AUTHOR AND EDITOR INFORMATION

Section 1 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

INTRODUCTION

Section 2 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Background

In 1939, Kanavel, author of the landmark Infections of the Hand, observed, "In almost all cases of serious infection the difficulty is to make a correct diagnosis both as to the nature of the infection and the position of the pus." Specific infections covered in this article include paronychia, felon, herpetic whitlow, tenosynovitis, and deep fascial space infections.

Pathophysiology

Few structures of the body are as complex or as unique as the human hand with the functions of sensation, mobility, and strength in one small area. The hand consists of multiple compartments and planes, the knowledge of which allows one to understand the pathophysiology, diagnosis, and treatment of hand infections.

Paronychia

Infection of the area of the lateral nail fold (paronychium) is typically due to superficial trauma (eg, hangnails, nail biting, manicuring, finger sucking). Artificial nails have also been associated with acute paronychia. Although paronychia typically starts as a cellulitis, its progression to abscess formation is not uncommon. Infection that spreads to the proximal nail edge is termed an eponychia. Occasionally, infection can spread under the nail plate itself, resulting in a subungual abscess.

Chronic paronychia resembles acute paronychia but is usually nonsuppurative. People at risk include those repeatedly exposed to water and/or irritants as well as those who are immunocompromised. Metastatic cancer, subungual melanoma, and squamous cell cancer may rarely present as chronic paronychia.

Felon

The distal palmar phalanx is compartmentalized by tangentially oriented fibrous septa. These septa result in a closed compartment at the distal phalanx, which helps prevent the proximal spread of infection. Infection typically is due to direct inoculation of bacteria by penetrating trauma but may be caused by hematogenous spread and by local spread from an untreated paronychia.

Infection results in edema and increased pressure within the closed compartment. This, in turn, can impair venous outflow and lead to a local compartment syndrome and myonecrosis. Invasion of the bone leads to osteomyelitis.

Herpetic whitlow

Herpes simplex virus (HSV) infection of the distal finger typically results from direct inoculation of the virus into broken skin. Infection by type 1 or type 2 HSV is clinically indistinguishable. As in herpes infections elsewhere in the body, it is believed that the virus can remain dormant in the neural ganglia, leading to recurrent infections.

Infectious tenosynovitis

Tendon sheaths consist of a visceral layer adherent to the tendon and a parietal layer. Notably, the flexor tendon sheath of the thumb is continuous with the radial bursae, whereas the flexor tendon sheath of the fifth digit is continuous with the ulnar bursae. In 80% of individuals, communication exists between the radial and ulnar bursae. The tenosynovial coverings of the second, third, and fourth digits do not communicate with either the radial bursae or the ulnar bursae in most individuals.

Infection within a flexor tendon sheath, as in other infections of the hand, usually is the result of direct inoculation of bacteria from penetrating trauma. 

One common cause of penetrating trauma occurs when one person strikes another person in the mouth, resulting in a fight bite. A tooth may penetrate the metacarpophalangeal (MCP) joint capsule or an extensor tendon. Because the injury occurs while the joint is in flexion, deeper injuries to the extensor tendon or the MCP joint capsule or bone can be easily missed when the hand is examined in extension. For more information, see Bites, Human.

Infection can also occur by hematogenous spread, with Neisseria gonorrhoeae as the offending agent in many cases. 

Pyogenic flexor tenosynovitis, an infection of the flexor tendon, is most common in the index, middle, and ring fingers and can form as early as 6 hours after the initial penetration.

Infection typically follows the course of the tendon sheath, which results in the spread of infection into the radial or ulnar bursae, depending on the primary tendon sheath involved. Elevated pressure within the tendon sheath due to infection may impair nutrient flow to the tendon. Tendon necrosis, impaired function, or both are disastrous sequelae of untreated elevated tendon sheath pressure.

Deep fascial space infection

The deep fascial spaces of the hand are potential spaces and consist of the dorsal subaponeurotic space, subfascial web space, midpalmar space, and thenar space. The dorsal subaponeurotic space lies dorsal to the extensor tendons of the hand. The subfascial web space is contiguous with the dorsal subcutaneous space of the digits. The midpalmar space is demarcated by the palmar interosseous muscles dorsally and the flexor tendons of the third, fourth, and fifth digits ventrally. Lastly, the thenar space extends from the long metacarpal bone to the thenar eminence and consists of the area between the adductor pollicis muscle dorsally and the flexor tendon of the second digit ventrally.

These compartments are susceptible to infection by direct penetrating trauma, spread from a neighboring compartment, or hematogenous seeding. Because of the dorsal location of the lymphatics, erythema and swelling commonly appear over the dorsum of the hand, even when the injury is of palmar origin.

