result from immature autonomic control of heart rate and blood pressure," write Nicole B. Witcombe, BSc, from the Ritchie Centre for Baby Health Research at Monash University in Melbourne, Victoria, Australia, and colleagues. "Previous studies have demonstrated that preterm infants have altered heart rate and blood pressure control at term-equivalent age; however, little information is available beyond this age. The aim of this study was to determine the effect of preterm birth on heart rate and blood pressure control over the first 6 months of life after reaching term-equivalent age, including the age at which [SIDS] risk is increased, to understand the pathogenesis of [SIDS]."
Daytime polysomnography was performed in 25 preterm and in 20 term infants at 2 to 4 weeks, 2 to 3 months, and 5 to 6 months of term-corrected age. A photoplethysmographic cuff (Finometer, Finapres Medical Systems BV) applied around the infant's wrist measured blood pressure during quiet and active sleep.
At all ages studied, the preterm group had lower blood pressure during both quiet and active sleep, but heart rate did not differ between groups. For the infants in the preterm group, average blood pressure was lower at 2 to 3 months' corrected age than at 2 to 4 weeks' and 5 to 6 months' corrected age and was lower in quiet sleep than in active sleep at all ages studied. Heart rate decreased with increasing age. At 5 to 6 months' corrected age, heart rate was lower in quiet sleep than in active sleep.
"Sleep state and age affect heart rate and blood pressure patterns in prematurely born infants over the first 6 months of term-corrected age," the study authors write. "It is notable that preterm infants had persistently lower blood pressure compared with age-matched term infants, signifying long-term alterations in cardiovascular control in infants born prematurely."
Limitations of this study include heterogeneity of the study sample; that 3 of the 25 infants studied were born small for gestational age; and matching of term and preterm infants for conceptual age, even though the period of peak SIDS risk in preterm infants occurs at an earlier conceptual age than the 2 to 3 months' age studied.
"We identified significant differences in [blood pressure] between preterm and term infants that may contribute to the increased risk of SIDS in preterm infants," the study authors conclude. "Additional studies examining baroreflex responses and cardiovascular variability during sleep are required to further understand whether preterm infants have impaired cardiovascular control during the early postnatal period. These studies may further explain the mechanisms involved in the increased risk for SIDS associated with preterm birth and the impact that this may have on the cardiovascular system later in life."
The National Health and Medical Research Council of Australia supported this study. The authors have disclosed no relevant financial relationships.
Pediatrics. 2008;122:e1242–e1248.
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[ 本帖最後由 goodcat1111 於 2008-12-18 09:35 編輯 ] |
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