Wound Care

General considerations

The injury: The mechanism of injury is important in assessing the degree of risk of complications of a given wound. For example, the farmer who pierces his foot with a manure-laden pitchfork is at high risk for gas gangrene and sepsis. Management would include extensive local wound care and possible admission to hospital for intravenous antibiotics. Mammalian bites present another risk situation for infection. Is there likely to be a foreign body present in the wound? Does the force of injury suggest there is likely to be extensive trauma to deeper tissues?

The patient: Consider complicating medical conditions such as diabetes, other immunosuppressed states including diabetes or other major organ dysfunction (such as renal or hepatic failure) and peripheral vascular disease. These all may affect both resistance to infection and wound healing itself.

Time of injury: The age of the wound is important in deciding the timing of closure, if at all.

Laceration	Age / Condition	Treatment
Extremity	< 12 hours and “clean”	suture primarily
Extremity	>12 hours older or “dirty”	Older or obviously contaminated or infected lacerations are best left alone for healing by secondary intention or tertiary intention (closure a few days later). Saline soaks and antibiotics usually will be required. If cosmetic or other functional considerations apply, then referral to a plastic surgeon is necessary.
Face	< 24 hours	suture primarily unless obviously infected (rare)

These times are based on common medical practice in Canada. A study of forearm and hand lacerations found that closure within 4 hours had a lower infection rate than more than 6 hours from injury.¹

Consultation: Emergency physicians may consider early referral of certain lacerations to an appropriate surgeon. Indications for referral could include:

• Deep lacerations that involve nerve, tendon (often flexor tendon injuries of the fingers) or bone,
  
• Complex or extensive lacerations that may be challenging to repair or are located in difficult anatomical areas.

Assessment of function and the importance of wound exploration

Assess wounds under optimal lighting with minimal bleeding. Important structures underlying any laceration or contusion should be assumed divided until proven otherwise. Motor, sensory and vascular function must always be assessed.

The physician, however, cannot rely only on tests of motor or sensory function to rule out injuries to tendon or nerve. Only a small portion of a tendon in the finger, for example, needs to remain intact to maintain function. However, if the patient is sent home with such a partial tendon injury, total rupture may occur when the tendon is stressed.

Note that there is no reliable test for isolating a particular wrist flexor or extensor, because more than one muscle performs the same function.

Therefore, wounds in the vicinity of important structures should be gently explored. If visualisation is difficult or the anatomy complex, then an appropriate surgeon should be consulted.

Tendon, nerve or vascular injuries are all too easy to miss unless due care is taken.

Finger Injuries

Injuries to the fingers and hands account for the majority of such cases. Tendon and nerve injuries of the fingers will now be reviewed, followed by a brief discussion of vascular injuries.

Tendon, nerve or vascular injuries are all too easy to miss unless due care is taken. In addition for testing function, these wounds should be gently explored. Injuries to the fingers and hands account for the majority of such cases.

A tendon is visualized through the open wound margin of this wound of the hand.

Finger Injuries

Tendon and nerve injuries of the fingers will now be reviewed, followed by a brief discussion of vascular injuries.

1. Extensor Tendon Injuries of Fingers: The anatomy of the extensor aponeurosis is depicted in the diagram below. Extension is accomplished through the action of the extrinsic digital extensors, and the interosseous and lumbrical muscles.
   
   Transection or avulsion of the central extensor slip from the base of the middle phalanx may allow the lateral band to slip in a volar direction and assume a PIP flexor action. This produces the classical “boutonniere deformity”. The patient may initially exhibit a full range of motion, including extension.

2. Flexor tendon injuries of fingers: A missed flexor injury of the finger may result in long term disability. The anatomy is depicted in the accompanying diagram. The profundus runs the entire length of the finger and inserts into the distal phalanx. If intact, the finger can move normally, even if the superficialis is divided.
   
