Chapter 14. Anesthesia—Local and Regional

When the equipment and the experienced personnel to give deep sedation or general anesthesia are not available, local and regional anesthetic techniques should be used. As one experienced anesthesiologist wrote, "We must assume that supplies of compressed gases will soon run out and replacements will be unobtainable. This leaves us with local techniques, spinal and epidural analgesia, all of which can be given by the surgeon in the absence of a trained anesthetist."1

Pharmacology

Topical anesthetics are slowly absorbed through normal skin. However, they are rapidly absorbed through the mucosa as well as through abraded, burned, and denuded skin. When using topical anesthetics in these areas—especially if used in the tracheobronchial tree—the maximum dose should be considerably less than that used for infiltration.2,3 Tetracaine, for example, produces higher blood levels at 5 minutes with mucosal application than with subcutaneous infiltration.4 When used in dentistry, topical anesthetics generally anesthetize only the outer 1 to 3 mm of mucosa.5

Common Anesthetics

Good topical anesthetics include lidocaine (lignocaine), cocaine, and tetracaine. Some anesthetics, such as procaine and mepivacaine, are not effective topically due to poor mucous membrane penetration.3

Lidocaine/lignocaine (amide) (2% to 10%) has a peak anesthetic effect in from 2 to 5 minutes. Its maximum safe total dose in a healthy 70-kg adult is ~250 mg and it is 3 mg/kg in children. Anesthetic effect lasts 30 to 45 minutes.2,3 Lidocaine gel 4% can be made by adding 2 mL of 2% lidocaine without epinephrine to 1 mL of a water-soluble jelly (e.g., K-Y). This gel works well, if placed under an occlusive dressing, to ease the pain of herpes zoster and other skin lesions.

Bupivacaine (amide) (0.25% to 0.5%) has a peak anesthetic effect in 2 to 5 minutes. Its maximum safe total dose in a healthy 70-kg adult is 400 mg/24 hours; it is 2 mg/kg in children, although it is not officially recommended for use in children <12 years old. Similarly, it is not recommended as a spinal anesthetic in those <12 years old. Anesthetic effect lasts 4 to 8 hours.

Cocaine (ester) (4% = usual dose) has a unique vasoconstricting effect. It reaches peak anesthetic effect in 2 to 5 minutes. However, it is addictive. The maximum safe total dose in a healthy 70-kg adult is 200 mg (2 to 3 mg/kg) and it is 2 mg/kg in children. The anesthetic effect lasts from 30 to 45 minutes.2,3 Staying within the maximum adult dose is easy if the standard package of 4 mL of the 4% solution is used. While making your own topical solution with cocaine obtained from noncommercial vendors may seem logical in an emergency, the problem is that neither the strength nor the purity of the ingredient is known.

Tetracaine (ester) (0.5% = usual dose) has a peak anesthetic effect in 3 to 8 minutes. The maximum safe total dose in a healthy 70-kg adult is 50 mg and it is 0.75 mg/kg in children. Its anesthetic effect lasts 30 to 60 minutes.2,3

Toxicity

Local anesthetics can produce allergic reactions, tissue damage, and systemic toxicity. Allergic reactions are most common with the amino-ester preparations (e.g., procaine, tetracaine). There is no cross-reactivity between the esters and amides (e.g., lidocaine, bupivacaine, mepivacaine). Allergic reactions to local anesthetics are rare, with most reported allergies not representing actual allergic reactions. Local tissue neurotoxicity can also occur, but it is rare.

Systemic toxicity is the most common and significant problem associated with local anesthetic use. Usually associated with inadvertent intravenous (IV) or intra-arterial injections, only mental status changes may occur before the onset of seizures. Classically, the progression from systemic toxicity is tongue numbness, light-headedness, visual disturbances, muscular twitching, unconsciousness, and seizures. Of course, patients receiving local anesthetics while sedated may have muscular twitching as the only sign before seizures. The treatment is to stop local anesthetic use, manage the airway, control the seizures, and support the patient until the central nervous system (CNS) effects of the drug wear off. The local anesthetics themselves do not cause CNS damage. Rather, the damage stems from hypoxia during the seizure and the associated coma.6

"Magic Mouthwash"

Many topical oral anesthetic formulations ease the pain from mucosal lesions. One that seems to work well, and that uses commonly available ingredients, is a mixture of equal parts of 2% viscous lidocaine, diphenhydramine elixir, and Maalox or Kaopectate (as a binder).2 Swish for 1 to 2 minutes and spit. This is especially useful in children with oral lesions that prevent the child from drinking/eating.

Sprays

Lidocaine for injection can be nebulized as an effective topical mucosal anesthetic. Some patients experience a strong bitter taste when lidocaine is administered this way; however, the taste is usually transient and this should not prevent the patient from receiving the medication. (Personal communication from Angela M. Plewa, Pharm.D., received April 8, 2008.) To use it, the best course is to dilute it to a 0.5% solution so that the maximum safe dose is not exceeded.

Creams

Anesthetic creams are useful to reduce pain before suturing, phlebotomy, or IV insertions. They are primarily used in children.

LET (lidocaine 4%, epinephrine 0.1%, and tetracaine 0.5%), which can be compounded locally, can be used to anesthetize small lacerations on the face and scalp before repair. This works particularly well in children and has less toxicity than TAC (tetracaine 0.25% to 0.5%, adrenaline 0.025% to 0.05%, and cocaine 4% to 11.8%), which was previously widely used. In an emergency, either works well. They both work in about 75% to 90% of patients. An older formulation mixing epinephrine in cocaine, termed "cocaine mud," had a very high complication rate; don't use it.

For LET solution, mix 100 mL 20% lidocaine HCl, 50 mL 2.25% racemic epinephrine (HCl salt), 125 mL 2% tetracaine HCl, 315 mg sodium metabisulfite, and 225 mL water. Make the gel by mixing the solution with methylcellulose.

The LET formula is effective both in a solution and as a gel. For the solution, paint it onto the wound edges with a cotton-tipped applicator. Then apply a cotton ball saturated with the solution to the wound. In about 20 minutes, the wound appears blanched and is ready to suture. Apply the gel to both the wound edges and the wound with a cotton-tipped applicator. As with the solution, the wound edges look blanched and the wound is ready to suture in about 20 minutes. Remove the gel before suturing.7

Patches

Anesthetic patches effectively anesthetize the skin and underlying area of painful lesions. They can be used for herpetic, post-herpetic, and rib fracture pain. They don't work when applied for joint pain.

To improvise a topical anesthetic patch for abrasions and wounds, soak gauze with a mixture of injectable lidocaine, tetracaine, and epinephrine and place it directly onto the wound for approximately 5 minutes.8 For rib fractures, use 700 mg lidocaine under a 10 × 14 cm occlusive dressing.

Local anesthetic infiltration generally works well, even when given by novices and those who don't use it regularly. It works by diffusing through the tissues without needing to know the specific neuroanatomy.

The key to giving successful local infiltration (also for regional blocks) is to wait long enough for them to take effect. There is a delay, a latent period, of up to 15 minutes between when the anesthetic is administered and when the area is anesthetized. (A good practice is to do the block, leave and do any paperwork associated with the case, and then return to do the procedure.) If pain—not pressure or touch sensation—still exists after 15 minutes, administer additional anesthetic. You can also give the patient mild sedation as an anxiolytic (often called a paramedication when given during the procedure). The most common reason that local anesthesia and anesthetic blocks do not work is that the clinician does not wait long enough.

Infiltration anesthesia uses larger volumes of weaker anesthetics (e.g., 100 mL of 0.5% lidocaine). Regional blocks of larger nerves use smaller volumes of more concentrated anesthetics (e.g., 10 mL of 2% lidocaine).

