Varieties of catgut: Surgical gut varies from plain catgut (the raw gut that has been gauzed, polished, sterilized, and packaged) to chromic catgut (that has undergone various intensities of tanning with one of the salts of chromic acid to delay tissue absorption time). Some examples of these variations and their absorption times follow in table 4-3. Suture Needles Suture needles may be straight or curved, and they may have either a tapered round point or a cutting edge point. They vary in length, curvature, and diameter for various types of suturing. Specific characteristics of suture needles are listed below.  Size: Suture needles are sized by diameter and are available in many sizes.  Taper point: Most often used in deep tissues, this type needle causes minimal amounts of tissue damage.  Cutting edge point: This type needle is preferred for suturing the skin because of the needle's ability to penetrate the skin's toughness.  Atraumatic (atraloc, wedged): These needles may either have a cutting edge or a taper point. Additionally, the suture may be fixed on the end of the needle by the manufacturer to cause the least tissue trauma. Preparation of Casualty Before suturing the wound(s) of any victim, the following steps should be taken to prepare the casualty. 1. Examine the casualty carefully to determine what materials are needed to properly close the wound. a. Select and prepare sterile instruments, needles, and suture materials. b. Position the patient securely so that access to the wound and suture tray is optimal. It is usually not necessary to restrain patients for suturing. c. Make sure a good light is available. 2. Strictly observe aseptic wound preparation. Use mask, cap, and gloves. Thorough cleaning and proper draping are essential. 3. Select an anesthetic with care. Consider the patient’s tolerance to pain, time of injury, medications the patient is taking or has been given, and the possible distortion of the tissue when the anesthetic are infiltrated. SELECTION OF ANESTHESIA.—The most common local anesthetic used is Xylocaine, which comes in various strengths (0.5%, 1%, 2%) and with or without epinephrine. Injectables containing epinephrine must never be used on the fingers, toes, ears, nose–any appendage with small vessels–because of the vasoconstricting effect of the epinephrine. Epinephrine is also contraindicated in patients with hypertension, diabetes, or heart disease. The three methods of anesthestia administration are topical, local infiltration, and nerve block. Topical anesthetics are generally reserved for ophthalmic or plastic surgery, and nerve blocks are generally accomplished by an anesthesiologist or anesthetist for the surgical patient. For a Corpsman, topical anesthesia is limited to the instillation of eye drops for mild corneal abrasions after all foreign bodies have been removed. DO NOT attempt to remove embedded foreign bodies. Nerve blocks are limited to digital blocks wherein the nerve trunks that enervate the fingers or toes are anesthetized. The most common method of anesthesia used by a Corpsman is the infiltration of the anesthetizing agent around a wound or minor surgical site. ADMINISTRATION OF ANESTHESIA.— Performing a digital block is a fairly simple procedure, but it should not be attempted except under the supervision of a medical officer or after a great deal of practice. The first step is cleansing the injection site with an antiseptic solution. The anesthetizing agent is then infiltrated into the lateral and medial aspects at the base of the digit with a small bore needle (25- or 26-gauge), taking care not to inject into the veins or arteries. Proper placement of the anesthesia should result in a loss of sensitivity in a few minutes. This is tested by asking the patient if he can distinguish a sharp 4-43 Type Gut Absorption Time A: Plain 10 days B: Mild chromic 20 days C: Medium chromic 30 days D: Extra chromic 40 days Table 4-3.—Absorption Times of Various Types of Surgical Gut