临床心肺转流中不同血流模式的能量特点分析

Analysis of blood flow energy characteristics of pulsatile and non-pulsatile flow during extracorporeal circulation

目的探讨临床心肺转流中搏动灌注（PP）、平流灌注（NP）血流携带能量的大小和频域特点。方法选取2017年1-12月上海交通大学医学院附属胸科医院心脏大血管外科单纯二尖瓣病变拟行二尖瓣置换或成形手术的60例患者资料，随机分为PP和NP两组，每组30例。在心肺转流动脉微栓过滤器出口处．利用能量等效压和富裕血流动力学能量计算心肺转流中血流能量的大小，并通过快速傅立叶转换对上述两种人工血流进行功率谱密度分析，探讨不同模式血流能量的频域分布特点。采用方差分析或t检验进行数据分析。结果PP组阻断后各时段能量等效压和富裕血流动力学能量分别是NP组的1．52-1．62倍和2．03-2．22倍。两组阻断前桡动脉生理性搏动血流能量构成均在40Hz以内，0-5Hz低频能量占90％以上；阻断后PP和NP低频谱能比均有所下降，NP组下降更明显。主动脉阻断后桡动脉和微栓两处0-5Hz、0-10Hz、0-40Hz频率范围功率谱密度估计值PP组和NP组的比值分别为9．51、4．68、3．59和3．87、2．69、2．38倍，各个频率范围内PP组血流能量均高于NP组，且频率越低，差异越大。PP和NP组三个频率范围功率谱密度估计值桡动脉处阻断前后的比值分别为2．86、2．83、2．75和14．70、12．74、9．85，PP组各频率衰减稳定在50％左右，而NP组衰减特别是低频衰减明显。PP和NP组三个频率功率谱密度估计值微栓和桡动脉处的比值分别为26．35、33．15、37．36和37．41、54．18、56．64，在从微栓到桡动脉的传导过程中，能量衰竭明显，以NP组为甚。结论在临床心肺转流中，PP比NP可提供更多能量。PP的能量频率结构和衰减特性与生理搏动相仿，以0。5Hz的低频能量为主，衰减相对较弱；NP血流能量衰减明显，以低频能量衰减为主。

Objective To analyze the magnitude of blood flow energy and characteristics of frequency domain between pulsatile flow and nonpulsatile flow during cardiopulmonary bypass and physiological flow. Methods From January 2017 to December 2017, 60 cases of patients with mitral valve disease scheduled for mitral valve replacement or repair at Department of Cardiasurgery, Shanghai Chest Hospital, Shanghai Jiaotong University were randomly divided into 2 groups ： pulsatile perfusion （ PP ） and non-pulsatile perfusion （NP）. The magnitude of blood flow energy during pulsatile and non-pulsatile was calculated using energy equivalent pressure （EEP） and surplus hemodynamic energy （SHE） while fast Fourier transformation （FFT） was used to perform power spectral density analysis to identify the frequency domain characteristics between artificial and physiological flow （prior to CPB ）. The data was analyzed by analysis of variance or t test. Results At the different time-points after occlusion, the EEP and SHE in PP group were respectively 1.52 to 1.62 and 2.03 to 2. 22 times higher than NP at the distal of artery filter. The power density analysis revealed that the blood flow energy of physiological pulsatile flow patterns was within 40 Hz and the ratio of low frequency energy was more than 90% before clamp. The spectral energy ratio of low frequency decreased in both group compared with physiological flow was more obvious in NP group at the radial artery. The ratio of estimated value of power density of PP and NP groups analysis showed the corresponding 0 to 5 Hz, 0 to 10 Hz, 0 to 40 Hz frequency range values measured at the radial artery and filter were 9. 51, 4. 68, 3.59 and 3.87, 2. 69, 2. 38 respectively after occulusion. In each frequency range, the energy of PP is higher than that of NP, and the lower the frequency, the greater the difference. The ratio of estimated value of power density of PP and NP groups for the three frequencies measured at the radial artery before and after occlusion were 2. 86, 2.83, 2. 75 and 14. 70, 12.74, 9.85 respectively, and decreased significantly in NP group and low frequency energy. The ratio of estimated value of power density of PP and NP groups under the three different frequencies measured at the radial artery and filter were 26. 35, 33. 15, 37. 36 and 37.41, 54. 18, 56.64 respectively, in the conduction process from filter to radial artery, energy exhaustion is significant, especially in group NP. Conclusions The PP provides significantly more energy than the NP whereby the PP is closer to the physiological pulsatile on the energy frequency structure and attenuation characteristics, with mainly low frequency energy of 0 to 5 Hz and weak energy attenuation. The energy loss of non-pulsatile flow is obvious, especially the low frequency energy.