To maximize efficiency when large numbers of patients require procedures done under local anesthesia, group them together. Do not interpose cases under general anesthesia, as this will only slow patient flow. Block the next patient while the surgeon is scrubbing for the first patient.9 When you must do a series of very short procedures under local or regional anesthesia, you can often block several patients at once using a longer-acting anesthetic (often containing epinephrine 1:200,000).

Local Anesthetic Medications

If a patient tells you that he is allergic to a local anesthetic, avoid that class of medications (usually an ester). Anesthetics in the ester class do not have an "I" before "caine" in their name (e.g., procaine, cocaine). The name of anesthetics in the amino amide class has an "I" before "caine" (e.g., lidocaine/lignocaine, mepivacaine). If you cannot use an anesthetic from the class that the patient is not allergic to (or if the patient doesn't know the drug he is allergic to), use one of the alternative medications described in the next section.

Anesthetics come as percent concentrations, with 1% equaling 10 mg/mL or 1 g of anesthetic per 100 mL. To dilute a local anesthetic, add sterile injectable saline. For example, adding 1 mL of anesthetic to 1 mL of saline changes a 1% solution into a 0.5% solution. If 3 mL of saline were added, it would become a 0.25% solution. An easy way to calculate the dose in milligrams is to use the formula: Volume (mL) × Concentration (%) × 10 = Dose (mg).10

When medication is scarce, reduce the needed dose of anesthetic either by diluting the solution or by adding epinephrine (adrenaline). Vasoconstriction increases an anesthetic's length of action. Yet, except for cocaine, local anesthetics (without epinephrine added) are vasodilators. Don't add epinephrine to cocaine; it is unnecessary and dangerous.

Premixed lidocaine with epinephrine may not be available. To determine the amount of epinephrine to add to the local anesthetic, remember that the typical 1:100,000 concentration means 1 mg of epinephrine for every 100 mg anesthetic; 1:200,000 concentration means 1 mg of epinephrine for every 200 mL anesthetic. Therefore, to make a 1:200,000 epinephrine-lidocaine solution, add 0.1 mL (0.1 mg) epinephrine 1:1000 to 20 mL of lidocaine. To do this, take 1 mL of epinephrine 1:1000 and dilute it to 10 mL with saline. Now you have a 1:10,000 epinephrine solution. Take 1 mL of this mixture and add 19 mL lidocaine. The total amount of solution you have is now 20 mL and the original epinephrine has been diluted 200 times = 1:200,000 solution.11

To reduce burning from the acidic pH of most local anesthetics (pH 4 to 5), add 1 mL sodium bicarbonate (1 mEq/mL) to every 10 mL of 1% lidocaine.12 While the traditional teaching is that local anesthetics are unreliable when used in the acidic environment of an abscess, reports suggest that a "double-buffered" solution of 2 mL of bicarbonate with 8 mL of lidocaine works well.13 Heating the anesthetic to body temperature also helps reduce pain.14

Alternatives to Local Anesthetics

If standard local anesthetics are not available or if the patient claims to be allergic to local anesthetics, a variety of alternatives can be used. These include medications with antihistamine activity, bacteriostatic normal saline (NS) with benzyl alcohol, sterile water, local cold, and pressure.

Antihistamines

Most injectable medications with antihistamine activity can be used as local anesthetics if diluted to a 0.05% solution with NS. None are as effective as standard local anesthetics, but they will certainly do if nothing else is available.15

Diphenhydramine hydrochloride (Benadryl) has been used successfully for dermal, urological, and dental anesthesia. It is very soluble in water. A 1% solution is prepared by diluting 1 mL of a standard 5% diphenhydramine solution for injection with 4 mL single-use NS solution for injection (without preservatives).12 It shouldn't be used in concentrations >1%, since that may cause ulcerations or tissue necrosis. Its duration of action is less than that of lidocaine with epinephrine and, even if buffered, it is more painful than lidocaine. A 0.5% solution can also be used, but it is considerably less effective than 1% lidocaine. Complications include sedation (occasional), local erythema (common), persistent soreness lasting up to 3 days (common), and skin sloughing (rare).12,16 Dimenhydrinate (Dramamine) also has local anesthetic activity.15

Tripelennamine (aka: pyribenzamine [PBZ]), a highly water-soluble antihistamine, is effective for a wide variety of regional nerve blocks in a 1% solution. As clinically effective as diphenhydramine, tripelennamine has fewer and less severe side effects. It can be used for urethral anesthesia17 and, in a 4% solution, as a mucosal anesthetic on the gums. In powdered form, it immediately relieves toothaches in a decayed tooth. It has been used as a 1% solution for topical anesthesia in the mouth and esophagus and, usually with epinephrine, for skin and dental block infiltration.18 Addition of epinephrine reduces local reactions and lengthens the anesthetic's effect up to four times. For pain relief, use between 5 mL (lingual nerve block) and 20 mL (dorsal sympathetic nerve block). For surgery done with a tripelennamine nerve block, use between 10 mL (finger block) and 35 mL (tendon graft). The anesthetic effect is prolonged by adding 1:100,000 epinephrine.19

Phenothiazines (e.g., promethazine [Phenergan], chlorpromazine [Thorazine]) are 23 times more potent than procaine as a local anesthetic.20 Chlorpromazine is effective as a local anesthetic at concentrations of between 0.1% and 0.2%. It has a wide safety margin, but should not be used with epinephrine. Even without a vasoconstrictor, it has a longer duration of action than most local anesthetics. One complication, orthostatic hypotension, usually occurs when chlorpromazine is used IV or in large doses.21 Although it has significant local anesthetic properties, chlorpromazine has never been generally used as a local anesthetic in humans.20–22

Water

Sterile water is a suitable anesthetic. Known to our predecessors as "aquapuncture," this method uses unpreserved sterile water, produced by simply boiling distilled water. As with other local anesthetic infiltration, injecting water works better on loose tissues and is less painful when the water is at body temperature and injected slowly. The analgesia lasts 10 to 15 minutes.23

Allen described the procedure he used, "To obtain the full analgesic effect, it is necessary to infiltrate the tissues to the point of producing a glassy edema, the skin or mucous membrane must be infiltrated intradermally and the infiltration carried down the full depth of the proposed incision; when this is done, analgesia is usually as profound as after infiltration with the weaker anesthetic solution, but tactility is little or not at all affected; the after-pain or discomfort is about the same as that following the use of other anesthetic solutions."23

Bacteriostatic Normal Saline

Benzyl alcohol, the preservative in bacteriostatic NS, is an ideal alternative local anesthetic. Inexpensive and readily available, bacteriostatic NS is frequently used to flush IV catheters and to dilute or reconstitute medications for parenteral use.

Benzyl alcohol (0.9%) can be mixed to a solution with 1:100,000 epinephrine. This formulation is less painful, but slightly less effective, than 0.9% buffered lidocaine. In children, the pain on injection is about the same as that with lidocaine.24 Without epinephrine, the anesthetic effect of benzyl alcohol lasts only a few minutes.25 With epinephrine, the anesthetic effect begins to diminish about 20 minutes after injection. Prepare a benzyl alcohol-epinephrine solution by adding 0.2 mL epinephrine 1:1000 to a 20-mL vial of multi-dose NS solution containing benzyl alcohol 0.9%.12

Antidepressants

Some antidepressants, such as amitriptyline, have shown good activity as both topical and injectable anesthetics. When the need is desperate, these can be used, although questions about their safety preclude their use under normal circumstances.26

Narcotics

Neither morphine nor meperidine (Demerol, Pethidine) works well as a local anesthetic. They have a potency about half that of chlorpromazine and slightly less than that of promethazine.22,27

Cold/Freezing (Local Anesthesia)

Apply cold to tissues to produce either local or regional anesthesia. (See also "Refrigeration Anesthesia: Amputations" later in this chapter.)

