LE 5002 Non Invasive Blood Pressure Meter
USER MANUAL
18
7.2.
ON THE PROPER TREATMENT OF THE ANIMALS
AND THEIR ENVIRONMENT.
•
The room or laboratory where the measurements are to be taken should be free
from environmental noises that may affect the animal’s tranquillity.
•
The animal should be treated and placed in the trap as unaggressively as
possible.
•
It is advisable to always take measurements at the same time, making sure that
the animal has fasted for at least three hours prior to beginning the experiment.
This will minimise the effects of faeces.
•
It may even be useful to cover the animal’s eyes for it to relax more.
•
In female animals the menstrual cycle should be taken into account. For males,
the increased testicle size due to heat in the enclosed space of the trap should be
considered.
•
Rodents must undergo a vasodilatation process.
7.3.
WHY MUST THE ANIMAL BE VASODILATED?
One basic and IMPORTANT premise must be realised: animals’ (particularly rats and
mice) blood pressure is a physiological variable that can change very quickly,
presenting disparate values that are greatly affected by external stimuli and the animal’s
state of mind.
If the animal is not in a “normal” (i.e. unstressed) condition when its pressure is taken,
the pressure values obtained will not be those expected. It is not like taking blood
pressure in human beings. The precautions to be taken to diagnose abnormal stress
should be obvious.
A stressed rodent may transmit the muscular tremors produced by anxious breathing to
its tail. These tremors will mask the signal of the heart beat to be captured by the
transducer, which will probably not pick up the pulsation of the blood due to the
occlusion of the cuff. Rather, it will continue to transmit the muscular tremors to the
pressure meter, which will lead to an erroneous interpretation by the equipment, since it
will behave as if collapse, needed to determine the value of systolic pressure, had not
taken place.
Another reason that it is necessary to have a relaxed animal is because the aim is to
measure the “baseline” values of its pressure and not stress-induced values, which are
always sporadic and much higher.
The fastest and most comfortable way of eliminating animal stress is to vasodilate them
by increasing body temperature. Heat in rats/mice produces exactly the same effect as in
human beings.
Obviously, relaxation can be achieved with other methods, although they involve great
precaution in the handling of the animals which generally render systematic
measurements of indirect pressure either impossible or very impractical.
