SURGICAL AIDS
Syllabus:
Surgical dressings, sutures and ligatures and their
standards.
Question:
Q.1 How will you sterilize surgical gauge and
bandages ? [1991] [4]
Q.2. What is the difference between sutures and
catguts?(1991) [4]
Q.3. What are the various steps in the manufacturing
of catguts?(1991) [4]
Q.4. How will you test the sterility of surgical
dressings? (1991) [4]
Q.5. Write notes on standards of sutures and
ligatures. (92-93) [4]
Q.6. What is sutures and ligatures ?(1993) [2]
Q.7. What is the differences between sutures and
ligatures ? (1994) [2]
Q.8. Name the different materials used for this
purpose mentioning their merits and
demerits. (1994) [14]
Q.9. What do you mean by surgical aids ? (1994) [3]
Q.10. What is catgut? (1994) [3]
Q.11 What are the standards that a good catgut must
possess ? (1994) [10]
Q.12 Note on: Surgical dressing. (1993) [4]
Q.13 Boilable and non-boilable catgut. (1993) [4]
Q.14 Synthetic absorbable catgut. (1993) [4]
Q.15 Metals used as surgical aids. (1993) [4]
SURGICAL AIDS
These are referred to a wide range of materials used
for dressing of wounds or injured or diseased tissues (Surgical dressings);
some are used to hold wound edges closely during healing (sutures and
ligatures). All these materials are collectively called surgical aids.
SURGICAL DRESSINGS
Definition Surgical dressing is a term
applied to a wide range of materials used for the dressing of wounds or injured
or diseased tissues.
Dressings may serve to :
i) Provide an environment for
moist wound healing.
[N.B.
Drying of the wound is a major factor in retarding wound healing and increasing
scarring. Dressings which prevent drying (or desiccation) provide an optimal
environment for autolysis, cell migration, granulation and
re-epithelialization.]
ii) Prevent maceration by
permitting evaporation or absorption.
[N.B.
In highly exudative wounds, excessive moisture and autolytic enzymes will
damage repairing tissue, and will provide a perfect culture medium for
microbes.]
iii) Promote haemostasis (i.e.
stops bleeding)
iv) Protect the wound from
further damage [e.g. mechanical damage, microbial invasion, dehydration,
maceration, chemical damage, alteration in pH.]
v) Reduce heat loss.
vi) Control microbial growth by
incorporation of antimicrobial drugs.
vii) Promote healing.
viii)Provide compression,
promoting haemostasis and reducing oedema.
ix) Reduce pain, increase
patient comfort and improve functional use for wound site.
x) Reduce odour.
xi) Improve appearance of the
wound site.
xii) Reduce overall costs
associated with wound treatment.
Features of an ideal dressing
i) The dressing should be
porous to water vapour; otherwise sweat from the surrounding skin, water
evaporated from the epidermis, and tissue fluid exuded from the wound will
accumulate and delay the healing process.
ii) It must be capable of
absorbing excess secretions.
iii) Free from substances that
cause tissue reactions , allergy or a hypersensitivity response.
[N.B.
Fluorescent agents (optical whiteners), used to improve the appearance of
bleached materials, delay healing.]
iv) It must be impervious to
micro-organisms.
v) It must be impervious to
fluid from outside.
vi) Capable of following joint
contours during movement.
vii) It should have tensile
strength to withstand stretching during movement.
viii)It must be non-inflammable.
ix) It must be sterilizable by
conventional means.
x) Capable of preventing
excessive movement of wound.
xi) Inexpensive.
It is obvious that not a single dressing has all of
the above qualities.
Classification of surgical dressings:
Functionally surgical dressings can be divided into primary,
and secondary dressing.
A primary
dressing directly come in contact with the wound. It may provide absorptive
capacity and may prevent desiccation, infection and adhesion of the secondary
dressing to the wound.