Locally applied cold provides extremely short-acting superficial anesthesia for "stab" abscess drainages, venipunctures, injections, and similar procedures. If ice is used, it must be in direct contact with the skin for at least 10 seconds immediately before the procedure. The effect lasts only a few seconds.28

Cold sprays for local anesthesia were developed in the mid-19th century. Various substances with low boiling points can be used, including ether, and alcohol cooled to −10°F (−23.33°C).29

Ethyl chloride (chloroethane) spray effectively anesthetizes a very small area of intact skin for a few seconds—approximately enough time to do a stab incision for an abscess. It works by "freezing" the skin. Because of its potent general anesthetic effect, ethyl chloride should never be used on the mucosa. It is available commercially as a cleaner (e.g., for VCR heads and computer keyboards) and as a medical spray. This chemical is flammable, and fires have occurred while using it with diathermy, for example, to remove a wart.30 It is a potent and potentially dangerous general anesthetic with abuse potential. Tetrafluoroethane spray, used to remove dust from personal computers, can serve as a handy substitute.31 (Don't inhale it; you'll pass out.)

An atomizer is used to spray the anesthetic. Directions for two homemade atomizers can be found under "Alternative Administration Methods" in Chapter 13, Analgesics. Hold the atomizer far enough from the body part being anesthetized to maximize the amount of spray reaching the skin before dissipating. If held too far away, the spray evaporates without anesthetizing. Protect sensitive parts, such as the eyes and anus, before the anesthetic is sprayed on surrounding areas.

Pressure

Direct pressure over an area produces a very transient anesthesia. As Allen wrote in 1918, "The benumbing effect of long-continued pressure upon any part of the body is well known; although some pain may be produced in the surrounding parts, it is possible to carry it to a point of depressing both tactile and painful impressions to a considerable degree; this is brought about in two ways, first the compression directly paralyzes the nerve-endings of the part, and, secondly, the anemia [actually, tissue hypoxia] intensifies this effect."32

Local Infiltration Techniques

Injection

Inject the anesthetic slowly. This markedly diminishes the patient's discomfort. Using buffered lidocaine also decreases pain, as described in the previous text.

Field Block

Use a simple field block for circumscribed lesions, such as cysts or small abscesses, and for larger structures, such as ears. Visualize a diamond surrounding the area to be anesthetized, and then inject two small wheals at the apex of the diamond. Next, block the four sides of the diamond through those wheals.

Local wound infiltration is effective for inguinal and umbilical hernia surgery, dental procedures, strabismus (eyes) surgery, and burr holes/craniotomies.33 For craniotomies, anesthetize the scalp surrounding the entire surgical area, as well as the underlying muscles and the periosteum.34 Use the greatest possible anesthetic dose, since the scalp is so vascular. Always use anesthetic with epinephrine.

Infiltrate‐and-Cut Anesthesia

In situations where there is no alternative, almost any surgical procedure can be done by cutting through a site that has been locally infiltrated with anesthetic, with continued anesthetic injections given as the operation proceeds.

The Vishnevsky technique, an "inject-and-cut" procedure once employed extensively in Russia, is possibly the simplest use of local anesthetics, since no knowledge of anatomy is required. The technique works very well for surgery outside of the abdomen and chest. Abdominal surgery is not quite as easy; it is simple enough to open the abdomen with this technique, but handling the viscera is a different matter. The technique is to inject unlimited volumes of weak procaine solutions (0.25% to 0.5%) without epinephrine. Procaine is the only completely safe anesthetic to use for this procedure, since it is metabolized very rapidly. Other local anesthetics are metabolized more slowly, and the patient can become toxic.35 If lidocaine is used, the limit is 200 mL of 0.25% lidocaine with adrenaline 1:500,000.

The primary danger of the Vishnevsky technique is inadvertent intravascular injection, which can be avoided by aspirating before injecting and keeping the needle moving. A "continuous apparatus" with Luer-Lok fittings is advantageous.36

Premedication/Paramedication

Premedicating patients may be useful when giving either regional or general anesthesia. It reduces patient anxiety and often lessens the amount of anesthetic that is needed. The drugs used for premedication, such as benzodiazepines, phenothiazines (especially the commonly used promethazine), and barbiturates, are commonly available. They can be administered orally, parenterally, or rectally.37 Benzodiazepines and barbiturates have the added benefit of raising the seizure threshold.

Hypnosis, even if patients use a hypnosis recording, is effective as a premedication. The significant benefits of hypnosis include decreased anxiety, decreased blood pressure, reduced blood loss, enhanced postoperative well-being, improved intestinal motility, shorter hospital stays, reduced postoperative nausea and vomiting, and a reduced need for analgesics.38 Hypnotic techniques are described later in this chapter.

If patients become anxious or experience pain while a regional block is being done or during a procedure after the administration of a regional block, give the patient an analgesic or an anxiolytic as paramedication. Paramedications that should be available in most situations are mild sedatives, opioids, or ketamine.

Regional blocks are more problematic for inexperienced practitioners than infiltration anesthesia. Nevertheless, simple nerve blocks are effective for a wide variety of procedures and operations. The blocks described here will usually provide good analgesia, even when the practitioner does them for the first time. Note that this book is not designed to describe the wide variety of regional blocks, even though they are remarkable tools when resources are scarce. Descriptions of nearly all the blocks you may need can be found at the New York School of Regional Anesthesia's free Web site: http://www.nysora.com/peripheral_nerve_blocks/index.1.html.

Scalp Block

The nerves to the forehead and scalp all run upward from about the line of the eyebrow anteriorly, and from the base of the skull posteriorly. Therefore, to block a region above this line you need only to inject a horizontal line of anesthesia below the area.39 The key is to make the anesthesia line long enough to block the cross innervation from nerves that are lateral to the site of injury. A good rule for blocking the face and scalp is to block both sides unless the lesion is very far to one side.

Hematoma Block

Hematoma blocks can provide sufficient analgesia in the distal forearm and some areas of the face (such as the nose) to reduce fractures. Useful in both adults and children, it is easier to perform, but less effective than an IV regional block (e.g., intravenous regional anesthesia [IVRA], Bier block) for forearm fractures.40 Nevertheless, if the necessary equipment or skilled personnel are not available to do IVRA, then a hematoma block offers a quick and easy method to obtain at least some, if not very good, anesthesia.

This block may be particularly useful in mass casualty situations, but it is not effective to treat fractures >24 hours old, since by then the hematoma has begun to organize.35

Technique

Palpate the fracture site and, under aseptic conditions, place the needle into the fracture hematoma. Aspirate to ensure that blood returns. Unlike other regional blocks, blood should be aspirated before injecting, to ensure that the needle is in the fracture hematoma so that the anesthetic can diffuse through it. Then, very slowly inject 5 to 10 mL of 2% lidocaine without epinephrine. Buffered lidocaine may cause less pain than unbuffered solution.

The block should take effect in approximately 5 minutes. This technique, useful both in adults and children, is most successful when applied as soon as possible after injury, as clotted blood will limit the spread of the analgesic. Infection is not thought to be a hazard if sterile solutions and apparatus are used and adequate skin preparation employed.36 The US military has found it occasionally useful to use ultrasound to locate the hematoma and guide needle placement.

Intra-Articular Anesthesia

If anesthesia (other than hypnosis) is needed to reduce a shoulder dislocation, an easy technique is to inject 20 mL of 1% plain lidocaine into the joint.41,42 This must be done under aseptic conditions. The technique is remarkably simple, since the joint space is easily identified (it's where the shoulder used to be) and accessible. It is at least as effective as using narcotics and benzodiazepines for the reduction.43

Intravenous Regional Anesthesia

Intravenous regional anesthesia (IVRA) involves administering a local anesthetic into an upper or lower extremity while blocking arterial flow and venous return with an inflated cuff.44 Used for more than 100 years, the technique is successful in >95% of cases. The advantages of this block, especially in austere situations, are that it is easy to perform, is not dependent on anatomical knowledge, requires minimal personnel, avoids the potential side effects of general anesthesia and systemic sedation, and provides rapid and complete anesthesia, muscle relaxation, and a bloodless field.45 Disadvantages include the limited duration of anesthesia (60 minutes), the relatively large dose of local anesthetic required, and the fact that it provides no postoperative analgesia.

