General observations:

If the wound or wounds are in areas where nerves may have been transected, obviously one should check for nerve deficits prior to administering local anesthesia.

Most physicians are unaware that local anesthesia can be accomplished essentially painlessly. Consequently, they believe that a certain amount of rather significant pain is involved in the process. I don’t ever recall being taught how to administer local anesthesia. Rather, think it was a matter of my observing a mentor doing it and then imitating him. It was only after completing seven years of postgraduate training, when I was in private practice, did I appreciate how relatively painless the process could be. I was blocking one of my great toes to remove an ingrown toenail and discovered that if the anesthetic solution was injected slowly, there was almost no pain. Later I became aware that by using a 30-gauge needle and by immediately preceding the skin penetration with a small pinch, the pain from the injection could be minimized and sometimes completely masked. About the same time, I became aware that by slowly dropping 2% lidocaine on an open wound for a moment or two enough topical anesthesia could be obtained that a 30-gauge needle could be inserted painlessly. Then it was just a matter of injecting slowly and advancing the needle slowly to make the procedure essentially pain free.  Ask the patient to tell you if they are experiencing any significant discomfort as the anesthesia is being injected. If they are, stop injecting for a few seconds and then resume.

In my experience, most ER physicians have been taught to use 1% plain lidocaine for anesthetizing wounds. They have been taught that 1% plain lidocaine reduces the risk of lidocaine toxicity and that adrenaline should be avoided because of its vasoconstrictive, cardiac, hypertensive and postoperative bleeding problems. The reality is, however, that 2% lidocaine with adrenaline is a preferable solution. 2% lidocaine provides less distortion of the wound margins because less is required. It also lasts longer and the adrenaline provides the advantages of vasoconstriction. This solution prolongs the anesthesia, decreases bleeding and reduces the risk of lidocaine toxicity. The fallacy of the old cliché about using local anesthesia with adrenaline about digits, the penis and the nose has already been discussed. Postoperative bleeding following adrenaline use, in my experience, is largely theoretical rather than actual and has not been a problem.

I have never seen a complication arising from the use of adrenaline with local anesthesia. Flaps have blanched only to resume normal color after the adrenaline dissipated. Cardiovascular symptoms secondary to local anesthetics containing adrenaline almost always have resulted from too rapid injection in richly vascularized areas such as the gums or buccal mucosa.

I never use sodium bicarbonate to counteract the acidity of lidocaine for two reasons. If the routine of administering local anesthesia outlined above is followed, the procedure is essentially painless. Secondly, the use of sodium bicarbonate involves introducing another risk factor, that of an improper mixture.

After using a 30-gauge needle - and I prefer a ½ inch length - to penetrate intact skin twice, switch to a new needle. The needles lose their sharpness rapidly.

Always use a 3-mL syringe when injecting local anesthesia, regardless of the size of the wound or wounds. A 3-mL syringe provides three advantages: it is easier to inject with a small syringe, a small syringe furnishes better control of the speed of injection, and one will tend to use less local anesthesia with a small syringe. It is a common economic observation that one’s personal financial expenditures usually mimic income.  The same philosophy applies here with local anesthesia.

Another advantage of a 30-gauge needle is that one can inject directly into the dirtiest of wounds without the risk of significant contamination. If the defect is so dirty that direct injection makes one squeamish, inject into a wound margin after obtaining topical anesthesia and then infiltrate the skin about the wound. The central part of a large wound can be anesthetized with a long 25-gauge needle inserted through the skin and deep to the wound surface. However, I have never seen a problem arise from directly injecting into a contaminated wound with a 30-gauge needle.

If you are dealing with multiple wounds, it is a good idea to anesthetize a small area of each wound initially, after obtaining topical anesthesia. By doing so, especially in pediatric patients, you have established an area of anesthesia in each wound while your preoperative sedation is at its maximum and you are less likely to arouse the patient later.

Debridement of large contaminated wounds often can be accomplished, after 2% topical lidocaine, with a ½% or 1/3% lidocaine with one part in 200,000 of epinephrine in the central part of the wound. Later the wound margins can be excised using 1% or 2% lidocaine with epinephrine.

