Buffered Local Anaesthetic: Difference between revisions
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The administration of local anaesthetic can be painful. There are many factors that increase influence pain. These are needle insertion, pH of the solution, and pressure from fluid distension. | |||
[[Lidocaine]] is a weakly basic amid and is unstable at its pH of 7.9. It is therefore prepared in acidic formulations to increase stability and shelf life, with a resultant pH of 4.7. This acidity, which is 1000 times more acidic than physiological pH, can cause tissue irritation with a stinging or burning pain. | |||
There have been many studies that have looked at buffering lidocaine with sodium bicarbonate to reduce its acidity. Sodium bicarbonate is safely metabolised by the kidneys. A Cochrane review in 2010 included 23 studies, and found that increasing the pH of lidocaine decreased pain with infiltration. The difference was -1.98 on a 1 to 10 scale in the cross-over studies, and -0.98 in the parallel group studies. There was a greater decrease in pain when the injectate contained adrenaline. It was safe with no adverse events or toxicity.<ref>{{#pmid:25993661}}</ref> | |||
In the US, many doctors routinely buffer their lidocaine. In the authors experience, it is relatively unknown in New Zealand and this low usage rate is believed to be based on cultural factors rather than the evidence. | |||
A common mixture is 10:1 of 1% lidocaine and 8.4% sodium bicarbonate. This ratio raises the pH of lidocaine to a physiological level. It can also be used with adrenaline. | |||
==References== | |||
<references/> | |||
{{Reliable sources|synonym1="buffered lidocaine"}} | |||
[[Category:Pharmacology]] | |||
[[Category:Procedures]] | [[Category:Procedures]] | ||
[[Category: | [[Category:Stubs]] | ||
Revision as of 21:46, 13 April 2021
The administration of local anaesthetic can be painful. There are many factors that increase influence pain. These are needle insertion, pH of the solution, and pressure from fluid distension.
Lidocaine is a weakly basic amid and is unstable at its pH of 7.9. It is therefore prepared in acidic formulations to increase stability and shelf life, with a resultant pH of 4.7. This acidity, which is 1000 times more acidic than physiological pH, can cause tissue irritation with a stinging or burning pain.
There have been many studies that have looked at buffering lidocaine with sodium bicarbonate to reduce its acidity. Sodium bicarbonate is safely metabolised by the kidneys. A Cochrane review in 2010 included 23 studies, and found that increasing the pH of lidocaine decreased pain with infiltration. The difference was -1.98 on a 1 to 10 scale in the cross-over studies, and -0.98 in the parallel group studies. There was a greater decrease in pain when the injectate contained adrenaline. It was safe with no adverse events or toxicity.[1]
In the US, many doctors routinely buffer their lidocaine. In the authors experience, it is relatively unknown in New Zealand and this low usage rate is believed to be based on cultural factors rather than the evidence.
A common mixture is 10:1 of 1% lidocaine and 8.4% sodium bicarbonate. This ratio raises the pH of lidocaine to a physiological level. It can also be used with adrenaline.
References
Literature Review
Literature Review
- Reviews from the last 7 years: review articles, free review articles, systematic reviews, meta-analyses, NCBI Bookshelf
- Articles from all years: PubMed search, Google Scholar search.
- TRIP Database: clinical publications about evidence-based medicine.
- Other Wikis: Radiopaedia, Wikipedia Search, Wikipedia I Feel Lucky, Orthobullets,
