The BiP Test: a modified loss of resistance technique for confirming epidural needle placement.

Abstract

Correct identification of the epidural space minimizes complications and ensures successful epidural blockade. The loss of resistance technique is the most common technique used for identification of the epidural space. However, sometimes loss of resistance occurs when the needle is not actually in the epidural space. The injection in this instance will result in the medication not being deposited in the epidural space. At other times, loss of resistance is not definitive. Further advancement of the needle may predispose to a wet tap. A simple manual technique was devised using pressure applied with two fingers (bi-digital pressure test; BiP Test). The technique helps distinguish true loss of resistance from a false loss of resistance. This technique adds a useful confirmatory test to the already well-known loss of resistance technique used to verify the position of the epidural needle.