Method

Place an intravenous (IV) line in the hand or the foot, depending on which extremity requires anesthesia. One or preferably two inflatable cuffs are placed over padding on the proximal extremity and secured by wrapping strong adhesive tape around them so they do not accidentally come off when inflated. The extremity is then exsanguinated by lifting it straight up and then wrapping it tightly, distal to proximal, with an Esmarch or other elastic bandage. If placement of an elastic bandage on the extremity is too painful due to trauma, compress the axillary or femoral artery for 5 minutes with the extremity elevated.

While the extremity is still elevated and wrapped, inflate the most proximal of the cuffs to well above arterial pressure (palpated at the distal extremity) or, if there is an attached manometer, to at least 250 mm Hg. Use a hemostat to clamp the inflation tube on the cuff, since the valves tend to leak (Fig. 14-1).

Remove the constricting bandage on the extremity and slowly inject (60 to 90 seconds) 0.5 mL/kg 0.5% lidocaine without preservative or epinephrine for upper extremity procedures and 1 mL/kg for the lower extremity.36,46 (Do not use more than 4 mg/kg lidocaine: For a 70-kg patient, this is 280 mg or 56 mL of 0.5% lidocaine.) The limb becomes blanched. At that point, inflate the more distal cuff (that is now over an anesthetized area) to the same pressure as the first cuff and deflate the first cuff. This usually reduces the patient's discomfort from the tourniquet.

Tourniquet pain usually begins about 20 minutes after single tourniquet inflation, although this can be delayed by using adjuvant medications (described in the subsequent text). Using the second, more distal tourniquet, significant pain typically occurs about 40 minutes after tourniquet inflation.47 Tourniquet pain is usually the limiting factor for how long the block can be used.44 There is also a minimum time for the tourniquet to remain in place. To prevent toxic effects from the anesthetic, do not release the tourniquet for at least 20 minutes after the injection, even if the procedure has been completed in less time. After 20 minutes, release the tourniquet for 5 seconds and reinflate it for 30 seconds three or four times. This permits the anesthetic to gradually be released into the circulation.

Because of the rapid reperfusion of the limb after tourniquet deflation, IVRA has typically provided minimal analgesia after surgery. Postoperative analgesia has traditionally been a major advantage of brachial plexus analgesia compared to IVRA.

This technique is contraindicated in patients with peripheral artery or sickle cell disease, with hypersensitivity to the anesthetic (although an alternative can be used), and with cellulitis at the injection site.48

Alternate/Improvised Methods

Improvised IVRA equipment can be fashioned from two normal blood pressure (BP) cuffs, enough adhesive tape to wrap completely around the cuffs several times so they don't "pop" off during the procedures, clamps for the BP cuff tubing so it doesn't leak during the procedure, an elastic bandage or similar elastic cloth (such as nylon stockings) to help exsanguinate the arm, an IV, a syringe, and the medications.

If BP cuffs are not available, you can use other cuffs, such as those often used to pressurize IV fluids. If there is no inflatable cuff, wrap a wide tourniquet around the extremity and use a dowel as a windlass to tighten it (similar to the tourniquets described in Chapter 21, Surgery/Trauma). The absence of a distal pulse that was previously palpable determines when arterial pressure has been exceeded. Carefully secure the windlass so it does not accidentally unwind during the procedure.

Forearm tourniquets may be an option for some distal upper extremity procedures. Several advantages are evident. Forearm tourniquet pain occurs later and is less severe than an upper arm tourniquet. In addition, approximately 50% less local anesthetic solution can be used with a forearm tourniquet, lowering the risk of toxicity. Finally, only half the amount of any adjuvant medication needs to be used to prolong the anesthetic effect or to decrease tourniquet pain.36,47 Calf tourniquets work well for foot and ankle anesthesia. Use them in a similar manner to a forearm tourniquet. Concerns regarding increased risk of nerve injury or poor tourniquet function with a forearm tourniquet have never been substantiated.47

For very short foot or hand/wrist cases, a "super-low" IVRA method is applicable. Prepare the patient as usual and inflate the cuff on the upper arm or upper leg. Just before injecting the anesthetic, place a 2-cm-wide rubber tourniquet, like the ones used to draw blood, above the wrist or ankle. Use about half the amount of anesthetic that would normally be injected for a standard IVRA. Both the upper leg and the upper arm tourniquet can be removed within 10 minutes. The benefit is that less anesthetic is used.49 The drawback may be pain from the tourniquet.

Alternative Anesthetics

A number of other anesthetics can be used if lidocaine is not available. Prilocaine seems to be the safest, although it is now widely unavailable. When bupivacaine, rather than lidocaine, is used for Bier blocks, the block's onset is slower, but analgesia is continued for 3 to 4 hours into the postoperative period.47,50 Alternative anesthetics used for IVRA are listed in Table 14-1.

Adjuvant Medications

A number of medications can be added to the injected solution to reduce the tourniquet and post-procedure pain associated with IVRA. They also decrease the amount of anesthetic needed.

Ketamine 0.1 mg/kg added to the anesthetic solution dramatically reduces tourniquet pain and decreases the need for paramedication during IVRA. Ketorolac (0.1 to 0.02 mg/kg, up to 20 mg) added during a standard IVRA reduces tourniquet pain and also provides 12 to 16 hours of postoperative analgesia. (There is no further benefit with larger doses.) Using a forearm tourniquet, 10 mg ketorolac IVRA provides even better postoperative analgesia than 20 mg of ketorolac does with an upper arm tourniquet.47

Adding clonidine (1 to 2 micrograms/kg) to IVRA significantly reduces tourniquet and postoperative pain. While better than local anesthetic alone, it is a less effective adjunct than ketamine.47,48,51 Narcotics should not be added. It's not clear that they are beneficial, and all produce nausea, vomiting, and dizziness when the cuff is deflated.47

Abdominal Operations

Several options are available to provide anesthesia for abdominal surgery other than using general anesthetics. These include abdominal field blocks, spinal or caudal blocks, local infiltration, and "tie and cry." The benefit is that these methods may avoid the need to use muscle relaxants and controlled respiration, which may not be possible depending upon the available resources. These techniques are particularly valuable on operations in the lower abdomen.