One needs to be constantly aware of the concentration and volume of the anesthetic solutions being used, especially when dealing with larger multiple wounds. Lidocaine toxicity, caused by too much lidocaine in the bloodstream at one time, can be avoided by adjusting the concentration and volume of lidocaine being injected. In considering maximal amounts of lidocaine safe to use, most students and residents ignore the time factor. The usual suggested volume of 1% lidocaine that can be injected at one time is 50 mL or 500 mg, or 25 mL of 2% lidocaine. As noted, if you need a large volume of anesthetic solution over a relatively brief period, dilute the solution and never use more volume than is necessary. Most complex wounds are time-consuming to repair and over time lidocaine is absorbed and more can be safely used.

Most practitioners use too large a needle and too large a syringe when obtaining local anesthesia. One way to acquire an appreciation of how relatively painless local anesthesia can be is to block one of your own fingers using a ½ inch 30-gauge needle and a 3-mL syringe, following the technique outlined at the end of this chapter.

Injecting directly into the palm of the hand or soul of the foot can be exceedingly painful, even with the small needle. I personally avoid injecting directly into these areas but instead start on the dorsum of the hand or foot and slowly work around to the area of concern. Also avoid injecting directly into the skin of the distal one half of the nose or the skin of the lips. The skin of the distal one half of the nose is not mobile and does not lend itself to a small pinch. Consequently, inject on the proximal dorsal area, where the skin is mobile and also less sensitive, and then work distally.  If there is an open wound on the lip, use topical anesthesia initially and then inject. If the skin is intact and you are excising a lesion, obtain topical anesthesia on the mucosa and inject through that.

The above routines may seem overly fastidious and time-consuming, but almost all patients will favor these approaches. With practice, the additional time required can be minimized. Again, the golden rule is applicable.

As noted previously, contaminated wounds resulting from blunt force are surrounded by areas of dirty abrasions. Dirty abrasions not associated with open wounds are also common. Most residents and many attendings do not appreciate the importance of adequate debridement of dirty abrasions and are also ignorant of the most efficacious way to accomplish the debridement. Often the least experienced member of the team is assigned to the task of cleaning up the abrasions when the team leader doesn’t know how to accomplish the task! A section in the chapter on Special Situations describes the technique.

Unless the contaminated abraded areas are extensive, the debridement often can be done under local anesthesia. 2% topical anesthesia often provides satisfactory pain relief for superficial abrasions. Infiltration with ½% or 1/3% lidocaine may be required for more extensive dirty ones.

Patients with increased bleeding times often will wash out local anesthesia as the repair progresses and will require additional infiltration. This washout obviously needs to be factored in when considering the risk of lidocaine toxicity. As referenced previously several times, about one half of the patients presenting themselves for wound repair in the emergency room will have increased bleeding times.

It is important to realize that one cannot appreciate the amount of local being injected from the proprioceptive feedback from the syringe plunger. One may be exerting a great deal of pressure and yet no solution is going into the tissue. It is necessary to check the markings on the syringe or the distention of the tissue to be sure that local actually is being injected.

Removing the needle from the syringe to refill the latter is best done with a curved mosquito hemostat rather than the plastic needle hub. You are much less likely to stick yourself using the hemostat. Placing the needle on a 4 x 4 sponge while the syringe is being refilled makes the needle more easily retrieved on a busy Mayo tray

With an extensive flap, such as a degloving injury of the scalp, anesthesia of the entire flap can obviously be obtained by injecting its base. Multiple wounds of the brow and anterior scalp can be anesthetized by injecting the inferior margin of the brow and thereby blocking the supraorbital and supratrochlear nerves.

Some have recommended using Marcaine along with lidocaine with the initial injection. I prefer to inject Marcaine at the end of the repair to prolong the anesthesia and to avoid the discomfort associated with Marcaine when used initially. If adrenaline was part of the primary lidocaine solution, plain Marcaine can be used to at the end of the procedure.

Students often inquire about nerve blocks in obtaining local anesthesia of traumatic wounds. With the exception of digital blocks and the occasional use of supraorbital and supratrochlear blocks, most of the time nerve blocks are not applicable. There are two reasons for the inappropriateness of nerve blocks. The first is that seldom is a traumatic wound located in an area where a single nerve block would provide adequate anesthesia. The second, and more cogent reason is that you want adrenaline in the wound to decrease the bleeding.

