EMERGENCY SEDATION AND PAIN MANAGEMENT - PART 8 pot

Deep Peroneal NerveAnatomyDistribution of anesthesiaTechnique PitfallsPosterior Tibial NerveAnatomy Distribution of anesthesiaTechnique Superficial Nerves of the AnkleGeneral Superficial

The use of a vasoconstrictor such as 0.5%

phenyl-ephrine is recommended prior to administration of

lidocaine (Fig ure 31-2) By increas ing the internal

diameter of the nares, vasoconstrictors may make tube

passage easier and less painful and may help prevent

epistaxis Although these benefits are theoretical only

(they are not based on the results of randomized,

placebo-controlled trials), the low likelihood of harm

associated with the use of vasoconstrictors make this a

reasonable strategy

FOLLOW-UP/CONSULTATION

CONSIDERATIONS

Once the tube has been placed, proper position must be

confirmed Insufflation of air is the most rapid and most

commonly used method in the ED, but does not reliably

detect whether the tube has advanced past the stomach

into the small intestine

Radiographic confirmation is the most definitive way

to confirm tube position, but is seldom performed solely

for the purpose on confirming NG tube position Other

methods of confirmation include aspiration of stomach

contents and observing the patient to speak (Table 31-2)

Confirming NG tube position by more than one method

will help avoid incorrect placement Once secured, most

patients tolerate the NG tube with only minimal

dis-comfort

SUMMARY

NG tube placement is a very painful procedure that iscommonly performed in the ED In nonemergentsituations, awake patients should receive topical anes-thesia prior to tube passage This is best accomplishedusing 4 ml of 10% preservative-free nebulized lidocainedelivered by facemask or 4.5 ml of 4% preservative-freeatomized lidocaine sprayed into the nares (1.5 ml) andpharynx (3.0 ml), accompanied by 2% intranasal lido-caine jelly The use of a vasoconstrictor such as phen-ylephrine, 0.5%, may help reduce pain and provideprophylaxis against nosebleeds

BIBLIOGRAPHY

1 Binswanger IA, Kral AH, Bluthenthal RN, et al Highprevalence of abscesses and cellulitis among community-recruited injection drug users in San Francisco Clin InfectDis 2000;30:579–581

2 Cullen L, Taylor D, Taylor S, et al Nebulized lidocainedecreases the discomfort of nasogastric tube insertion:

A randomized double-blind trial Ann Emerg Med2004;44:131–137

3 Ducharme J, Matheson K What is the best topical anestheticfor nasogastric insertion? A comparison of lidocaine gellidocaine spray and atomized lidocaine J Emerg Nurs2003;29:427–430

4 Frazee BW, Lynn J, Charlebois ED, et al High prevalence

of methicillin-resistant staphylococcus aureus in

emergen-cy department skin and soft tissue infections Ann Emerg2005;45:311–320

Table 31-2 Methods to confirm successful NG tube placement

Radiographic evaluation Tip of the NG tube within the stomach lumen Most definitive method of confirmation

Takes time to obtain More expensive than other methods Insufflation of air Rush of air while listening under the left coastal

margin with a stethoscope

Simple and rapid Does not reliably detect whether the tube has advanced into the small intestine Increased pressure to instilling air suggests tube kinking or malposition

Immediate burp suggests esophageal position Aspiration of stomach

contents

Fluid with a pH less than 4 (has a 95%

probability of being in the stomach)

Fluid with a pH  6 may indicate respiratory tract placement 2% of patients will have an alkaline stomach pH

Ask the patient to speak Patient able to speak; inability to speak suggests

respiratory tract placement

Some small bore tubes may allow the patient to speak despite tracheal placement

5 Gallagher JE Nasogastric tubes: Hard to swallow Ann

Emerg Med 2004;44:138–141

6 Miller WC, Awe R Effect of nebulized lidocaine on

reactive airways Am Rev Respir Dis 1975;111:739–741

7 Murphy EL, DeVita D, Liu H, et al Risk factors for skin

and soft-tissue abscesses among injection drug users: A

case-control study Clin Infect Dis 2001;33:35–40

8 Nott MR, Hughes JH Topical anesthesia for the insertion

of nasogastric tubes Eur J Anesthesiol 1995;12:287–290

9 Singer AJ, Konia N Comparison of topical anesthetics and

vasoconstrictors vs lubricants prior to nasogastric

intuba-tion: A randomized controlled trial Acad Emerg Med

1999;6:184–190

10 Singer AJ, Richman PB, Kowalska A, et al Comparison ofpatient and practitioner assessments of pain fromcommonly performed emergency department procedures.Ann Emerg Med 1999;33:652–658