A secondary
dressing is placed over the primary dressing for further protection, absorptive
capacity, compression or occlusion. Although some dressings are solely primary
or secondary in nature, others have the characteristics of both. The following
classification can be made:
i) primary wound dressings
ii) primary/secondary wound
dressings
iii) secondary dressings (a) Absorbents
(b) Bandages
(c) Adhesive tapes
iv) Protectives
PRIMARY WOUND DRESSINGS
Plain gauze
This is a soft cotton cloth of plain weave, open
texture and filmsy appearance.
Use: Because the cotton is in the form of spun threads
and not loose fibres (contrast cotton wool) gauze can be applied directly to
the wounds. It absorbs water readily but unless many folds thickness are used,
it is not bulky enough to cope with the exudate or give adequate protection to
a large wound. Hence, it is usually covered with more absorptive and protective
dressing.
Wicks of gauze are used, after surgery, for draining
exudate from large wounds.
Impregnate
gauze
Cotton, rayon or cellulose acetate gauze has been
impregnate with a variety of substances such as petroleum or paraffin, vaseline
or petrolatum emulsion.
They are used to reduce its adherence to wounds.
Oiled silk: This is a silk fabric of plain weave, evenly water
proof by treatment with drying oils. Oiled silk is used
i) to cover wet dressings, such
as poultices and compress to keep them moist.
ii) to protect clothing from
dressing.
Paraffin gauze dressing: This is a sterile dressing
consisting of pieces of cotton, rayon or cotton and rayon gauze impregnated
with yellow soft paraffin or it for use in warm countries, soft and hard
paraffin.
Paraffin gauze dressings are used in skin grafting
and for paraffin prevents adherence to the tissues and the open nature of the
gauze allows air to reach the wound and exudate to drain away into secondary
absorbent dressing.
Film dressing: are films of polyurethane with acrylic or
polyether adhesives.
i) In lightly exuding wounds
they permit enough evaporation to promote moist wound healing and prevent
maceration.
ii) Film dressings exclude
bacteria from wounds and permit bathing and observation of the wound.
iii) They will adhere well to
intact skin and have a low adherence for wound tissues.
PRIMARY / SECONDARY WOUND DRESSINGS
Composite dressings: consists of lightly
absorbent rayon or cotton pads sandwiched between porous polyethylene films.
Hydrogels are cross-linked polymer such as
poly-vinyl-pyrrolidone (PVP), cross-linked polyethylene oxide gel or
polyacrylamide in which the wound exudate may be trapped.
Uses: Hydrogels are non adherent
dressings, which through semipermeable film allow a high rate of evaporation
(and cooling) without compromising wound hydration. This makes them useful in
burn treatment.
Hydrogels are very useful in hairy areas where
entrapment of hair into the dressing would not be traumatic.
Calcium alginate dressings:
Alginic acid is naturally occurring polysaccharide
derived from a type of seaweed. The calcium salt is a fibrous non-woven
dressings which are highly absorbent.
Use: They
are used on moderate to highly exuding wounds.
They
may be held in place with gauze tape or a film dressing.
SECONDARY WOUND DRESSINGS
ABSORBENTS
Surgical cotton
The raw cotton fibre, mechanically cleaned of dirt
and processed to remove the natural waxes on the cotton fibres. The fibres are
defatted with alkali, bleached, washed and dried. It is available as rolls or
small balls.
Use:
i) It absorbs water readily
hence used for absorbing wound exudates. However, as its fibres are loose (i.e.
not in the form of a thread, they irritate and adhere to raw tissues, hence
cotton should be separated from wounds by a woven fabric dressing.
ii) it can be used for cleaning,
swabbing and medicating wounds and for applying bactericidal solutions to the
skin before surgery.
Surgical gauzes:
The function of surgical gauze is to provide an
absorbent material of sufficient tensile strength for surgical dressings.
Processing: Raw cotton fibre is
cleaned and spun or twisted into thread, and the threads are woven into an
open-mesh cloth. It is then bleached white and defatted to increase the
absorbency.
Use: Various forms of pads,
compressed and dressings are made from surgical gauze, alone or with absorbent
cotton, tissue paper and other materials.
