Batchinsky Andriy I, Cooke William H, Kuusela Tom, Cancio Leopoldo C
U.S. Army Institute of Surgical Research, Fort Sam Houston, TX, USA.
Crit Care Med. 2007 Feb;35(2):519-25. doi: 10.1097/01.CCM.0000254065.44990.77.
To improve our ability to identify physiologic deterioration caused by critical illness, we applied nonlinear and frequency-domain analytical methods to R-to-R interval (RRI) and systolic arterial pressure (SAP) time series during hemorrhagic shock.
Prospective, randomized, controlled trial.
Animal laboratory of a government research institute.
Twenty swine (weight 36.4+/-0.11 kg).
Fixed-volume hemorrhage followed by resuscitation; off-line analysis of RRI and SAP data.
Anesthetized swine (shock group, n=12) underwent withdrawal of 30 mL/kg blood in 10 mL/kg decrements. A control group (n=8) received maintenance fluids only. Electrocardiogram and arterial pressure waveforms were acquired at 500 Hz. Eight hundred-beat data sets were analyzed at six time points: at baseline, after each blood withdrawal, after lactated Ringer's resuscitation, and after infusion of shed blood. Nonlinear methods were used to estimate the complexity (approximate entropy, sample entropy, Lempel-Ziv entropy, normalized entropy of symbol dynamics), RRI bits per word, and fractal dimension by curve lengths and by dispersion analysis of the RRI and SAP time series. Fast Fourier transformation was used to measure the high-frequency and low-frequency powers of RRI and SAP. Baroreflex sensitivity was assessed in the time domain with the sequence method. Hemorrhagic shock caused decreases in RRI complexity as quantified by approximate entropy, sample entropy, and symbol dynamics; these changes were reversed by resuscitation. Similar but statistically insignificant changes in fractal dimension by curve lengths were seen. RRI high-frequency power decreased with hemorrhagic shock-indicating withdrawal of vagal cardiac input-and was restored by resuscitation. Similar changes in baroreflex sensitivity were seen. Hemorrhagic shock did not affect SAP complexity.
Hemorrhagic shock caused a reversible decrease in RRI complexity; these changes may be mediated by changes in vagal cardiac control. Assessment of RRI complexity may permit identification of casualties with hemorrhagic shock.
为提高我们识别危重病所致生理功能恶化的能力，我们将非线性和频域分析方法应用于失血性休克期间的R - R间期（RRI）和收缩压（SAP）时间序列。
前瞻性、随机、对照试验。
一家政府研究机构的动物实验室。
20头猪（体重36.4±0.11千克）。
固定容量出血后进行复苏；对RRI和SAP数据进行离线分析。
麻醉后的猪（休克组，n = 12）以每次10 mL/kg的递减量抽取30 mL/kg血液。对照组（n = 8）仅接受维持液。以500 Hz采集心电图和动脉压波形。在六个时间点分析800次心跳的数据集：基线时、每次抽血后、乳酸林格氏液复苏后以及回输自体血后。使用非线性方法通过曲线长度以及RRI和SAP时间序列的离散分析来估计复杂度（近似熵、样本熵、Lempel-Ziv熵、符号动力学归一化熵）、RRI每字位数和分形维数。使用快速傅里叶变换测量RRI和SAP的高频和低频功率。采用序列法在时域评估压力反射敏感性。失血性休克导致RRI复杂度降低，如通过近似熵、样本熵和符号动力学所量化；这些变化在复苏后逆转。通过曲线长度观察到分形维数有类似但无统计学意义的变化。RRI高频功率随失血性休克降低——表明迷走神经对心脏的输入减少——并在复苏后恢复。压力反射敏感性也有类似变化。失血性休克未影响SAP复杂度。
失血性休克导致RRI复杂度可逆性降低；这些变化可能由迷走神经对心脏控制的改变介导。评估RRI复杂度可能有助于识别失血性休克伤员。
