• 
• 

Three Part Question

In [patients requiring subcutaneous administration of local anaesthetic] is [buffered or plain lignocaine infiltration] better at [inducing less pain at the infiltration site]?

Clinical Scenario

A 8 year old child has a 3cm wound requiring local anaesthesia prior to wound closure. While preparing a measured amount of lignocaine, you wonder if buffering with sodium bicarbonate will reduce the pain of administration.

Search Strategy

Medline 1966 to 5/99 using the Winspirs interface.
[exp Lidocaine] AND [exp sodium bicarbonate OR exp buffers OR exp bicarbonates]

Search Outcome

Search outcome 173 papers were identified of which 157 were irrelevant; 1 extra paper on update. The remanining 17 papers are shown in the table.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Christoph RA et al, 1988, USA	25 adult volunteers	Double blinded randomised controlled clinical trial	Visual analogue derived pain scores	Significant reduction in pain with buffered lignocaine use	Markedly differing sites were used for each injection
Bartfield JM et al, 1990, USA	91 adult patients with traumatic lacerations	Double bind randomised controlled crossover clinical trial	Visual analogue scale derived pain scores	Buffered lignocaine is significantly less painful than plain	Actual pain scores and confidence limits not given
McGlone R et al, 1990, UK	20 volunteers	Double blinded randomised controlled crossover trial	Visual analogue derived pain score	Significant reduction in pain scores using buffered lignocaine solutions	No confidence intervals
Bartfield JM et al, 1993, USA	31 adult patients undergoing digital nerve block	Double blinded randomised controlled crossover clinical trial	Visual analogue derived pain scores	Buffered lignocaine significantly less painful than plain	Again no pain scores and confidence limits given
Matsumoto AH et al, 1994, USA	150 patients undergoing interventional radiography procedures	Double blinded randomised controlled clinical trial	Visual analogue derived pain scores	Significant reduction in pain after use of buffered lignocaine	Use of a crossover design may have been more appropriate to let each patient act as own control
Mader TJ et al, 1994, USA	32 adult volunteers receiving warm or room temperature buffered or plain lignocaine	Double blinded randomised controlled crossover trial	Visual analogue derived pain scores	Significantly lower pain scores for warmed buffered lignocaine	Room temperature buffered lignocaine was no better than warm plain lignocaine. Significant results only occur if warmed and buffered.
Nelson AL, 1995, USA	46 females undergoing subcutaneous contraceptive implant procedure	Double blind randomised controlled crossover trial	Mean pain scores experienced on lidocaine and buffered lidocaine infiltration	29% reduction in mean pain scores using buffered lidocaine	Neither actual scores nor confidence limits given so importance difficult to appreciate
Brogan GX Jr et al, 1995, USA	45 adults with traumatic lacerations receiving plain, warmed or buffered lignocaine	Single blinded randomised controlled clinical trial	Visual analogue scale derived pain scores	Warmed and buffered lignocaine were significantly less painful than plain lignocaine. No significant difference between warm or buffered lignocaine.	Single blinded
Fitton AR et al, 1996, UK	30 patients undergoing bilateral pinnaplasty	Double blinded randomised controlled crossover clinical trial	Visual analogue derived pain scores	Significant reduction in pain with buffered lignocaine	Operator blinding was not clearly identified
Parham SM et al, 1996, USA	42 adult volunteers	Double blinded randomised controlled crossover volunteer study	Visual analogue derived pain	Significantly reduced pain on infiltration with buffered lignocaine	nil of note
Friedman HE et al, 1997, USA	30 adult volunteers?	Double blinded randomised controlled crossover trial	Visual analogue derived pain score	Significantly reduced pain of infiltration after use of buffered lignocaine	No confidence intervals
Scarfone RJ et al, 1998, USA	42 adult volunteers receiving buffered and plain lignocaine at both slow and fast infusion rates	Single (patient) blinded randomised controlled crossover trial	Visual analogue scale derived pain scores	No significant difference in pain scores generated after use of buffered and plain lignocaine	2 different infusion rates used for buffered and plain. Numbers probably to small to identify a difference between plain vs buffered at each infusion rate
Palmon SC et al, 1998, USA	40 adult volunteers receiving plain and buffered lignocaine using 2 differing needle guages	Double blinded randomised crossover volunteer study	Visual analogue derived pain scores	Buffered lignocaine was significantly less painful	Timing of pain scoring after injection not stated
Colaric KB et al, 1998, USA	20 adult volunteers receiving warmed and room temperature plain lignocaine in addition to warmed and room temperature buffered lignocaine	Double blinded randomised controlled crossover volunteer study	Visual analogue derived pain scores	Buffered lignocaine solutions were significantly less painful than warm or room temperature plain lignocaine	nil of note
Masters JE, 1998, NZ	40 adult patients undergoing elective minor operations requiring local anaesthesia	Double blinded randomised controlled crossover clinical trial	Visual analogue derived pain scores	Significant reduction in pain with use of buffered lignocaine	Non-standardised infiltration methods
Newton CW et al, 1999 USA	194 neonates undergoing circumcision	Double blinded randomised controlled clinical trial	Crying as assessed by a Neonatal behavioural assessment score	No significant difference found between plain and buffered groups	Objectivity of a scoring neonatal crying
Fatovich DM and Jacobs IG, 1999, Australia	136 children undergoing dermal laceration repair in the emergency department 135 adults undergoing dermal laceration in the emergency department	Double blind randomised controlled study	Visual Analogue Scores for pain on administration of local. Nurse and parent VAS for children	No significant difference in VAS scores between use of plain or unbuffered lignocaine	None significant

