Saline through the epidural needle: what volume?

Abstract

Listen

Translate article

To the Editor: I read with interest the article by Gadalla et al.1 However, it seems to me that the same effect can be accomplished with a smaller volume of saline administered through the epidural needle. In the author’s practice the loss of resistance to saline (LORS; 1.5–2 mL) is used for the identification of the epidural space with an 18-gauge Tuohy-Schliff epidural needle. A 27-gauge Pencan needle is inserted inside the epidural needle, 5 μg of fentanyl combined with 2.5 mg of levobupivacaine is injected intrathecally, the spinal needle is withdrawn, and 2 to 2.5 mL of normal saline is injected through the epidural needle. A 20-gauge multi-orifice epidural catheter is then inserted into the epidural space. Using this technique I have had an incidence of intravascular cannulation by the epidural catheter of 4% (unpublished data). This may be explained by the fact that with the LORS technique as opposed to the loss of resistance to air technique (LORA) some fluid is injected in the epidural space at the time of the epidural space identification. However, and importantly to the contrary, Rolbin et al. noted that there was no advantage to the injection of 3 mL of fluid into the epidural space before insertion of an epidural catheter.2 In conclusion I would challenge the authors to study several groups of patients receiving different volumes of normal saline (for example 2.5, 5, 10 mL) and use both LORS and LORA techniques for identification of the epidural space.