Doom and Bloom: Suture Basics For The Off-Grid Medic: Needles

Continuing their earlier article on suturing, the Altons at Doom and Bloom Medical followup with an article devoted to suture needles in Suture Basics For The Off-Grid Medic: Needles.

Basic diagram of a suture (by medscape.com)

In my recent article “Suture Basics For The Off-Grid Medic “,  I gave some thoughts on suture materials, especially as they apply to closing skin lacerations. Your skin is your armor, and anything that breaches it can cause a life-threatening infection.

Although the decision to close a wound should never be automatic, simple skin lacerations can often be cleaned and closed successfully by the off-grid medic. Sutures are just one of a number of ways to accomplish this goal and allow acceleration of the healing process. Today, we’ll discuss the qualities of suture needles.

(Note: This article is for educational purposes only. If the medical system in your area is intact, seek it out to treat lacerations or other medical issues!)

Suture needles are made of a corrosion-resistant stainless steel alloy that is sometimes coated with silicone to permit easier tissue penetration.

Basic diagram of a suture (medscape.com )

A suture needle has three sections: the point, the midportion or body, and the swage. The swage is the “end” of the needle and is where the thread is attached. The midportion is usually curved at an arc, and the point is, well, pointy.

SWAGING

Before about 1920, suture needles had “eyes” and string was separate; the surgeon had to thread the eye of the needle. Since then, sutures became a single continuous unit. This process of connecting suture needle and string is called “swaging”.

Swaging dealt with a number of disadvantages associated with using separate needles and thread. In the old method, two lengths of string were formed on either side of the eye. Passage of a double strand of suture through tissue led to more tissue trauma and, perhaps, a higher risk of infection. Also, the suture string was more likely to become unthreaded or frayed.

THE IDEAL SUTURE NEEDLE

Suture needles perform based on a number of qualities, including strength and sharpness. The strength of a needle refers to its resistance to deformation during use, limiting the amount of trauma to tissue. Sharpness measures the ease of penetration into tissue and is dependent on factors involving not only the point, but the shape of the body of the needle.

Just as suture thread has ideal characteristics, the effective suture needle would be:

  • Made of high-quality stainless steel
  • The smallest diameter possible
  • Stable in the grasp of the needle holder
  • Capable of running suture material through tissue with minimal trauma
  • Sharp enough to penetrate tissue with minimal resistance
  • Sterile and corrosion-resistant to prevent introduction of microorganisms or foreign materials into the wound
  • Rigid enough to go through tissue, but flexible enough to bend before breaking

Not all suture needles meet the above criteria, but will suffice for the basic needs of the medic.

NEEDLE TYPES

There are a number of different needle types variations at the point, body, and swaged end:

Common needle types with cross sections at midportion and point (ethicon.com)

Cutting Needles: The shape of the suture needle on cross-section may vary dependent on the particular need. The point of this shape to have more cutting edges. On cross section, it appears triangular. These needles are effective in penetrating thick, firm tissue, like skin.

There are two common types of cutting needles. “conventional” and “reverse”. Conventional cutting needles have the third edge of the “triangle” on the inner surface of the needle. Reverse cutting needles have the third edge of the triangle on the outer surface of the needle’s arc. The reverse edge is even stronger and able to penetrate tendons and other tough tissues, while decreasing the amount of trauma during the procedure.

Tapered Needles: These needles are round on cross-section and can pass through tissue by stretching more than cutting. A sharp tip at the point becomes round, oval, or square shape as you approach the swage. The taper-point needle minimizes trauma in delicate and easily-penetrated tissues such as organs or intestinal lining.

Blunt Needles: These don’t come to a sharp point, but are rounded at the end. These are best used for suturing liver, kidney, and other delicate organ tissue without causing excessive bleeding.

BODY SHAPES

Suture comes in many shapes, but 3/8 circle and 1/2 circle are most commonly used for learning

The body of a needle is important for interaction with the needle holder instrument and the ability to easily transfer penetrating force to the skin. A needle must be stable in the jaws of the needle holder to give maximum control and prevent bending.

The midportion comprises most of the needle’s length and is commonly curved into a 3/8 circle arc for skin or 1/2 circle for close spaces. Of course, other curvatures are available. Straight needles may be used if dealing with easy-to-reach tissues such as certain types of skin closures.

Next time, we’ll discuss the instruments you’ll use when closing a laceration with sutures.

Doom and Bloom: Suture Basics for the Off Grid Medic

The Altons at Doom and Bloom Medical have an article on Some Suture Basics for the Off-Grid Medic. More photos at article.

suture basics

Many animals, (insects, spiders, shrimp, crabs) have an exoskeleton as a protective covering. Humans have their skeleton on the inside, so we depend on the largest organ of the body, our skin, instead.

Skin represents the armor that protects the body from invasion by debris and microbes. A breach in that armor increases the chance of infection that may spread throughout (called “sepsis”) and become life-threatening.

