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Three Part Question

In [adults with suspected femoral shaft fracture] is there an association between [pain relief with femoral nerve block] and [delayed or missed diagnosis of compartment syndrome]

Clinical Scenario

A 30 year old man is brought into A&E following a bicycle accident. He is complaining of agonizing pain in his Right thigh. On examination his thigh is very swollen and any attempt to move it is extremely painful. You suspect a femoral shaft fracture and want to administer some strong analgesia and a splint and send him for x-ray. The orthopaedic registrar complains that a femoral block could potentially mask the symptoms of a compartment syndrome. You are wondering if there is any evidence to support this.

Search Strategy

The following databases were searched:
MEDLINE(R) 1966 to July 2005 using the OVID interface
EMBASE 1980 to 2005 July using the OVID interface
All EBM Reviews - Cochrane DSR, ACP Journal Club, DARE, and CCTR using the OVID interface
Medline search: [{exp Nerve Block/ or exp Anesthesia, Local/ or exp Anesthetics, Local/ or exp BUPIVACAINE/ or exp LIDOCAINE/ or exp PRILOCAINE/ or (nerve$ and block$).mp. or (an?esthe$ and local).mp. or (an?esthe$ and block$).mp. or BUPIVACAIN$.mp. or (LIDOCAIN$ or LIGNOCAIN$).mp. or PRILOCAIN$.mp. or (regional and an?esthe$).mp. or (regional and block$).mp. or (regional and analgesia).mp. or (local and analgesia).mp.} AND {exp Femoral Fractures/ or (exp thigh/ and exp fracture/) or (fem#r$ and fracture$).mp. or (thigh and fracture$).mp.} AND { exp Compartment Syndrome/ or (compartment$ and syndrome$).mp. or (volkmann$ and contracture$).mp.}] LIMIT to human AND English
EMBASE search: [{exp Nerve Block/ or exp Anesthesia, Local/ or exp Anesthetics, Local/ or exp BUPIVACAINE/ or exp LIDOCAINE/ or exp PRILOCAINE/ or (nerve$ and block$).mp. or (an?esthe$ and local).mp. or (an?esthe$ and block$).mp. or BUPIVACAIN$.mp. or (LIDOCAIN$ or LIGNOCAIN$).mp. or PRILOCAIN$.mp. or (regional and an?esthe$).mp. or (regional and block$).mp. or (regional and analgesia).mp. or (local and analgesia).mp.} AND {exp Femoral Fractures/ or (exp thigh/ and exp fracture/) or (fem#r$ and fracture$).mp. or (thigh and fracture$).mp.} AND { exp Compartment Syndrome/ or exp Volkmann Contracture/or (compartment$ and syndrome$).mp. or (volkmann$ and contracture$).mp.}] LIMIT to human AND English
EBM search: [{((nerve$ and block$) or (an?esthe$ and local) or (an?esthe$ and block$) or BUPIVACAIN$ or (LIDOCAIN$ or LIGNOCAIN$) or PRILOCAIN$ or (regional and an?esthe$) or (regional and block$) or (regional and analgesia) or (local and analgesia)).mp.} AND { ((fem#r$ and fracture$) or (thigh and fracture$)).mp.} AND {((compartment$ and syndrome$) or (volkmann$ and contracture$)).mp.}] LIMIT to human AND English

Search Outcome

Altogether 3 papers were found in Medline, 6 in Embase and 1 in all EBM, of which none were relevant.

Comment(s)

No reliable evidence or any official guidance has been found to contraindicate the administration of a femoral block. In theory, pain disproportionate to the injury is thought to be the most important indicator of acute compartment syndrome in awake patients(1). However the diagnostic value of this sign is doubtful since the fracture as such, can cause intolerable pain. Strong analgesia at this point will allow for a relatively painless application of a splint which in turn will provide adequate immobilization of the limb. With the splint in place it is easier and less painful to transfer and position the patient in the x-ray department. Plus it is thought to reduce haematoma formation(2). 1. Mithofer K. Lhowe DW. Vrahas MS. Altman DT. Altman GT. Clinical spectrum of acute compartment syndrome of the thigh and its relation to associated injuries. Clinical Orthopaedics & Related Research. (425):223-9, 2004 Aug. 2. James E Keany, MD, FACEP, Fractures, Femur, http://www.emedicine.com/emerg/topic193.htm

Clinical Bottom Line

There is no evidence to associate a femoral nerve block with a delayed or missed diagnosis of compartment syndrome.