Cabrera Schulmeyer M C, Vargas J, De la Maza J, Labbé M
Departamento de Anestesiología Universidad de Valparaíso, sede Hospital Clínico Fuerza Aérea de Chile, Santiago de Chile.
Rev Esp Anestesiol Reanim. 2010 Mar;57(3):136-40. doi: 10.1016/s0034-9356(10)70187-0.
Spinal anesthesia reduces arterial blood pressure mainly because of vasodilation secondary to blocking preganglionic fibers in the sympathetic nervous system. It is hypothesized, however, that spinal anesthesia may also be a direct cause of some degree of myocardial depression. These factors may be studied by means of transthoracic echocardiography to detect changes in left ventricular function following start of spinal anesthesia.
Left ventricular function was assessed in ASA 1 patients before spinal anesthesia, by means of measurements of left ventricular systolic and diastolic volumes, ejection fraction, the Doppler transmitral (E and A) and tissue (E', A', and Sm) inflow velocities, and the left ventricular outflow tract velocity. The measurements were repeated after the start of spinal anesthesia.
Fifty-five patients (58% men; mean [SD] age, 46.9 [15.7] years) were studied. The spinal block caused a significant reduction in systolic and diastolic arterial blood pressures (P < .0009). Diastolic function also decreased (the E wave from 69.52 [11.24] to 61.59 [10.82] cm x s(-1) and the A wave from 50.18 [10.69] to 43.67 [13.75] cm x s(-1); P < .0001). Also reduced was the left ventricular outflow tract velocity, from 18.77 (4.89) to 15.64 (4.75) cm x s(-1) (P < .00001). There were no significant changes in systolic and diastolic volumes or ejection fraction. There was no correlation between the level of spinal block and the magnitude of changes.
Left ventricular function was compromised after spinal anesthesia without significant changes in left ventricular volumes. We can infer that the reduction in arterial blood pressure after a spinal block might be due to some degree of direct ventricular depression.
脊髓麻醉主要通过阻断交感神经系统的节前纤维继发血管舒张来降低动脉血压。然而，据推测脊髓麻醉也可能在一定程度上直接导致心肌抑制。可通过经胸超声心动图研究这些因素，以检测脊髓麻醉开始后左心室功能的变化。
在脊髓麻醉前，通过测量左心室收缩和舒张容积、射血分数、多普勒二尖瓣（E和A）及组织（E'、A'和Sm）流入速度以及左心室流出道速度，对美国麻醉医师协会（ASA）1级患者的左心室功能进行评估。在脊髓麻醉开始后重复进行测量。
共研究了55例患者（58%为男性；平均[标准差]年龄为46.9[15.7]岁）。脊髓阻滞导致收缩压和舒张压显著降低（P<.0009）。舒张功能也下降（E波从69.52[11.24]降至61.59[10.82]cm·s⁻¹，A波从50.18[10.69]降至43.67[13.75]cm·s⁻¹；P<.0001）。左心室流出道速度也降低，从18.77（4.89）降至15.64（4.75）cm·s⁻¹（P<.00001）。收缩和舒张容积及射血分数无显著变化。脊髓阻滞平面与变化幅度之间无相关性。
脊髓麻醉后左心室功能受损，而左心室容积无显著变化。我们可以推断，脊髓阻滞后动脉血压降低可能是由于一定程度的直接心室抑制。