Other forms of secondary dressings are:
i) sanitary napkins
ii) eyepads
iii) disposable under pads
iv) cotton-tipped appliances
etc.
BANDAGES
The function of bandages is to hold dressings in
place by providing pressure or support. They may be inelastic, elastic or
become rigid after shaping for immobilization.
common Gauze Roller Bandages: Each bandage is in one
continuos piece, tightly rolled and substantially free from loose threads. It
may be of various widths and lengths for various purposes.
Muslin Bandage Rolls: This bleached cotton cloth
of plain but closely weaved. They are very strong and are used wherever gauze
bandages do not provide sufficient strength or support. They are frequently
used to hold splints or bulky compression dressing in place.
Elastic bandages:
(1) Cotton
and Rubber Elastic Bandages: This bandages has a cotton weft but the warp
contains rubber threads.
(2) Crepe
bandage is elastic but contains no rubber. The warp threads are of cotton
and wool and the weft threads are cotton. The wool content is not less than
33(1/3)%
The arrangement of the warp threads:
1 two-fold cotton thread with an S twist
2 wool threads
1 x two-fold cotton thread with Z twist
2 wool threads
The opposite twists of the alternate cotton threads
gives the bandage its considerable elasticity.
Use: Crepe bandage conforms well to body contours
allowing limited movement and stretching if swelling takes place. Hence it is
very useful -
i) for giving light support to
sprains and strains
ii) for correctional purposes
and
iii) as a compression bandage.
(3) Cotton
Conforming Bandage
If cotton gauze is mercerized under very carefully
controlled conditions the fibres become bent (crimped) and this imparts
elasticity to both warp and weft. The sides of the fabric are folded into the
centre to avoid rough edges and produce a thicker, more absorbent layer.
Uses: Cotton conforming bandages are used to protect and
secure dressings.
There is no need to reverse turn it during
application. The overlapping parts do not slip because the crimped fibres tend
to interlock.
ADHESIVE TAPES
When some adhesives are spread over a backing
membrane it is called an adhesive tape.
This tapes are used
(i) to secure dressings and
appliances firmly in place.
(ii) for support and compression
e.g. for fractured ribs and clavicles, sprains and leg ulcers etc.
The adhesive tapes differ with the type of backing
membrane (e.g. pain cloth, elastic cloth, plastic film).
Depending on the adhesive the tapes may be
subdivided into two categories:
(i) rubber based adhesive and
(ii) acrylate adhesive.
Rubber based adhesive tapes:
These are cloth-backed rubber adhesives. these are
used principally where heavy support and a high level of adhesion are required.
Acrylate adhesive tapes
In this case non-woven or fabric backing are spread
with acrylate adhesives.
Acrylate adhesives are hypoallergenic i.e. they do
not produce any allergic reaction.
Rubber adhesives generally contains a large number
of components of which few may cause the allergy.
Because acrylate adhesives are basically a
unipolymeric system, they eliminate the possibility of allergy.
STERILIZATION OF SURGICAL DRESSINGS
Surgical dressings are packed in drums made of steel
and sterilized by moist heat sterilization; the outline of the process is as
follows:
By horizontal
automatically controlled autoclave:
i) Suitably packed dressings
are correctly loaded into the chamber (autoclave).
ii) The door is closed and steam
is admitted to the jacket.
iii) Air is partially or almost
completely removed by vacuum.
iv) Dry saturated steam is
admitted and if, necessary may be used to displace the rest of the air.
v) Heating up and exposure are
carried out; air (drained from the dressings) and condensate are automatically
discharged meanwhile. Either 1150C is maintained for 30 mins or 1210C
is maintained for 15 mins.
vi) After the stipulated period
the supply steam is cutoff and the chamber is vented.
vii) The dressings are dried
either by drawing a high vacuum or by using a partial vacuum to suck warm
sterile air through them.
viii)When high vacuum drying has
been used the vacuum is broken by admitting sterile air.