11 Specktor M, Kaplan J, Kelley J, Wheary J, Dalsey W.Nebulized or sprayed lidocaine as anesthesia for nasogas-tric intubations Ann Emerg Med 2000;7:406–408

12 Wolfe TR, Fosnocht DE, Linscott MS Atomized lidocaine

as topical anesthesia for nasogastric tube placement: Arandomized double-blind placebo-controlled trial AnnEmerg Med 2000;35:421–425

S E C T I O N 4 T O P I C A L , L O C A L , A N D R E G I O N A L

A N E S T H E S I A A P P R O A C H T O T H E E M E R G E N C Y P A T I E N T

Techniques

Douglas C Dillon and Michael Gibbs

SCOPE OF THE PROBLEM

HistoryPAIN CONSIDERATIONS AND MANAGEMENT

TopicalIntradermalRegional BlocksDigital Nerve BlockGeneral

AnatomyDistribution of anesthesiaTechnique

Transthecal Digital Nerve BlockGeneral

AnatomyDistribution of anesthesiaTechnique

PitfallsHand BlockGeneralUlnar Nerve BlockAnatomyDistribution of anesthesiaTechnique

PitfallsMedian NerveAnatomyDistribution of anesthesiaTechnique

PitfallsRadial NerveAnatomyDistribution of anesthesiaTechnique

PitfallsAnkle BlockGeneralSole of the footDorsum of the foot

205

Deep Peroneal NerveAnatomy

Distribution of anesthesiaTechnique

PitfallsPosterior Tibial NerveAnatomy

Distribution of anesthesiaTechnique

Superficial Nerves of the AnkleGeneral

Superficial PeronealAnatomy

Distribution of anesthesiaTechnique

Sural NerveAnatomyDistribution of anesthesiaTechnique

Saphenous NerveAnatomyDistribution of anesthesiaTechnique

PitfallsFacial BlocksGeneralSupraorbital and Supratrochlear NervesAnatomy

Distribution of anesthesiaTechnique

Infraorbital NerveAnatomyDistribution of anesthesiaTechnique

Mental Nerve BlockAnatomy

Distribution of anesthesiaTechnique

FOLLOW-UP/CONSULTATION CONSIDERATIONS

BIBLIOGRAPHY

SCOPE OF THE PROBLEM

History

Prior to the late nineteenth century, local pain control

for lacerations and fractures was only achieved by

minimizing the pain response centrally, typically with

opioids or alcohol In 1860, cocaine was isolated by

Albert Neimann and later refined into a local anesthetic

for ocular surgery by Carl Koller in 1884 Within a year,

William Halsted and Richard Hall reported the use ofcocaine in performing the first successful nerve block ofthe infraorbital plexus The two major drawbacks tococaine – toxicity and addiction – provided the drive tosearch for alternative anesthetics

In 1904, Alfred Einhorn discovered novocaine, whichbecame the local anesthetic of choice for 30 years Thelimitations of novocaine or procaine, a short duration ofaction and high rate of allergic reactions, led to the

