Biomedical Engineering Reference
In-Depth Information
much smaller decreases in body temperature when the
body's own thermoregulatory system fails (i.e. secondary
hypothermia).
The body's initial response to low body temperature is
an increase in cardiac output accompanied by peripheral
vasoconstriction and shivering. However, as the tempera-
ture decreases, these adaptive mechanisms fail, which leads
to rapid loss of body heat. Regardless of the cause of low
body temperature, hypothermia is exacerbated when the
core body temperature drops below 34
C (94
F) because
that is the point at which the body's thermoregulatory
system becomes impaired. At temperatures less than 31
C
(88
F), thermoregulation ceases completely, and death is
imminent unless intervention occurs (
Serrano, 2007
).
In an effort to prevent hypothermia, animals that are
anesthetized for research or clinical procedures should be
frequently monitored. Shelter from the elements should be
provided to animals that are housed outdoors during the
coldest months of the year. Adding hay to shelters or
providing radiant heat sources may also prevent the loss of
body heat.
Hypoglycemia
Neonatal, anorexic, fasted, and New World primates are
at higher risk of hypoglycemia.
l
Clinical signs of hypoglycemia are neurological
in
l
nature.
Handheld glucose measuring devices are considered
standard equipment in any nonhuman primate facility.
l
Clinical Signs
Decreased core body temperature may be accompanied by
subcutaneous edema, bradycardia, hypotension, cardiac
arrhythmias, muscle rigidity, weakness, pulmonary edema,
pneumonia, acute respiratory distress syndrome (ARDS),
unconsciousness, and necrosis of the extremities (
Plunkett,
2000
).
Intravenous dextrose with frequent blood glucose
assessment is the cornerstone of treatment and should be
accompanied by treatment
l
to address neurological
signs.
Early recognition and treatment are critical to a positive
outcome.
l
Diagnostics
Hypothermia is diagnosed by assessing the history, taking
an accurate core body temperature, and observing the
characteristic clinical signs.
Etiology/Risk Factors/Transmission/Species
Hypoglycemia is defined as the abnormal decrease of
glucose concentration in the blood. It has a wide variety of
causes and has far ranging deleterious physiological
consequences, including death, if left untreated. An in-
depth review of all the causes of hypoglycemia is outside
the scope of this section, but a review of at-risk populations,
diagnosis, and treatment is provided.
Hypoglycemia in nonhuman primates may be sponta-
neous or caused by a number of experimental techniques
and treatments. Spontaneous cases of hypoglycemia occur
more frequently in neonates (
Brady et al., 1990, 1991;
Hendrix and Tarantal, 1994
), anorectic or fasted animals,
and New World nonhuman primate species (
Abee, 1985;
Brady, 2000; Fortman et al., 2002
). While hypoglycemia is
more prevalent in the aforementioned species and age
groups, it should be ruled out whenever a nonhuman
primate demonstrates clinical signs consistent with hypo-
glycemia. Acute or chronic debilitating conditions that
induce anorexia or hormonal pertubations increase the risk
for spontaneous hypoglycemia. Nonhuman primates
treated with exogenous insulin for diabetes mellitus are at
risk for developing hypoglycemia if their health, activity,
and carbohydrate intake is not monitored closely. As
a preferred animal model for neuroscience, endocrinology,
infectious disease, and toxicology research, the nonhuman
primate is widely utilized in experimental studies that may
directly or indirectly induce hypoglycemia.
Treatment/Management/Prognosis
Treatment for hypothermia includes gradual re-warming at
a rate no faster than 1
4
F) per hour. This may be
accomplished with blankets or towels, re-circulating warm
water blankets, warm water bottles or fluid bags, incubator-
type cages (in the case of smaller species and neonates),
forced warm air blankets, and/or heated intravenous fluids.
Fluids may be supplemented with potassium and/or
dextrose as indicated by serum biochemistry results.
Caution should be used if electric heating pads are used as
these increase the risk of thermal burns and electric shock.
Warm water re-circulating blankets and forced warm air
systems are preferable to electric heating pads. Severe
cases of hypothermia may be treated with warm peritoneal,
gastric, or pleural lavage or warm enemas (
Plunkett, 2000
).
Efforts should be discontinued when the body temperature
reaches 36.7
C (98
F). Frostbitten extremities and tissues
should be warmed and loosely bandaged if still vital and
debrided and/or amputated if necrotic in order to minimize
the risk of sepsis associated with gangrene. Analgesics and
antibiotics should be administered as needed. Oxygen
therapy may be warranted, and arrhythmias should be
addressed as necessary (
Plunkett, 2000
).
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