Page 15 - Basic Monitoring in Canine and Feline Emergency Patients

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Fig. 1.2. Heparinized and non-heparinized microhematocrit tubes are demonstrated along with the clay used to seal
one end of the tube and an example of the hematocrit reading card.

utilize minimal quantities of whole blood, and oxidized and generates an electrical current that is
measure the ketone body 3-HB. Specifically, proportional to the concentration of l-lactate in
whole blood is placed within an electrochemical the sample. This method is utilized by all the hand-
strip. Within that strip, hydroxybutyrate dehy- held point-of-care units and by most blood gas
drogenase oxidizes the 3-HB to acetoacetate analyzers to measure l-lactate.
+
while simultaneously reducing NAD to NADH. Most commercially available units found in vet-
The meter will then re-oxidize the NADH to erinary medicine are handheld. They are small,
+
NAD , generating a current detected and meas- generally cost-effective, require very small amounts
ured by the meter. The amount of current is of blood, and require minimal maintenance or cali-
directly proportional to the amount of NADH bration. Most units use test strips or cartridges and
created (and hence the amount of 3-HB) in the the time to results is reliable and quick, usually
blood sample. When operated properly, these seconds to minutes. For example, the i-STAT
units produce accurate results in a very short (Abbott Point-of-Care, Abbott Laboratories,
period of time and can be used serially to monitor Abbott Park, Illinois, USA; see Fig. 1.5) handheld
response to therapy. Table 1.5 lists the various instrument has a cartridge for measuring lactate.
point-of-care meters available and indicates those Figure 1.9 shows the Lactate Plus (Nova Biomedical,
that can also measure ketones. Normal ketone Waltham, Massachusetts, USA) that uses test strips.
levels in heathy patients are reported as Table 1.6 provides a list of commercially available
<0.32 mmol/L in dogs and 0.11 mmol/L in cats. lactate meters.

1.3 Indications
Lactate
Physical exam
The methodology utilized by most point-of-care
testing units to measure l-lactate is enzymatic The importance of the physical exam cannot be
amperometry. Hydrogen peroxide produced by a understated and it is an integral first step in
reaction between l-lactate and lactate oxidase is evaluating ALL patients. A staged physical exam

Physical Examination and Point-of-care Testing 7