Hughes N, Johnson M D, Datta S, Philip J
Department of Anesthesia, Brigham and Women's Hospital, Boston, MA 02115.
Reg Anesth. 1992 Sep-Oct;17(5):292-4.
Migration of an epidural catheter into the subarachnoid space is a potentially lethal complication of continuous epidural anesthesia. We evaluated the use of pump pressure measurement during infusion in detecting such an occurrence.
Pump pressures at two flow rates (P1 and P10) and epidural space pressure (P0) were measured hourly in eight consecutive ASA Physical Status I parturients receiving continuous epidural anesthesia and compared to those of a patient whose catheter migrated into the subarachnoid space. In addition, total resistance to infusion (Rtot) was calculated as the slope of the least squares regression line linking pressure and flow. Epidural resistance (Repi) was computed as the difference between total resistance and catheter resistance; Repi = Rtot - Rcath.
In epidural catheters, average P0 and P10 were 13 +/- 4 mmHg and 23 +/- 4 mm Hg, respectively, and did not change over time. Rtot and Repi averaged 960 +/- 180 RU and 980 +/- 120 RU, respectively. Pump pressures in the subarachnoid catheter were 10 mmHg for P0 and 20 mmHg for P10, while Rtot was 1000 RU.
We conclude that epidural and subarachnoid space resistance is essentially zero and the pump pressure in the system is used to overcome the catheter resistance. Both spaces offer the same total resistance to infusion and, therefore, pump pressure will not change when a catheter migrates into the subarachnoid space.
硬膜外导管误入蛛网膜下腔是连续硬膜外麻醉潜在的致命并发症。我们评估了输注过程中泵压力测量在检测此类情况中的应用。
对8例连续接受硬膜外麻醉的美国麻醉医师协会（ASA）身体状况Ⅰ级的产妇，每小时测量两种流速（P1和P10）下的泵压力及硬膜外腔压力（P0），并与导管误入蛛网膜下腔的患者进行比较。此外，计算输注总阻力（Rtot），即压力与流速之间最小二乘回归线的斜率。硬膜外阻力（Repi）通过总阻力与导管阻力之差计算得出；Repi = Rtot - Rcath。
硬膜外导管中，平均P0和P10分别为13±4 mmHg和23±4 mmHg，且随时间无变化。Rtot和Repi平均分别为960±180 RU和980±120 RU。蛛网膜下腔导管的泵压力，P0为10 mmHg，P10为20 mmHg，而Rtot为1000 RU。
我们得出结论，硬膜外腔和蛛网膜下腔的阻力基本为零，系统中的泵压力用于克服导管阻力。两个腔隙对输注的总阻力相同，因此，当导管误入蛛网膜下腔时泵压力不会改变。
