Prospective Examination of Epidural Catheter Insertion

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Abstract
Background: Although it is generally accepted that inserting epidural catheters 3-4 cm into the epidural space minimizes complications, no prospective randomized examination of epidural catheter insertion length has been published. Methods: Eight hundred healthy parturients requesting epidural analgesia were randomized to have open-tip epidural catheters inserted 2, 4, 6, or 8 cm within the epidural space. The incidences of intravenous cannulation, unilateral sensory analgesia, and subsequent catheter dislodgment were recorded. Catheter insertions that resulted in intravenous cannulation or unilateral analgesia were incrementally withdrawn and retested with additional local anesthetic to determine the effectiveness of epidural catheter manipulation. Results: Epidural catheters inserted 8 cm within the epidural space were more likely to result in intravenous cannulation. Epidural catheters inserted 2 cm within the epidural space were less likely to result in unilateral sensory analgesia but were more likely to become dislodged. Twenty-three percent of epidural catheters inserted > 2 cm within the epidural space required manipulation. Epidural catheters inserted 2 or 4 cm required replacement more often than epidural catheters inserted 6 or 8 cm. Ninety-one percent and 50% of epidural catheters that resulted in unilateral sensory analgesia and intravenous cannulation, respectively, provided analgesia for labor and delivery after incremental withdrawal. Conclusions: Epidural catheters should be inserted either 2 cm when rapid labor is anticipated or 6 cm when prolonged labor or cesarean delivery is likely. Additionally, epidural catheters that result in intravenous cannulation or unilateral sensory analgesia can be manipulated effectively to provide analgesia for labor and delivery.