Anatomical landmarks or ultrasound for guiding femoral nerve blocks in adults?

April 29, 2008

May 8, 2008

Dr Helen Mansfield, A and E ST3 (Bath RUH)

In [adults requiring a femoral nerve block] does [ultrasound guidance or use of anatomical landmarks] provide [better analgesia]?

You see an elderly lady who has sustained a fractured neck of femur and remains in discomfort following administration of opiates. You wish to perform a femoral nerve block. The department's ultrasound machine is currently in use and there is no nerve stimulator. You wonder how successful a nerve block guided by anatomical landmarks will be, or whether you should wait for the ultrasound machine to be free.

Medline 1950 to date, EMBASE 1974 to date, Cochrane library performed 29.04.08

Medline; [Nerve block OR femoral nerve] AND ultrasound, ltd to human and clinical trials.
EMBASE; [Nerve block OR femoral nerve OR peripheral nerve] AND ultrasound, ltd to human and clinical trials.
Cochrane; Femoral nerve blocks AND ultrasound

Medline; 58, EMBASE; 77, Cochrane 15, (8 reviews and 7 trials), titles and abstracts screened to reveal one review protocol of relevance which is not yet complete.

There are many trials which compare efficacy of femoral nerve blocks under ultrasound guidance vs. nerve stimulator but none that directly compare an approach via anatomical landmarks ie the inguinal ligament and the femoral pulse vs. ultrasound. Emergency departments vary in the equipment they have available often restricting the use of ultrasound. If a significant difference was found departments may have a stronger business case for such equipment.

There is no evidence directly comparing femoral nerve blocks under ultrasound guidance vs. anatomical land marks. Clinicians should employ a method with which they feel comfortable and have the equipment to facilitate.