Marcaine

Abstract

Local anesthetic agents are administered before many ambulatory cutaneous operations. The injection of the local anesthetic agent is often the only painful aspect of the procedure. There are various factors that determine how painful the anesthetic administration may be. These include the preparation used, the size of the needle and syringe used, injection technique, depth of injection, attitude of the physician, and more. In this article, we present the different techniques we apply to achieve minimal pain during the injection of local anesthetics.

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Introduction

The purpose of local anesthesia is to render the surgical field completely anesthetic in order to perform painless surgery. It is often observed that during anesthetic infiltration the surgeon inflicts some discomfort on the patient. The expertise of a surgeon is determined not only by his surgical capabilities, but also by his bedside manner and his ability to minimize the pain during infiltration of local anesthesia. Practicing the art of near-painless anesthesia during administration of local anesthetics may be a significant factor in enhancing the surgeon's reputation.

The pain perceived during administration of local anesthetics is a two-part phenomenon. The first sensation is caused by the needle puncture, which causes a short, intense pain. The second pain involves activation of nociceptors in the skin responding to both the chemicals in the infiltrated agent and rapid distention of the tissue. The second sensation is both more intense and more prolonged.

This paper will present a review of the literature and a summary of the authors' clinical experience with techniques and agents that can be used to minimize pain due to the needle stick and infiltration of local anesthetics. Employing these methods may affect how the patient reacts to the procedure, cooperates at the time of surgery, and ultimately perceives the surgical experience.

The Ten Commandments

1. Communication -- Talk to the patient in a calm reassuring voice and promise to be patient and gentle.

2. Injected Agent -- Start the anesthesia with lidocaine 1%, without adrenaline solution, at room temperature.

3. Tools -- Use a 1cc syringe and a 30G needle.

4. Alert -- Inform the patient before injecting the needle, so it will not come as a surprise.

5. Injection Technique -- Puncture the skin in a quick short maneuver while stretching or pinching the area with the other hand.

6. Depth -- Inject subdermal and not intradermal.

7. Bleeding/Anesthetic Time Control -- As soon as the area is anesthetized switch to Marcaine[R] and adrenaline solution.

8. Mode of Injection -- Inject slowly in small volume pulses and not continuously.

9. Gate Control -- While injecting with one hand, tap with a finger on the adjacent skin.

10. Distraction -- Talk with the patient during the procedure about his occupation, hobbies, family, and so forth.

Discussion

Communication and Psychology

Psychological factors can be very important in lowering the patient's stress. Because pain perception is subjective, and patients treated under local anesthesia are awake, behavioral measures to reduce anxiety may be helpful. A friendly, unhurried attitude of the physician and staff is reassuring and can contribute to pain control. Quiet background music may calm and distract the patient.

If the patient is very nervous, talk to him in a calm and reassuring voice, promising to be patient and gentle. If the patient is being monitored you will be surprised to see how fast he reacts to this simple maneuver with a decrease in pulse rate and blood pressure. Inform the patient of the impending injection before puncturing the skin. A distracting conversation is important while injecting the local anesthesia; ask the patient about his occupation, hobbies, children, vacations, and so forth. Some patients may benefit from premedication with oral tranquilizers like diazepam 5 mg.

Needle Size and Skin-Puncture Technique

Stretch the skin at the area of needle insertion. If it is the nose that is being injected, pinch it firmly. Insert the needle in a quick short maneuver, preferably through a pore in the skin.

Use small diameter needles (#30 gauge). The sharpness of the needle allows easy penetration even of thick surfaces like the palm and sole. One inch or longer needles decrease the number of needle sticks required, but these may be flexible and less easy to control.

Pierce the skin at an angle of 90 degrees, so that the tip of the needle transects fewer nerve endings. Replace the needle with a new one when multiple injections are performed, as the needle tip becomes dull with repetitive use.

Topical and Injected Agents

Topical Anesthesia

Topical anesthesia may be used to reduce the pain associated with the needle stick. The major advantage is painless insertion of the needle. However, for some agents onset is prolonged (one hour or longer) and the anesthetic effect is short lived.

Topical Anesthetic Creams

There are several creams that are used for topical anesthesia. The most commonly used is EMLA cream. EMLA cream (an eutectic mixture of lidocaine 2.5% and prilocaine 2.5%) is an effective topical anesthetic on normal, intact skin for local analgesia. When applied under an occlusive dressing for at least one hour, EMLA reduces needle-stick pain. (1) Another effective agent is Betacain Gel. (2)

We believe that the usage of these agents is time consuming and more suitable for surface procedures like laser treatment since they cannot relieve the second type of pain (chemical and tissue distention).

