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
· Easy to use
enough to hold wound edges together
to retain strength for the time needed to heal
to cause infection, tissue reaction, or significant scarring
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
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:
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.
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”.
first manufactured sutures were given sizes from #1 (thinnest) to #6
(thickest). #4 suture would approximate the string on a tennis racquet.
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.
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.
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).
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.
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.
are used today to close tissue that heals rapidly, such as vaginal lacerations
from childbirth or in the oral cavity.
are synthetic. These include:
Monocryl (poliglecaprone 25)
Dexon (polyglycolic acid)
sutures retain their tensile strength for varying lengths of time. They cause
less tissue inflammation due to an absorption process different than that of
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.
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.
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.)
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”).
sutures can be separated into synthetic single-stranded monofilaments and
braided natural or synthetic multifilaments.
monofilaments include Ethilon (nylon) and Prolene (polypropylene). Braided
natural multifilaments include braided surgical silk or cotton. Ethibond is the
most commonly-used synthetic multifilament.
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.
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
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.
Joe Alton MD
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