As such, there are circumstances where a break in the skin should be closed with materials known as sutures. The decision to close skin should not be automatic and depends on many factors (discussed in previous articles on this site). Once that decision is made, however, the correct choice of suture material impacts the strength and effectiveness of the healing process.

THE IDEAL SUTURE

All wound closure methods have their advantages and disadvantages. Your choice should depend on the careful evaluation of the wound, as well as an understanding of the properties of a given suture material.

The optimal suture should be:

·           Sterile

·           Easy to use

·           Strong enough to hold wound edges together

·           Able to retain strength for the time needed to heal

·           Unlikely to cause infection, tissue reaction, or significant scarring

·           Reliable in its everyday use with every type of wound

It’s difficult to find a single suture type that meets all of the above criteria, but there are many that will do if chosen properly.

TISSUE HEALING

The time needed for healing should impact the choice of suture materials. The interval it takes for a tissue to no longer require support from sutures will vary depending on tissue type:

Days: Muscle, subcutaneous tissue like fat, and skin

Subcutaneous tissue is sometimes called the “hypoderm”. It’s connected to the deep layer of skin (the “dermis”). The skin and muscle in many areas of the body are separated by a layer of subcutaneous fat. Fat will appear as yellowish globules below the whitish dermis.

Weeks to Months:  Fascia or tendons

Fascia is connective tissue beneath the skin that attaches, covers, stabilizes, and compartmentalizes muscles and other internal organs. A tendon is connective tissue attaching a muscle to a bone.

CATEGORIZING SUTURE DIAMETERS

Around a century ago, the average suture consisted of a needle through which a separate string was threaded. This method was used for thousands of years until the process of swaging was invented. A swaged suture has the thread built into the blunt end of the needle, making surgical sutures a single unit for the first time.

In the United States and many other countries, a standard classification of sutures has been in place since the 1930s.  This classification identifies stitches by type of material and size of the “thread”.

The first manufactured sutures were given sizes from #1 (thinnest) to #6 (thickest). #4 suture would approximate the string on a tennis racquet.

As technology advanced, even thinner sutures were produced that were titled beginning at 0 (pronounced “oh”). Just like double-ought buckshot is bigger than triple-ought, 2-0 (pronounced “two-oh”) suture is thicker than 3-0 (pronounced “three-oh”). If you are doing microsurgery, you’re going down all the way to 8-0, 9-0, or 10-0. Size 7-0 is about the diameter of a human hair.

The suture thread used should be the smallest size which will give adequate tensile strength to keep skin together. Finer sutures have less tissue reaction but are more difficult to handle for the inexperienced. The off-grid medic should consider using somewhat thicker sutures that can be more easily handled.

ABSORBABLE SUTURES

Absorbable chromic gut suture

In addition to diameters, sutures are classified as absorbable and non-absorbable.  An absorbable suture is one that will break down spontaneously over time (but not before the tissue has mostly healed).

Absorbable sutures have the advantage of not requiring removal.  They can be used in a number of deep layers, such as muscle, fat, organs, etc.  A classic example of this is “catgut”, actually made from the intestines of cows or sheep. Since these sutures are made from multiple fibers, they remain extremely strong in the first few days of healing.

plain “catgut”

Catgut is usually found in “plain” and “chromic” varieties. Plain gut absorbs very quickly but has a tendency to cause tissue inflammation. When dipped in a chromic salt solution, catgut retains tensile strength in the body longer and causes less of a reaction, while still remaining absorbable.

Gut sutures are used today to close tissue that heals rapidly, such as vaginal lacerations from childbirth or in the oral cavity.

Newer absorbables are synthetic. These include:

  • PDS (polydiaxonone)
  • Monocryl (poliglecaprone 25)
  • Vicryl (polyglactin)
  • Maxon (polyglyconate)
  • Dexon (polyglycolic acid)

These sutures retain their tensile strength for varying lengths of time. They cause less tissue inflammation due to an absorption process different than that of gut.

Vicryl sutures are used for approximating muscle or fat layers, as well as lower layers of skin. Maxon and Monocryl can also be used for soft tissue as well as for cosmetic procedures where visible sutures aren’t desired. PDS is used to stitch muscle and fascia tissue.

Besides the classic synthetic sutures, new subtypes such as Vicryl Rapide, Vicryl Plus and PDS II exist. These may take less or more time to dissolve than the originals.

(Aside: Every physician has their own preference for sutures that relate to their experience, schooling, and other factors. For example, it is considered old-fashioned by many to use stitches for closing surgical incisions on skin, as most close skin wounds with staples. A randomized, clinical trial, however, found that women who had C-sections with dissolvable stitches were 57% less likely to have wound complications than those whose wounds were closed with staples. I used this method (known as a “subcuticular” closure) with good results for 20 years.)

