Mair P, Kornberger E, Schwarz B, Baubin M, Hoermann C
Department of Anaesthesia and Intensive Care Medicine, University of Innsbruck, School of Medicine, Austria.
Acta Anaesthesiol Scand. 1998 Nov;42(10):1139-44. doi: 10.1111/j.1399-6576.1998.tb05266.x.
The mechanism responsible for the forward blood flow associated with external chest compression is still controversial. Evidence for both blood flow caused by direct cardiac compression and blood flow generated by a general increase in intrathoracic pressure has been found in experimental as well as clinical studies. No data are available concerning the mechanism causing forward blood flow in hypothermic patients undergoing cardiopulmonary resuscitation. Therefore, echocardiographic findings during external chest compression in seven hypothermic arrest victims are reported.
All transesophageal echocardiographic studies performed at the Anaesthesia department between 1994 and 1997 were reviewed and seven hypothermic patients with transesophageal echocardiography performed during cardiopulmonary resuscitation were identified.
An open mitral valve or a circumferential reduction in aortic diameter during the compression phase was found in four of seven patients, indicating that primarily an increase in intrathoracic pressure (thoracic pump mechanism) generated forward blood flow. In three patients, mitral valve closure during external chest compression indicated that direct cardiac compression (cardiac pump mechanism) contributed to forward blood flow. Two patients studied during active compression-decompression cardiopulmonary resuscitation demonstrated enhanced right ventricular filling and aortic valve opening during active decompression of the thorax.
In contrast to normothermic arrest victims, an open mitral valve during external chest compression is a common finding during hypothermia, indicating that thoracic pump mechanism is important for forward blood flow during cardiopulmonary resuscitation in hypothermic arrest victims. Aortic valve opening in two hypothermic arrest victims suggests forward blood flow also during active decompression of the thorax with the Cardiopump.
与胸外按压相关的前向血流机制仍存在争议。在实验研究和临床研究中均发现了直接心脏按压导致的血流以及胸腔内压力普遍升高产生的血流的证据。目前尚无关于低温心肺复苏患者中导致前向血流机制的数据。因此，报告了7例低温心脏骤停患者胸外按压期间的超声心动图检查结果。
回顾了1994年至1997年在麻醉科进行的所有经食管超声心动图研究，并确定了7例在心肺复苏期间进行经食管超声心动图检查的低温患者。
7例患者中有4例在按压阶段发现二尖瓣开放或主动脉直径周向缩小，表明主要是胸腔内压力升高（胸腔泵机制）产生了前向血流。3例患者在胸外按压期间二尖瓣关闭，表明直接心脏按压（心脏泵机制）有助于前向血流。2例在主动按压-减压心肺复苏期间接受研究的患者在胸腔主动减压期间显示右心室充盈增强和主动脉瓣开放。
与正常体温心脏骤停患者不同，低温期间胸外按压时二尖瓣开放是常见表现，表明胸腔泵机制对低温心脏骤停患者心肺复苏期间的前向血流很重要。2例低温心脏骤停患者的主动脉瓣开放表明在使用心肺复苏器进行胸腔主动减压期间也有前向血流。