For more on hand anatomy, see Hand, Anatomy.

Mortality/Morbidity

Infections of the hand (especially dominant-hand infections) can be devastating and frequently require admission for antibiotic therapy and/or surgical intervention. Possible complications are outlined below (see Complications).

CLINICAL

Section 3 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

History

• Paronychia
• • Recent trauma to the lateral nail fold
  • In acute paronychia, history of nail biting or manicuring
• In chronic paronychia, history of repeated exposure to water and/or irritants (Those at risk may include people that frequently wash dishes or perform housekeeping duties.)
• • In children, history of finger sucking
  • Erythema and pain in early stages, followed by frank abscess formation with increased pain
  • History of diabetes (One study found that pediatric and adolescent patients with type 1 diabetes mellitus had an increased frequency of paronychia over the control group [34.4% vs 23%, respectively].)¹
• Felon
• • Recent trauma to finger pad
  • Pain, typically throbbing in nature
  • Swelling, pressure, and erythema
  • Presence and/or progression from paronychia
• Herpetic whitlow
• • Genital herpes in self or partner
  • Health care worker (not as common as once believed, likely secondary to increased protection with standard body-substance precautions)
  • Children with gingivostomatitis
  • Most commonly on tip of finger rather than on shaft
  • Localized pain, pruritus, and swelling followed by the appearance of clear vesicles
  • Typically localized to 1 finger only (symptoms involving more than 1 finger are more typical of coxsackievirus infection)
• Infectious tenosynovitis
• • Recent penetrating trauma to the hand
  • Gonococcal infection, particularly disseminated infection
  • Pain, especially with passive extension of the finger
  • Edema of the entire finger
  • Variable history of fever
• Deep fascial space infection
• • Recent penetrating trauma to the hand
  • Recent or untreated tenosynovitis
  • Palmar blister (may result in subfascial web space abscess)
  • Pain and edema of the hand
  • Pain with movement of the fingers
  • Variable history of fever

Physical

• Paronychia
• • Edema, erythema, and pain along lateral edge of the nail fold
  • May have extension to the proximal nail edge (eponychium)
  • Presence of frank abscess formation and fluctuance, although less common in chronic cases
  • Subungual abscess (floating nail) if pus has extended under the nail plate
• Felon
• • Painful, tense, and erythematous finger pad
  • Pointing of abscess possibly present
  • Signs typically limited to area distal to the distal interphalangeal joint because of anatomic constraints
  • Evidence of penetrating trauma
• Herpetic whitlow
• • Clear vesicles on an erythematous border localized to 1 finger
  • Pain, typically out of proportion to findings
  • Edema
  • Turbid or cloudy fluid in vesicles, possibly suggesting a superimposed pyogenic infection
  • In later stages, coalescence of vesicles to form an ulcer
  • Distal finger pulp that remains soft, which may help distinguish HSV infections from bacterial felons
• Infectious tenosynovitis
• • The 4 cardinal signs, first described by Kanavel, include the following:
  • • Tenderness along the course of the flexor tendon
    • Symmetric edema of the involved finger
    • Pain on passive extension (believed by some authors to be the most important sign)
    • Flexed resting posture of finger
  • All 4 signs possibly not present early in the course of infection
  • May have associated lymphangitis, lymphadenopathy, and fever
• Deep fascial space infections - All possibly presenting with lymphangitis (identified dorsally), lymphadenopathy, and fever
• • Dorsal subaponeurotic abscesses - Result in swelling and pain on the dorsum of the hand and pain with passive movement of the extensor tendons (difficult to distinguish from dorsal subcutaneous infection)
  • Subfascial web space infections - Present with pain and swelling on the dorsum and palmar surfaces of the hand (Because the subfascial space is contiguous with the dorsal subcutaneous space, tracking of infection from the former to the latter results in a collar button abscess named for its hourglass shape.)
  • Midpalmar space infections - Present with pain, swelling, loss of palmar concavity, pain with movement of the third and fourth digits, and dorsal swelling secondary to the tracking of infection dorsally along the lymphatics
  • Thenar space infections - Result in marked swelling of the thumb-index web space, flexed and abducted resting posture of the thumb, and pain with passive adduction

