Page 21 - Basic Monitoring in Canine and Feline Emergency Patients

Table 1.6. Commercially available lactate meters.

Sample
Range
VetBooks.ir Lactate analyzer Mobility (mmol/L) Time to result volume (μL) Sample Strip/cartridge/
sensor card
type
(seconds)
Stat Strip Lactate
blood
Connectivity a Handheld 0.3–20 13 0.6 Whole Strip
Lactate Scout 4 a Handheld 0.5–25 10 0.5 Whole Strip
blood
Lactate Plus a Handheld 0.3–25 13 0.7 Whole Strip
blood
i-STAT b Handheld 0.3–20 120 95 Whole Cartridge
blood
Nova Prime Plus Transportable 0.4–20 60 130–135 Whole Sensor card
Vet a blood
a Nova Biomedical, Waltham, Massachusetts, USA; Abbott Point of Care, Abbott Laboratories, Abbott Park, Illinois, USA.
b
often multifactorial and can involve one or more return of color. Reasons for prolongation include,
than one of the following: upper airway disease, but are not limited to, shock, dehydration, vaso-
pulmonary parenchymal disease, pleural space dis- constriction, severe vasodilation, hypothermia, or
ease, thoracic wall injury, primary cardiovascular any other condition that compromises circulation
disease, pain, stress, or anemia. The respiratory rate or delivery of blood to tissues or leads to poor
is normally counted as breaths per minute (see vascular tone. CRTs can also be rapid (i.e. less
Table 1.2 for normal rates in dogs and cats). than 1 second). This is most commonly seen in
Assessing the quality of the respirations is also situations with supra-normal vascular tone such
important and has the potential to provide informa- as compensatory shock (i.e. the smooth muscle
tion to help localize the problem to a specific location in the vasculature is very taut allowing rapid
along the respiratory tract. Hearing crackles, wheezes, return of blood to the tissue bed).
or rales (abnormal clicking, bubbling, or rattling What actually constitutes a normal or abnormal
sounds) within the lungs can be indicative of primary CRT is a subject of debate. CRT in humans was first
pulmonary parenchymal disease. Significant inspira- promoted in 1947 by Beecher as a way to assess a
tory stridor (sound produced as a result of disruption patient in shock. Initially, published parameters were
of airflow) in a patient could be indicative of laryn- considered ‘normal’ (no signs of shock), ‘definite
geal paralysis, upper airway obstruction as a result of slowing’ (slight to moderate shock), and ‘very slug-
a polyp or mass, or collapsing trachea to name a few gish’ (‘severe’ shock). In 1980, Champion and col-
examples. The presence of decreased lung sounds leagues incorporated these ranges into the human
during auscultation might lead one to be concerned ‘Trauma Score’ and in so doing set the normal CRT
about the presence of pleural effusion or pneumotho- as less than 2 seconds despite a lack of scientific data
rax. In cases with severe respiratory distress, decreased to support this as being normal. Subsequently, stud-
lung sounds are an indication for immediate thoraco- ies related to CRT have determined that CRT actu-
centesis to relieve the distress. If fluid is obtained and ally varies with age and temperature (Schriger and
analyzed from thoracocentesis, it can be both a diag- Baraff, 1988) and that further research is needed to
nostic and therapeutic intervention. establish the true validity and usefulness of the CRT
as an accurate measure of circulatory status.
To date no studies evaluating CRT and its use as a
Capillary refill time
predictor of perfusion or circulatory status in veteri-
CRT is tested when a mucosal surface (usually the nary medicine have been identified, and normal has
oral mucosa) is pressed until the color leaves and continued to be the initially proposed <2 seconds. As
the tissue bed blanches. The time that it takes for such, the importance of the CRT is somewhat unclear.
the color (and therefore blood) to return to that The authors propose that it is most important to seri-
tissue bed is called the CRT. It is generally consid- ally examine the CRT and note changes rather than
ered to be prolonged when it takes >2 seconds for the actual documented CRT. Also, evaluating the CRT

Physical Examination and Point-of-care Testing 13