早產兒心率變異性之分析研究

The analysis of heart rate variability for preterm infants

「心率變異性」乃是影響控制心臟之自主神經對於不同生理狀況反應的結果。對於早產兒心臟功能的變化影響之研究是一項比較少見之方向。藉由本研究能分析出早產兒心率變異性之特性、足月新生兒與早產兒間之差異性，以使早產兒疾病對於心臟功能之影響能獲得更詳細的資料，進而使早產兒疾病治療能有更多的幫助。本研究將所有新生兒分成足月兒與早產兒兩組。自2004年11月起至2005年05月，於高雄榮民總醫院新生兒加護病房、小兒加護病房、及嬰兒室中，共有35個足月新生兒與22個早產兒合乎本研究之條件。平均懷孕週數(mean gestational age)：足月兒為38.714±0.946週，早產兒為33.124±3.161週；平均出生體重(mean birth body weight)：足月兒為3168.54±483.39公克，早產兒為1919.70±493.08公克。早產兒的平均RR interval與SDNN明顯比足月兒低(459.81±38.28ms vs. 426.91±39.86ms, p=0.003與32.56±13.36ms vs. 21.13±16.96ms, p=0.006)。而早產兒normalized LF與LF/HF的比值比足月兒小(78.59±17.71ms2 vs. 68.73±18.53 ms2, p=0.049與7.22±5.69ms2 vs. 4.45±3.17, p=0.042)。結果發現足月兒的心跳速率比早產兒低，心率穩定度亦比早產兒高，此一現象證實，隨著年齡增加而mean RR interval亦增（即心跳速率下降），乃是副交感神經功能逐漸成熟，交感神經功能影響逐漸下降的結果。然而，本文以某醫學中心的案例研究卻發現早產兒的LF/HF值比足月兒來得低，可能由於早產兒的自主神經功能比起足月兒不成熟，此一逐漸成熟的過程將使心率變異性中LF/HF值逐漸上升。

「Heart rate variability」is the result of heart controlled by autonomic nerve system which responses to various physiological condition. It is little direction that study is performed for cardiac function to preterm neonates .By this research, we can analyze the specificity of heart rate variability of preterm neonates, the difference between full-term and preterm neonates, and get more information about the influence to cardiac function resulted from preterm diseases in order to get more utility to treatment for preterm diseases. This research divides enrolled neonates into full-term and preterm. From November of 2004 to May of 2005, 35 full-term and 22 preterm neonates enroll this research in the NICU, PICU, and BR ofVGH-KS. Mean gestational age of full-term and preterm neonates is 38.714±0.946 and 33.124±3.161 weeks, respectively; mean birth body weight of full-term and preterm neonates is 3168.54±483.39 and 1919.70±493.08 grams, respectively. The mean RR interval and SDNN of preterm neonates are significant lower than those of full-term neonates (459.81±38.28ms vs. 426.91±39.86ms, p=0.003 and 32.56± 13,36ms vs. 21.13±16.96ms, p=0.006); the normalized LF and LF/HF ratio of preterm neonates are lower than those of full-term neonates (78.59±17.71ms2 vs. 68.73±18.53 ms2, p=0.049 and 7.22±5.69ms2 vs. 4.45±3.17, p=0.042). We find the heart rate of full-term is lower and the stability of heart rate is higher than those of preterm neonates; this impact proves that the increase of mean RR interval (or decrease of heart rate) by age increasing results from maturation of parasympathetic nervous function and decrease of sympathetic nervous ftinction. In addition, we find the LF/HF ratio of preterm is lower than that of full-term neonates, it is believed that since the function of autonomic nerve system of preterm is less mature than that of full-term neonates, this process of progressive maturation causes the LF/HF ratio elevation.