Epinephrine in digital nerve block

Epinephrine in digital nerve block

Report by P P Mohan, Research Fellow, Gastrointestinal Surgery

Checked by P T Cherian, Specialist Registrar, Hepatobiliary Surgery

Good Hope Hospital NHS Trust, Sutton Coldfield, University Hospital Birmingham, UK.

Abstract

A short cut review was carried out to establish whether epinephrine (adrenaline) is safe to use in digital nerve blocks. A total of 16 papers were found using the reported search, of which seven represented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results, and study weaknesses of these best papers are presented in table 2. The clinical bottom line is that epinephrine (1:200 000 to 1:100 000) is safe to use in digital blocks.

Table 2.

Author, country, date	Patient group	Study type	Outcomes	Key results	Study weaknesses
Sylaidis et al, 1998, UK	100 consecutive patients. Digital block using 2% lignocaine with 1:80 000 epinephrine	Observational	Digital–brachial pressure index (ratio of digital to brachial artery systolic blood pressures)	Mean fall of 19% in digital–brachial pressure index following the block (SD 14.6%).	The digital blood pressures were not measured at the end of procedure
			Finger tip temperature	Mean increase of 0.8 (SD 2.3)°C following block
			Digital artery blood flow (10 patients, duplex scanner)	Blood flow returned to normal by 1 h in all cases
			Ischaemic damage	None
Wilhelmi et al, 1998, USA	23 digital bocks using 1% lignocaine with epinephrine (1:100 000 or 1:200 000)	Observational	Ischaemic damage	None	Small case series, use of two different strengths of epinephrine
Wilhelmi et al, 2001, USA	Study group (n = 31) had digital block using 1% lignocaine with 1:200 000 epinephrine. Control group (n = 29) had 1% lignocaine plain	Randomised control trial	Need for tourniquet	Study group = 9/31, control group = 20/29, (p<0.002)
			Need for further anaesthetic dose	Study group = 1/31, control group = 5/29 (p = 0.098)
			Ischaemic complications	None
Denkler, 2001, USA	Review of all reported cases of ischaemic digital necrosis associated with the use of epinephrine from 1880 to 2000	Review	Presence of confounding factors in reported cases of ischaemic damage	21 out of 48 reported cases of digital gangrene involved the use of epinephrine. Confounding factors such as inappropriate concentration of epinephrine, use of older local anaesthetics, excessive volume of injection, prolonged use of tourniquet, use of hot soaks and infection were identified with all reported cases of gangrene
Altinyazar et al, 2004, Turkey	24 adults undergoing blocks in fingers or toes with 2% lignocaine and 1:100 000 epinephrine	Observational study	Digital artery blood flow at 10 min	Fall in peak systolic velocity by 60% and end diastolic velocity by 90%	Small study
			Digital artery blood flow at 60 min (n = 21)	Blood flow returned to pre‐block measurement
			Digital artery blood flow at 90 min (n = 3)	Blood flow returned to pre‐block measurement
Krunic et al, 2004, USA	Review of all reported cases of digital gangrene associated with the use of epinephrine from National Library of Medicine	Review	Presence of confounding factors in the reported cases	21 reported cases of digital gangrene involved the use of epinephrine. Factors such as inappropriate mixing of epinephrine, use of older agents, inappropriate use of tourniquet, use of hot soaks, infection, and large volume of injection were associated with the reported cases. No case reported epinephrine as the sole cause of gangrene	Historical review
Andrades et al, 2003, USA	Study group (n = 21) received 2% lignocaine with 1:100 000 epinephrine and control group (n = 22) received 2% lignocaine	Randomised control trial	Pain score at 1 h	Study group = 1.4, control group = 4.1 (p<0.05)	Small study
			Need for further anaesthetic dose	Study group = 4%, control group = 24% (p<0.05)
			Duration of analgesia	Study group = 4.6 h, control group = 2.4 h (p<0.05)
			Ischaemic damage	None

Three part question

In [adult patients with no underlying vascular compromise undergoing digital block] is [local anaesthetic with low dose epinephrine as safe as local anesthetic alone] at [achieving analgesia without causing ischaemic complications]?

Clinical scenario

A 25‐year‐old man presents to the emergency department with a traumatic laceration to his left index finger. The wound needs a thorough clean and will require suturing and you decide to do this using a digital nerve block technique. A colleague who has recently worked in plastic surgery suggests you use epinephrine (1:100 000) to help with haemostasis, but you have always been told that this can cause finger necrosis and that it should never be done. You wonder whether in fact this is true and decide to look at the evidence for yourself.

Search strategy

Medline search using Pubmed “Anesthesia”[MeSH] OR “Anesthesia, Local”[MeSH]) OR “Nerve Block”[MeSH] AND “Epinephrine”[MeSH] AND “Fingers”[MeSH].

Outcome

Sixteen papers were retrieved, of which seven were found to be relevant, including two randomised control trials, three observational studies and two reviews (table 2).

Comments

Two review articles carefully examined the previously reported cases and found that no case had epinephrine as the sole cause of ischaemic complication. Two studies examined the digital perfusion using Doppler flow, and concluded that the blood flow returned to normal by 1 h after epinephrine injection. Other randomised and observational studies showed longer duration of anaesthesia, better analgesia, less need for tourniquets and no ischaemic damage with the use of epinephrine.

This is clearly a controversial topic as it has been emergency medicine dogma that vasoconstrictive agents should not be used in digits. However, the evidence does not support this assertion for all patients. Clinicians may decide to use low concentration epinephrine when they feel this may help the procedure and where there is no underlying reason not to do so.

Clinical bottom line

In the absence of underlying vascular compromise, epinephrine (1:200 000 to 1:100 000) is safe to use in digital blocks along with local anaesthetics.