206 Topical, Local, and Regional Anesthesia Approach to the Emergency Patient

search for a more ideal local anesthetic In 1934, Nils

Lo¨fgren and Bengt Lundquist produced what has come

to be known as lidocaine

In the twenty-first century, a multitude of anesthetic

options are available (Tables 32-1and 32 -2), allowing the

practitioner to choose topical, local, or regional

anes-thesia based on wound/fracture location, depth of injury,

patient age, patient compliance, and preference of the

patient Emergency anesthesia and analgesia providers

should be well versed in anesthetic techniques for fracture

reduction, laceration repair, and dermal instrumentation

PAIN CONSIDERATIONS AND MANAGEMENT

Adequate local anesthesia is not difficult to obtain and

may be gained by topical, local, or regional anesthesia

The amide and ester local anesthetics work by reversibly

binding to sodium channels When applied to nerve

tissues, these agents inhibit the propagation of nerve

impulses The smaller nerve fibers are the first fibers to be

affected causing a reduction in pain and temperature

sensation followed by loss of touch, deep pressure

sen-sation, and finally motor function When choosing a

local anesthetic agent, three factors guide the appropriate

selection: onset of clinical effects, duration of clinicaleffects, and agent toxicity (Tables 32-1and 32-2)

TopicalTopical anesthetics can be broken into two categories:those used on intact skin prior to dermal instrumenta-tion and those used on open skin for pain control orprior to wound repair

Eutectic mixture of local anesthetics (EMLA) was thefirst topical anesthetic for dermal instrumentation found

to be as efficacious as infiltration of local anesthesia.EMLA is an alkaline mixture of lidocaine and prilocaineapplied as a cream to intact skin At a high pH, bothagents exist in the nonionized form, allowing rapiddiffusion through membranes Although EMLA iseffective, the slow onset of clinical effects requires atleast 40 min of application time prior to the procedure.Liposome-encapsulated tetracaine, liposome-encapsulatedlidocaine, and tetracaine have all been compared to EMLAand are found to be equally efficacious, with liposome-encapsulated lidocaine having the shortest onset of action(Table 32-1)

The first topical anesthetic used on an open dermis was atetracaine, adrenaline, and cocaine (TAC) mixture The

Table 32-1 Topical anesthetic agents

Intact dermis EMLA(lidocaine and prilocaine) Thick layer applied over the

Open dermis Lidocaine, epinephrine, 1–3 ml applied directly 10–30 min or

Mucosa

tetracaine (LET) area to be anesthetized until wound edges blanche

to be anesthetized Viscous lidocaine Apply with cotton swabs 2–5 min

over the area to be anesthetized

cocaine component of this combination has more recently

been replaced with lidocaine owing to the potential for

central nervous system and cardiovascular toxicity A

lidocaine, epinephrine, and tetracaine (LET) mixture is

usually synthesized by a local hospital pharmacy in

accor-dance with the concentration preferences of local clinicians

Intradermal

Achieving adequate anesthesia for laceration repair by

subdermal injection is the mainstay of local anesthesia in

the emergency department A local anesthetic may be

directly infiltrated into most clean lacerations or

deli-vered as a field block for more contaminated wounds

The proper plane of injection is just beneath the dermis

in the subcutaneous tissue Avoid injection directly into

the dermis as this causes considerably more pain

Injecting the agent slowly, with a small-gauge needle will

also decrease patient discomfort

The selection of an anesthetic agent should be guided

by three factors: onset of action, duration of action, and

toxicity The onset of action of a local anesthetic is a

function of the pKa (the pH at which 50% of the drug is

ionized and 50% of the drug is nonionized) If the

ambient pH is higher than the pKa of the agent; a higherpercentage of the drug will be nonionized Nonionizeddrug diffuses more rapidly across lipid membranes;thus, the onset of action is shorter Although clinicianstypically will not select an anesthetic based on the pKa ofthe agent, alkalinization of the drug is a useful andstraightforward method for decreasing the onset ofaction and improving patient comfort This can be done

by adding standard strength sodium bicarbonate to theanesthetic at a ratio of 1:10, bicarbonate to anesthetic.Anesthetic duration of action has important clinicalimplications Although lidocaine continues to be theanesthetic of choice, owing to its bioavailability, rapidonset of clinical effects, and low allergenic profile, manyproviders use bupivacaine for enhanced postprocedurepain control owing to the longer duration of clinicaleffects

The toxicity of local anesthetics occurs with sodiumchannel blockade in non target tissues, primarily thebrain and heart There is a dose-related clinical progres-sion of local anesthetic toxicity from subtle neurologicalsymptoms to refractory seizures and ultimately, cardio-vascular collapse (Figure 32-1)

