Theory Of Operation - CareFusion PulseTrace PCA2 Manual Operativo

∆RI (GTN) = Mean of baseline RI – Mean of post GTN RI
∆RI (GTN) is used as a control for non-endothelial dependent
vasodilation and ∆RI (SLB) to assess endothelial function. This
protocol has been used in several studies.
Notes: Optimal delivery of Salbutamol is the key to ensuring
reproducible results and naïve subjects should be given some
practice in the use of the inhaler and spacer beforehand.

Theory of operation

A typical digital volume pulse
(DVP) measured by the photo-
plethysmography transducer is
shown in the adjacent graph.
Please refer to section Typical
Waveforms (page 29) for more
examples.
When the heart expels blood into the circulation, it creates a pulse,
which propagates along the arteries. The first part of the DVP
waveform (systolic component, in blue) is formed as a result of the
direct propagation of this pulse from the aortic root to the finger.
As well as travelling down the arm, the direct pulse propagates along
the aorta toward the lower body. At every change in diameter and
at arterial bifurcations, part of the pulse is reflected back. All these
reflections add up and can be considered as a single reflected wave
arising from the lower body. This reflected wave travels back up the
aorta and then down the arm to the finger to form the second part of
the DVP (diastolic component, in green). The upper limb provides a
common conduit for both the directly transmitted wave and the
reflected wave and, therefore, has little influence on the contour of
the DVP.
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