Calligaro Keith D, Dougherty Matthew J
Section of Vascular Surgery, Pennsylvania Hospital, Philadelphia, USA.
J Vasc Surg. 2005 Oct;42(4):684-9. doi: 10.1016/j.jvs.2005.06.003.
A carotid artery stump pressure (SP) of < 50 mm Hg and abnormal electroencephalography (EEG) changes have been suggested as indications for selective shunting in patients undergoing carotid endarterectomy (CEA) under general anesthesia. We attempted to determine the optimal SP threshold that correlated with neurologic changes in awake patients undergoing CEA using cervical block anesthesia (CBA) and performed a cost comparison with EEG monitoring.
Between July 1, 1995, and December 31, 2004, SP was measured during 474 CEAs performed under CBA by inserting a 19-gauge butterfly needle into the common carotid artery. A saline-filled intravenous bag in the patient's contralateral hand was connected to pressure tubing to generate waveforms with hand squeezing that could be visualized on a monitor. Systemic pressure was maintained approximately 10 mm Hg higher than baseline. Accurate SPs were confirmed by the finding of flatline waveforms after internal carotid artery clamping. Selective shunting was performed when neurologic changes occurred (aphasia, inability to squeeze the contralateral hand, decreased consciousness), regardless of SP. During this same period, 142 patients underwent CEA using GA, and SP was also measured.
Shunting was necessary because of neurologic changes in 7.2% (34/474) of all CEAs performed using CBA: 0.9% (3/335) with SPs > or = 50 mm Hg systolic vs 1.0% (4/402) with SPs > or = 40 mm Hg systolic, and 22% (31/139) with SPs < 50 mm Hg systolic vs 42% (30/72) with SPs < 40 mm Hg systolic. If these 474 CEAs had been performed using GA, shunts would have been used in 29% (139/474) of patients for a SP < 50 mm Hg systolic vs 15% (72/474) for a SP < 40 mm Hg systolic. In patients not shunted, the perioperative stroke/death rate was 1.2% in patients (4/332) with SPs > or = 50 mm Hg vs 1.0% (4/398) with SPs > or = 40 mm Hg. Three of the four strokes occurred > 24 hours postoperatively and were unrelated to lack of shunting and ischemia. There was no significant difference in the percentage of patients with SPs > or = 50 mm Hg who underwent CEA using CBA (70%, 335/474) vs GA (67%, 96/142) during this time period. At our hospital, charges for SPe measurement, including anesthesia charges and tubing, were 229 dollars per case vs 3439 dollars per case for EEG monitoring. Use of SP measurements in these 474 patients would have resulted in reduced charges of 1,521,540 dollars compared with EEG monitoring if CEA had been performed under GA.
Using 40 mm Hg systolic as a threshold, the need for shunting (15%) and the false-negative rate (1.0%) for SP in our series were equivalent to the results of EEG monitoring during CEA reported in the literature. However, charges for SP measurements are dramatically lower compared with EEG monitoring. Our results suggest that a carotid artery SP > or = 40 mm Hg systolic may be considered as an equally reliable but more cost-effective method to predict the need for carotid shunting during CEA under GA compared with EEG monitoring, but further investigation is warranted.
有人提出，在全身麻醉下行颈动脉内膜切除术（CEA）的患者中，颈动脉残端压力（SP）<50 mmHg及异常脑电图（EEG）变化可作为选择性分流的指征。我们试图确定在使用颈丛阻滞麻醉（CBA）行CEA的清醒患者中，与神经功能变化相关的最佳SP阈值，并与EEG监测进行成本比较。
在1995年7月1日至2004年12月31日期间，在474例接受CBA的CEA手术中，通过将一根19号蝶形针插入颈总动脉来测量SP。患者对侧手中一个充满生理盐水的静脉输液袋连接到压力管上，通过手动挤压产生可在监护仪上看到的波形。全身压力维持比基线高约10 mmHg。通过夹闭颈内动脉后出现平线波形来确认准确的SP。当出现神经功能变化（失语、无法挤压对侧手、意识下降）时，无论SP如何，均进行选择性分流。在同一时期，142例患者接受了全身麻醉（GA）下的CEA手术，也测量了SP。
在所有使用CBA进行的CEA手术中，7.2%（34/474）因神经功能变化而需要分流：收缩压SP≥50 mmHg的患者中为0.9%（3/335），收缩压SP≥40 mmHg的患者中为1.0%（4/402），收缩压SP<50 mmHg的患者中为22%（31/139），收缩压SP<40 mmHg的患者中为42%（30/72）。如果这474例CEA手术使用GA进行，对于收缩压SP<50 mmHg的患者，29%（139/474）会使用分流装置，对于收缩压SP<40 mmHg的患者，15%（72/474）会使用分流装置。在未进行分流的患者中，收缩压SP≥50 mmHg的患者围手术期卒中/死亡率为1.2%（4/332），收缩压SP≥40 mmHg的患者为1.0%（4/398）。4例卒中中有3例发生在术后24小时以上，与未分流和缺血无关。在此期间，使用CBA进行CEA的收缩压SP≥50 mmHg的患者百分比（70%，335/474）与使用GA的患者（67%，96/142）之间无显著差异。在我们医院，测量SP的费用，包括麻醉费用和管道费用，每例为229美元，而EEG监测每例为3439美元。如果在GA下进行CEA，与EEG监测相比，在这474例患者中使用SP测量将导致费用减少1521540美元。
以40 mmHg收缩压作为阈值，我们系列中分流的必要性（15%）和SP的假阴性率（1.0%）与文献报道的CEA期间EEG监测结果相当。然而，与EEG监测相比，SP测量的费用要低得多。我们的结果表明，与EEG监测相比，收缩压SP≥40 mmHg可被视为在GA下CEA期间预测颈动脉分流必要性的同样可靠但更具成本效益的方法，但仍需进一步研究。