Intra-Abdominal

Local Abdominal Anesthesia

When patients are very ill and equipment, skills, or both are in short supply, consider using local anesthesia plus appropriate preanesthetic medication to do abdominal procedures. Allen wrote, "All simple operations, such as gastrostomy, gastrotomy, colostomy, appendectomy, and gallbladder drainage, are quite satisfactorily performed on suitable subjects (when not too nervous or apprehensive) when the parts are fairly easily accessible, and not matted down by inflammation or adhesions to the parietal peritoneum or surrounding organs."52

Thin patients with relaxed abdominal walls are ideal for this type of anesthesia. However, "as a general rule all very stout individuals and those with tense rigid abdominal walls are difficult to handle in any serious intra-abdominal operation, for as soon as the abdomen is opened the contents bulge out."52 During laparotomies using only a local anesthetic block, patients sense a vague intra-abdominal weight or fullness that becomes crampy if the surgeon puts traction or pressure on the internal organs. If you encounter an inflamed appendix or diseased gall bladder while using local anesthetic for a midline incision, make a separate incision to take them out rather than displacing them toward the midline.52

Field Block

Use a rectus muscle block to provide anesthesia for a laparotomy incision. This can be combined with sedation or light general anesthesia. To do the block, place anesthetic beneath the rectus muscle in each of its ten compartments (five on each side). Using a 20-gauge, 5-cm needle, enter the abdominal wall through anesthetic skin wheals (marked * in Fig. 14-2) raised at the center of each compartment. After aspirating, inject 10 mL of 0.5% lidocaine with 1:500,000 epinephrine at each site. Insert the needle vertically into each compartment, feeling the resistance from the anterior sheath as it is penetrated. After traversing the muscle, resistance from the posterior sheath is felt. At that point, after aspirating, inject the anesthetic. A midline or paramedian surgical incision line should also be infiltrated with 0.25% lidocaine with 1:500,000 epinephrine. This only blocks the abdominal wall for the incision. Blocking visceral reflexes requires the surgeon to block the vagus and the splanchnic plexus once the abdomen is open and the viscera mobilized.36

Braun's Method

Another method to anesthetize the abdominal wall for an abdominal midline incision is to inject around the field in a more-or-less rhomboid shape (Fig. 14-3, method illustrated on upper abdomen). Inject anesthetic two or three fingerbreadths on each side of the midline. Starting on this line,

At two or more points, depending upon the extent of the proposed incision, a long needle is directed obliquely outward, injecting as it is advanced, piercing the rectus sheath, which is recognized by its slight resistance to the needle, and advancing some little distance within this muscle until it is quite freely injected; the needle is then partially withdrawn, when it is advanced again in two or more directions above and below, slightly increasing the angle each time, thus making the injection in something of a fan-like shape; this is done along the line of cutaneous anesthesia at two or more points, having the fan-like areas of infiltration come in contact with the one above or below. The same procedure is repeated on the opposite side. These two lateral lines of infiltration are joined above and below by subcutaneous infiltration.52

Allen's Method

While Braun's method works well in thin subjects, a better technique in obese patients is to establish a wall of anesthesia along the proposed incision line from the skin to the peritoneum. Raise an intradermal wheal midway along the proposed incision line. Insert a long needle through the wheal and liberally inject anesthetic superiorly and inferiorly, and then into the rectus sheath on either side (Fig. 14-3, method illustrated on lower abdomen). As with the other methods, deeper injections are made once the abdomen is open.52

Inguinal Hernia Repair

Inguinal hernia repair is much more common in Third World countries than it is in the West. As one group of surgeons wrote, "Local anesthesia has been identified as the most favorable anesthesia for elective inguinal hernia repair with respect to complication rate, cost-effectiveness, and overall patient satisfaction…. All surgeons in resource-poor countries should be encouraged to use local anesthesia more frequently for elective inguinal hernia repair. Valuable resources in sub-Saharan African hospital could be saved, especially if used in combination with outpatient surgery."53

The simplest anesthetic technique for inguinal and femoral hernia repair is for the surgeon to continuously infiltrate the area of incision, then directly infiltrate the neck of the sac.36 This infiltrate-and-cut or Vishnevsky technique was described earlier in this chapter.

Amid and colleagues describe a more precise method of using local anesthesia for elective hernia repair: (a) subdermal infiltration along the line of incision (approximately 5 mL), (b) intradermal injection along the line of incision (approximately 3 mL), (c) deep subcutaneous injection (approximately 10 mL), (d) subfascial infiltration immediately underneath the aponeurosis of the external oblique to anesthetize all three major subfascial nerves (approximately 8 to 10 mL), (e) pubic tubercle and hernia sac injection—as much as required for complete anesthesia, and (f) splashing local anesthetic into the canal and in the subcutaneous space before closing to reduce postoperative pain (optional).54

Tie‐and-Cry Method

Tie-and-cry anesthesia may be the safest way of anaesthetizing a child if there is no access to either special pediatric anesthesia equipment or ketamine. The general principle is that if your skills are limited, do only what is safe for the child.

While seemingly barbaric, under such circumstances, the safest anesthesia for an abdominal operation in a child weighing >15 kg is to use an intramuscular injection of midazolam 0.15 mg/kg or lorazepam 0.05 mg/kg. (Intramuscular diazepam has erratic absorption.) Combine this mild sedation with local lidocaine infiltration, being careful not to exceed the maximum safe dose.

Restrain the child by papoosing in a sheet (Fig. 14-4) or tying the arms and legs to splints or to a papoose board. Secure the child's limbs, but provide access to the airway, chest, and abdomen. The descriptive name for this procedure comes from the child remaining at least partly conscious and crying.

A problem with this technique, as with many abdominal cases using local anesthesia, is that returning the intestines to the peritoneal cavity may be difficult since the abdominal muscles are not relaxed. As King wrote, "Such anesthesia is far from ideal, but when anesthetic skills really are minimal, it probably gives the child the best chance of living. It really is a procedure for desperate emergencies only."55

Fascia-Iliaca (Ilio-Fascial) Block

The fascia-iliaca compartment block (FICB) is an excellent method to relieve pain from a fractured hip and, in many cases, knee pain. The FICB is similar to the commonly used 3-in-1 block, although the FICB has been shown to be simpler to perform, safer (being distant from any major structures), faster acting, and more effective (at least in adults) for simultaneously blocking the lateral femoral cutaneous nerve of the thigh and the femoral nerves.56 It is ideal for austere situations, since it can easily be done by novices, and remedies the difficult problem of analgesia without monitoring for fractured hips and femurs.

To do the block, place the patient in the supine position and identify the inguinal ligament. Prepare the skin and drape the site. Identify the (imaginary) line that joins the middle of the pubic tubercle to the anterior superior iliac spine. Find the point 1 cm below the juncture of the lateral and medial two-thirds of that line. Insert a 21-gauge, 2-inch injection needle perpendicular to the skin at that point (Fig. 14-5). Insert the needle until you feel a loss of resistance as the needle passes through the fascia lata. Keep advancing the needle until a second loss of resistance occurs as the fascia iliaca is pierced (often described as two "pops"). With an attached syringe, first aspirate to exclude intravascular injection, and then inject approximately 0.3 mL/kg of 0.25 bupivacaine or 1% lidocaine.56

Foot/Ankle Blocks

Blocking completely around the ankle at the level of the top of the malleoli (along with one deep injection to block the hallux [big toe] if necessary) completely blocks the entire foot.

A 4-cm-long, 23-gauge needle works for all injections. Low concentrations of local anesthetic (e.g., 0.25% bupivacaine) will suffice in most cases, since it's necessary to block only the smaller sensory nerves.14

All five nerves can be blocked with the patient supine, although it is often easier to block the posterior tibial and sural nerves with the patient prone and the foot hanging off the end of the stretcher. To block the posterior tibial nerve in a supine position, flex the knee and place the ankle on top of the contralateral shin. This allows access to the medial and lateral malleolus.

Plantar (Sole) Surface

All ankle blocks are at the level of superior portion ("top") of the malleoli. Enter at the border of the Achilles tendon and aim the needle toward the tibia (medially) and fibula (laterally). If the patient gets paresthesias with either insertion, withdraw the needle slightly and inject 3 to 5 mL of a local anesthetic, such as 0.25% bupivacaine. If not, for posterior tibial infiltrations, advance the needle until it contacts the tibia, withdraw 0.5 cm, and inject 5 to 7 mL of anesthetic. For the sural nerve, if the patient does not experience paresthesias, advance to the fibula and inject 5 to 7 mL as you withdraw the needle to the skin.

Dorsum of Foot

The three other blocks, all done from one injection site, anesthetize the dorsum of the foot. For all three blocks, insert the needle 1 cm lateral to the extensor hallucis longus tendon or just lateral to the anterior tibial artery, if it can be palpated.