Comment(s)

One rare occasion in emergency medicine where PRCT's do exist! There is conflicting evidence here but the biggest study which was set in the ED suggests buffering not useful. The pro-buffer papers were smaller not as well conducted and were in volunteers or conducted in an elective setting.

Clinical Bottom Line

In both children and indeed adults the evidence for buffered lignocaine in the acute setting does not support its mandatory use. Local expert advice should still hold.

References

1. Christoph RA, Buchanan L, Begalla K, et al. Pain reduction in local anaesthetic administration through pH buffering. Ann Emerg Med 1988;17(2):117-20.
2. Bartfield JM, Gennis P, Barbera J, et al. Buffered versus plain lidocaine as a local anaesthetic for simple laceration repair. Ann Emerg Med 1990;19(2):1387-9.
3. McGlone R, Bodenham A. Reducing the pain of intradermal lignocaine injection by pH buffering. Arch Emerg Med 1990;7(2):65-8.
4. Bartfield JM, Ford DT, Homer PJ. Buffered versus plain lidocaine for digital nerve blocks. Ann Emerg Med 1993;22(2):216-9.
5. Matsumoto AH, Reifsnyder AC, Hartwell GD, et al. Reducing the discomfort of lidocaine administration through pH buffering. J Vasc Interv Radiol 1994;5(1):171-5.
6. Mader TJ, Playe SJ, Garb JL. Reducing the pain of local anaesthetic infiltration. Ann Emerg Med 1994;23(3):550-4.
7. Nelson AL. Neutralizing pH of lidocaine reduces pain during Norplant system insertion procedure. Contraception 1995;51(5):299-301.
8. Brogan GX Jr, Giarrusso E, Hollander JE, et al. Comparison of plain, warmed and buffered lidocaine for anaesthesia of traumatic wounds. Ann Emerg Med 1995;26(2):121-5.
9. Fitton AR, Ragbir M, Milling MA. The use of pH adjusted lignocaine in controlling operative pain in the day surgery unit. Br J Plast Surg 1996;49(6):404-8.
10. Parham SM, Pasieka JL. The effect of pH modification by bicarbonate on pain after subcutaneous lidocaine injection. Can J Surg 1996;39(1):31-5.
11. Friedman HE, Jules KT, Springer K, et al. Buffered lidocaine decreases the pain of digital anaesthesia in the foot J Am Podiatr Med Assoc 1997;87(5):219-23.
12. Scarfone RJ, Jasani M, Gracely EJ. Pain of local anaesthetics: rate of administration and buffering. Ann Emerg Med 1998;31(1):36-40.
13. Palmon SC, Lloyd AT, Kirsch JR. The effect of needle gauge and lidocaine pH on pain during intradermal injection. Anesth Analg 1998;86(2):379-81.
14. Colaric KB, Overton DT, Moore K. Pain reduction in lidocaine administration through buffering and warming. Am J Emerg Med 1998;16(4):353-6.
15. Masters JE. Randomised controlled trial of pH buffered lignocaine with adrenaline in outpatient operations. Br J Plast Surg 1998;51(5):385-7.
16. Newton CW, Mulnix N, Baer L, et al. Plain and buffered lidocaine for neonatal circumcision. Ostet Gynecol 1999;93(3):350-2.
17. Fatovich DM, Jacobs IG. A randomised controlled trial of buffered lignocaine for local anaesthetic infiltration in children and adults with simple lacerations. J Emerg Med 1999;17(2):223-8.