An interesting application was reported in Mohs surgery. Lidocaine 2% gel prolonged the anesthesia of injected lidocaine by 48% when used on open wounds between the stages of Mohs micrographic surgery. (3) Alternatively, the senior author (IZ) recommends the use of sponges soaked with lidocaine 4% + adrenalin to obtain a similar effect.

Thermal (Cold) Anesthesia

Applying cold to the skin produces a brief local anesthetic effect that is effective in reducing or eliminating needle-stick pain. This topical anesthetic may be as simple as massaging the site with an ice cube or the use of a volatile spray such as ethyl chloride. When a spray is employed, the eyes must be shielded and inhalation of the gas minimized. Their over-use may cause blistering and hypopigmentation and may result in inferior quality of tissue specimens. (4-6)

Injected Agents

Acidity of the solution is a major factor producing pain during local infiltration. The lower the pH level of the solution, the more intense the pain. Therefore, buffering the solution decreases the infiltration pain. This is done by adding sodium-bicarbonate to lidocaine by a 1:9 ratio. Buffering reduces the infiltration pain by increasing the onset rate of analgesia. (7) Only the uncharged base form can diffuse across the nerve membrane and produce a nerve block. Thus, the proportion of uncharged base to charged cation controls the rate of onset of anesthesia. A rise in pH changes the equilibrium in favor of the uncharged base form. (8)

There is a difference in the acidity of the anesthetic drugs:

* Lidocaine (pH 6.6) is less acidic then lidocaine with epinephrine (pH 4.6).

* Lidocaine 1% is less acidic then lidocaine 2%.

* Lidocaine is less acidic then bupivacaine (Marcaine[R]). (9)

While there is a considerable body of literature supporting the use of sodium bicarbonate as a buffering agent, the authors do not find it is consistent with their clinical experience and do not use it.

[FIGURE 1 OMITTED]

Start local infiltration with lidocaine 1% solution. Only when the area is numb, inject bupivacaine + adrenaline in order to get a longer anesthetic time and vasoconstriction for better bleeding control.

Intradermal versus Subdermal

Infiltration can be performed at two different depths, intradermal or subdermal. Superficial intradermal infiltration raises a wheal. Although this technique produces immediate anesthesia, the infiltration phase is very painful. In contrast, subdermal injection takes a longer time to achieve anesthesia (6 minutes), but the infiltration is significantly less painful. (5,10) The different degree of pain can be explained in two ways. First, in the superficial dermis the density of nociceptors is greater compared to the deep dermis. Second, the wheal is a result of rapid local tissue expansion, a process known to be very painful. As the duration of anesthesia following deep or superficial injection is similar, the only justification for rapid wheal-producing superficial-dermal injection would be the need for immediate numbing of the site, or to raise the tissue prior to biopsy (hydro-dissection). (10)

Rate and Mode of Injection

Rate of injection is an important factor in controlling the pain of injection. When the anesthetic agent is injected slowly, the infiltration can be virtually painless. (11) The use of 1cc syringes helps to obtain a slow rate and low volume of injection.

Pulse versus Continuous Injection

While slowly injecting the local anesthetic, it is important to inject in pulses and not in one long continuous injection (Figure 1). Pulse injection cause less pain then continuous injection.

Look at the syringe and push only 1 graduation (0.1cc). Count to 3 then push an additional graduation, and so on for 2 or 3 injections, while looking at the patient's face and assessing his or her pain. Then you may push two graduations at a time, and eventually complete the infiltration.

If the patient complains of severe pain no matter what you do, it might mean that the needle is touching a nerve. Stop the injection! Withdraw the needle slowly and insert it again at a different location.

[FIGURE 2 OMITTED]

Fanlike Injection

A fanlike injection technique limits the number of needle insertions. If it is necessary to reinsert the needle, this should be done through an area that has already been anesthetized so the needle-stick pain can be eliminated. (5)

Local Nerve Direction

Injections should follow the anatomical course of the nerves; the needle should begin proximally and follow the nerve distally. A good example is on the extremities. Begin at the proximal side of the nerve and continue distally. (5)

Peripheral Nerve Blocks

Peripheral nerve blocks produce anesthesia of a large area of skin using a single injection. Their use should be encouraged whenever possible. However, several points should be kept in mind.