To block the deep peroneal nerve (blocking the area between the hallux and second toe; see Fig. 14-6, shading D), insert the needle at 90 degrees to the skin and inject 3 to 5 mL of 0.25% bupivacaine deep to the fascia on either side of the tibial artery. This is an important block for any surgery on the hallux, such as removing an ingrown toenail.

For the superficial peroneal nerve (most of the dorsal surface of the foot; see Fig. 14-6, shading B), withdraw the needle to just below the skin surface and aim it toward the lateral malleolus. Inject 5 mL subcutaneously between the lateral malleolus and the anterior border of the tibia.

To block the saphenous nerve (the medial malleolus area) inject 5 mL as the needle progresses toward the medial malleolus, trying not to enter the saphenous vein.14

Acupuncture

Acupuncture works well in the hands of clinicians with superb training in the technique. However, that is not true for treatment from those who dabble in it. Although the only necessary equipment is needles, the real requirement is skill and practice. Unfortunately, acupuncture is not a technique that a novice can improvise.

Background

Direct application of cold to a body part can produce temporary anesthesia. For example, Baron Larrey, Napoleon's chief surgeon, reported that soldiers' wounds barely hurt and that amputations were "practically painless" if the limbs were exposed to the cold air. (The ambient temperature at the Battle of Eylau, February 1807, was −28°C [−18.4°F].) Arnott first used ice bags with salt to anesthetize limbs during surgery. In most settings, ice bags are preferable to, and more readily available than, cold exposure, although both work. Cooling also intensifies the action of all local anesthetics.29

In the early 1940s, surgeons at major US hospitals and in the US Navy found that they could perform lower extremity amputations on elderly and unstable patients using ice for intraoperative anesthesia and postoperative analgesia.57

Use

The following method provides complete surgical anesthesia for about 1 hour. The anesthesia is sufficient to perform extremity amputations without pain.58,59

This method is not truly a "freezing" technique, since the temperature of ice is 0°C (32°F), and a body's tissues have a freezing point below 0°C. In addition, a film of water at 0°C, rather than the ice, is in contact with the skin. After the ice has been applied for four hours, the skin temperature measures 20°C.58

Most often used on patients with infected or gangrenous limbs, refrigeration anesthesia has proved to be a safe option in aged and high-risk patients. Patients with ischemic limbs do the best with the technique, since the cooling does not drop their core temperature. (Little of the extremity's cold blood ever circulates. That's why the limb is being amputated.) Using this procedure, the general diabetic status of the patients did not deteriorate, even when the amputations were done through infected areas. The patients did well postoperatively, and they were usually hungry and ate soon after the operation. They generally had no appreciable change in their vital signs during refrigeration, the operative procedure, or postoperatively. Overall, the mortality and morbidity in these patients was reduced at major hospitals that used this method.58

Adjunctive Meds

Little adjunctive analgesia is necessary for this procedure. Some protocols routinely administered a narcotic before doing anything. In some cases, narcotics were administered as the leg was being manipulated or immediately after preoperative tourniquet placement, but that was rarely necessary.57,58,60

Nearly all patients experienced pain during only the first 15 to 20 minutes after immersion in the ice pack, before the extremity got numb. After this period, the patient often read, rested, or slept.60

Preparing for Refrigeration

Since the basic idea is to immerse the extremity in ice, a suitable container is needed. For feet and ankles, use a bucket. For more proximal surgery, a metal tank with a removable lid to add ice and a padded hole through which to place the leg is required. (A wooden box or a rubber bag—such as a body bag—can also be used, but these will deteriorate with repeated use.) The metal troughs (Fig. 14-7) have a round padded (with sponges or rubber) opening at their upper end, with a sliding top through which the extremity is inserted. At the lower end of the tank, there is a hole for drainage with a spigot, which can be closed when en route to the operating room.57,60

To prepare the supine patient, first protect his bed with a full-length rubber sheet and place a thin blanket under him for warmth.60 Then elevate the limb and apply three bags of cracked ice to an area just above where the amputation is to occur. Secure them with a dressing; leave them in place for 15 minutes. This is where a tourniquet will be applied. Just before the 15 minutes are up, apply an Esmarch (or other elastic) bandage from above the area of inflammation to the tourniquet site.57,58 Then immediately remove the ice bags, put cotton batting or a bandage over area to protect the skin, and apply the tourniquet.

Tourniquet

Wrap rubber tourniquets around the limb twice and secure with a surgical clamp. Some physicians apply two tourniquets, in case one loosens. Once the tourniquet is in place, remove the Esmarch bandage.57 The tightness of constriction necessary to stop circulation differs with the patient, the location on the limb, and other variables. Difficulties seem to be less in the thigh, in spite of its thickness, than in the upper part of the calf, where the main artery is protected between bones.59 It is unclear whether the tourniquet should be placed close to the amputation site, so as to leave the narrowest possible zone of chilled and bloodless tissue, or whether it can be placed higher, for example, above the knee for amputation through the calf.

Ice

Immediately after the application of the tourniquet, immerse the extremity in ice. If patients can sit up, those needing amputations of the foot and lower leg can immerse the area in a bucket of ice water and cracked ice. For amputations of the thigh, pack the extremity in finely cracked ice, with the patient lying in bed, and usually in one of the troughs described previously.

Using the trough, place a thin layer of chipped ice (approximately 1 to 2 inches deep) in the bottom. Gently place the leg on the ice, taking care that no sharp pieces pierce the skin. Place the tank as high into the groin as possible, using the padding for protection. Protect the genitals with a bath blanket or Turkish towel. Cover the entire limb with crushed ice (about 150 pounds is sufficient). The ice must extend to 2 inches above the tourniquet. Because of the size and awkward shape of the trough, it is difficult to anesthetize the upper thigh. However, you can form a pouch by pulling a rubber draw sheet through the hole in the upper end and then fill it with ice.57,58,60

Raise the head of the bed by placing small blocks under the bed frame at that end; this tilts the bed and facilitates drainage from the foot of the bed (Fig. 14-8). The bevel in the ice container at the proximal end may be used as a urinal or bedpan.57 Place hot water bottles (120°F[49°C]) around the genitals and along the unaffected leg to protect them from the cold. Use care to prevent burning the patient. Remake the top of the bed with a bath blanket next to the patient.60

Since the metal tank "sweats," wrap it in a large rubber sheet with a hole connected to a tube going to the bucket at the foot of the bed.60 Completely cover the tank by drawing the large rubber sheet around it.

It is prudent to inspect the limb one or more times 20 or 30 minutes after beginning refrigeration. Blanching of the foot is the rule, especially if the leg was elevated before applying the tourniquet. If any sizable arteries remain open, the foot will be darkly cyanosed, and the tourniquet should be readjusted. Any influx of blood makes for incompleteness or delay of anesthesia.59

The optimum length of preoperative refrigeration varied with the amputation level. In the typically thin, weak patients with arteriosclerosis, the optimum length of preoperative limb refrigeration for amputations at the thigh was 2 to 2.5 hours57–59; for disarticulation at the knee or through the middle of the leg, 2 hours; for the lower half of the leg or the foot, 1.5 hours58,59; and for the metatarsus or the toes, 1 hour.59 The limbs were examined at intervals, and ice was added as necessary.

