Camann W, Trunfio G V, Kluger R, Steinbrook R A
Department of Anesthesia, Brigham and Women's Hospital, Boston, MA 02115, USA.
J Clin Anesth. 1996 Nov;8(7):564-7. doi: 10.1016/s0952-8180(96)00143-2.
To determine the effect of different electrocardiographic (ECG) filtering modalities on ST-segment changes during cesarean delivery. We compared the use of narrow and standard bandwidth ECG filtering modes in assessing ECG-detected ischemic changes in healthy patients undergoing routine, elective cesarean delivery.
Prospective, nonrandomized clinical trial.
Academic medical center.
20 healthy parturients undergoing elective cesarean delivery with regional anesthesia.
Continuous 5-lead ECG monitoring was performed in all 20 study parturients. The same incoming ECG signal was divided by a special cable and displayed on two Marquette 7010 monitors. Leads I, II, and V5 were analyzed. One of the monitors filtered the signal with a 0.07 to 100 Hz filter (DIAG), the other with a 0.3 to 40 Hz filter (MON). The ST segment was analyzed continuously by electronic comparison with a template established as a baseline at the beginning of the case. This continuous output was led in digital form every 15 seconds to an IBM PC computer for data analysis.
In each of the leads analyzed, the mean MON versus DIAG different showed a bias, with MON showing consistently lower (ie, more negative) readings than DIAG. Using different criteria for ST depression (> 0.25, > 0.5, or > 1.0mm), we categorized patients as showing more ST depression on either MON or DIAG. With the 0.25 mm criterion, ST depression was identified significantly more often in MON then DIAG in leads H and V5 (p < 0.05). Using the other criteria, the differences were similar, but were not statistically significant. In general, very few instances of ST depression were identified in lead I. No patient had sequelae indicative of intraoperative myocardial ischemia, such as chest pain, dyspnea, persistent ectopy, or hemodynamic instability.
In patients at low risk for myocardial ischemia, narrow bandwidth (monitor mode) ECG filtering reveals greater degrees of ST-segment depression than does standard (diagnostic mode) ECG filtering. Studies examining ST-segment phenomena would be facilitated by including a description of the ECG filtering-technique.
确定不同心电图（ECG）滤波方式对剖宫产期间ST段变化的影响。我们比较了窄带和标准带宽ECG滤波模式在评估接受常规择期剖宫产的健康患者中ECG检测到的缺血性变化时的应用情况。
前瞻性、非随机临床试验。
学术医疗中心。
20名接受区域麻醉的择期剖宫产健康产妇。
对所有20名研究产妇进行连续5导联ECG监测。同一输入的ECG信号通过一根特殊电缆分开，并显示在两台Marquette 7010监护仪上。分析I、II和V5导联。其中一台监护仪使用0.07至100Hz滤波器（诊断模式）对信号进行滤波，另一台使用0.3至40Hz滤波器（监护模式）。通过与病例开始时建立为基线的模板进行电子比较，持续分析ST段。这个连续输出每15秒以数字形式导入一台IBM个人计算机进行数据分析。
在分析的每个导联中，监护模式与诊断模式的平均差值显示出偏差，监护模式显示的读数始终低于诊断模式（即更负）。使用不同的ST段压低标准（>0.25、>0.5或>1.0mm），我们将患者分类为在监护模式或诊断模式下显示出更多的ST段压低。采用0.25mm标准时，在II导联和V5导联中，监护模式下ST段压低的识别显著多于诊断模式（p<0.05）。使用其他标准时，差异相似，但无统计学意义。一般来说，I导联中很少发现ST段压低的情况。没有患者出现提示术中心肌缺血的后遗症, 如胸痛、呼吸困难、持续性异位心律或血流动力学不稳定。
在心肌缺血低风险患者中，窄带（监护模式）ECG滤波比标准（诊断模式）ECG滤波显示出更大程度的ST段压低。描述ECG滤波技术将有助于对ST段现象的研究。
