Biomedical Engineering Reference
In-Depth Information
Clinical Signs
Early signs of hypoglycemia include irritability, weakness,
lethargy, ataxia, nervousness, and disorientation. Late and
more serious signs include collapse, coma, and seizure
activity. In many cases, animals are found unconscious in
their cage.
considered. Some clinicians prefer to dilute the initial dose
of 50% dextrose in 5% dextrose or sterile water to create
a 20% solution prior to injection and thereby reduce the
osmolality of the infused solution (
Meleo and Caplan,
2000
). Dextrose 5% in water (D5W) is not suitable as the
sole treatment for a hypoglycemic animal because admin-
istration of the corrective glucose dose using D5W would
cause volume overload. Oral supplementation by feeding
a meal or offering glucose-containing fluids may be
attempted in conscious animals. Early administration of
oral glucose using calorically dense supplements may
prevent the progression to more severe signs and uncon-
sciousness. Adequate treatment of the hypoglycemic
patient requires frequent blood glucose measurements, as
the required dose of dextrose for an individual patient
cannot be predicted. Doses for dextrose administration are
guidelines only and should be tailored to each individual
based on the severity of hypoglycemia and its response to
treatment. The uptake of glucose by cells is accompanied
by the intracellular transport of potassium, so the serum
potassium concentration should be monitored in patients
receiving dextrose infusions and supplemented in most
cases. This is particularly important for animals that are
unable to eat (
Meleo and Caplan, 2000
).
In severe cases, seizure activity may not respond to
glucose therapy because of cerebral hypoxia and edema.
This should be suspected in a patient that does not regain
consciousness within 20
Diagnostics
Hypoglycemia is a life-threatening disorder that is easily
treated if rapidly identified. Basal plasma glucose concen-
trations in macaque species (46
60 mg/dl M. mulatta,
e
48
69 mg/dl M. fascicularis) are typically lower than
common domestic animals and New World species
(72
e
220 mg/dl C. jacchus jac-
chus)(
Yardbrough, 1984; Fortman et al., 2002
). Handheld
glucose measuring devices and reagent strips are available
over the counter and are considered standard equipment in
any facility where nonhuman primates are treated or housed.
As discussed in the section “Initial assessment and diagnostic
evaluation of the critical patient”, these monitors allow
accurate and rapid assessment of blood glucose which enable
the clinician to make informed treatment decisions without
the need to wait for results from a clinical laboratory. If
samples will be sent to a clinical laboratory to corroborate
results from the handheld glucose monitor, serum must be
separated from red blood cells promptly or whole blood
should be collected in sodium fluoride tubes to prevent
erroneously low blood glucose measurements. A definitive
diagnosis of hypoglycemia can be made if the administration
of glucose alleviates clinical signs, because Whipple's triad
will have been satisfied (i.e. clinical signs of hypoglycemia,
low plasma glucose, and resolution of signs with adminis-
tration of glucose) (
Meleo and Caplan, 2000
).
Because there are a wide variety of primary disease
states that may cause secondary hypoglycemia, the list of
primary differential diagnoses is extensive. A basic workup
including complete blood count, serum chemistry analysis,
and urinalysis should be performed in any animal exhibit-
ing hypoglycemia. Many of the diseases that cause hypo-
glycemia can be ruled out after the results of the initial
history and physical examination are assessed.
e
133 mg/dl S. sciureus,124
e
30 minutes of normalization of
its blood glucose. Seizure activity that does not respond to
glucose administration may require administration of
midazolam 0.05
e
0.15 mg/kg i.m. or i.v. (
Hawk et al.,
2005
) or diazepam 1 mg/kg i.m. or i.v. (
Hawk et al., 2005
)
and phenobarbital. Treatment for cerebral edema includes
oxygen administration, elevation of the head ~ 30
above
the horizontal plane, and hypertonic therapy. The two
commonly administered hypertonic agents are mannitol
(1.65
e
2.2 g/kg i.v. over 20 minutes; California National
Primate Research Center (CaNPRC), 2009) and hypertonic
saline. Both agents are effective and as yet it is unclear if
there is a superior choice (
Hopper, 2006
). Cardiovascular
support is also vital in these patients to ensure adequate
cerebral perfusion.
In cases of hypoglycemia that are refractive to glucose
administration, glucagon has been used in both human and
veterinary medicine to increase blood glucose levels in
emergency situations. Glucagon is a protein hormone that
is produced by the pancreatic islets of Langerhans and
promotes an increase in blood glucose by increasing the
rate of glycogen breakdown in the liver. In veterinary
medicine it has been administered as a 50 ng/kg intrave-
nous bolus followed by 10
e
Treatment/Management/Prognosis
Individuals at risk, as mentioned above, should have regular
blood glucose monitoring performed whenever hospital-
ized. Untreated hypoglycemia can cause irreversible and
potentially fatal brain injury. All patients with serious
neurological signs referable to hypoglycemia should be
treated immediately by intravenous administration of
dextrose at a dosage of 1
15 ng/kg/h i.v. constant rate
e
2 ml/kg of a 50% dextrose
solution. If the animal responds, continuous intravenous
administration of a 5% dextrose solution should be
infusion.
The prognosis for the hypoglycemic patient is depen-
dent on the nature of the primary disease and the severity of
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