Causes

• Paronychia
• • Staphylococcus aureus and Streptococcus species are most common in acute cases.
  • Candida albicans (95%) and atypical mycobacteria are causes in chronic cases and in patients who are immunocompromised.
  • Anaerobes may be involved in the pediatric population secondary to finger sucking and children's playing in unhygienic spaces.
• Felon: S aureus is the most common causative organism, but gram-negative organisms have been identified.
• Herpetic whitlow: HSV-1 or HSV-2 is responsible.
• Infectious tenosynovitis
• • S aureus and Streptococcus species commonly are isolated; however, some authors believe that N gonorrhoeae should be considered a possible pathogen until excluded by culture data.
  • Eikenella corrodens is observed in infections caused by human bites.
  • Pasteurella multocida and Capnocytophaga infections caused by cat and dog bites can progress rapidly to septic shock and death.
• Deep fascial space infections
• • S aureus and Streptococcus species are most commonly isolated.
  • Organisms mentioned for infectious tenosynovitis also apply to deep space infections. This may be the result of local spread from infected neighboring tendon sheaths.

DIFFERENTIALS

Section 4 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Other Problems to be Considered

Septic joint
Primary hand tumors
Trauma, lacerations and tendon injury
Vascular disorders

WORKUP

Section 5 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Lab Studies

• Paronychia and felons: These often require no laboratory tests since the diagnosis is made clinically.
• Herpetic whitlow: The diagnosis can be confirmed by a Tzanck test, which demonstrates the presence of multinucleated giant cells in a scraping taken from the base of an unroofed vesicle.
• Infectious tenosynovitis and/or deep fascial space infections
• • As the infected spaces are drained and debrided in the operating room, preoperative laboratory tests (CBC with differential; prothrombin time/activated partial thromboplastin time; electrolytes; ECG, if age appropriate) may be requested by the hand surgeons and/or the anesthesiologist, but the diagnosis is made clinically.
  • Cultures are obtained in the operating room.

Imaging Studies

• Radiography
• • Because trauma often is a contributing factor in most hand infections, plain radiographs are useful in excluding fractures and retained foreign bodies if they are radiopaque.
  • Radiographs help identify subcutaneous or subfascial gas formation, if present.
  • Radiographs may indicate osteomyelitis.

Other Tests

In cases of severe infection causing vascular insufficiency, Doppler ultrasonography may assist in evaluation.

TREATMENT

Section 6 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Emergency Department Care

• Paronychia
• • In acute paronychia, if no frank abscess or fluctuance is noted along the lateral nail edge, frequent hot soaks and possibly a short course of antibiotics may result in resolution of the infection.
  • If pus is present, drainage of the area is required.
  • • Perform a digital nerve block using lidocaine without epinephrine.
    • Using a No 11 scalpel blade held parallel to the nail, elevate the lateral nail fold at the site of the abscess to allow for drainage of pus.
    • If a large amount of pus is expelled, a small wick is left in the incision to allow for continued drainage.
    • If pus has tracked beneath the nail, the removal of an adjacent longitudinal section of the nail may be necessary to promote drainage.
    • If a subungual abscess results in a floating nail, remove a portion of the nail or trephinate the nail to allow for complete drainage.
  • After drainage and wick placement, dress the finger appropriately.
  • Update tetanus booster status as needed.
  • In chronic paronychia, treatment consists of avoiding predisposing factors and initiating topical steroids and antifungal agents. Surgical intervention is indicated only if medical treatment fails.
• Felon
• • If frank abscess formation is present or the finger pad is tense, incision and drainage is indicated.
  • • This should not be undertaken lightly because improper placement of the incision can lead to scarring, sensory loss, unnecessary pain, instability of the finger pad, and spread of infection into the adjacent tendon sheath.
    • Elevation of the eponychial fold with a No 11 blade is quick, usually painless, and effective, and if there is pain it is extremely brief, less so than the pain of a digital block so local anesthesia is not typically needed. Discuss the procedure with the patient to alleviate their fears. Extensive incision or penetration of the finger with the blade is unnecessary, simple elevation of the fold will do; therefore, no nerve block is needed. If the patient requests it, a digital nerve block can be performed for comfort.
    • A longitudinal incision over the area of greatest fluctuance is the safest procedure when incision and drainage is required. Many other procedures, including hockey-stick or fish-mouth shaped incisions, are no longer recommended because of injury to neurovascular structure.
    • To avoid penetration of the tendon sheath, the incision should not extend to the distal interphalangeal crease.
    • Using a hemostat, bluntly dissect the wound to promote drainage.
    • Irrigate the cavity copiously and loosely pack with a gauze wick.
  • After irrigation and loose packing of the wound, apply a dry gauze dressing and overlying splint.
  • Update tetanus booster status as needed.
• Herpetic whitlow: Apply a dry gauze dressing to the affected finger to prevent further spread of the lesion.
• Infectious tenosynovitis and/or deep fascial space infections: ED care consists of making the correct diagnosis, providing pain relief, initiating antibiotic therapy, elevating and immobilizing the hand, and consulting an experienced hand surgeon promptly for definitive treatment. Experienced surgeons in the operating room should perform the incision and drainage.

