Advanced Medical Emergency and Critical Care Center, Yamaguchi University Hospital, Ube, Yamaguchi 755-8505, Japan.
J Crit Care. 2010 Jun;25(2):313-6. doi: 10.1016/j.jcrc.2009.06.047. Epub 2009 Sep 24.
Heart rate variability (HRV) is widely used to evaluate autonomic nervous function; however, real-time monitoring of HRV has rarely been attempted in the intensive care unit (ICU). We report our experience in performing real-time monitoring of HRV in our ICU.
We investigated 10 critically ill patients on total ventilatory support. Heart rate variability analysis was performed using the MemCalc system, which is a noninvasive, real-time analysis system. The low-frequency (LF) component of HRV reflects sympathetic and parasympathetic modulation, whereas the high-frequency (HF) component mainly reflects parasympathetic modulation. The LF/HF ratio represents a measure of sympathetic/parasympathetic balance.
The HRV parameters for patients breathing spontaneously after extubation were significantly higher than those for patients on total ventilatory support. These findings suggest that mechanical ventilation under sedation may reduce autonomic nervous function in critically ill patients. In a representative case with septic shock, systolic blood pressure and LF/HF ratio showed a significant increase after intravenous infusion of epinephrine and then the HF component showed a significant increase due to vagal reflex.
The MemCalc system is practicable for real-time monitoring of HRV in the ICU. Heart rate variability parameters may offer useful information in the management of critically ill patients.
心率变异性（HRV）广泛用于评估自主神经功能；然而，在重症监护病房（ICU）中很少尝试实时监测 HRV。我们报告了在 ICU 中进行 HRV 实时监测的经验。
我们研究了 10 名接受完全通气支持的危重症患者。使用 MemCalc 系统进行 HRV 分析，该系统是一种非侵入性的实时分析系统。HRV 的低频（LF）成分反映交感和副交感神经调节，而高频（HF）成分主要反映副交感神经调节。LF/HF 比值代表交感神经/副交感神经平衡的衡量标准。
拔管后自主呼吸的患者的 HRV 参数明显高于完全通气支持的患者。这些发现表明，镇静下的机械通气可能会降低危重症患者的自主神经功能。在一例感染性休克的代表性病例中，静脉注射肾上腺素后，收缩压和 LF/HF 比值显著升高，随后由于迷走反射，HF 成分显著增加。
MemCalc 系统适用于 ICU 中 HRV 的实时监测。心率变异性参数在危重症患者的管理中可能提供有用的信息。
