Tanaka M, Nishikawa T
Department of Anesthesia, Akita University School of Medicine, Japan.
Anesth Analg. 1999 Sep;89(3):632-7. doi: 10.1097/00000539-199909000-00016.
A recent study demonstrated that changes in both heart rate (HR; positive if > or = 10bpm increase) and T-wave amplitude (positive if > or = 25% increase) reliably detect accidental intravascular injection when a full test dose containing epinephrine 0.5 microg/kg is injected intravascularly. We designed this study to prospectively determine whether a smaller dose of epinephrine would produce reliable HR and T-wave changes in sevoflurane-anesthetized children. We studied 80 ASA physical status I infants and children (6-72 mo) undergoing elective surgeries during 1.0 minimum alveolar anesthetic concentration sevoflurane and 67% nitrous oxide in oxygen. After the administration of i.v. atropine 0.01 mg/kg, the patients were randomly assigned to receive either i.v. saline (n = 20), an i.v. test dose (0.1 mL/kg) consisting of 1% lidocaine with 1:200,000 epinephrine (epinephrine 0.5 microg/kg group, n = 20), an i.v. test dose (0.05 mL/kg) (epinephrine 0.25 microg/kg group, n = 20), or an i.v. test dose (0.025 mL/kg) (epinephrine 0.125 microg/kg group, n = 20) via a peripheral vein to simulate the intravascular injection of the test dose. HR and systolic blood pressure were recorded every 20 and 30 s, respectively, and T-wave amplitude of lead II was continuously recorded for subsequent analysis. After the i.v. injection of the test dose, all children in the epinephrine 0.5 and 0.25 microg/kg groups developed positive responses based on the peak T-wave amplitude, whereas all children in the epinephrine 0.5 microg/kg group and 17 children (85%) in the epinephrine 0.25 microg/kg group elicited a positive response according to the peak HR criterion. No false-positive responses were observed with saline injections. Children in the epinephrine 0.125 microg/kg group showed clinically unacceptable efficacy based on either criterion. We conclude that the efficacies of detecting an intravascular injection of the test dose based on the hemodynamic and T-wave criteria are reduced with smaller doses of epinephrine and that HR and T-wave changes are still useful indicators in most patients if epinephrine 0.25 microg/kg is accidentally injected intravascularly.
To determine whether an epidurally administered local anesthetic has been unintentionally injected into a blood vessel, a small dose of epinephrine is often added to a local anesthetic. We found that an increase in T-wave amplitude > or = 25% in lead II and a heart rate increase > or = 10 bpm are useful indicators for detecting the accidental intravascular injection of a small dose of epinephrine in sevoflurane-anesthetized children.
最近一项研究表明，当静脉注射含肾上腺素0.5微克/千克的全量试验剂量时，心率（HR；若增加≥10次/分则为阳性）和T波振幅（若增加≥25%则为阳性）的变化能可靠地检测出意外血管内注射。我们设计本研究以前瞻性地确定较小剂量的肾上腺素是否会在七氟醚麻醉的儿童中产生可靠的心率和T波变化。我们研究了80例美国麻醉医师协会（ASA）身体状况为I级的婴儿和儿童（6至72个月），他们在七氟醚最低肺泡有效浓度为1.0且氧气中氧化亚氮浓度为67%的情况下接受择期手术。静脉注射0.01毫克/千克阿托品后，将患者随机分配接受静脉注射生理盐水（n = 20）、含1:200,000肾上腺素的1%利多卡因静脉试验剂量（0.1毫升/千克）（肾上腺素0.5微克/千克组，n = 20）、静脉试验剂量（0.05毫升/千克）（肾上腺素0.25微克/千克组，n = 20）或静脉试验剂量（0.025毫升/千克）（肾上腺素0.125微克/千克组，n = 20），通过外周静脉注射以模拟试验剂量的血管内注射。分别每20秒和30秒记录心率和收缩压，并持续记录II导联的T波振幅以供后续分析。静脉注射试验剂量后，肾上腺素0.5和0.25微克/千克组的所有儿童基于T波振幅峰值出现阳性反应，而肾上腺素0.5微克/千克组的所有儿童和肾上腺素0.25微克/千克组的17名儿童（85%）根据心率峰值标准引发阳性反应。注射生理盐水未观察到假阳性反应。肾上腺素0.125微克/千克组的儿童基于任一标准显示出临床不可接受的效果。我们得出结论，基于血流动力学和T波标准检测试验剂量血管内注射的效果会因肾上腺素剂量较小而降低，并且如果意外血管内注射0.25微克/千克肾上腺素，心率和T波变化在大多数患者中仍是有用的指标。
为确定硬膜外给予的局部麻醉药是否意外注入血管，常向局部麻醉药中添加小剂量肾上腺素。我们发现，II导联T波振幅增加≥25%和心率增加≥10次/分是检测七氟醚麻醉儿童中意外血管内注射小剂量肾上腺素的有用指标。
