Identification of the epidural space: stop using the loss of resistance to air technique!

In a prospective trial involving 547 women, Evron et al. reported a 16% incidence of difficult epidural catheter insertion following a LOR with air technique, while in those patients treated with fluid for the LOR only 4% had a difficult catheter insertion (13). Evron et al. also showed that with air more inadvertent intravascular insertions of the epidural catheter occurred (13). This was however not confirmed by Beilin et al. and Sarna et al. who reported a similar incidence of intravascular catheters (43, 6). Beilin et al. and Sarna et al. were also unable to find a difference in the incidence of paresthesias during epidural catheter insertion between patients treated with saline or patients treated with air (43, 6).