Jaffe R A, Siegel L C, Schnittger I, Propst J W, Brock-Utne J G
Department of Anesthesia, Stanford University School of Medicine, California, USA.
Reg Anesth. 1995 Mar-Apr;20(2):152-5.
The object of this study, using transesophageal echocardiography (TEE) in anesthetized patients, was to investigate the occurrence of venous air embolism (VAE) when air is injected into the epidural space.
Six patients between the ages of 18 and 50 years (ASA I-II) undergoing general anesthesia in a supine position for nonthoracic surgical procedures were studied. Prior to general anesthesia, an epidural catheter was placed into the epidural space using a Tuohy needle and a standard saline loss-of-resistance technique. Following verification of proper catheter placement, general anesthesia was induced and the trachea intubated. Thereafter, a TEE probe was inserted into the esophagus. After a 10-minute control period, and during continuous TEE videotape recording, 5 mL of air was rapidly injected into the epidural space through the epidural catheter. This was followed 10 minutes later by the epidural injection of 5 mL of room-temperature preservative-free saline. Microbubble echo targets were quantified in a range from 0 to 4+.
Venous air microbubble emboli appeared in the circulation within 15 seconds after injecting either air or saline into the epidural space.
No evidence of clinically significant VAE was seen in any patient. The results suggest that drugs injected into the epidural space may have unexpectedly easy access to the venous circulation with a potential to produce unwanted systemic effects. Clinicians should be alert to the possibility that local anesthetics, or any other drug placed epidurally, may rapidly enter the systemic circulation even without the intravenous placement of an epidural catheter.
本研究的目的是在麻醉患者中使用经食管超声心动图（TEE），调查向硬膜外腔注入空气时静脉空气栓塞（VAE）的发生情况。
研究了6例年龄在18至50岁之间（ASA I-II级）、仰卧位接受非胸部手术全身麻醉的患者。在全身麻醉前，使用Tuohy针和标准盐水阻力消失技术将硬膜外导管置入硬膜外腔。确认导管位置正确后，诱导全身麻醉并进行气管插管。此后，将TEE探头插入食管。在10分钟的对照期后，在连续TEE录像期间，通过硬膜外导管将5 mL空气快速注入硬膜外腔。10分钟后，硬膜外注射5 mL室温无防腐剂生理盐水。微泡回声目标按0至4+进行量化。
向硬膜外腔注入空气或盐水后15秒内，静脉空气微泡栓子出现在循环中。
未在任何患者中发现具有临床意义的VAE证据。结果表明，注入硬膜外腔的药物可能意外地容易进入静脉循环，有可能产生不良的全身效应。临床医生应警惕局部麻醉药或硬膜外使用的任何其他药物即使在未静脉置入硬膜外导管的情况下也可能迅速进入体循环的可能性。