Consultations

Prompt consultation with an experienced hand surgeon is indicated for patients with evidence of infectious tenosynovitis, deep fascial space infections, or osteomyelitis. Cases of chronic paronychia that do not respond to initial therapy should be referred to a dermatologist.

MEDICATION

Section 7 of 12  

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• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

The goals of pharmacotherapy are to eradicate the infection and to prevent complications. With the rise of methicillin-resistant Staphylococcus aureus as a cause of hand infections, coverage with appropriate antibiotics is important. In this era, cephalexin alone is inappropriate coverage for hand infections, and coverage for all infections should include MRSA coverage.

Drug Category: Antibiotics

Therapy must cover all likely pathogens in the context of the clinical setting.

Drug Category: Toxoids

These agents are used to induce and boost active immunity.

Drug Category: Topical steroids

These agents are used in the treatment of chronic paronychia. They have anti-inflammatory properties and cause profound and varied metabolic effects. Corticosteroids modify the body's immune response to diverse stimuli.

Drug Category: Topical antifungal

These agents are used in the treatment of chronic paronychia.

FOLLOW-UP

Section 8 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Further Inpatient Care

• Patients with evidence of infectious tenosynovitis or deep fascial space infections require inpatient treatment consisting of parenteral antibiotics and definitive incision and drainage by an experienced hand surgeon.
• Inpatient splinting and occupational therapy for range of motion is essential to preserve function.

Further Outpatient Care

• Paronychia
• • Instruct the patient with acute paronychia to soak the affected finger 3-5 times per day in warm water.
  • If a wick was placed, the patient usually can remove it easily after 24 hours if it has not fallen out already.
  • Schedule follow-up care with the primary care doctor or at the ED for 48 hours after initial incision.
  • Antibiotics, if prescribed, should be continued for 3-5 days.
  • In cases of chronic paronychia, topical steroids and antifungal agents should be initiated.
  • Pain medication may be prescribed as indicated.
• Felon
• • Reevaluate the wound 48 hours after initial incision.
  • At this time, remove the packing and irrigate the wound.
  • If continued drainage is present, loosely repack the wound and schedule another follow-up appointment in 24 hours.
  • If no further drainage is present, repacking is unnecessary.
  • Instruct the patient to keep the wound clean by washing it twice daily with warm, soapy water followed by a clean gauze dressing.
  • The patient should continue antibiotics for 5-7 days.
  • Pain medication may be prescribed as indicated.
• Herpetic whitlow
• • Instruct the patient to keep the affected area clean and covered with a dry dressing to prevent further transmission of the virus.
  • Oral acyclovir may be involved in preventing recurrence or in immunocompromised patients.
  • Pain medication may be prescribed as indicated.

Transfer

• Emergency medicine physicians should feel competent and comfortable with the treatment of paronychia, felons, and herpetic whitlow.
• Because of the specialized care required for infectious tenosynovitis and deep fascial space infections, transfer of patients with such infections may be necessary if those services are not available at the presenting hospital.
• Prior to transfer, splint the affected area, update tetanus booster as needed, and initiate antibiotic therapy.

Deterrence/Prevention

• All care should be taken to avoid manicures or other salon procedures with unclean implements.
• All wounds and abrasions to the hand should be taken seriously and thoroughly cleaned and dressed until healed. Careful observation and prompt medical evaluation will avoid complications.

Complications

• Paronychia
• • Subungual abscess
  • Osteomyelitis of the distal phalanx
  • Development of a felon
  • Chronic infection
• Felon
• • Osteomyelitis of the distal phalanx
  • Skin pulp necrosis
  • Sinus tract formation
  • Septic joint
  • Tenosynovitis
  • Inappropriate incision and drainage technique, resulting in sensory loss, tendon injury, spread of infection, or instability of the finger pad
• Herpetic whitlow
• • Oral inoculation or transmission of virus
  • Inappropriate treatment (eg, misdiagnosed as a felon) with incision and drainage, allowing viral spread into healthy tissue
  • Viremia occurrence possible
• Infectious tenosynovitis
• • Tendon destruction
  • Functional disability
  • Extension of infection to deep fascial space
• Deep fascial space infection
• • Functional disability
  • Tendon destruction
  • Sepsis
  • Hand loss

Prognosis

• Paronychia
• • Most resolve in 2-4 days.
  • Chronic infections are likely fungal infections and are typically more difficult to treat.
• Felon: The prognosis is good, with healing in 1-2 weeks.
• Herpetic whitlow
• • Infection usually resolves in 2-4 weeks.
  • Recurrence is not uncommon because virus may lay dormant in neural ganglia.
• Infectious tenosynovitis and/or deep fascial space infection: These have a fair prognosis, depending on the extent of tissue destruction, bony involvement, preexisting vascular insufficiency, and systemic complications (eg, bacteremia, sepsis).

