Ultrasound standard for obturator nerve block: the modified Taha's approach

Abstract

if a peripheral nerve block catheter was to be placed. In eight of 15 patients, a continuous peripheral nerve block catheter was inserted. After local anaesthetic injection ( Fig. 1D), the progress of the sensory block was assessed at 5 min intervals for the first 20 min. Sensory function was assessed as sensation to pinprick with a 23 gauge needle in the tibial (plantar area of the foot) and common peroneal (dorsal area of the foot) anatomical territories. Sensory function was graded as follows: zero, normal; one, moderate sensory loss; or two, complete sensory loss. Additionally, static and dynamic visual analogue scale scores were measured. A total score of three out of four was considered as successful sensory block.According to our results, the block success rate was 100%, and the static and dynamic visual analogue scale scores were zero at 20 min. No complications, including vascular puncture and local anaesthetic toxicity, were observed. A paraesthesia response was elicited in five of 15 patients. Postoperative neurological examination after recovery of sensory and motor function of the lower limb revealed no neurological deficit.A pocket-sized ultrasound linear probe seems to facilitate popliteal sciatic nerve block, providing a feasible and safe technique for perioperative pain management in patients with lower limb injuries. Further studies are required in order to validate our observations.

Advances of Techniques in Deep Regional Blocks

“…In the article reviewing obturator nerve block for this special issue, proximal approaches are recommended whenever possible, and the best patient position (supine or lithotomy) is yet to be determined. Although the authors worried about difficult alignment of the needle with the transducer in the supine position, needle visualization can be greatly facilitated by a true echogenic needle and meanwhile maintaining the eye, hand, needle, transducer, and ultrasound machine all in the same plane [ 1 ] according to recent advances in physical ergonomics [ 2 , 3 ]. Furthermore, the supine position naturally keeps the leg straight and slightly externally rotated, which yields the best imaging on the obturator nerve [ 4 ].…”

Transversus Abdominis Plane Block: An Updated Review of Anatomy and Techniques

“…After making the skin aseptic, we suggest performing the lateral/posterior approach first and then the subcostal approach, to keep the probe aseptic. In other words, the probe is placed in the gravity-dependent part as a general rule below the needle insertion site for single-shot peripheral nerve blocks [ 65 , 66 ]. Jelly introduction into the central part of the body should be avoided whenever possible, even if it is aseptic [ 67 ], and ultrasound gel itself near peripheral nerves may cause inflammation [ 68 ].…”

Ultrasound-Guided Obturator Nerve Block: A Focused Review on Anatomy and Updated Techniques

“…This retrograde spread of liquid through the obturator canal is key to understanding why the ultrasound-guided proximal approach for ONB, which is provided by a single interfascial injection of local anesthetic, works successfully. Several proximal approaches for ONB have been reported [ 17 , 23 , 31 , 35 , 42 ], all of which target the plane between the pectineus and obturator externus muscles as the site for injection of local anesthetic but use different patient positions (i.e., supine or lithotomy), transducer locations (i.e., the inguinal crease or medial thigh), modes of needle insertion (i.e., out-of-plane or in-plane), and needle trajectories (i.e., anterior-to-posterior, inferior-to-superior, or lateral-to-medial).…”

“…The same patient and transducer positions were used in the reports published by Anagnostopoulou et al [ 17 ], Taha [ 23 ], and Lin et al [ 42 ]. These proximal approaches are performed with the patient in the supine position and the hip slightly abducted and externally rotated.…”

“…Out-of-plane ultrasound-guided needle insertion is essentially inferior to an in-plane technique in terms of being able to observe the position of the needle tip in real time [ 43 ], although Taha reported a 100% success rate without complication using his approach in 60 patients [ 23 ]. The approach devised by Lin et al [ 42 ] entails in-plane lateral-to-medial needle insertion with the same transducer position. In-plane ultrasound guidance allows visualization of the needle tip in real time, which may help to decrease the risk of inadvertent vessel or nerve injury.…”