STERILITY TEST OF SURGICAL DRESSINGS
Cotton wool, gauze, lint and adhesive plasters are
examples of dressings that may require sterile. Before sterilization cotton
wool may be heavily contaminated with microorganisms. As an example, gauze may
carry about 15 organisms/ cm2 . Since surgical dressings are used in
direct or close contact with wounds or, in the case gauze, within the operation
field during surgery the method of confirming sterility must be reliable.
Sampling:
Samples are of about 1 g or 10 cm2 are
taken from woven of non-woven fabric respectively. These are chosen from
different places, including regions, such as the centre (contamination is
minimum) and the outside (where the
probability of contamination is maximum). A test and if required (and possible)
two more repeat samples are taken.
Controls:
To check the tester’s technique and the
bacteriological condition of the atmosphere, a control is performed at the same
time as the test. items that have been recently sterilized by a process known
to ensure sterility are used for this purpose. They should be equal in number
to the test items and preferably identical in structure. No growth should occur
in any container.
Elimination of
inhibitory action:
Some surgical dressing are impregnate with
antimicrobial agents which may interfere with the growth of microorganisms in
the culture medium. The action of antimicrobial agents in medicated dressings
is eliminated either by including a suitable inactivator in the culture medium
or preferably by membrane filtration.
Procedure:
1. The test is performed in an
asepsis room or a screen provided with laminar flow of sterile air.
2. The dressings are generally
wrapped in double wrapping. The area through which the outer wrapper is to be
opened is first painted by Weak Iodine Solution B.P. and left for 5 mins. The
outer wrapper is cut along the painted sterile line with a sharp scalpel or
blade. The dressing is pulled out off the outer wrapping. The dressing is also
drawn out of the inner wrap by a similar method.
3. If the dressing is a bigger
one then 1 g or 10cm2 samples are cut by a pair of sharp scissors
from different area of the fabric.
4. Each portion of the dressing
are inoculated into separate wide mouthed container containing 50, 100 or 150
ml of a suitable culture medium (e.g. fluid thioglycolate medium U.S.P.). It is
then incubate at 32 ± 20C for at least
10 days.
5. Interpretation:
i) If there is no growth in any
of container the batch passes.
ii) If growth occurs in only one
container the test is repeated and, if the same result is obtained again. a
second repeat is allowed.
iii) The product fails if there
is growth in all three tests of the same organism is found in two.
SUTURES AND LIGATURES
·
A surgical suture is a strand or fiber used to hold wound edges
in application during healing.
·
A ligature is a thread or string without a needle which is used
to tie blood vessels and other tissues together.
CLASSIFICATION OF SUTURES
(i) Absorbable and (ii) Non-absorbable
ABSORBABLE SUTURES
Surgical gut /
Catgut
Catgut is prepared from the intestine of the sheep.
N.B. The name is said to be derived from the word
“kit-gut” (a ‘kit’ being a small violin used in olden times)
(i) Raw material; When sheep are slaughtered
the intestines are roughly washed and placed in cold brine for transport.
(ii) Washing: The intestines are washed
thoroughly with water.
(iii) Splitting: The intestinal tube is
fitted over the end of a flat curved peg and then splitted longitudinally with
a knife into “smooth” ribbons.
(iv) Mechanical processing: Mechanical processing remove
the innermost mucosa and the outer muscularis and serosal layers, essentially
leaving only the submucosa. This appears as a thin, strong network consisting
chiefly of collagen.
(v) Chemical processing: At this stage the ribbons
may be tanned or hardened by soaking in solution of chromic salts. This causes
delay in the absorption depending on the strength of solutions used. Such
products formerly were designed as 10, 20, or 40 days catgut, on the assumption
that these sutures would remain for such periods in normal tissues. The
variations in catgut depends on the variations in patients and on the sites of
implantation. Two varieties of catgut, as distinguished by their resistance to
absorptive action by tissue enzymes are described in the USP as Type - plain or untreated and
Type
C - medium treatment.