NONABSORBABLE SUTURES

Nonabsorbable sutures are those that stay in the body indefinitely or, at least, for a very long time. Normally. They are best used in skin closures or situations that require prolonged tensile strength.

Nonabsorbable sutures can be used in deep layers in certain situations. They cause less tissue reaction, although a small remnant may be felt where the body’s immune system walled it off (known as a “granuloma” or “encapsulation”).

Nonabsorbable sutures can be separated into synthetic single-stranded monofilaments and braided natural or synthetic multifilaments.

Single-stranded monofilaments include Ethilon (nylon) and Prolene (polypropylene). Braided natural multifilaments include braided surgical silk or cotton. Ethibond is the most commonly-used synthetic multifilament.

Nylon monofilament suture

Monofilaments like Nylon are slightly less likely to harbor bacteria, whereas braided multifilaments have tiny nooks and crannies which may serve as hideouts for microbes. The difference in infection rate is very small, however.

Monofilaments also glide more easily through tissue, but may require more knots to stay in place than a braided multifilament like silk. While multifilamentous thread tends to come out straight, monofilaments retain the same S-shape in which they were packaged. This is more an annoyance for the inexperienced than anything else.

Braided surgical silk suture

Braided surgical silk is easier to handle than nylon, especially for novices, and is often used for teaching purposes. 2-0 and 3-0 are sizes considered too thick by many surgeons, but are useful for teaching aspiring off-grid medics to learn surgical knot-tying. Although scarring may be more noticeable, this is a secondary issue in survival scenarios.

The off-grid medic must know skills ordinarily not taught to the average citizen. Wound closure is one of these skills, but must be combined with a working knowledge of when closure is appropriate and when it isn’t. We’ll discuss these issues in future articles.

American Partisan: Ditch Medicine – Laceration Management

From the medical staff at American Partisan is this primer on the care of lacerations in austere conditions, Ditch Medicine: Laceration Management.

Lacerations are trauma which result in cutting or tearing of skin and possibly underlying tissue. Please note that deep lacerations that are complicated by the involvement of injuries to major arteries, tendons, nerves or abdominal cavity contents are not usually treatable in primitive conditions.

Initial Care for Lacerations

Most bleeding is initially controlled with pressure. Wounds without deep involvement should be surgically repaired if possible to speed healing, reduce infection, and improve cosmetic and functional results. The approximation of the skin edges can be achieved with steri-strips, skin glue, staples, or sutures (stitches). Before any wound is repaired, a few simple rules should be understood.

  • The longer a wound is left open to the environment, the more bacteria it will collect and therefore has a greater chance of infection, especially if the wound is closed by trapping these bacteria within the wound.
  • Most wounds can be closed within 12 hours of the injury (since the bacteria count won’t be terribly high). Since the face and neck have increased blood flow compared to most other body parts this extra blood flow helps the wounds fight infection and promotes healing, therefore wounds to the face and neck may be closed up to 48 hours after the injury.
  • Wounds that are to be closed must be thoroughly cleaned of any debris using forceps (tweezers) and using generous washings with clean or sterile water or saline. One source suggested using fresh urine from person without urinary infection since that should be sterile (I think I would rather use boiled water).

Creating Saline Solution for Laceration Washes

Saline solution can be made by adding one tablespoon of salt to 1 gallon of water or adding 1 teaspoon of salt to 1 L of water. Another irrigation solution can be made by adding 5 mils of household bleach to 1 L of clean water. Washing the area with Betadine or hibiclens before closure should be performed. Ragged wound edges and the tips of angularly cut tissue should be removed so that the wound edges to be approximated are smooth and will be likely to heal.

Steri-Strips, skin glue, and sutures may be the most useful ways to close a wound in a primitive environment. Staples may be used but require removal with a specialized removal tool which may not be readily available. Steri-Strips (tape) and skin glue can be applied to many wounds to hold the skin edges together until healing occurs. These are less secure than sutures (especially in larger deeper wounds) but maybe faster, require less technical skill, and may offer an improved cosmetic result.

For larger deeper wounds, sutures may be best for closure. Some wounds may have skin loss such that closure of the skin edges may be under some tension. The strength of sutures would be better for that closure, over glue or Steri-Strips. Sometimes tissue loss may be extensive enough that complete skin edge approximation may not be successful. Some gap in the skin edges may be allowed in these circumstances. Tissue loss with tension on the closure would require that the sutures be left for a longer period of time until the skin has stretched and relaxed enough so that there is no significant tension at the wound before removal of the sutures. In wounds without tension on the face, the sutures may usually be removed in about 3 to 5 days (this rapid removal is because of the high blood flow which speeds healing). The sutures on wounds of the trunk without tension may be removed in about 10 days. Sutures in the hands and feet are usually removed in about 10 to 14 days…

Click here to read the entire article at American Partisan.