When using topical anesthesia on lip or tongue wounds of young children, it is important to avoid getting the solution in the mouth. By so doing, anesthetization of the glottic area and aspiration can be prevented. Placing a dry sponge in the labial sulcus to absorb runoff is a convenient way to manage this problem. Careful positioning of a dry sponge when using topical anesthesia on a wound of the distal tongue will accomplish the same goal.

Before beginning debridement and repair, check to be certain anesthesia is adequate. Some patients require more time for anesthesia to take effect and some need more volume than ordinarily is required.

Occasionally a patient will tell you that they are allergic to all “caines.” They have been advised by their physician or dentist to avoid all local anesthetics. Allergy to lidocaine is exceedingly rare with only a small number of cases having been reported in the world literature. I manage patients allergic to all “caines” by scheduling their procedure in an outpatient setting or in the emergency room and by having an anesthesiologist present. Anesthesiologists all seem to be aware of the extreme unlikelihood of a patient having lidocaine allergy. I inject a small amount of lidocaine to prove to the patient that they are not allergic to lidocaine even though they may be allergic to multiple other “caines.” Many of these patients have been subjected to general anesthesia for minor procedures because of a reaction to a non-lidocaine local anesthetic. The extreme unlikelihood of a patient having a reaction to lidocaine is not widely appreciated by physicians and dentists.

Digital blocks:

As discussed previously, lidocaine with adrenaline may be used safely on most digital blocks. Certainly, if the patient has a history of peripheral vascular disease, Raynaud’s or similar problems, plain lidocaine should be employed. Use 2% lidocaine instead of 1%. Start on the proximal dorsal aspect of the digit and inject through the skin a split second following a tiny pinch at the injection site. Then inject very slowly, asking the patient to tell you if there is significant discomfort. After injecting as far as possible on the ulnar or radial side (and remember you should be using a 3-mL syringe and a ½ inch 30-gauge needle), withdraw the needle enough to allow reorienting it to the other side, without removing the point through the skin and repeat the procedure. At this stage in the block you should have used only two to two and one-half milliliters of lidocaine. Withdraw the needle, refill the syringe and block the volar digital nerves on each side by injecting the needle through an anesthetized area of the web space. Use the remainder of the 5 mL of anesthetic to block the volar aspect of the proximal part of the proximal digit. By following this routine, digital blocks can be almost painless. When blocking digits in children of any age, decrease the volume to an appropriate amount. Repair in an adult supplement the block with 0.5 mL of 0.5% Marcaine around each volar digital nerve at the base of the digit. This will provide anesthesia up to 4 to 6 hours or longer. Decrease the amount of Marcaine with children depending on the size of the digit.

Anesthetization of the nose for reduction of nasal fractures or rhinoplasty:

One can anesthetize the nose essentially painlessly if the following steps are followed:  Premedication with morphine at an appropriate dose makes the procedure less stressful. Begin by topical anesthetization of nasal mucous membranes on each side with 4% topical lidocaine on cotton-tipped applicators. The distal 1 cm or so of the nasal airways is lined with vestibular skin so the applicators need to be inserted beyond the skin. The topical lidocaine will anesthetize both the mucosal perichondrium of the septum as well as the mucous membrane of the lateral walls within a few minutes. Then, using a 3-mL syringe and a ½ inch 30-gauge needle and 2% lidocaine with epinephrine, balloon out the mucoperichondrium on each side. At the junction of the septum and side wall of the nose, angle the needle toward the nasal dorsal skin and slowly infiltrate as the needle passes through the medial crus of the upper lateral cartilage. The patient will feel a slight tinge when the needle goes through the cartilage. Then slowly raise a small wheal on the dorsum of the nose by infiltrating the nasal subcutaneous tissue slowly. Once the overlying skin becomes anesthetized, which will be within a few seconds, one can inject through the wheal to block the remaining skin and subcutaneous tissue of the nose.

By going slowly, the entire procedure can be essentially painless. If a rhinoplasty is contemplated, it is important to block the mucous membrane at the base of the lateral wall on each side with 1 mL or so of the injectable anesthetic solution. The same step may be necessary prior to reducing extensive nasal fractures. Anesthetizing the nose in this fashion requires a few extra minutes but the patient will be appreciative. I prefer 4% lidocaine to cocaine as a topical anesthetic because of the exceedingly unlikelihood of an allergic reaction to lidocaine. It is important not to distort the contours of the nose by injecting too much lidocaine. Only a small amount of 2% is required to provide adequate anesthesia.