In other terms they may be called as ‘plain’,
‘chromic’ or ‘extra chromic’.
(vii) Spinning: The
ribbons are next tied at the ends in groups of two, three or more, depending on
the gauge of thread to be prepared, pulled to an even tension and spun.
Hardening and chromicising may be done at this stage, but here it produces a
case-hardened effect, the center of the string being unaffected by he chromic
solution.
(viii)Drying: This is done in an
atmosphere conditioned with regard to temperature and humidity, the strings
being kept under a suitable tension.
(ix) Finishing: The dried strings are
‘polished’ by mechanical means. This is really a smoothing process, in which
the strings are rubbed against an abrasive surface to produce a smooth, uniform
string of circular section.
(x) Sterilization: The sheep intestine is
normally infected with bacteria and is likely to contain pathogenic organisms
such as the sporing anaerobic bacteria responsible for tetanus and gas
gangrene.
The gut may be sterilized by chemicals, heat or
ionizing radiations.
Chemical process: In this process the guts are sterilized by
immersing them in iodine solution for a prolonged period. The disadvantage with
this method is the variable increase in absorption time in the body.
The heat process:
Tubing: Suitable lengths of gut are
coiled on a heat-resistant fibre card and placed in glass tubes along with a
label of heat-resisting material, printed with heat-resistant ink.
Drying: The tubes are placed in
baskets and dried in a drying oven in which the temperature is raised slowly to
avoid damaging the gut. When thoroughly dried it is ready for the sterilization
process which may be done in one of two ways.
1. The baskets of tubes are
placed in an autoclave containing an anhydrous fluid such as toluene or xylol.
A temperature of 1600 C is maintained for several hours. [N.B. The
catgut consists of collagen, which is converted into gelatin if heated in
presence of moisture hence the anhydrous solvents are used.]
2. Alternatively, the heating
may be done in a non-pressure vessel using an anhydrous liquid of high boiling
point so that a temperature of 1600 C can be readily maintained.
The tubes are then filled with sterile tubing fluid
and sealed by fusion of the glass. This part of the process must be done under
stringent aseptic conditions.
Ionizing
radiation process: In this process the prepared gut is packed in aluminum
foil envelopes
containing 90 percent isopropyl alcohol as a preservative The packets are then passed through a gamma
irradiation area on a conveyor system. Thus catgut is sterilised when sealed in
final container and the process is a rapid one. Each suture receives a minimum
dose of 2.5 megarads (unit of radiation).
BOILABLE AND NON-BOILABLE CATGUT
If the tubing fluid is anhydrous the tubes may be
boiled before opening it for use; this type of catgut is called “boilable
catgut”.
If the tubing fluid contains water the tubes of the
catguts are labeled ‘Non-boilable’. This is a warning to avoid the use of heat
in sterilizing the outside of the tube prior to opening it for use.
Non-boilable guts are more popular because the water
in the tube keeps it pliable and immediately ready for use. The non-boilable
tubes are filled with alcohol containing a small quantity of water.
SYNTHETIC ABSORBABLE SUTURES
Polymers derived from
i) condensing the cyclic
derivative of glycolic acid (glycolide),
ii) mixtures of glycolide and
lactide (derived by cyclizing lactic acid)
iii) dioxanone and glycolide with
tetramethylene carbonate
have shown to possess high tensile strength and
absorbability.
The first two polyesters mentioned are melt-extruded
into multifilament yarns which then are braided into various sizes of sutures.
The second two polyesters are provided as pliable
monofilaments.
Sterilization: They are packaged without
fluid and sterilized with ethylene oxide to avoid degradation.
Synthetic absorbable sutures do not undergo the
enzymatically mediated absorption process that is well-known for catgut.
Rather, the suture is broken down completely by simple hydrolysis as it resides
in the tissue. Tissue reaction is minimum since scavenger leukocytes are not
involved significantly in the absorption process.
Standards:
The following tests are given in the British Pharmaceutical Codex.
