Evaluation of femoral nerve blockade following inguinal paravascular block of Winnie: are there still lessons to be learnt?

Abstract

SummaryLower limb peripheral nerve blocks are used to provide surgical anaesthesia or postoperative analgesia. Anatomical texts imply that femoral and saphenous nerve blocks be evaluated by sensory testing of the skin overlying the anterior aspect of the thigh, and the medial aspect of the foot, respectively. We have mapped the distribution of anaesthesia in 25 adults following femoral nerve blockade, performed using the inguinal paravascular technique of Winnie. There was substantial interindividual variation in the area of anaesthesia. Only the skin overlying the middle third of the medial thigh was consistently blocked in 100% of patients. The distribution of anaesthesia conformed to anatomical text descriptions in 24% of cases. We conclude that demonstration of complete quadriceps paralysis confirms femoral nerve blockade. Failing that, sensory evaluation of a femoral nerve block should involve testing the skin of the middle third of the medial aspect of the thigh. The skin overlying the anteromedial aspect of the middle third of the leg should be evaluated for saphenous nerve block.

Comparison of sciatic psoas compartment block and sciatic femoral 3-in-1 block for knee arthroscopy

“…The femoral approach combines inguinal paravascular (3-in-1) and sciatic nerve block. Femoral block is the most commonly used peripheral regional technique [12,13]. It is performed easily, but it may not always produce an effective block of the lateral femoral cutaneous and obturator nerves.…”

Comparison of Parasacral and Posterior Sciatic Nerve Blocks Combined with Lumbar Plexus Block

“…In a study on patients who underwent elective knee arthroscopy, regions of complete sensory loss were mapped after femoral block, which was made using inguinal paravascular block of Winnie, and it was demonstrated that there was substantial interindividual variation in the area of sensory loss. Hence, it was concluded that absence of sensory anaesthesia of the skin overlying the antero-superior aspect of the thigh or medial malleolus was not suggestive of an unsuccessful nerve block (17). In our study, 8 patients from each group (40%) had painful sensation to pinprick test in areas innervated by LFC nerve, whereas none of the patients declared that they had painful sensation in areas innervated by superficial and deep peroneal nerve, PFC nerve and other tibial nerves.…”

The threshold elicited motor response via an in situ femoral nerve catheter predicts analgesia following total knee replacement

“…If the minimum threshold current was higher (<0.8 mA) or if no motor response was elicited, 20 mL of 0.25% (50 mg) of ropivacaine was administered as above. Patients were assessed using a 21-gauge needle for pinprick sensory anesthesia of the femoral nerve distribution (middle third of the medial aspect of the thigh and the anteromedial middle third of the leg) by an observer unaware of the dose administered, at 5-minute intervals for 30 minutes 3. Femoral nerve blockade was considered ‘complete’ if there was a lack of pinprick sensation in the femoral nerve distribution of the thigh and calf within 30 minutes.…”