First, inject into the tissue immediately surrounding the nerve rather than into the nerve. Second, avoid intra-arterial injections. Third, wait 5 to 10 minutes for optimal anesthesia to take place. Due to the larger diameter of the cutaneous nerve, it takes time for the medication to diffuse. (5)

[FIGURE 3 OMITTED]

Gate Control

The Gate Control theory (12) states that nerve impulses evoked by injury are influenced in the spinal cord by other nerve fibers that act like "gates," either preventing the impulses from getting through or facilitating their passage, "deciding" whether or not the information will be conveyed to supra-spinal brain areas where it can be interpreted as "pain." In other words, the spinal cord is not a passive receiver of pain information. The gating mechanism within the spinal cord closes in response to normal stimulation of the fast conducting "touch" nerve fibers, but opens when the slow conducting "pain" fibers transmit a high volume and intensity of sensory signals. The gate can be "closed" again if these signals are countered by renewed stimulation of the large fibers.

This can be applied clinically, if the surgeon scratches or taps the patient's skin adjacent to the site where the needle will be inserted. The tapping activates the large diameter "touch" fibers to "close" the gate for impulses carried by nerve impulses evoked by injury from the needle insertion. If those impulses are blocked from entering the spinal cord, the patient may feel less or no pain. The tapping should begin 1 or 2 seconds before and continue throughout the needle insertion and infiltration. Using this technique, pain from the needle stick or infiltration may be prevented (13) (Figure 2).

The Gate Control theory can be applied by using different types of small hand and finger massagers that produce vibration at the injected area. These massagers can be purchased at wide-spread "gadget shops." The vibrations from such massagers almost eliminate the pain associated with the infiltration of local anesthetics and are an excellent technique for children (Figure 3).

Summary

The ability to provide painless local anesthesia to patients undergoing ambulatory surgery should be an important part of the modern medical practice. This can be accomplished with knowledge of the different anesthetic agents and by acquiring the skills mentioned above.

References

1. Gajraj NM, Pennant JH, Watcha MF. Eutectic mixture of local anesthetics (EMLA) cream. Anesth Analg. 1994;78:574-583.

2. Friedman PM, Fogelman JP, Nouri K, et al. Comparative study of the efficacy of four topical anesthetics. Dermatol Surg. Dec 1999;25(12):950-4.

3. Robins P, Ashinoff R. Prolongation of anesthesia in Mohs micrographic surgery with 2% lidocaine jelly. J Dermatol Surg Oncol. 1991;17:649-652.

4. Holmes HS. Options for painless local anesthesia. Postgrad Med. 1991;89:71-72.

5. Randle HW. Reducing the pain of local anesthesia. Cutis. 1994;53:167-170.

6. Serup J. Punch biopsy of the skin: effect of temperature and local anesthesia with ethyl chloride freezing. J Dermatol Surg Oncol. 1983;9:558-561.

7. Christoph RA, Buchanan L, Begalla K, Schwartz, S. Pain reduction in local anesthetic administration through pH buffering. Ann Emerg Med. 1988;17:117-120.

8. Covino BG. Physiology and pharmacology of local anesthetic agents. Anesth Prog. 1981;28:98-104.

9. Knowles WR. Minimizing pain due to local anesthesia. J Dermatol Surg Oncol. 1990;16:489.

10. Arndt KA, Burton C, Noe JM. Minimizing the pain of local anesthesia. Plast Reconstr Surg. 1983;72:676-679.

11. Stegman SJ, Tromovitch TA, Glogau RG. Basics of Dermatologic Surgery. Chicago: Yearbook Medical Publishers, Inc; 1982:27.

12. Grekin RC, Auletta MJ. Local anesthesia in dermatologic surgery. J Am Acad Dermatol. 1988;19:599-614.

13. Bourke DL. Counter-irritation reduces pain during cutaneous needle insertion. Anesth Analg. 1989;64:379.

Isaac Zilinsky MD, (a,b) Eran Bar-Meir MD, (b) (equal co-authors) Ruth Zaslansky DSc, (c) David Mendes MD, (b) Eyal Winkler MD, (b) Arie Orenstein MD (b)

a. Mohs Unit, Chaim Sheba Medical Center

b. Department of Plastic and Reconstructive Surgery, Chaim Sheba Medical Center

c. Department of Anesthesia and Intensive Care, Chaim Sheba Medical Center affiliated with the Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel

Address for Correspondence

Eran Bar-Meir, MD

Kfar Maas

P.O.B. 5345

49925, Israel

e-mail: eranbarmeir@yahoo.com

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