Biomedical Engineering Reference
In-Depth Information
appendage injuries requiring amputation. Amputation
surgery of a finger, toe, or tail uses the same principle. The
appendage must be disarticulated (
Aronson, 2003
)
through the interphalangeal or intercoccygeal joint, which
is best accomplished with a tourniquet placed proximally
to avoid major bleeding. The skin cut should be made in
the shape of letter Von each side of the bone so that it can
be closed in a tapered fashion. The skeletal muscles
should be used to cover up the articular cartilage and
sutured in a tight fashion to prevent major bleeding when
the tourniquet is released. A layered subcuticular suture
pattern should be used for skin closure to minimize
picking.
bleeders use the hemostatic means described earlier.
Surgeons should be familiar with principles of vascular
surgery (
Figures 14.5, 14.6
) in case a vessel repair or
anastomosis is necessary. Proper application of these
principles will reduce the incidence of intravascular
thromboembolism and occlusion. The material of choice
for closure, repair, and anastomosis is polypropylene,
because it is the least thrombogenic. Nylon, poly-
dioxanone, and polybutylate coated braided polyester have
also been used.
Trachea
In aspiration of a foreign body (e.g. small
toy, food, unattached endotracheal tube), radiological
and endoscopic means should assist in diagnosis.
Attempt nonsurgical removal using a laryngoscope and
grasping instruments. If surgery is necessary, attempt
removal through a small tracheotomy. If partial resec-
tion is necessary, avoid cutting the jugular vein, carotid
artery, and recurrent laryngeal nerve, remove lesioned
tracheal rings, and re-anastomose using simple inter-
rupted and tension-relieving patterns while reconnect-
ing cartilages.
Thoracic Cavity
Two basic approaches are midline (sternal) and lateral
(intercostal). The intercostal muscles should be cut crani-
ally to each rib as larger blood vessels are located caudally.
Induced pneumothorax creates atmospheric intrathoracic
pressure, thus making the lung recoil impossible, and
necessitates using positive pressure ventilation. For closure,
insert a chest tube between the ribs, tunnel two rib spaces
forward to penetrate the thorax, close the muscles, subcu-
taneous tissues, and skin in layers around the tube and place
a purse string stitch. Restore the negative intrathoracic
pressure by air evacuation with a syringe attached to the
chest tube using a three-way stop-cock to prevent air
backflow into the chest. Some surgeons submerge the distal
end of the chest tube in sterile saline and overinflate
the lungs, thus pushing the air out of the pleural cavity
through the chest tube. Once the air bubbling in saline has
stopped, the tube is removed and the wound sealed. The
pleura does not typically require suturing, but muscles and
subcutaneous tissues are best closed with absorbable
synthetic materials (e.g. polyglactin, polyglycolic acid,
polydioxanone).
Esophagus
Esophageal surgeries are prone to post-
operative complications because of swallowing and respi-
ratory motion, segmental blood supply, and lack of
omentum. Absorbable synthetic material is recommended
for closure.
Intestine
The principles of intestinal closure listed below,
proposed by Halsted, Travers, and Lembert (
Bojrab et al.,
1983
), still apply:
Incorporate the submucosal layer in the anastomosis
(
Figure 14.7
).
l
Anastomose
to
provide
serosa-to-serosa
contact
l
Abdominal Wall
The basic approaches are: midline, paramedian, lateral
vertical, lateral horizontal, and semicircular (caudal to the
diaphragm insert). Peritoneum should be closed with
absorbable suture using continuous pattern and the
muscles and fascia with absorbable suture using inter-
rupted pattern. Subcutaneous tissues and/or the sub-
cuticular layer should be apposed with absorbable material
using continuous pattern, and skin closed as described
earlier.
(
Figure 14.7
).
Minimize trauma and contamination.
l
Maintain an adequate blood supply.
l
Avoid tension across the anastomosis (Bojrab et al.,
1983).
l
Recommended materials for intestinal surgeries should
have a low tissue drag: monofilament synthetic absorbable
(polydioxanone, polyglyconate) or nonabsorbable (nylon,
polypropylene) or staples are recommended. Where
possible the suture line reinforcement should be done using
the omentum, which has an extensive vascular and
lymphatic supply and exhibits angiogenic, immunogenic,
and adhesive properties that assist in restoring blood
supply, controlling infection, and establishing lymphatic
drainage. Stapling devices can also be used for gastro-
intestinal anastomoses.
Tubular Structures
Blood Vessels
Surgeons are advised not to cut and where
possible use a permanent or temporary ligation before
cutting to avoid bleeding. It is vital to assure the organ of
interest has an ample blood supply. When dealing with