   

   Profundus tendon testing of long finger D3	Superficialis tendon testing of long finger D3

   
   The testing of these tendons – both the profundus and the superficialis is shown
   above. The test of the superfialis tendon can only be accomplished with all of the other digits being restrained in extension. Moreover, it is not reliable for the index finger. These tests do NOT replace exploration and visualization of the tendons in the wound.
   
   

3. Digital nerve injuries: The digital nerves exit the hand in the region of the volar web spaces, tracking along the medial or lateral aspects of the fingers.
   
   The digital nerves run immediately adjacent to the flexor tendons.
   
   Numbness or complete loss of feeling is not necessarily noted by the patient immediately even if there is complete transection of the nerve. A peculiar or unusual sensation in the territory of the nerve may be the only subjective description.
   
   If there is digital arterial bleeding, then the digital nerve is likely to be injured.
   
   Sensory testing is best done using two-point discrimination.
   
   If the history or physical findings suggest the possibility of a digital nerve injury, then exploration to visualise the digital nerve is necessary. A referral to a plastic surgeon is necessary. However, digital nerve injuries beyond the level of the DIP joint are not repaired and do not require referral.

4. Vascular Injuries
   Most arterial and venous injuries occur within the traumatised limbs. Early diagnosis is important.
   
   Consider the proximity of the wound to arterial structures. A history of bright red blood spurting from a wound indicates an arterial injury. Often, by the time of evaluation within the Emergency Department, this bleeding has stopped because of vasospasm (or uncommonly because of hypovolemic shock).
   
   The presence of a bruit or thrill frequently indicates a significant vascular lesion. Look for the classic six “P’s” in the distal extremity:
   

   pain
   pallor
   pulselessness
   paresthesia
   paresis
   poikilothermia

   Pulses may or may not be absent depending on the degree of injury.
   
   Venous injuries that are significant may be difficult to diagnose. These usually co-exist with arterial or nerve injuries. Arteriovenous fistula may occur.
   
   Compartment syndrome: Look out for
   1. Passive stretch pain of the muscles within the compartment
   2. Compartment swelling

The involved compartment needs to be released immediately.

Local anesthetics

There are two major groups of local anaesthetics: esters and amines.

1. Esters : procaine (Novocaine), and tetracaine (Pontocaine)
2. Amines: lidocaine (Xylocaine) and bupivacaine (Marcaine).

If a past allergy is reported, an anesthetic from another class can be used. Most often, however, the allergy is to the preservative used in the lidocaine multidose vials. Therefore, one option is to use a single-dose lidocaine preparation that does not contain preservatives.

For routine Emergency room use, a mixture of lidocaine 1%, with or without epinephrine 1/100,000 parts, is recommended. For regional nerve blocks, a 2% solution is used. The lidocaine 2% solution can be combined with equal parts of the Marcaine 0.25% solution to obtain relatively quick, yet longer lasting anaesthesia. The anaesthetic effect of lidocaine lasts less than an hour, but as long as two hours if the epinephrine containing preparation is used. Marcaine’s effect lasts from 12-24 hours. This would be important, for example, in the case of a distal digit amputation, where longer-term anaesthesia is desired. Some patients continue to experience considerable pain even after simple suturing, and Marcaine could significantly reduce such pain.

Epinephrine is commonly used as an adjuvant to reduce bleeding and slow anaesthetic absorption systemically. A noticeable decrease in wound bleeding will be noted in about seven minutes. Epinephrine should be avoided in those patients with vasospastic disorders, those with crush or circumferential extremity injuries, or those on beta-blockers. The use of epinephrine in the fingers, toes or penis has classically been contraindicated, because of its supposed propensity to cause vasospasm in these areas.

A toxic dose of Xylocaine (lidocaine) is 3 mg per kg intravenously; 5 mg per kg when injected without epinephrine into the wound margin, and 7 mg per kg when injected with epinephrine into the wound margin. There is evidence that the toxic dose may actually be much higher than usually quoted. The toxicity of Marcaine is one-quarter that of lidocaine, on a weight to weight basis.

