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在美国，每年大约发生30万例院外心脏骤停(OHCA)，存活率约为8%最初的节律可能是心室颤动(VF)、无脉性室性心动过速(VT)、心搏停止或无脉性电活动(PEA)。三分之二的OHCA初始无除颤可能性的心动过速(PEA)或心室停搏，与初始可除颤心动过速(室颤和无脉性室性心动过速)相比，其发生率在一直增加1 ,19。 进一步探究！ 几项具体的科学研究表明，院内PEA的发生率约为停搏事件的35% - 40%。20,15对于院外心脏骤停，PEA的发生率为22% - 30%。5,6 PEA骤停与预后不良相关，院外心脏骤停的生存到出院率在2% - 5%之间。17,3此外，与表现为初始节律的PEA相比，除颤后出现的无脉电活动与较差的预后相关，0% - 2%的患者在除颤后出现PEA存活到出院，与快速狭窄复杂节律相比，除颤后慢而宽复杂节律的PEA与恶化的预后临床结果相关。 
PEA，以前被称为电机械分离，发生在有组织心电活动但无脉搏可触及的患者机械收缩的缺失，这是由消耗心肌细胞ATP储存和抑制心肌纤维收缩的因素造成的，包括缺氧、缺血、代谢性酸中毒和离子扰动(特别是钾和钙的变化)。所有心脏骤停节律，即无脉节律，如果不属于无脉性室性心动过速、室颤或心搏停止的范畴，都被认为是无脉性电活动。 
再探病因与治疗！ 无脉电活动的各种原因包括严重缺氧、严重酸中毒、严重低血容量、张力性气胸、电解质失衡、药物过量、败血症、大面积心肌梗死、大面积肺栓塞、心脏填塞、低血糖、体温过低和创伤。2010年开始美国心脏协会心肺复苏和紧急心血管护理指南列出了在试图诊断PEA的原因时应评估和治疗的“5H和5T”。它们是缺氧、低血容量、低体温、高/低钾、氢离子(酸中毒)、张力性气胸、心包填塞(心脏)、中毒和血栓(心脏/肺)。通常情况下，由于疾病的时效性和复苏过程中缺乏明确可识别的病因，对PEA中的每个患者都采用了相同的标准化治疗流程，特别是在院前的条件下。PEA停止节律的特征可能有助于确定谁将受益于积极的心脏后临床干预，如治疗性低温。2,8,18,9 
尽管大多数医务人员将PEA定义为没有机械活动的电节律，Mehta进一步将PEA划分为伪PEA和真PEA。伪PEA是一种严重的心源性休克状态，不足以维持灌注压力(因此无法检测到脉搏)伪PEA存在灌注压力小于60mm Hg的主动脉脉压。在伪PEA中，心电活动伴随着心肌收缩，但不足以产生可触及的脉搏。因此伪PEA是一种严重的休克，冠状动脉灌注减少导致心肌功能下降，从而进一步出现低血压。引起伪PEA的病理性损伤阻碍了心血管系统提供全身循环的能力在PEA的病因谱中，伪PEA常由低血容量、快速心律失常、心脏收缩力降低或循环障碍引起，如肺栓塞、心包填塞和张力性气胸引起，伪PEA节律常为窄QRS复杂心动过速。 
真正的PEA代表了一种更严重的病理生理学，其中完全没有机械收缩——一种心脏机械活动与心律的真正脱钩与伪PEA的主动脉压力降低不同，真PEA的特征是没有任何主动脉脉冲压力。真正的PEA的特征是非常慢的节律和宽QRS波的特征是异常自主节律的特征，通常表现为心室慢速，宽QRS波(QRS >0.12秒)。与真正的PEA相关的病因通常包括大心肌梗死、多器官衰竭、严重的代谢失衡，如高钾血症、药物过量、体温过低、酸中毒和长时间的心脏骤停。 PEA是一种具有多种病因的疾病过程，有效的治疗可能包括逆转心脏骤停的原因了解潜在的无脉电活动原因和治疗方法将使医务人员能够在统计上没有积极结果的情况下提供最好的治疗。 参考文献如下： 1. Abrams HC, McNally B, Ong M,
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