Comments by "Hittite Charioteer" (@hittitecharioteer) on "Giving injections wrongly" video.

  1. More likely local analgesic. Even with the inclusion of 1: 10,000 adrenaline, the l.a. won’t take if you inject into a blood vessel – because the circulation will flush the l.a. away from the nerves being targeted.
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  2.  @twmd  In dentistry it is possibly the most-used combination for local analgesia. The amounts injected by dentists are very small, and although the l.a. is mildly vasodilating (ie mildly hypotensive) it is the adrenaline (Americans may know it as epinephrine) that causes the localised vasoconstriction that is intended to keep the l.a. in the area of the nerves being blocked. For your information only: prilocaine 2% plain is the most used choice in UK by podiatrists as an l.a. for digital blocks BECAUSE it is mildly vasodilating and thus deemed the safe approach for use on distal appendages. I'm unsure if it remains the case in USA, but back in the 1990s their podiatrists were allowed to use lidocaine with adrenaline (possibly in an even lower amount than the 1: 10,000). Best practice is changeable in all the world's fields of practice. Of course, it needs to be borne in mind that l.a. deployed by podiatrists is followed by tourniquet application. So unlike dentists, there is a small risk of causing a delayed restoration to the vascularity of the area operated on – the real danger being it failing to restore sufficiently quickly that it leads to lasting tissue damage, and in extremis, necrosis.
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  3.  @twmd  You are welcome. Digital ring blocks are a particular risk. Taking a toe as an example, there are four sensory nerves that enter it: one each side at the top/dorsum, and one each side on the underside/plantar aspect. All the nerves branch out and cover the entire toe – in what is commonly called a "nerve plexus". So, even if a podiatrist operates on a lesion in just one small discrete area and on one side of the digit/toe, it necessitates l.a. injected to block all four nerves. This is essentially why regulatory authorities took the view that the inclusion of adrenaline as an adjunct in peripheral surgery was not "best practice" or recommended. (I do believe podiatric surgeons may indeed use the inclusion of adrenaline – but it would be for superficial use and at a level considerably proximal to the toes. Clearly, elsewhere in the body eg. the scalp which is heavily vascularised, there is no such risk of causing a injurious ischaemia. Forgive me if I have bored you; but I sense you are interested. Indeed others may in time stumble on this exchange and add their own knowledge to what we have shared. Regards 🤝🇮🇪
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