Sterility
tests:
The tests for sterility are intended for detecting the presence of viable forms
of microorganisms on the surgical suture materials.
Method 1: The suture materials are washed with a sterile
fluid, the fluid is then passed through a filter membrane (for filtering
bacteria), the filter membrane is then incubated in sterile medium and observed
for minimum of 7 day. If any viable form of microorganisms were present in the
suture material they will grow.
Method-II: The suture materials are incubated in culture
medium for not less than 14 days. If microorganisms are present they will
render the medium turbid.
Gauge: This is measured by means
of a dial reading micrometer at several points along the strand.
Tensile
strength:
This is done by means of a machine in which the load necessary to rupture the
gut is measured, the tests being performed on ‘straight’ and ‘knotted’ samples.
NON-ABSORBABLE SUTURES
This group of sutures are relatively resistant to
attack by normal tissue fluids.
When non-absorbable sutures are used for skin
closure, they usually are removed after the wound has healed to the point where
suture support is no longer necessary.
Generally silk, linen, cotton, metallic wire, nylon
and dacron are given in USP.
Silk:
Degummed commercial silk fibres consists chiefly of
the protein fibroin as extruded by the silk-worm. Many such fibers are twisted
into a single strand of various diameters as specified in USP, and sold in the
natural colour or after dyeing.
Silk sutures are handled easily, and tolerated well
by body tissue, although they may cause significant tissue reaction. The
microorganisms can remain concealed in the interstices of silk strand and may
protect them from antimicrobial agents. So chronic wound may not heal unless
the suture is removed.
Silk occasionally migrates from the site of
implantation and comes to the surface.
In certain sites the knots may produce irritation
and may remain encapsulated in the tissue.
Dermal Silk
These sutures consists of natural twisted silk
encased in an insoluble coating of tanned gelatin of other protein. This
coating must withstand autoclaving without stripping.
Its purpose is to prevent the in-growth of tissue
cells which would interfere with its removal after use as a skin or dermal
suture.
Cotton and
Linen
Sutures derived from cellulose, they are twisted
from fiber staple, have moderately high tensile strength and are stable to heat
sterilization.
Synthetic non-absorbable sutures:
Nylon is a polyamide obtained
from the condensation of adipic acid and hexamethylenediamine or from the
polymerization of caprolactum.
It is strong, water-resistant and can be used for
all suturing and ligating.
Polyester
fibres are
multifilament synthetic fibres. They are prepared by melt-extruding
polyethylene terephthalate into fine filaments which are then braided into
various sizes.
The polyester sutures do not lose strength in
contact with water or body fluids, for this reason they are used for permanent
reinforcement as, for example, in installation of artificial heart valves.
They have the advantage of excellent knot holding
characteristics and are available in the natural colour or dyed to enhance
visibility in the surgical field.
Polyoelfin
fibres :
Examples are polyethylene and polypropylene.
Polypropylene sutures compared to monofilament
nylon, tie more secure knots and have a very low order of tissue reactivity.
Because of the smoothness, they slip through tissue in-growth, they may be
removed easily when necessary. They are widely used in cardiovascular and other
surgical specialties.
Metallic sutures:
Silver: Among the older materials
which are still used to some extent are silver wire, foil and other forms.
Silver though has some antiseptic action but in some tissues it produce
irritation.
Stainless
steel is a
ferrous alloy is resistant to chemical attack has been used widely in the form
of wire sutures, fixation plates, screws and other items.
Stainless steel sutures are available both as
twisted and monofilament strands and presents the strongest available material.
However, they are relatively difficult to use and are employed most commonly in
areas where great strength is required, such as in the repair of the sternum
after chest surgery.
REFERENCES
1. Cooper & Gunn’s
Dispensing for Pharmaceutical Students, 12th edn. pp.270.
2. Cooper & Gunn’s Tutorial
Pharmacy, 6th edn., pp.429.
3. Remington: The Science and
Practice of Pharmacy, 19th edn., pp.1873.