basics of Suturing and Wound Management

Assessment

• Mode of injury: blunt, penetrating, blast.
• Time of injury.
• Type of wound: puncture, laceration, incision, crush, burst, bite. (Consider removing rings from injured fingers before oedema starts.)
• Location: proximity to major vessels (potential damage to blood supply for healing), nerves and organs.
• Shape: linear, curved, stellate, Y-shaped, inverted V, etc.
• Depth and direction: risk to underlying tissues, skin tension lines.
• Potential foreign body: suggestive history – whether it will be radio-opaque or require ultrasound scan location.
• Potential underlying structural injury: bone fracture, tendon rupture, organ perforation.

Haemostasis

This may be spontaneous. However, it may require:

• Pressure.
• Elevation.
• Tourniquet.
• Clamp/suture (for arterial bleeders).

Analgesia

Do not forget analgesia; this is not only humane but facilitates the remainder of management.

Local anaesthesia

• Topical: tetracaine-lidocaine combinations can be used to good effect on wounds in children, even if just to allow infiltration of local anaesthetic.
• Infiltrative: most often lidocaine (up to 3 mg/kg. NB: a 1% solution contains 10 mg/mL). Caution is generally advised in the use of adrenaline (epinephrine) especially around end arterioles such as those in digits, the penis, etc. However, there is insufficient evidence to justify this fear.^[1] If used, the lidocaine dose can be increased up to 7 mg/kg.

Skin preparation and wound toilet

• Don’t put alcohol or detergents inside the wound.
• Tap water has been shown to have as low, or lower, infection rates as proprietary antiseptic solutions.
• The usual compromise is to use sterile saline.
• Irrigation:
  • This is more important where there is high risk of infection.
  • The aim is to remove foreign matter and bacteria.
• Use 50-100 mL/cm saline under pressure (syringe with 25G needle).
• Also consider debridement of ragged, non-viable skin edges.
• If necessary you can trim hair; however, avoid shaving.
• Remove faoreign bodies but make sure personnel and equipment to control any increase in bleeding are at hand.

materials

There are a number of suture materials available, but it is beyond the scope of this module to cover them in any detail. In selecting a particular suture, the physician needs to consider the physical and biological characteristics of the material in relation to the healing process.

Suture materials can be broadly categorized as absorbable and non-absorbable. Absorbable sutures do not require removal as they are digested by tissue enzymes. Non-absorbable or permanent sutures need to be removed at a later date.

Absorbable sutures can be further divided into rapidly absorbing (days) and slowly absorbing (months). The choice will depend on the rate at which the particular tissue regains its strength. Fortunately, the choice is often not an issue in the Emergency Department because most wounds encountered there require support for a matter of days to weeks. Sutures available in the Emergency Department will meet this requirement.

Both absorbable and non-absorbable sutures are graded for size or diameter of the strand. The grading system uses the letter O and the number of stated O’s indicates the size. The more O’s, the smaller the size. For example, a 6-O is smaller than a 4-O. Accordingly, tensile strength of a particular suture type increases as the number of O’s decreases.

The needles supplied with sutures also have important features. In general, for Emergency Department use, needles are either large or small and either cutting or non-cutting. Large needles have the advantage of closing a deeper layer of tissue with each “bite”. The concern with small needles is that there will be inadequate closure of deep subcutaneous tissues, leaving potential space for hematoma formation. However, small needles create smaller puncture wounds and may have the advantage of reducing scarring

Cutting needles have at least two opposing cutting edges to facilitate passage through tough tissue. These needles are used for skin closure. Non-cutting or tapered needles are used to close subcutaneous tissue, muscle and fascia. They have sharp points, but do not have cutting edges.

