Epidural space identification exploration by a fiber optic tip-force sensing needle

Epidural space insertion is a common needle surgery for regional anaesthesia, such as labor pain relief and lower extremity surgery. But detection of needle entry into epidural space can be difficult, which currently is highly depended on a hand-feeling skill named loss-of-resistance (LOR). To provide the clinicians with a better real-time visual signal, this paper presents a novel tip force sensing needle with a fiber optic sensor mounted at its exact tip. Based on realistic requirements, an 18G tip-force sensing needle was firstly designed, and then characterized via a commercial force sensor. To assess the feasibility of epidural space identification, a trial experiment on swine ligaments/tendons was conducted. Then repeated swine spine insertion experiments were performed on epidural space identification. The results show that it can provide reliable force information to distinguish epidural space from surrounding tissues.