Leighton B L, Topkis W G, Gross J B, Arkoosh V A, Lee S H, Huffnagle H J, Huffnagle S L
Department of Anesthesiology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
Anesthesiology. 2000 Jun;92(6):1617-20. doi: 10.1097/00000542-200006000-00018.
Multiport epidural catheters are popular; however, the reliability of the air test has not been evaluated with this catheter design. The authors determined the effectiveness of aspirating for blood and the air test in detecting intravascular multiorifice epidural catheters.
Three hundred women in labor underwent placement of a blunt-tip, three-hole, 20-gauge, lumbar epidural catheter. If there were no signs of spinal anesthesia, 3 ml lidocaine or bupivacaine was injected and the patient was observed for signs of spinal anesthesia. If there were no signs of spinal anesthesia, the authors injected 1 ml air through the epidural catheter while listening to the maternal precordium using a Doppler fetal heart rate monitor. Catheters through which blood was aspirated were air-tested and replaced. Patients with air-test-positive, blood-aspiration-negative catheters received 100 mg lidocaine through the catheter and were questioned about toxicity symptoms. The authors injected bupivacaine-fentanyl through aspiration-negative,air-test-negative catheters and recorded the sensory analgesic level 20 min later.
The authors aspirated cerebrospinal fluid through one catheter and documented intravascular placement in 11 catheters. Results of the air test and blood aspiration were positive for eight catheters. Blood could not be aspirated from one air-test-positive catheter; perioral numbness developed in the patient after lidocaine injection. Blood was freely aspirated from two air-test-negative catheters. In the remaining 288 catheters, bupivacaine-fentanyl injection produced epidural analgesia in 279 patients and no effect in 9 patients.
The authors obtained false-negative results with both catheter aspiration and the air test. Fractionating the local anesthetic dose is important when using multiorifice epidural catheters.
多端口硬膜外导管很常用；然而，这种导管设计的空气试验可靠性尚未得到评估。作者确定了抽吸血液及空气试验在检测血管内多孔硬膜外导管方面的有效性。
300名分娩期妇女接受了钝头、三孔、20号腰段硬膜外导管置入。若无脊麻迹象，则注入3毫升利多卡因或布比卡因，并观察患者有无脊麻迹象。若无脊麻迹象，作者通过硬膜外导管注入1毫升空气，同时使用多普勒胎儿心率监测仪监听产妇心前区。抽吸出血液的导管进行空气试验并更换。空气试验阳性、抽吸血液阴性的导管的患者通过导管接受100毫克利多卡因，并询问有无毒性症状。作者通过抽吸阴性、空气试验阴性的导管注入布比卡因-芬太尼，并在20分钟后记录感觉镇痛平面。
作者通过一根导管抽出了脑脊液，并记录了11根导管的血管内置入情况。8根导管的空气试验和抽吸血液结果呈阳性。一根空气试验阳性的导管无法抽出血液；利多卡因注射后患者出现口周麻木。两根空气试验阴性的导管可自由抽出血液。在其余288根导管中，布比卡因-芬太尼注射使279例患者产生了硬膜外镇痛效果，9例患者无效果。
作者在导管抽吸和空气试验中均获得了假阴性结果。使用多孔硬膜外导管时，分次给予局部麻醉药剂量很重要。