Operating Room

Bring the patient to the operating room (OR) with the extremity in ice.58,60

When the surgical team is ready, place the patient on the table and unpack his extremity from the ice. Remove the limb from the ice, dry it off, and it is ready for amputation. Do not remove the tourniquet, but prepare the extremity as usual and amputate. If the tourniquet is properly applied and securely fastened and the chilling is continuous to all parts at the correct temperature, there is complete local anesthesia so that the patient is not aware when the nerve is cut or the bone is sawed.59

After removing the limb, ligate the large vessels, remove the tourniquet, and then ligate other small bleeders. It is imperative to use cold instruments and cold normal saline solution in the procedure. About half of the cases are closed without drains. In the face of definite infection, the stump can either be drained or be left open.58

Postoperative Care

The usual dressing consists of one layer of petroleum jelly gauze across the wound, then a few layers of dry gauze, surrounded by bare ice bags. For example, place one bag beneath the stump and two sloping tent-like bags at the sides to avoid pressure on the limb.59 Pain can usually be controlled with the ice bags and a small bandage over the incision.58

The nurses should prepare the routine postoperative bed for the patient, who is often placed in a semi-Fowler's position immediately. Because no nausea or shock is present, the patient can immediately begin progressing to a normal diet.60

Gradually warm the wound over several postoperative days. One method to raise the temperature is to make the dressings a little thicker each day.59 Another is to apply three ice bags to the stump for the first 24 hours, then two ice bags for the second 24 hours, and one ice bag for the third postoperative day.57

Both the degree and the duration of cooling are entirely empiric, guided by the wound's appearance.59 The warming time for the extremity depends upon the blood supply and the degree of infection present. In the presence of good blood supply, remove the ice bags in 24 hours. Infection increases the time of postoperative thawing.58 Sutures are normally left in for an unusually long time, since healing is slowed proportionally with the low temperature.59

Crossman and colleagues found that no harm was caused by either the duration or the extent of refrigeration. Tourniquet marks were visible for a day or two without significance; neither contractures nor paralysis was seen. Likewise, there was no sign of thrombosis or other damage to blood vessels, and no special tendency to necrosis or infection indicating lowered tissues resistance.59

Testing an anesthetic block is a two-edged sword. Boutlon advised that

Elaborate testing of the block with needles is undesirable. A patient will tolerate a surgical incision felt by him as light touch on a numb area and will be surprised and pleased when he is told that the operation is in progress but, if he is repeatedly asked, ‘do you feel that', before or at the start of the procedure, he will give a positive answer even if he feels only the slightest sensation because he loses confidence thinking that the doctor himself is unsure of the efficiency of the block. Testing should be surreptitious; if a needle is boldly inserted through the skin of the surgical area, and the patient does not react, all is well!36

In practice, minimal testing, such as touching the skin with the back of the scalpel at the incision point, allows the patient an opportunity to receive additional anesthetic, if needed.

Spinal anesthesia is an excellent, safe technique that has a wide range of uses, especially in austere situations. One caution in hypovolemic or seriously ill patients is that spinal blocks cause vasodilation. A rule of thumb is first to give patients 500 to 1000 mL normal (0.9%) saline (NS). At that point, if a patient's pulse rate is higher than their systolic blood pressure, do not use this technique.61

Spinal anesthesia is one procedure you might not be willing to do without prior experience. Non-anesthesiologists who have experience performing lumbar punctures (spinal taps) may be able to provide anesthesia with these blocks with little difficulty. Administering epidural blocks requires some prior hands-on experience under supervision.

Medications for Spinal Anesthesia

Local anesthetic agents are either heavier (hyperbaric) or have the same specific gravity (isobaric) as the cerebral spinal fluid (CSF). Hyperbaric solutions tend to spread down (due to gravity) from the level of the injection, while isobaric solutions are not influenced in this way. It is easier to predict the spread of spinal anesthesia when using a hyperbaric agent. Isobaric preparations may be made hyperbaric by the addition of dextrose.

Any medication injected into the thecal space must be taken from a previously unopened vial. Do not use anesthetics from multi-dose vials, as they contain potentially harmful preservatives and solutions may be infected from prior use.

Lidocaine and bupivacaine are commonly used for spinal anesthesia, although tetracaine and procaine are used occasionally if the procedures are very short (procaine) or very long (tetracaine). They usually come as regular (isobaric) or "heavy" (hyperbaric) solutions (Table 14-2). Administering increasing amounts of the same anesthetic preparation results in higher levels being blocked.62 The amount of anesthetic needed varies with the medication used, the level to be blocked, and whether the medication is isobaric or hyperbaric. Even with the same amount and type of medication, however, the level blocked varies with the patient's position and characteristics (age, height, weight, pregnancy, sex), site and speed of injection, and direction of the needle's bevel.63  Table 14.3 lists typical types of solutions and patient positions to block the appropriate levels for several typical surgical procedures.

If available, isobaric bupivacaine 0.5% is best for lower limb surgery. It provides longer anesthesia than lidocaine. Hyperbaric 0.5% lidocaine or bupivacaine is useful for lower abdominal and pelvic/urogenital surgery. Add 5% glucose (D5W) to the anesthetic to make the heavy solution, if it is not premixed. Dependent on gravity, hyperbaric medications localize based on the patient's position.

A number of alternative local anesthetics can be used for spinal anesthesia. If standard solutions are not available, modifying some of these medications with epinephrine, dextrose, or NS may be necessary.

Bupivacaine 0.5% hyperbaric (heavy bupivacaine) is the best agent to use if it is available. Plain (isobaric) 0.5% bupivacaine can also be used. Bupivacaine usually lasts from 2 to 3 hours. Cinchocaine 0.5% hyperbaric (heavy) solution is similar to bupivacaine.

Lidocaine/lignocaine achieves its best results when using a 5% hyperbaric (heavy) lidocaine solution. This lasts 45 to 90 minutes. Isobaric lidocaine 2% can also be used, but it has a shorter duration of action. Add 0.2 mL epinephrine 1:1000 to lidocaine to prolong its duration of action. Mepivacaine, if used as a 4% hyperbaric (heavy) solution, is similar to lidocaine.

Tetracaine 1% solution can be prepared with dextrose, NS, or water for injection. It has a long duration of action.

If typical spinal anesthetics are unavailable, use meperidine/pethidine 5% solution (50 mg/mL), which has local anesthetic properties and is a versatile agent. The standard IV preparation is preservative-free and isobaric. A dose of 0.5 to 1 mg/kg is usually adequate for spinal anesthesia. It has a rapid onset but can also wear off quickly.66 Using meperidine is less expensive than using bupivacaine for spinal anesthesia.67

Technique

Premedicate the patient, if possible. Some patients may be very anxious about being awake during surgery, especially for amputations or other mutilating procedures. Do a lumbar puncture with the needle's bevel facing toward the patient's head. (While the official doctrine is to have the bevel aimed laterally, experienced anesthesiologists have found that this forces the needle to move laterally as it passes through the tissues. [Denny Bastrom, MD, oral communication, September 1, 2008.]) If a caudal (saddle) block is desired, place the patient in the sitting position.

To reduce the incidence of a post-spinal tap headache, use a large intramuscular injection needle as an introducer through the skin and muscle, if a Sise introducer is unavailable. Insert the needle through the interspinal ligament (not through the dura) and then pass a small-gauge spinal needle through this larger needle. However, before doing this, be certain that the first needle is large enough to allow the spinal needle to pass through it. Insert the needle through the dura into the subarachnoid space, keeping the bevel lateral.68

When CSF appears, immobilize the needle by resting the back of the nondominant hand firmly against the patient while using the thumb and index finger to hold the needle's hub. Tightly attach the syringe with the anesthetic to the needle. Hyperbaric solutions are viscous and, with a high resistance to injection, may spill if the syringe is not firmly connected. Gently aspirate to check if CSF can still be withdrawn; then slowly inject the local anesthetic. Once injected, withdraw the needle.66

Hyperbaric solutions tend to settle in the dependent portions of the sac, while isobaric solutions usually will stay where they were injected, diffusing slowly in all directions. When hyperbaric agents have been used, putting a patient "head-down" can cause the block to extend cephalad for about 20 to 30 minutes after it was performed.66 Using this principle, a saddle (perineal) block using a hyperbaric anesthetic is best done in the sitting position, with the patient remaining in that position until the anesthetic level has become "fixed."62

Testing the Spinal Block

To test the block's effectiveness, ask the patient to lift her legs. If she can't, the block is at least at the level of the mid-lumbar region. To test sensation, first test for a loss of temperature sensation using an ether or alcohol-soaked swab. Touch the patient's chest or arm where they can feel the cold swab. Then test the legs, moving up to the lower abdomen until the patient again feels the swab's coldness. If this is ambiguous, gently pinch blocked and unblocked areas until the level can be ascertained. Do not touch the patient and ask, "Do you feel this?" Touch sensation may persist even if there is no pain.66

Several problems can occur with spinal blocks: having no apparent effect, being too low, affecting only one side, or being too high. Note that moving a patient in any way in the first 10 to 20 minutes following injection increases the height of the block.