Table 32-2 Local anesthetic agents

Agent Lipid solubility a Protein binding b Duration (min) Onset c (min) Max dose mg/kg (w/epi)

Amides

Esters

Alternatives for patients with reactions to amides and esters

c The onset of action of an anesthetic is determined by the total dose of anesthetic given and the pKaof the drug.

d Diphenhydramine solution comprised of 4:1 normal saline and 5% diphenhydramine.

e Benzyl alcohol solution comprised of 0.2 ml of epinephrine 1:1,000 to a 20-ml vile of normal saline containing benzyl alcohol 0.9%.

208 Topical, Local, and Regional Anesthesia Approach to the Emergency Patient

Allow 5–10 min for full anesthesia with lidocaine and

15–20 min with bupivacaine injection If this procedure

does not provide complete anesthesia, more anesthetic

may be needed by either reapplication of the digital nerve

block or performance of a transthecal digital nerve block

Transthecal Digital Nerve Block

General

The transthecal approach utilizes the flexor tendon sheath

to apply anesthetic to the digital nerves (Figure 32 -3)

This procedure can be performed in addition to, or as an

alternative to, a digital nerve block

Anatomy

The flexor tendon sheath encases the flexor tendon on

the palmar side of the digit The sheath begins just

proximal to the palmar crease of the hand

Distribution of anesthesia

The transthecal digital nerve block provides anesthesia

to the entire digit

Technique

Identify the palmar crease along the palmar aspect of the

hand Have the patient flex the finger to be blocked if

possible to improve visualization of the flexor tendon At

the level of the distal palmar crease, puncture the skin at a

45 angle until the ‘‘pop’’ of the flexor tendon sheath is

felt If this sensation is not detected, continue to insertthe needle until the needle contacts bone Withdraw theneedle 2–5 mm and inject 2–3 ml of anesthesia

When the needle is in the flexor tendon sheath, theanesthesia should flow easily Allow 5–10 min for fullanesthesia with lidocaine or 15–20 min with bupivacaine.Pitfalls

Not performing a transthecal block with a failed dorsaldigital block

Hand BlockGeneralThese blocks are excellent blocks for lacerations, puncturewounds, or bony dislocations of the hand They can beused in part or in combination to provide anesthesia to theentire hand When performing a complete hand block,the ulna, median, and radial nerves should be blocked.Ulnar Nerve Block

AnatomyIdentify the flexor carpi ulnaris and ulnar artery by havingthe patient deviate their hand in an ulnar direction at thewrist (giving the thumbs up) (Figure 32-4) The flexor carpiulnaris is the most medial (ulnar) tendon The ulnar arterycan be palpated just medial and dorsal to the tendon.The ulnar nerve lies between the ulnar artery and theflexor carpi ulnaris tendon The ulnar nerve innervates

Figure 32-2 Digital Anesthetic placed as shown blocks both the dorsal (a) and palmar (b) digital

nerves, ensuring circumferential anesthesia of the finger In using the sequence shown, the prior

injection provides relief from the injection to follow (For color reproduction, see Color Plate 32-2.)

210 Topical, Local, and Regional Anesthesia Approach to the Emergency Patient

the flexor pollicis brevis, abductor pollicis, palmaris

brevis, abductor digiti minimi, flexor digiti minimi

opponens digiti minimi, the medial two lumbicals, and

all the interossei muscles

Distribution of anesthesia

This procedure provides anesthesia to the entire fifth

digit, half of the fourth digit, and the medial aspect of

the hand and wris t (Figu res 32-5and 32-6 )

Technique

The surgical field should be prepared just proximal

(1–2 cm) to the most distal wrist crease Raise a wheal of

anesthetic in the subcutaneous space and insert the needle

under the flexor carpi ulnaris 1 cm just palmar to the

ulnar styloid If blood is aspirated, withdraw the needle afew millimeters and aspirate again, the nerve is moresuperficial from the injection point Inject approximately5–7 ml of anesthetic

To block the cutaneous branches of the ulnar nerve,inject 3–5 ml of anesthetic just above the tendon of theflexor carpi ulnaris

