Kikutani Takehiko, Sugimoto Kikuzou, Shimada Yoichi
Department of Anesthesiology, Nippon Medical School, Second Hospital, Kanagawa 211-8533.
Masui. 2003 May;52(5):494-9.
After induction of spinal anesthesia, thoracic epidural pressure and left saphenous venous pressure were monitored and recorded during supine hypotensive syndrome in 8 pregnant patients who underwent elective cesarean section.
A 22 G venous catheter was inserted into the left saphena, and an epidural catheter for 18 G needles was positioned 5 cm cephalad in the epidural space through a Tuohy needle at the T 11-12 intervertebral space. Each catheter was connected to a pressure transducer, and recording was started in a supine position immediately after induction of spinal anesthesia with 0.5% isobaric bupivacaine at the L 3-4 intervertebral space.
In all patients, epidural pressure and peripheral venous pressure synchronously increased as soon as they began to recover from hypotension and tachycardia regardless of uterine displacement to the left.
The synchronous increase in both pressures was late after the hypotension probably because sympathetic block with spinal anesthesia inhibited vasoconstriction of the lower extremity, a factor to compensate for supine hypotensive syndrome. Only collateral flow via epidural venous plexus emptying into azygos system could not compensate for decreased venous return to the right atrium from obstructed inferior vena cava, and differences in the degree of compression of the inferior vena cava by gravid uterus would affect the recovery from supine hypotension.
在8例行择期剖宫产的孕妇中，诱导脊髓麻醉后，于仰卧位低血压综合征期间监测并记录胸段硬膜外压力和左大隐静脉压力。
将一根22G静脉导管插入左大隐静脉，并通过在T 11-12椎间隙的Tuohy针将一根用于18G针的硬膜外导管置于硬膜外间隙头侧5cm处。每根导管连接到一个压力传感器，在L 3-4椎间隙用0.5%等比重布比卡因诱导脊髓麻醉后立即开始在仰卧位进行记录。
在所有患者中，无论子宫是否向左移位，一旦她们开始从低血压和心动过速中恢复，硬膜外压力和外周静脉压力均同步升高。
低血压后这两种压力同步升高较晚，可能是因为脊髓麻醉引起的交感神经阻滞抑制了下肢血管收缩，而下肢血管收缩是代偿仰卧位低血压综合征的一个因素。仅通过硬膜外静脉丛流入奇静脉系统的侧支血流无法代偿下腔静脉受阻导致的右心房静脉回流减少，妊娠子宫对下腔静脉的压迫程度差异会影响仰卧位低血压的恢复。