No Block

If the patient still has full power in her legs and normal sensation after 10 minutes, repeat the block.

Not High Enough

If using a hyperbaric solution, tilt the supine patient head down so the solution runs up the lumbar curvature. Also, raise the patient's knees to flatten the lumbar curvature. If using a plain solution, turn the patient 360 degrees, from supine to prone, and back to supine.

One-Sided or Too Low on One Side

If using a hyperbaric solution, place the patient on the inadequately blocked side for a few minutes and tilt the table into a slightly "head-down" position. If using an isobaric solution, place the patient on the side that is blocked.

Too High

While rare, this can occur quickly. These patients often complain of difficulty breathing or of their arms or hands tingling. Do not tilt the table "head-up." Get help; this is life-threatening. Treat this by monitoring, assisted ventilation, treating hypotension (raising legs and using a vasopressor, such as ephedrine or phenylephrine), and treating bradycardia (atropine first, then ephedrine or epinephrine).

For those experienced in doing epidural blocks, some improvisation may be necessary. For example, since the block should be done using a fairly thick needle with a rounded, not-too-sharp point, if a standard Touhy needle with a Huber point is not available, make one by bending the end of an ordinary spinal needle at a 45-degree angle. Grind off the tip so that only a small part of the bent end remains and then smooth it with a grindstone or file. Be certain that the lumen remains open so that the plastic catheter can pass through.68

A simple and cheap alternative to the standard spring-loaded syringe to identify the epidural space can be easily improvised (Fig. 14-9). Make two wedge-shaped slots on opposite sides of a standard disposable syringe plunger. Then carefully make two holes on each side of the syringe barrel's flange. The holes on each side and the slot in the plunger should line up. Cut a rubber band, pass it through one set of holes, and insert the ends through the holes on the other side of the syringe. Tie the rubber band's ends. Then slip the rubber band over the top of the plunger, lodging it in the plunger's slots so it doesn't slip off.69

If a standard epidural medication is not available, ketamine may be used either alone or as an adjunct to local anesthetics. Using ketamine greatly prolongs the analgesia provided by single-shot epidural techniques, although preservative-free ketamine preparation must be used to avoid neurotoxicity.70

Hypnosis is perfectly suited to be an anesthetic technique in austere circumstances. Easy to learn, the technique requires no equipment, has a rapid onset, can be used for anesthesia and analgesia, and has no complications. Additionally, patients can later use it themselves for post-procedure pain relief.

Hypnosis, a state of wakeful suggestibility, has been used for millennia in medical and religious practices under various names. In the 19th century, the English surgeon John Elliotson and the Scottish surgeon James Esdaile performed hundreds of surgical procedures with hypnosis as the sole anesthetic, with decreased mortality compared with other methods.71 On the battlefield, Podiapolsky found that nearly all wounded soldiers, no matter what their nationalities, responded "with exceptional facility" to hypnosis, although he did not use it for major operations.72

Hypnosis is being used successfully to anesthetize patients for a wide variety of operations and procedures requiring conscious sedation.73,74 Much of the benefit is due to the patient's relaxed state and to distraction, rather than to specific suggestions to not feel discomfort.38 Potential symptom-oriented uses of hypnosis include: (a) to treat possible conversion reactions; (b) to treat pain associated with dislocation and fracture reductions; (c) to treat acute stress reactions, posttraumatic stress disorders, and factitious seizure; (d) to relieve the anxiety of needle phobias; (e) to treat the pain of burns; (f) to treat headaches; (g) to prepare patients for surgery, pelvic or post-rape examinations, or labor; and (h) to relieve pain and anxiety prior to emergency department (ED) procedures, such as suturing or incisions and drainage. If no other option exists, it can also be tried as anesthesia, although it works best as an adjunct to low-dose anesthesia.41,42

Technique

Although practitioners use many methods for inducing hypnosis, physicians and emergency medical services personnel have found the following method extremely easy to learn and use. The process is described to the patients as a way to relax, so any misconceptions they have about hypnosis will not interfere with their cooperation.41,42 As Boulton described it, "In the particular context of ‘difficult circumstances' hypnosis is often best practiced without the patient being aware that it is being employed; all that is necessary is that the patient should not be actively hostile to the technique. A tranquil and secure atmosphere and warm, comfortable conditions are important in promoting the successful practice of hypnosis."36

The clinician first explains the concept of patient and clinician cooperation, frequently described as permissive hypnosis. This helps allay the common adult fear of domination, control, or coercion by the clinician; children rarely experience this.41,42

During the "preinduction" phase, rapport is established with the patient. (In adults having prior experience with or exposure to hypnosis, their experiences and the relationship between this technique and their experiences are discussed.) A key element in all cases, but especially in a noisy prehospital or ED environment, is to reinforce that the patient should listen only to the clinician and that the process will proceed at the patient's pace without pressure. The clinician should speak in a firm, quiet manner, in no way reacting to any of the noisy or distracting activities in the immediate vicinity.41,42

Induction

Begin by instructing the patient to close his eyes and to relax. Unlike adults, children in stressful conditions are already considered in Stage 1 hypnosis, and so are generally more susceptible to hypnotic suggestions. The patient is then asked to concentrate on his toes, imagining/producing sensations of heaviness and pleasant warmth in the limbs as "all of the muscles in your toes relax." For most people, feelings of heaviness are easier to imagine than warmth, but this is not consistent. The clinician should continue to suggest both sensations. A significant amount of time (30 to 45 seconds) is spent helping the patient to concentrate on and relax the toes. If this can be accomplished, the remainder of the procedure is much easier.41,42

The clinician then suggests that the patient feel the warmth or heaviness flow up into the feet, then the legs, thighs, and so forth. A significant indication that the technique has been successful is the regularization of the patient's breathing. A suggestion to the patient at this time should be to slow their rate of breathing and further allow the entire body to relax. Suggest that with each exhalation, the patient will become more and more relaxed. The patient is then told that he will feel relaxed, sleepy, and will "travel in your mind to a very pleasant place, perhaps a beach or mountain." A suggestion can be made that the patient will not remember the process of and pain during the upcoming procedure.41,42 Then do the procedure.

Testing the depth of hypnosis is pointless in a clinical setting; results are what matter. The key is whether the patient cooperates with the procedure, relaxes enough (e.g., joint reductions), or has diminished pain.

Emergence

The techniques related to getting patients to emerge from a hypnotic state may not be needed. If hypnosis is being used alone for the manipulation associated with reducing forearm fractures (or joint dislocations), the patient normally arouses immediately following the procedure. However, if a posthypnotic suggestion for pain relief or selective amnesia has been given, this still may be in effect. It can be reversed before the end of hypnosis, if desired.41,42

For those patients in very deep hypnosis (~15% of patients), it may be necessary to deliberately awaken them at the end of the procedure. The simplest method is to say: "I am going to count to ten and your eyes will open and you will feel perfectly normal. 1, 2, beginning to wake, 3, 4, lighter and lighter, 5, 6, eyes beginning to open, 7, 8, nearly awake, 9, 10, quite awake."36