Pitfalls

If bone is struck, withdraw the needle and direct it morepalmar

Median NerveAnatomyIdentify the flexor carpi radialis and the palmaris longustendons at the palmar aspec t of the wrist (Figu re 32-7)

Figure 32-3 Thecal The MCP joint and metacarpal head are palpated, and the point of injection is

estimated as just proximal to the joint in the midline (at the proximal palmar crease) A 25-gauge needle

is advanced at 45, tip distal, through the tendon/mesotendon complex (shown in blue) until bone is

encountered Anesthetic is injected and the needle is slowly withdrawn Loss of resistance locates the

needle tip within the mesotendon, where 2 ml of anesthetic is injected Diffusion of anesthetic out of the

mesotendon blocks adjacent palmar digital nerves (For color reproduction, see Color Plate 32-3.)

The palmaris longus, if present, is usually the more

prominent of the two tendons and can be identified by

having the patient flex at the wrist To help identify the

flexor carpi radialis, have the patient flex and abduct the

wrist The median nerve is lateral (radial) to the

pal-maris longus tendon and between the palpal-maris longus

and the flexor carpi radialis

The median nerve provides motor innervation to the

thenar muscles (abductor pollicis brevis, flexor pollicis

brevis, opponens pollicis) and the first and second

lumbricals

Distribution of anesthesiaThe median nerve provides sensation to the lateral threeand a half digits except the dorsal aspect of the thumb,and the corresponding area of the palm (Figures 32-5and32-6)

TechniqueThe surgical field should be prepared across the entirevolar surface of the wrist at the proximal palmar crease.Raise a wheal of anesthetic in a subcutaneous space andinsert the needle until it pierces the deep fascia

Figure 32-4 Ulnar Illustration A demonstrates the technique for identifying the flexor carpi ulnaris (f.c.u.)

tendon During ulnar deviation and flexion of the wrist, both the FCU and the pisiform to which it

attaches are palpated In C, the lateral approach to the ulnar nerve is shown The needle is oriented

horizontally beneath the FCU and inserted to a depth of 1.0–1.5 cm, where a 3–5 ml depot of anesthetic

follows negative aspiration B shows the subcutaneous field block of the dorsal ulnar nerve branches,

extending from the site of insertion of the ulnar block to the midline posterior wrist (For color

reproduction, see Color Plate 32-4.)

212 Topical, Local, and Regional Anesthesia Approach to the Emergency Patient

Avoid injecting too distal within the carpal tunnel,

which may exacerbate any carpal tunnel syndrome

Radial Nerve

Anatomy

Locate the radial styloid at the proximal portion of the

anatomi c snuf f box (Fig ure 32-7) The anatomic snuff

box is just distal to the radial styloid and formed bythe extensor tendon of the pollicis brevis and longus.The superficial branch of the radial nerve runs justabove the styloid process of the radius and providesdigital branches to the dorsum of the thumb, indexfinger, and lateral half of the middle finger Severalbranches run over the anatomic snuff box The nervedivides into two major branches about two finger

Figure 32-7 Median and radial The top left illustration demonstrates the technique for identification of

the palmaris longus (p.l.) tendon through wrist flexion during finger and thumb opposition As shown to

the right, the median nerve (m) is blocked between the p.l and flexor carpi radialis (f.c.r.) tendons,

following a perpendicular insertion just radial to, or through, the p.l tendon.

The radial nerve (r) block begins with a depot of 2–5 ml of anesthetic directly adjacent to the palpated

radial artery at the level of the proximal wrist crease and continues dorsally as a subcutaneous field

block extending to the dorsal mid-wrist, as shown in the lower left figure (For color reproduction, see

Color Plate 32-7.)