Prior to the administration of local anaesthetics, check the sensory and motor nerve response, and for allergy (very rare). The pediatric literature supports the use of a topical anesthetic such as LET (a combination of lidocaine, epinephrine and tetracaine) prior to needle infiltration to reduce the pain. Slow injection by a small needle (such as a 25, 27 or 30 Gauge) will reduce the pain of infiltration.

Adverse reactions to local anaesthetics may take several forms.

Adverse Reactions to Local Anaesthetics
Type	Incidence	Mechanism	Symptoms
Vasovagal	Common		nausea, light-headedness bradycardia vasodilatation hypotension syncope
Epinephrine related	Common		“ rash” tremor, headache palpitations abdominal and uterine cramps
Toxic (>3mg /kg IV, >5 mg/kg without epinephrine, > 7 mg/kg with epinephrine)	relatively common	IV leak (? From regional blocks?)	tachycardia arrhythmia CNS excitation, depression seizure, coma
Allergic	rare to amides uncommon to esters	IgE mediated ? methylparaben preservative ? antioxidants (sulphites)	angioedema bronchospasm tachycardia hypotension

If there is doubt about allergy, in minor cases, plain normal saline can be injected into the wound margin to stretch the skin, thereby affording some degree of anaesthesia.

Malignant hyperthermia is now considered NOT to be precipitated by the use of lidocaine. Traditionally, in this setting, an ester has been utilised.

Tetanus prophylaxis - Tetanus vaccination
The tetanus disease itself is a serious one but relatively rare in Canada.

An identifiable acute injury occurs in the majority of cases (70%). Puncture wounds and lacerations account for most cases. Interestingly, approximately one-half of these injuries occurred indoors. Only a small percentage of cases occur in previously properly “immunised” patients. The incubation period is from two days to two months.

Tetanus vaccines must be administered intramuscularly. The anterolateral thigh is recommended in infants and the deltoid muscle in older children and adults. These adsorbed vaccines should not be administered subcutaneously as sterile abscess can form.

Since 1982, all school children in Ontario are required by law to be immunised. As of 1987, it is the law in Ontario that physicians inform their patients of the risks and benefits of immunisation. Adverse reactions to primary immunisation with tetanus toxoid are rare. The booster dose, however, can cause local erythema and swelling. Overuse of tetanus vaccines can lead to Arthus type reactions, urticarial reactions, and angioneurotic edema , and rarely, peripheral neuropathy and anaphylaxis.

Tetanus immune globulin (human) is a passive immunising agent containing preformed antibodies. Serum sickness can occasionally occur especially in the past when the globulin was derived from horse sera.

The decision to administer tetanus prophylaxis in the Emergency room depends on the current immunisation status of the patient and the liability of tetanus contamination in a given wound. In this Emergency Department, the order for a “tetanus booster” usually means that tetanus polio (Salk type) inactivated vaccine is administered.

Several protocols for the administration of tetanus prophylaxis are available.
The Canadian Immunization Guide – 6^th Edition – 2002 is available at

http://www.hc-sc.gc.ca/pphb-dgspsp/publicat/cig-gci/.

Prophylactic oral, IM or IV antibiotics in wound care of routine lacerations
There is NO evidence (based on many clinical studies and a meta-analysis) to support the routine use of prophylactic oral, IM or IV antibiotics to prevent wound infections after closure of routine lacerations. Antibiotics do NOT substitute for proper wound cleansing.
Prophylactic antibiotic treatment is, however, proven to be of value in the treatment of animal and human bites in particular. See D. Special Situations in Wound Care / Mammalian bites
``Use of antibiotics should be individualized based on the degree of bacterial contamination, the presence of infection-potentiating factors, such as soil, the mechanism of injury, and the presence or absence of host predisposition to infection. In general, decontamination is far more important than antibiotics. Prophylactic antibiotics should be used in most human, dog, and cat bites, intraoral lacerations, open fractures, and exposed joints or tendons.`` From Management of lacerations in the emergency department. O. Capellan and J. Hollander Emergency Medicine Clinics of North America. Volume 21, Number 1, February 2003