Patient Education

• Instruct patients on proper wound care including warm soaks, if indicated, and dressing changes.
• Inform patients of the signs and/or symptoms of worsening infection, including increased pain, edema, redness, warmth, or fever.
• Emphasize the importance of follow-up care and wound reevaluation with the primary medical doctor or the ED physician.
• Instruct patients to avoid predisposing factors, such as nail biting, manicuring, and repeated exposure to water and/or irritants.
• For excellent patient education resources, visit eMedicine's Infections Center and Hand, Wrist, Elbow, and Shoulder Center. Also, see eMedicine's patient education articles Paronychia (Nail Infection), Finger Infection, Hand Injuries, and Finger Injuries.

MISCELLANEOUS

Section 9 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Medical/Legal Pitfalls

• Misdiagnosis
• Incomplete therapy (eg, failing to drain a tense felon)
• Failure to promptly consult an experienced surgeon when indicated
• Failure to consider N gonorrhoeae in patients with infectious tenosynovitis
• Inappropriate therapy (eg, fish-mouth incision for initial drainage of a felon)

ACKNOWLEDGMENTS

Section 10 of 12  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

The authors and editors of eMedicine gratefully acknowledge the contributions of previous authors, Amy K Rontal, MD, and Heatherlee Bailey, MD, to the development and writing of this article.

MULTIMEDIA

Section 11 of 12  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

Media file 1:  A paronychia can progress to a felon if left untreated.
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Media file 2:  A herpetic whitlow. Image courtesy of Glen Vaughn, MD.
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Media file 3:  Paronychia incision and drainage.
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REFERENCES

Section 12 of 12

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Acknowledgments
• Multimedia
• References

1. Kapellen TM, Galler A, Kiess W. Higher frequency of paronychia (nail bed infections) in pediatric and adolescent patients with type 1 diabetes mellitus than in non-diabetic peers. J Pediatr Endocrinol Metab. Jun 2003;16(5):751-8. [Medline].
2. Antosia RE, Lyn E. Hand. In: Rosen, ed. Emergency Medicine Concepts and Clinical Practice. 5^th ed. 2002:493-535.
3. Bach HG, Steffin B, Chhadia AM, Kovachevich R, Gonzalez MH. Community-associated methicillin-resistant Staphylococcus aureus hand infections in an urban setting. J Hand Surg [Am]. Mar 2007;32(3):380-3. [Medline].
4. Butler, KH. Incision and drainage. In: Roberts JR, Hedges JR, eds. Clinical Procedures in Emergency Medicine. 4^th ed. 2004:739-744.
5. Daniel CR 3rd, Daniel MP, Daniel J, Sullivan S, Bell FE. Managing simple chronic paronychia and onycholysis with ciclopirox 0.77% and an irritant-avoidance regimen. Cutis. Jan 2004;73(1):81-5. [Medline].
6. Gill MJ, Arlette J, Buchan K. Herpes simplex virus infection of the hand. A profile of 79 cases. Am J Med. Jan 1988;84(1):89-93. [Medline].
7. Goldstein EJ, Barones MF, Miller TA. Eikenella corrodens in hand infections. J Hand Surg [Am]. Sep 1983;8(5 Pt 1):563-7. [Medline].
8. Hausman MR, Lisser SP. Hand infections. Orthop Clin North Am. Jan 1992;23(1):171-85. [Medline].
9. Kanavel AB. Infections of the Hand. 1939;17-410.
10. Rockwell PG. Acute and chronic paronychia. Am Fam Physician. Mar 15 2001;63(6):1113-6. [Medline].
11. Siegel DB, Gelberman RH. Infections of the hand. Orthop Clin North Am. Oct 1988;19(4):779-89. [Medline].
12. Talan DA, Citron DM, Abrahamian FM, Moran GJ, Goldstein EJ. Bacteriologic analysis of infected dog and cat bites. Emergency Medicine Animal Bite Infection Study Group. N Engl J Med. Jan 14 1999;340(2):85-92. [Medline].
13. Wolanyk DE. 17. Infections. In: Hart RG, Uehara DT, Wagner MJ,. Emergency and Primary Care of the Hand. Irving,Tx: The American College of Emergency Physicians; 2001:219-246.

Article Last Updated: Feb 11, 2008