214 Topical, Local, and Regional Anesthesia Approach to the Emergency Patient

breadths proximal to the distal wrist crease (or

ana-tomical snuff box)

Distribution of anesthesia

The radial nerve provides sensory innervation to the

dorsal lateral half of the hand and the dorsal aspect of

the thumb (Figu res 32-5 and 32-6) The radial nerve

provides no motor innervation to the intrinsic muscles

of the hand The radial nerve provides innervation for all

of the extensor muscles in the posterior forearm

Technique

The surgical field should be prepared across the entire

dorsal surface of the wrist, including the radial styloid

and the anatomic snuff box Raise a wheal of anesthesia

in the subcutaneous space and inject 5–7 ml of

anes-thetic just above the radial styloid, directing the needle

first medially and then laterally

Pitfalls

The distribution of the radial nerve is less predictable;

therefore, a generous amount of anesthesia should be

injected

Ankle Block

General

An ankle block is essentially a block of four branches of the

sciatic nerve (deep and superficial peroneal, tibial, and sural

nerves) and one cutaneous branch of the femoral nerve

(saphenous nerve) (Figure 32 -8) This is an excellent block

to use as in combination or in part for lacerations, fracture

reductions, and exploring wounds Although there is some

overlap, sensory innervation in the foot can be broken

down into posterior and anterior nerves

SOLE OF THE FOOT.The tibial and sural nerves provide

sensory innervation to the sole of the foot

DORSUM OF THE FOOT.The superficial peroneal, the deep

peroneal, and the saphenous nerves provide sensory

innervation to the dorsum of the foot

Deep Peroneal Nerve

Anatomy

The deep peroneal nerve lies in the groove between the

extensor hallucis longus and the tibialis anterior tendon

The hallucis longus can be located by having the patientflex and extend the big toe The tibialis interior can belocated by having the patient dorsi flex the foot andinvert the ankle The injection site should be at the level

of the superior malleolus and between the two tendons.Distribution of anesthesia

The deep peroneal nerve provides sensation to the webspace between the first and second toe and a small areajust proximal to the first and second toe on the plantaraspec t of the foot (Figur es 32-9–32-1 2)

TechniqueThe surgical field should be prepared across the anteriorsurface of the ankle between the superior aspect of themedial and lateral malleoli Raise a wheal of anesthesia

in the subcutaneous space and direct the needle betweenthe tendons of the hallucis longus and the tibialisanterior at the level of the superior malleoli Insert theneedle until it is deep to the tendons or bone is struck.Inject approximately 5 ml of anesthetic Withdraw theneedle and redirect 30 laterally and then 30 mediallyand provide an additional 3–5 ml of anesthetic

If anesthesia in the saphenous distribution is alsodesired, withdraw the needle to the level of the subcu-taneous tissue and redirect medially toward the medialmalleolus Inject an additional 5 ml in the subcutaneousspace This technique will block the saphenous nerve

PitfallsAvoid inadvertent saphenous vein puncture

Posterior Tibial NerveAnatomy

The posterior tibial nerve runs just behind the medial leolus and just posterior to the posterior tibial artery Likethe deep peroneal, the posterior tibial nerve is deep to thefascia The posterior tibial nerve can be located just poste-rior to the medial malleolus just superficial to the artery.Distribution of anesthesia

mal-The posterior tibial nerve provides the majority of thesensation to the plantar aspect of the foot with minorcontributions from the deep peroneal and sural nerve(Figures 32-9–32-12) The posterior tibial nerve alsoprovides sensation to the heel of the foot

Figure 32-8 Ankle Blocks of each of the five nerves providing sensation below the malleoli are shown In A, the lateral and posterior placement of a subcutaneous field block of the sural nerve (sur) between the Achilles tendon and the lateral malleolus is depicted Medially, the posterior tibial (p.t.) nerve is blocked just posterior and 0.5–1 cm cephalad to the posterior tibial artery This approach is emphasized in C, which also shows the subcutaneous block of the saphenous (s.a.p.h.) nerve.

B illustrates anatomy relevant to the deep peroneal (d.per.) nerve block The insertion site is 1 cm cephalad to the base of the medial malleolus and between the anterior tibial (t.a.) tendon and extensor hallucus longus (e.h.l.) tendon, with the needle directed 30, tip lateral In addition, the subcutaneous field block of the superficial peroneal (s.per.) nerve is shown (For color reproduction, see Color Plate 32-8.)

216 Topical, Local, and Regional Anesthesia Approach to the Emergency Patient