Suture placement

A needle holder is used to grasp the needle at the distal portion of the body, one half to three quarters of the distance from the tip of the needle, depending on the surgeon’s preference. The needle holder is tightened by squeezing it until the first ratchet catches. The needle holder should not be tightened excessively, because damage to both the needle and the needle holder may result. The needle is held vertically and longitudinally perpendicular to the needle holder

Incorrect placement of the needle in the needle holder may result in a bent needle, difficult penetration of the skin, or an undesirable angle of entry into the tissue. The needle holder is held by placing the thumb and the fourth finger into the loops and placing the index finger on the fulcrum of the needle holder to provide stability (see the first image below). Alternatively, the needle holder may be held in the palm to increase dexterity

The tissue must be stabilized to allow suture placement. Depending on the surgeon’s preference, toothed or untoothed forceps or skin hooks may be used to grasp the tissue gently. Excessive trauma to the tissue being sutured should be avoided to reduce the possibility of tissue strangulation and necrosis.

Forceps are necessary for grasping the needle as it exits the tissue after a pass. Before removal of the needle holder, grasping and stabilizing the needle is important. This maneuver decreases the risk of losing the needle in the dermis or subcutaneous fat, and it is especially important if small needles are used in areas such as the back, where large needle bites are necessary for proper tissue approximation.

The needle should always penetrate the skin at a 90° angle, which minimizes the size of the entry wound and promotes eversion of the skin edges. The needle should be inserted 1-3 mm from the wound edge, depending on skin thickness. The depth and angle of the suture depends on the particular suturing technique. In general, the two sides of the suture should become mirror images, and the needle should also exit the skin perpendicular to the skin surface.

Knot tying

Once the suture is satisfactorily placed, it must be secured with a knot.^[35] The instrument tie is used most commonly in cutaneous surgery. The square knot is traditionally used.

First, the tip of the needle holder is rotated clockwise around the long end of the suture for two complete turns The tip of the needle holder is used to grasp the short end of the suture. The short end of the suture is pulled through the loops of the long end by crossing the hands, so that the two ends of the suture are on opposite sides of the suture line. The needle holder is rotated counterclockwise once around the long end of the suture. The short end is then grasped with the needle holder tip and pulled through the loop again.

The suture should be tightened sufficiently to approximate the wound edges without constricting the tissue. Sometimes, leaving a small loop of suture after the second throw is helpful. This reserve loop allows the stitch to expand slightly and is helpful in preventing the strangulation of tissue because the tension exerted on the suture increases with increased wound edema. Depending on the surgeon’s preference, one or two additional throws may be added.

Properly squaring successive ties is important. In other words, each tie must be laid down perfectly parallel to the previous tie. This procedure is important in preventing the creation of a granny knot, which tends to slip and is inherently weaker than a properly squared knot. When the desired number of throws is completed, the suture material may be cut (if interrupted stitches are used), or the next suture may be placed.

Suggested sizes and durations

• Child’s face: 6’0 monofilament nylon; remove after 3-5 days.
• Other parts of children: 5’0 catgut; deep part absorbs and the top part sloughs off after 10-14 days.
• Adult’s face: 5’0 monofilament nylon; remove after 5 days.
• Adult hand: 4’0 nylon; remove after 7 days.
• Adult scalp: 3’0 nylon/silk; remove after 5 days.
• Adult arm/trunk/abdomen: 3’0 nylon/silk; remove after 9-14 days.
• Adult leg: 3’0 nylon; remove after 14 days.

Risk factors for delayed healing

• Size, location and motion of wound.
• Age.
• Genetics.
• Race.
• Marfan’s syndrome, connective tissue disorders.
• Nutrition; deficiencies in protein, vitamins A, C, E, B1 (thiamine), other B vitamins, and zinc have been shown to retard healing. However, supplements to non-deficient patients probably have little or no benefit.
• Local infection.
• Ischaemia.
• Glucocorticoid therapy.
• Diabetes mellitus.
• Smoking.
• Foreign bodies.

Dressings

• The first layer in contact with the wound surface should be non-adherent – eg, a lightly lubricated gauze with interstices.
• Occlusive dressings can lead to maceration with retained fluid.
• The next layer should be absorbent material to attract any wound exudate.
• Finally, soft gauze rolls tape can be used to secure the initial materials in place.
• Dressings may not be necessary if the wound is dry and extra protection is not required.

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