Chapter 5
The Integumentary System
165
5
is sterile for about 24 hours. TereaFer, bacteria, fungi, and
other pathogens easily invade areas where the skin barrier is
destroyed, and they multiply rapidly in the nutrient-rich en-
vironment of dead tissues. Adding to this problem is the fact
that the immune system becomes deficient within one to two
days aFer severe burn injury.
Burns are classified according to their severity (depth) as
first-, second-, or third-degree burns. In
first-degree burns
,
only the epidermis is damaged. Symptoms include localized
redness, swelling, and pain. ±irst-degree burns tend to heal in
two to three days without special attention. Sunburn is usually
a first-degree burn.
cancers, but its incidence is increasing rapidly (by 3–8% per
year in the United States). Melanoma can begin wherever there
is pigment. Most such cancers appear spontaneously, and about
one-third develop from preexisting moles. It usually appears as
a spreading brown to black patch (±igure 5.8c) that metastasizes
rapidly to surrounding lymph and blood vessels.
Te key to surviving melanoma is early detection. Te chance
of survival is poor if the lesion is over 4 mm thick. Te usual
therapy for melanoma is wide surgical excision accompanied by
immunotherapy (immunizing the body against its cancer cells).
Te American Cancer Society suggests that we regularly ex-
amine our skin for new moles or pigmented spots. Apply the
ABCD rule
for recognizing melanoma:
A
symmetry:
Te two sides of the pigmented spot or mole
do not match.
B
order irregularity:
Te borders of the lesion exhibit
indentations.
C
olor:
Te pigmented spot contains several colors (blacks,
browns, tans, and sometimes blues and reds).
D
iameter:
Te spot is larger than 6 mm in diameter (the size
of a pencil eraser).
Some experts add an E, for elevation above the skin surface.
Burns
Burns are a devastating threat to the body primarily because of
their effects on the skin. A
burn
is tissue damage inflicted by
intense heat, electricity, radiation, or certain chemicals, all of
which denature cell proteins and kill cells in the affected areas.
Te immediate threat to life resulting from severe burns is
a catastrophic loss of body fluids containing proteins and elec-
trolytes. Tis leads to dehydration and electrolyte imbalance,
and then renal failure (kidney shutdown) and circulatory shock
(inadequate blood circulation due to reduced blood volume).
²o save the patient, the lost fluids must be replaced immediately
via the intravenous (IV) route.
Evaluating Burns
In adults, the volume of fluid lost can be estimated by computing
the percentage of body surface burned using the
rule of nines
.
Tis method divides the body into 11 areas, each accounting for
9% of total body area, plus an additional area surrounding the
genitals accounting for 1% of body surface area
(Figure 5.9)
.
Te rule of nines is only approximate, so special tables are used
when greater accuracy is desired.
Burn patients also need thousands of extra food calories
daily to replace lost proteins and allow tissue repair. No one
can eat enough food to provide these calories, so burn patients
are given supplementary nutrients through gastric tubes and
IV lines. AFer the initial crisis has passed, infection becomes
the main threat and sepsis (widespread bacterial infection)
is the leading cause of death in burn victims. Burned skin
Anterior and posterior
head and neck, 9%
4
1
/
2
%
4
1
/
2
%
Anterior and posterior
upper limbs, 18%
Anterior and posterior
lower limbs, 36%
100%
Totals
Anterior and posterior
trunk, 36%
Anterior
trunk, 18%
9%
9%
(Perineum, 1%)
4
1
/
2
%
Figure 5.9
Estimating the extent and severity of burns using
the rule of nines.
Surface area values for the anterior body surface
are indicated on the human figure. Total surface area (anterior and
posterior body surfaces) for each body region is indicated to the
right of the figure.
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