Biomedical Engineering Reference
In-Depth Information
Fluid and Electrolyte Administration
Fluid therapy is indicated in nonhuman primates with a 7%
or greater dehydration. The common routes of adminis-
tration include: intravenous, subcutaneous, intraperitoneal,
and oral. Intravenous administration of fluids is typically
the method of choice for fluid therapy. Venepuncture is
described above. One can either utilize a hypodermic
needle or a vascular catheter for access to the vein. The
needle or catheter is then attached to the fluid administra-
tion set for administration of fluids. The amount of fluid
needed for replacement depends on the patient's status. Of
primary concern is the status of the blood volume and later
concern is directed to restoration of total body water and
electrolytes. Subcutaneous fluids are given for mild dehy-
dration and typically utilized when the intravenous route is
not an option. When administrating fluids subcutaneously,
isotonic fluids should be used and no more than 5
advantages to direct measurement. The placement of the
catheter into an artery can be performed using a cutdown to
access the vessel or with a percutaneous stick. Once the
catheter has been placed it is flushed with a heparin solution
and connected to a pressure transducer connected to
a recording device. The arterial line must be frequently
flushed as the high pressure of the artery can push blood
into the line causing a clot and leading to a false reading.
Indirect
The gold standard of indirect blood pressure is the
auscultatory method but automated oscillometric blood
pressure devices are very commonly used in today's prac-
tice especially for anesthesia monitoring and acute care
settings. Cuff size is extremely important when measuring
blood pressure with either of these methods. It is recom-
mended to use a cuff with a width that is 40
10 ml/kg
should be given at each injection site. The rate of subcu-
taneous fluid flow is governed by patient comfort. These
fluids are aseptically administered and multiple sites are
required to provide adequate fluid volume. Generally, all
subcutaneous fluids are reabsorbed within 6
e
60% the
circumference of the limb being used. The cuff should be
affixed snugly but not tight enough to hinder circulation.
Positioning of the patient and the cuff are critical to obtain
accurate readings. The shaved tail (
Chester et al., 1992
), an
upper or lower forelimb, or an upper or lower hind limb
have been used successfully. Wherever the location, the
cuff should be at the level of the right atrium.
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8 hours. If
fluids are still noted subcutaneously after this time, the use
of intravenous fluids to reestablish peripheral perfusion
should be considered. Intraperitoneal administration of
fluids is quick, easy and the fluids will generally be
absorbed quickly, increasing the circulating volume. The
potential of bacterial peritonitis, perforating viscera and
decreasing ventilation from impeding diaphragmatic
excursion are concerns that must be considered. The size of
hypodermic needle is selected in relation to the size of the
nonhuman primate. Oral administration of fluids is often
utilized by placing either a nasogastric tube or gastric tube
in the stomach of the nonhuman primate (described
previously in this chapter). Factors to consider for oral
administration of fluids include: the clinical condition of
the nonhuman primate, the time required to administer the
oral fluids, and the available technical assistance.
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Electrocardiogram
Electrocardiogram (ECG) may be used to diagnose heart
disease (
Brady et al., 2003
) and to assist with anesthesia
monitoring. Commonly, blunted alligator clips or
subdermal pin electrodes are used when collecting data on
anesthetized animals. Skin patch electrodes may also be
used and may even be placed under a primate jacket for
conscious data collection. Telemetry solutions are also
available but are used mostly for research applications.
Electrodes are usually placed just proximal to the elbow
joint on the forelimb and just proximal to the stifle on the
hindlimb. Electrode paste may be used to improve elec-
trode contact. Position of the subject during the examina-
tion does not appear to effect ECG recordings (
Taylor and
Gleason, 2010
).
Blood Pressure
Blood pressure may be obtained using direct or indirect
methods. Direct methods using intraarterial catheterization
are the most accurate but are quite invasive. Indirect
methods are less invasive and easy to apply but are not
always consistent. Recommendations for blood pressure
measurement have been published (
Kurtz et al., 2005;
Pickering et al., 2005
).
Pulse Oximetery
Pulse oximeters are used to measure the oxygen saturation
of hemoglobin and pulse rate. The pulse oximeter utilizes
a light source and photodector to measure light absorbance
of tissue and indicates the level of oxygen saturation.
Probes work best when placed on nonpigmented, hairless
tissues. The tongue is a common place to affix the probe but
a finger, toe, palm, tail, or even vulva can be used as
appropriate.
Direct
Blood pressure can be measured directly with an
indwelling arterial catheter connected to an external pres-
sure transducer. Accuracy and reliability are the major
