氯胺酮和咪达唑仑对儿童心率变异的影响

目的观察氯胺酮和咪达唑仑静脉麻醉对儿童心率变异（HRV）的影响。 方法选择5～6岁的手术患儿，随机分为2组，氯胺酮组（n=23）患儿静脉注射氯胺酮2mg/kg，咪达唑仑组(n=21)患儿静脉注射咪达唑仑0.2mg/kg。两组患儿维持自主呼吸。监测患儿的心率（HR）、平均动脉血压（MAP）和脉搏氧饱和度（SpO₂）；记录用药前后HRV参数，包括总功率（TP）、低频段（LF）和高频段（HF），计算LF和HF的标准化值nuLF（LF/TP×100%）和nuHF（HF/TP×100%）。结果氯胺酮麻醉后TP和HF降低(P<0.05)，LF变化不明显，nuLF由（63±16）% 升至（71±13）%(P<0.05)，nuHF由（32±15）% 降至（21±13）%(P<0.05)。咪达唑仑麻醉后TP和LF降低(P<0.05)，HF无明显改变，nuLF由（65±15）%降至（48±16）%(P<0.05)，nuHF由（33±15）%升至（42±16）%(P<0.05)。 结论氯胺酮和咪达唑仑静脉麻醉对儿童HRV产生不同影响，氯胺酮兴奋交感神经活性，咪达唑仑抑制交感神经活性。

Effects of ketamine and midazolam on heart rate variability in children

To study the effects of ketamine and midazolam on heart rate variability (HRV) in children. Methods Forty-four children aged 5 to 6 years old (ASA I) were randomly divided into two groups, and intravenously received 2mg/kg ketamine (n=23) or 0.2mg/kg midazolam (n=21). All patients kept spontaneous respiration. Heart rate (HR), mean arterial pressure (MAP) and pulse oxygen saturation (SpO₂) were monitored. HRV parameters including total power (TP), low frequency component (LF) and high frequency component (HF) were recorded before and after drug administration. Normalized unit power was derived as follows: nuLF=LF/TP×100%, nuHF = HF/TP×100%. ResultsThe levels of TP and HF decreased (P<0.05), nuLF increased from （63±16）% to （71±13）% (P<0.05) and nuHF attenuated from （32±15）% to （21±13）% (P<0.05) after ketamine administration. While after receiving midazolam, the value TP and LF reduced（P<0.05）, nuLF decreased from（65±15）% to （48±16）%（P<0.05）and nuHF increased from （33±15）% to（ 42±16）%（P<0.05）. ConclusionKetamine and midazolam have different effects on HRV in children, indicating enhancement of sympathetic nerve tension by ketamine and inhibition of sympathetic nerve tension by midazolam.